Insulating a Durisol ICF Foundation

Hey folks, sorry for the time span since the last post.  I have been concentrating on keeping my building journal up to date.

As I recently have had some free time due to yet another set of medical setbacks, I recently finished editing and uploading a video showing my process of adhering the Roxul ComfortBoardIS mineral wool insulation to my ICF foundation.


The Soprema Colphene Torch'N Stick membrane would typically be used on a site formed concrete foundation, but because I am using a ICF product from Durisol (made from mineralized wood fibre and cement slurry), I too could use this torch on membrane (a process that would destroy conventional EPS foam ICF forms).  The 'tacking' of the insulation to the membrane is only a light mechanical bond and is only suitable for a temporary support of the insulation (or dimple board and other protection sheets) until the backfill takes place.  You would not be able to use the method for a permanent attachment in an above grade assembly.

Once the insulation was attached, I then fastened dimple sheet to the insulation, installed a granular drainage plain, geotextile, and then compacted backfill.  You can read about these steps on my "coming out of the hole" journal entry.

The overall foundation assembly will have multiple layers of safety and will be very durable, but the installation is costly and very time consuming. I can understand why many of these steps are not incorporated into most residential construction. But then, most residential below grade basements are wet to some degree. As my friend Murray Frank often says "You never hear a comment 'It smells as good as a basement'".

Thanks for visiting folks. I will hopefully post a review of all the products I have used to create my foundation walls within the next few weeks. A majority of the products get a thumbs up from a technical standpoint, but one in particular is a two thumbs down with extreme prejudice.  I encourage you to subscribe if you want to be notified of when this review is posted.

Foundation Rebar Installation Primer

Wow - cannot believe it was last November when I last posted to this blog!  I promise to start writing more technical posting (as opposed to the daily journal entries found at my building web site).

I posted this on my journal as well, but felt it was important enough to also post here.

I received some feedback to my journal posting yesterday that was suggesting I should look at the 'other' ICF manufacturers if I wanted to know how Rebar was 'supposed' to be placed.  I did and the result sure is scary.  Because you are allowed to install ICF walls without ANY engineering assistance (as long as you meet the building codes requirements including max unsupported wall height) and therefore engineering inspection, there is a plethora of miss-information out there regarding the requirements for rebar reinforcing of an ICF wall.

At least the BC Building code makes it pretty clear on the requirements, but I suspect that because the Municipal inspector is not present at time of pour, these requirements may not be adhered to - at least that is what is evidenced by one of the discussion forums I visited last night.

So - lets first look at the BC Building Code requirements.


The Horizontal rods are to be installed every 2 ft vertically and are to have 1-3/16" inside minimum cover (30mm) meaning that the rod is to be held off the outboard surface of the inside ICF panel to allow 1-3/16" of concrete to be present on the inside face of the bar.

The Vertical rods are to be installed per tables BCBC 9.15.4.5 A to C depending on core thickness and height of wall.  The first options calls for vertical rod placed every 16" horizontally with again 1-3/16" inside cover (30mm) minimum.

Obviously both vertical and horizontal bars are unable to occupy the same plane off the inside face of the foundation, so the code also specifies a max cover by stating the bars are to be "located located in the inside half of the wall section".

My requirements were much more stringent because of the height of the wall.  The engineer specified vertical bars every 12" horizontally and horizontal bars every 2' vertically.  I was not given a range for the vertical bar - it required 1.5" of inside cover.  When I asked if 2" or even 2.5" would be OK, I was informed that they would have to rerun all of the calculations and that they suspected there would be problems.  So, I did by best to ensure 1.5" cover.

My drawings also specified 1.5" cover for the horizontal bars, but I failed to abide by that when placing the bars.  Because I drew up the structural drawings (with the instructions received from the engineer), and had drawn the horizontal in the centre of the core, and because I am more of a visual person instead of word person - I placed the horizontal bar down the middle of the blocks during installation.  Fortunately, my blunder was forgiven.  When doing the calculations for the wall, the engineer had generally only used the vertical bars in the strength calculations and the horizontal bars were more present for crack control. I was very relieved (and thank-full to Tacoma for providing very fast responses to all of my rebar questions), as by the time I had discovered the blunder, all of the horizontal bar had already been placed.  While waiting for the reply to come the following morning, I tossed and turned all night worrying I was going to have to disassemble the wall or pay for a fibre additive to add to the concrete for strength, like the Helix fibre (you may remember from an earlier posting, I was looking at this but had ruled it out as being too costly considering it could not replace ALL of the vertical rods).

The most important point of this primer is that you MUST pay attention to the cover stated for each bar installation.  A bar placed without the appropriate cover almost becomes a bar that no longer contributes to the strength of the wall. For instance, if the bar was placed on the outside half of the core, you may as well not even have it there.  This brings me to the next part of my primer.

Rebar chair is used to hold rod at a precise cover off the inside face of the forms.

Why is rebar installed in concrete anyway? 

Concrete has awesome compression strength but is quite poor in tension. Because the weight of the back-filled soil is pressing on the foundation, it wants to  'bow' inward under the pressure.  This would place the outside half of the core into compression but would place the inside half under tension (just like a floor joist but in a vertical plane).  The inside half of the concrete core is trying to stretch to accommodate the bow.  As concrete is not good when pulled on, the stretching would eventually cause the concrete to fracture.  By placing rebar into the concrete, it prevents the concrete from stretching too far and fracturing.  The closer the bar is to the inside face of the concrete core, the more tension forces it will encounter.  Another way to look at this is the distance it would take to run or drive around the outside of a track compared to the inside lane of a track.  The further outboard you get, the farther you run or the longer the circuit is.

So, if your wall is designed with 1.5" inside cover, that means the engineer has calculated the stresses of the wall at that 1.5" plane and ensured to call out a rebar pattern that can accommodate those stresses. If there is not enough cover, then there will not be enough concrete to properly capture the bar and keep it in place, but if there is too much cover the rebar will not be able to remove enough of the load from the 'stretch' of the wall and the concrete will fracture. If the rebar was placed in the outside half of the core, it would no longer be subjected to ANY tension and in fact would be being squeezed by the surrounding concrete that is under compression forces.

While researching this last night I came across the installation instructions for a very popular rigid foam based ICF (and the manufacturer that was reportedly sued in the West Vancouver failure).  They instruct the installer to "Place plastic sleeves (1½" [38mm] conduit) over stub steel for later placement of vertical steel" meaning to slip chunks of plastic conduit over the dowels placed in the footing to later capture the bottom end of the vertical rod.  But as the dowels are placed typically down the centre of the footing, this would place the vertical rods down the neutral plane of the foundation wall, or a spot it will do very little good to resist the tensions of the foundation wall.

I also came across this forum on greenbuildingtalk.com discussing the placement of the steel and it was very clear a majority of the contributors did not truly 'get it'. Lets quickly correct some of the miss-information.  

• Why do we tie off rebar under some circumstances?

Simply to hold the bar in the RIGHT position until the concrete has been poured and can hold the bar for us.  It provides NO structural strength whatsoever. 

So why is the tying off of the rebar inspected before pouring by the engineers? Why is it important that the tie-off securely fastens the bars together?  Because as we have discussed above, it is critical that the bar is placed in the right position to ensure it can bare the intended load.  As the tie wire is quite brittle, if the bars can move slightly because of not being tied-off tightly, there is a chance the sudden shock of the movement could break the wire which would now allow for the bar to move substantially out of position.

• Is it important that the horizontal bars are tied to the vertical bars (something that cannot be done in ICF construction)? 

No - full stop.  Each orientation of the bar is typically handling separately calculated loads and not considered an 'assembly' (In some extreme cases I do believe it is a 'grid' that is designed, but in these cases sophisticated FEA software is used and the bar must be welded together not tied).

• Is staggering the horizontal bars to capture the vertical bar the required solution?

No - this is only appropriate for above grade ICF installations.  In order to ensure the vertical bar was placed inboard enough on the core, the inside horizontal bar would not have enough cover.

• Why is it important to tie-off splices?

You need to ensure that the bars are fully encased in concrete.  If the bars were not tied tight to each other, they would allow small pockets to form between the bars that were too small for the flow of concrete.  This would provide a weak point because the bar would now not be in communication with the concrete and therefore unable to bare the intended load.  This is why bars in close proximity, and in the same plane, need to be tightly bundled or held apart a minimum distance by means of chairs or other securing.

• Why do the vertical bars not need to be tied-off or otherwise captured to the footing dowels?

Footing dowels or any other dowels have nothing to do with the tension stresses a concrete  assembly is under.  Their sole purpose is to tie the concrete on each side of a cold seam (concrete poured at two different occasions) together.  SO in the case of a footing dowel, the purpose is to ensure the foundation wall cannot 'slip off (shear)' of the footing.  This is why most codes also allow the formation of a key in the footing, instead of the dowels, to capture the bottom side of the foundation.

Hope this has been of some assistance. Should there be something that you disagree with, then please provide documented background for your disagreement and I will reconsider.

Thanks for visiting.

SENWiEco concludes testing of DURISOL ICF Block

When choosing a foundation your options are typically a site formed and poured concrete wall or some form of insulated concrete form (ICF) wall.  Early on in the process I gravitated to an ICF wall because it would eliminate the need to hire forming crews and rent and fabricate forms.

When looking at ICF, the traditional product is made from some form of EPS foam which has a very high embodied energy, lots of off-gassing, and is made from non-renewable components. The foam industry (EPS and XPS) will try to 'green-wash' this by stating the foam, as an insulation, reduces heat loss and reduces carbon output over the lifespan of the dwelling.  Yes this is true for ANY insulation, so choosing an insulation with a starting lower embodied energy will put you that much further ahead on your reduction goals. So again, early in the process I looked for a product that on the surface was friendlier to the planet.

One of the benefits of all ICF walls is that they typically require a smaller concrete core than a standard foundation.  The code allows for a 5.5" core on ICF walls where a standard site formed wall generally start at 8".  The reason for this escapes me because the ICF product itself is not considered structural so why would all walls not be allowed to be only 5.5" regardless of forming method.  If someone knows the answer to this please post a comment.  The smaller core of the ICF significantly reduces the concrete needed and therefore the cost and embodied energy of the overall wall.

One of the other downsides to a typical ICF forming material (foam), is that you end up with too much insulation on the inboard face of the core.  This decouples the core from the interior environment and can lead to condensation in some isolated cases, but more importantly it limits the walls ability to be a moderating force to the homes inside environment. An exposed concrete wall can buffer the temperatures by acting as a thermal mass.

The further downside to foam style ICF blocks is that just about everyone loves them from rats to ants.  They burrow and nest in the product creating holes in your thermal blanket.  They are also quite fragile and can be easily damaged during construction and require significant blocking during pouring to prevent blow-out.

My quest for the perfect block led me to the Durisol product.  It is made with virgin but scrap wood (manufacturing waste and tree tops).  This wood is chipped and then through a patented process, the organics are removed to create a mineralized wood fibre (think petrified wood).  This is then added to a cement slurry and formed into the ICF block.  This process and product would help meet my goals to dramatically reduce the embodied energy of the foundation.

There is another similar product made by Faswall, but my research indicated that this product utilized non-virgin wood sources like used pallets and had a lot more dimensional tolerance issues with the block itself.  I also was informed that Faswall was initially going to be a licensee of Durisol but ended up swiping the formulation and heading out n their own.  This did not sound like the right fit for me so I focused on Durisol even though it meant I would have to freight them from back east.

Once I decided to seriously consider Durisol, I then wanted to ensure it was suitable for the task. My immediate concern was that the blocks would rot.  But the product has been used for decades as sound abatement walls on highways (where some of the wall is always buried) and I received a letter from the Ontario Ministry of Transport advising that they have never had to repair a wall due to decay (just traffic accident damage).

My next concern was how would this wall act from the point of view of air and moisture movement.  It was made clear from the beginning, that I would need a independent air barrier as this product was air permeable (it has webs that penetrate through the concrete core so the core is not continuous).   So this was a negative against the product when compared to foam, but as I wanted a bullet proof building enclosure, I had always planned on an robust WRB (water resistant barrier) on the exterior of the foundation.  I think the idea of 'damp-proofing' a foundation wall in a rain forest climate is ludicrous and had always planned on Water Proofing my wall.  And a waterproof membrane is almost always also an air barrier.

My next concern was how the blocks would act if subjected to regular wetting.  The manufacturer claimed the product was unable to support capillary action and had some university testing to support.  But I was not satisfied and so set out to torture test the product over 16 months.  I started the experiment in Jan of 2013 (Begin experiment).  At the eight month mark I posted the status) Status at 8 months) and then altered the block to also contain the concrete core.  The experiment concluded on June 1, 2014.




All off my testing supported the manufactures claims.  This was a free draining assembly that did not support moisture movement from the outboard to inboard face.   I will also be preventing moisture movement through the footings via a FastFoot mebrane and also using a touch-on or self-adhered AB/WRB mebrane on the outside face of the foundation and so will have a very durable and forgiving assembly.  I now felt confident using this product on my project and have now received the product on site.  Once the excavation is complete, I will post some videos on the installation of the product (visit my project journal for the tribulations in getting these goods to site).

As I have time (may be at end of construction, I will also try to post some cost comparisons between the various options and the embodied energy numbers).

Thanks for visiting.

Durisol ICF lowers the embodied energy of a dwelling.

Stuart Staniford at the Early Warning blogspot discusses the reduction in Embodied Energy a Durisol Foundaiton represents in a low embodied energy dwelling.  In his case study, the use of a Durisol ICF foundation over a conventional concrete foundation improved the "net carbon emissions" by 100%.

His analysis showed the the original carbon emissions associated with the foundation in the dwelling he modeled dropped from aprox 7.5 tons with no opportunity for sequestered carbon to just under 7 tons but now with the ability to also sequester close to 1.75 Tons.

Baseline with standard concrete foundations (http://earlywarn.blogspot.ca)

Utilizing Durisol ICF Block (http://earlywarn.blogspot.ca)

Durisol, FastFoot, EPS vs. XPS, PHPP, and Enginners - Oh My!

Sorry for the absence, been pretty busy of late.  I thought I would provide a brief update as to where we are.

1) Our testing of the Durisol ICF continues: after 8 months of continuously drenching the outer panel with water, we still do not have significant inward capillary action.  We will now fill the bays with concrete and see what difference this will make.  (8 month Status Video).

2) We are also progressing our testing of the fabric footing from Fab-Form called FastFoot. This product is used to replace the typical framing of footings and then provide a lasting protection from rising damp.  After 6 months of testing, there has been no noticeable moisture penetrating through the fabric.  However, we have realized that if the capillary flow was small enough, it would evaporate out the top as fast as it penetrated through the fabric.  So we will modify this experiment by creating a sealed envelope of the product around a paper towel and submerging it in water.  We will then open it in a few months time to determine if the paper towel has seen any observable wetting. (6 month status video)

3) The next experiment we will start is to compare the water uptake and thermal performance of EPS vs. XPS.  It is generally accepted knowledge within the building science community, that XPS is more water resistant than EPS. But there recently has been some discussion on LinkedIn that disputes this claim (LinkedIn Posting).  The post points to a 15 year case study performed by a EPS foam company that  may call into question the standard test (ASTM C 272) may not be accurate when taking into account long term moisture take-up. In a discussion I had with a local engineer, they advised that XPS is more moisture resistant, but EPS dries faster.  So I speculate that if the foam is only periodically getting wet and then is able to dry between wetting (granular layer below slab), then EPS may perform better than XPS depending in the cycles of wetting.

In order to try and come to some conclusion on this, I will run the following experiment:

- 12"x12"x2" samples of both 30# XPS and 30# EPS will be buried in my back yard in an area they will get wet often or just stay wet (near a fish pond).  They will be down around 4-5ft.
- Equal number of samples of each will be submerged below water in a sealed Tupperware container
- Equal number of pieces will be sealed inside a large zip lock back and put on a dark shelf in a conditioned space (no UV).
- Finally, an equal number of pieces will be just left loose on the dark shelf.

I hope to bury these samples within the next week (I am just waiting for some FoamGlass samples from Pittsburgh Corning to also include in the test).  All samples will be then tested for thermal resistance at the end of approx 6 months time to determine any changes to the control (samples sealed in zip lock bag).

4) I would like to accurately model the planed dwelling for heating and cooling loads.  I am a certified Residential Hydronic Designer, but have never been satisfied with the rather gross estimation calculations provided in the TECA manual.  The best software I have come across to date, is the PHPP produced by the Passive House Institute. Unfortunately, it has been a couple of years since I took the week long training course in PHPP and now do not remember enough of the nuances to correctly navigate my way through it.  A posting on a few of the LinkedIn groups netting over a dozen offers of help including several for free.  Once I solidify my design (see next topic), I will do the bulk of the entry into PHPP (entails entering in the volume of all of the surfaces like floors, walls, ceilings, windows, doors, etc.) and then choose the best of the respondents to work with.  One of the key needs will be to model many of the details in THERM to calculate the thermal bridge credits to enter into PHPP (it for instance presumes a fairly poorly detailed exterior corner and if you build with continuous insulation, you actually get a credit).

5) It appears that once again, I am in the need of a structural engineer.  I have had the worst luck I have ever had finding a vendor for this task.  I initially chose someone last spring who came recommended by two different people.  Initial communications had gone well, but on the first day of actual design, the project went south really quickly.  In hindsight, I believe the engineer was unfamiliar with ICF foundations (concrete poured inside permanent forming).  My first clue was when he insisted in designing a standard 8" foundation INSIDE the ICF.  This would have bumped me up to the 12" Durisol block instead of the planned 10" (costing substantially more for the block, freight to Vancouver, and the extra concrete). As a comparison, the BC Building Code allows for a 5.5" concrete core in an ICF.  The next issues was an insistence that I must use 2x6 studs for structure. When I tried to point out that only 2x4 Studs were required for structure and that the bump up to 2x6 construction was actually to meet the insulation needs of the 2006 code, and that as I had continuous EXTERNAL insulation, this was not applicable to me, they just stated that they only designed in 2x6 studs.  At this point the engineer suggested he step aside and I was in full agreement.

This was a very low point for me, because of this and a topic I will talk about in an upcoming post, my goals to start building in 2013 was not going to be met.  My wife and I came to a realization in March that it was not going to happen and that putting off for one more year made a lot more sense.  Of course this meant that I sloughed off from designing for a while and got out of the habit of working on it.  I picked it back up in earnest in June.  I decided to look for ways yet again to shrink the structure.  The District of North Vancouver building bylaw for my neighbourhood is VERY restrictive.  There is a rule that the upper floor cannot be larger than 75% of the lower floor.  Of course this goes against sound building envelope principles that dictate a cube as the 'perfect' structure, as it represents the smallest building envelope.  Anyway, I was able to shrink the upper floor enough so that I could meet the 75% rule if I added all my left over FSR to the bottom floor.  I will then go for a variance asking them to waive the 75% rule and not make me make the dwelling bigger than I need or want.

In June I received a list of engineers, who all reportedly work in ICF, from my friend Murray Frank.  I started to go through the list contacting each one and asking if they were interested.  Out of the seven names provided, 1 was out of business, 1 did not do residential, 1 was no longer doing ICF (and was actually an expert witness in a law suite against a prominent Foam ICF supplier), 1 was just not interested, 1 was never reached after lots of telephone tag, 1 was too busy, and I just did not get the right vibe from the last one (was too much like the one I parted ways with in March).  SO, so far I was batting 0 for 8.  The people on the list of five, provided three additional names.  Out of those three, 1 was too busy, 1 never returned my initial call, and 1 was not interested in ICF because of water ingress concerns (remember this one, I will come back to them).  This list of three recommended  2 more names and out of those two names, one was too busy (was a person I contacted back in March who was too busy then as well), and 1 sounded again like the fellow I had hired last March and I could see would not be a good match.  Scouring colleagues turned up another  4 names, 1 of which is not interested in ICF, 1 of which was not really recommended unless I had a basic design and did not need to ask questions, 1 which is in Ontario but licensed to practice in BC, and 1 of which looked like they basically only did large commercial work when I went to their website.  If you are keeping score, I am 0 for 16 plus 1 possible who works from Ontario.

I decided to go back to the person who did not like ICF due to water ingress concerns. I talked to him on the phone and assured him, my design with a full torch on membrane and several drainage planes would not have the same liability.  I was able to get his trust back when I explained that the ICF I was using was Dursiol and that yes I could do a full torch on without melting the ICF (something you cannot do with a foam ICF).  He agreed to meet with me and after a productive meeting, I felt comfortable proceeding with him and told him I would like to proceed on July 2.  That has been the last time I have heard from him.  After several follow up emails and phone calls, there has been no action.  I suspect the hold-up is based on some project requirements I have designed to.  I want to chose environmentally and IAQ friendly floor trusses, and for me, this means I want to eliminate the OSB I-Joists. I found a company in Quebec (TriForce) that uses the tops of Black Spruce trees to fabricate industry leading spans of 22ft with only a 11-7/8" deep truss.  This was great, as I have a height restriction in my neighbourhood (so need to keep my floor cavities as shallow as possible) and also want a fairly open floor plan.  This product fit the bill and I designed my floor plan around it.  The engineer had not heard of the product and seems to be reluctant to check it out and approve it.  I suspect he is just too busy to mess with something he is not familiar with.  But meeting my project requirements is important, I would need to redesign the whole floor plan if the 22ft spans was not approved by him,  as my wife and I do not want a bunch of drop down beams cutting off a nice 9ft ceiling space.

SO, it appears that I am back to square one yet again and that the fellow from Ontario may be my last chance at a touch down unless some of the people who were busy in June and July are now available.  I really was not expecting this task to be at all difficult, but it appears that as soon as there is a slightly abnormal quality to your project, a lot of vendors just are not equipped to deal with the extra effort required.  Out of the list of 17, I will re-approach 4 of them.

Lets hope threes a charm.

Thanks for reading - Cheers.

Deadlines, Roadblocks, & Reality

We missed a major deadline last Friday, which in reality had no chance of ever being met.

In order to meet my prescribed schedule (get dry before Sept 30), I had identified Friday the 8th of March as the day I needed to apply for permits.  I had allowed 4 weeks for the permit process and anticipated starting to dismantle the existing dwelling in mid April.

A visit to the District Hall on Friday identified that this schedule was unrealistic on many fronts and will need to be completely rethought. Up until this point, I have had this naive assumption that everything would just fall into place as I progressed through the planning and build process. I was counting on good karma to be by my side and pave all the paths through the myriad of steps leading up to and through the build.

Well, it seems I have been optimistic on a laughable scale.

Things turned south the first time back in September of 2011 when I found out the District was not adopting similar measures, as surrounding municipalities have,  to promote energy-efficient building envelopes (more on this in a separate post).   I should have clued in then, that this would not be ‘easy’.  This led to a 1-year hiatus from active design while I pondered the way forward and advanced my knowledge in the science of building enclosures.  In September of 2012, I restarted the design with a goal to reduce footprint and harvest as much solar energy as practical for my region and lot.  I have put considerable effort into finalizing this design over the last 6 months ramping up over the last two months to 'full time' in order to complete the 3D model and 2D plans in time for this week’s permit application (something I was generally successful in doing).

But then a string of current setbacks made this timeframe impossible to meet, starting with the structural engineering which I had assumed would be straightforward and quick.  Earlier last week I had to part ways with the initial structural engineer I had chosen for the project.  Within the course of our first real day of activity on the design, it became clear that he was not the right person for the job.  I needed someone familiar with Insulated Concrete Foundations (ICF) and someone who was proficient with Part 9 construction of the building code and could think outside the box, because this is a fairly innovative design that will not have been seen by many people.  It became clear pretty quickly that neither of these needs was going to be filled by my original selection, and we both agreed that this was not the right project for him.  I had learned long ago to go with my gut when working with people, and was relieved at how quickly this situation came to a resolution.  Recently, I had witnessed a friend's build, where a gut feeling was put aside by them in selecting an architect, and that decision plagued the entire build, which further reinforced my conviction.   I vowed that I would not repeat this experience.

This left me with under a week to find an engineer and complete the structural design so that I could still submit for permits 'on time'. This turned into the second major roadblock as I was unable  to find any engineers familiar with ICF that were available on short notice.  This has been compounded by a lawsuit currently in the works (to the tune of $1M) involving an ICF project in the Lower Mainland where the dwelling had to be torn down after construction due to a faulty ICF foundation installation.  News of this lawsuit is spreading across the engineering community and I spoke with two engineers this last week who no longer design in ICF construction. In speaking with the engineer who is acting as the expert witness for the plaintiff in this case, it appeared that there were concerns with one of the major brands of foam ICF, and how the structural rebar is held in place (or not), and also a concern on the ability of the concrete to fully encase the rebar in this ICF design.  I am not proposing to use this foam ICF, or any foam ICF for that matter, and will try to pry an assessment of the system I would like to use from this individual over lunch sometime soon.

With any hope of engineering completion at least a month or more away, I went to the District Hall yesterday to enquire about the permit application process.  An engineer had mentioned I could apply for the permits without the calculations being completed and just submit the calc’s when needed during the plans review process.  This was not a strategy recommended by the District.  They advised that checking would not proceed without all required documents.  So I really need a complete package before submitting my application.  Realistically this would set the start back a month or more.

While at the District, I was also informed that the approval process was currently taking 6 weeks or more and that because I would need to apply for a variance, I could probably expect double that time.  So all together I was looking at around a 3-4 month delay in the commencement of the build. This would prevent me from getting the roof on and the place generally water-proof until Dec/Jan which is a build condition I am unwilling to accept.  It has been my intention from day one that I would not be doing exterior construction during the wettest and coldest months of the year in order to protect sensitive building materials like the TGI's from becoming saturated and because it just is not any fun building in the cold or torrential rains (I remember my first winter job site experience where we had to build a fire each morning to thaw out the pneumatic lines).

The final stumbling block presented by the District Friday, was an initial refusal to allow a holiday trailer to be parked on site, which I propose to live in during the build.  This is key to our budget, as rent in my neighbourhood is around $1600 for basement suites and $4000+ for upper floors of a house.  With the anticipated build time of 18 months, this would result in a $30K - $75K reduction in our available budget (10% - 20%), and a serious challenge to our cash flow. The District is concerned about site safety and the safety of their services which I totally understand, but I am confident that solutions exist for all of the concerns if we just think a little bit out of the box.

This all lead to a decision on Friday to delay the project start date by a year.  I will still work on completing the design, getting material pricing, solving the living on site issue, putting some much needed attention into the onside Building Lab project, and just generally getting better prepared for the build.  But I will hold off applying for permits until probably September.  This would give the approval process six months before we would anticipate breaking ground.

I am significantly relieved by this decision, as although I was ready for the building permit, I had not finished the electrical and plumbing design and would have had to work those out during the evenings as I was building.  This way I can thoroughly prepare all aspects of the build and be in much better shape next March.  This will also allow me to concentrate on some landscaping in the back yard this year, which will make neighbours very happy.  This also gives more time to get the project’s website up and running.  

On some levels I feel like I have failed, and I have.  But in a larger regard, I have succeeded to make the right decision to ensure the desired successful outcome, and for that I am proud.

I will continue to document my journey over the next year as there will be many decisions I can now research before making.  Does ICF make sense?  Why do I want to buy floor trusses from Quebec? Rain Water and Grey Water Heat Recovery, do they make sense?  How much of an existing structure can be diverted from a landfill?

I hope you will continue to visit, and I look forward to any comments or questions you might have.

Product Testing Continues at SENWiEco

SENWiEco continues testing products that we hope to incorporate into our upcoming build.

The R-Guard products from Prosoco are standing up well to our accelerated temperature torture testing.

After 7 days of extreme testing, the Durisol ICF block shows no sign of capillary action horizontally through the product.

We have now started testing the waterproof capacity of Fab-Form's FastFoot fabric footing forms.

SENWiEco considers the Durisol CBWF ICF Block for below grade foundations

Anyone who has read my previous blog entries knows by now that I like to verify and do things for myself.  SO it should come as no surprise that I will perform some testing on another ‘new’ product I am considering for my upcoming build.

As mentioned repeatedly on my blog, my focus on this build is a bullet proof and energy efficient building enclosure to lower my impact to this planet.  I am targeting R10/20/40/60 (Slab/Foundation/Walls/Roof) and these are effective values not nominal (so values after taking into consideration all thermal bridging). 

With these targets identified, it makes sense to optimize what ever insulation is installed by placing in locations less effected by thermal bridging.  This usually means putting most/all of the insulation on the interior of the structure or exterior of the wall or roof assemblies.  Now which side you put the insulation on is very important for preventing condensation.  In a Cold-heating-dominated-climate like Vancouver, you want to keep the sheathing above the dew-point potential so that if any interior air leaks into the wall assembly, it will not condense on the back side of the sheathing which can often cause rot and mould. 

Continuous exterior insulation is a great way to prevent thermal bridging (your insulation is firing on all cylinders) and keeps your sheathing, or in this case your foundation walls, warm and dry.  For this reason, an ICF form system makes a lot of sense.  In typical ICF formed walls, there is an interior panel of insulation attached to an exterior panel of insulation with plastic or metal ties.  The concrete is then placed to fill in the gap down the middle. 

From an insulation point of view, the continuous nature of the ICF panels is great and represents a thermal bridge free design.  Your nominal insulation is the same as your effective insulation R values.  However, you do end up with a thickness of insulation on the interior face of the foundation.  This prevents the concrete from acting as a thermal mass that would otherwise allow it to help moderate interior temperatures.  Insulation inboard of the concrete core can also represent a dew-point potential if the concrete pulls away from the foam as it cures and air leakage results.  Finally as the product is made from oil, it can represent strong off gassing potential and a real fire spread and toxic fumes risk if your drywall is not continuous or is damaged and a fire occurs.

But for me, the biggest demerit, against the foam based ICF’s, is that they are made from foam and therefore oil.  If your goal of creating a low energy house is to reduce your impact on the planet, it hardly makes sense to use a product that is the most responsible for human’s impact on the planet today.  We will be no further ahead if we create a demand for foam ICF on a mass scale, as this will just continue the dependence on a product we really need to start considering leaving in the ground.

Now many of you will say the benefits of foam ICF outweigh the use of an oil derived product.  You are at least locking away a lot of the carbon that would be created if the oil was otherwise used for combustion.  At least in a product like this, it will stay buried for probably 50-100 years (and there may even be a potential of recycling the product at the end).  And any increase in insulation decreases the amount of electricity and gas used in homes to provide heat and air conditioning. To an extent, I agree with this rational.  I do not believe you should abandon products just because they are made of oil.  In many categories, the alternative ‘green’ products are not suitable for use and have durability issues.  The regular replacement of an unsuitable component can represent just as large an embodied energy, as using a more suitable oil derived product.  However when you do have a suitable non-oil based alternative, you should do everything possible to incorporate it into your design. It was with this frame of mind, that I started looking at the Durisol ICF block for my upcoming build.

The benefits of a cement-bonded-wood-fibre (CBWF) block are:

• Made from recycled-wood and cement powder,
• Places all of its insulation outboard of the slab,
• Can be left as a final surface within the basement,
• Can be attached to anywhere in the field of wall (do not need to hunt for hidden plastic tabs to fasten drywall or framing to),
• Incorporates a drainage plane within the product,
• Is mold and rot resistant,
• Is bug and rodent proof, and
• Best of all – does not burn easily or give off noxious fumes if it does. 

Now for its negatives:

• Highly air permeable (a benefit of regular ICF is that the concrete core is an air barrier).  The material of these blocks is highly porous and the block has webs that connect the outer and inner panels together THROUGH the concrete core.
• These webs are not just an air path; they are also possible water and likely a vapour path.
• There is at least a passing concern that the block could rot in a below grade application.

In researching this product, I was unable to find any comments on-line that the product had ever broken down below grade from decay.  The manufacturer provided an Ontario MOT testimonial that stated they had never had to repair the product due to decay (the product is used extensively above ground, and partially submerged, as a road side noise abatement fences) after 30 years of use. 

The product has been manufactured since 1953, so certainly has been on the market a long time.  If there were significant failures, it would be readily visible on the web. 

So what’s the catch? 

Well the product has not had a huge uptake for below grade installations to date.  The manufactures claims they have a dozen or so projects a year on average in Ontario and I have found 2-3 blogs on the net describing the use of the product.

What’s the risk?

Well, unlike traditional ICF, the interconnecting webs of each block penetrate through the concrete core.  This provides a path for air, vapour, and possibly moisture travel. 

The air barrier is fairly easy to address with a fully adhered membrane outboard of the block (this still leaves some interesting details at the footing level and will probably require some thinking out of the box to seal on the interior face near the basement floor slab - more on this in the future). An airtight drywall approach (ADA) could also be implemented.

The vapour barrier again will be generally dealt with by the fully adhered exterior membrane. Besides, even regular formed concrete foundations have a considerable moisture movement through them from out to in, which is why you should never have a vapour barrier (just a retarder) beneath the drywall in the below grade basement (NO POLY! EVER!!!).

Now for the real issue: What is the danger of liquid water transport through the webs to the interior face of the block, either under hydraulic pressure or capillary action? 

Durisol partnered with the University of Toronto to study the drainage properties of the CBWF ICF block back in the mid to late 90’s.  This UOFT report confirmed the manufacturer’s claims that the product did not support horizontal capillary movement and that liquid moisture drained readily through the material.  In fact the free draining rate of the product was a whopping .5 gpm through a piece of material that was 3.5” Thick, 8” wide and 11.3’ (yes ft) tall.  In another test, where a sample was fully saturated and then allowed to air dry, the retained moisture after 60 minutes was only 38% and the sample had lost a majority of its moisture after just ten minutes.

So far, this all looks great!

Figure 1: Durisol 12” Thermal Block in the R21 configuration (5.5” Concrete Core)

Figure 2: (LEFT) Semi-rigid mineral wool insulation insert on the outboard side of the block. (RIGHT) Product is created with a mixture of recycled-clean-mineralized-wood-fibre and cement powder.

 

 

 

But unfortunately, I rarely accept others reported results at face value.  I wanted to put the product through a more rigorous testing protocol (in my opinion).  So enter the DBTTC or Durisol Block Torture Testing Chamber!

Figure 3: (Left) 28”l x 19”w x 15”t tub with a selection of Cactus Club takeout containers as standoffs in the bottom.  These support the block without being susceptible to rising damp.  They also isolate the outer and inner webs so that water flowing down the outer web does not flow along the support to the inner web. (Middle) A small water pump is rated for 70 GPH @ 0” head so probably around 40-50 GPH in my configuration. (Right) The containers are 2.5” tall and the water level was set at the halfway point so there is approximately ¾” gap from the top of the water to the bottom of the block (should allow for enough air movement around the bottom of the block so that the humidity does not build up too high and skew the results.

Figure 4: The inboard side of the block surface registered at 11.1% MC.  The block has been sitting in my living room for about a week (which by the way, translates to an indoor air relative humidly of 55% which is what I have the bathroom fan humidistat set to).

Figure 5: I also took the MC of the webs from within the inside journals that the concrete would be placed in.  This will be an easier location to monitor.  I had a reading of 10.4 and 9.3% MC (difference was probably due to a variation in density of the product at the tested location due to the random makeup of the wood fibre).

Figure 6: The Test

Over the next week or so, I will leave the pump on 24/7.  Water flows out of the plastic tube that has been drilled with holes at a regular interval.  The water is draining through the outer panel as fast as it is added at the top where it drips back into the tub and repeats the cycle.

Over time, I will measure the moisture content of the inboard panel exterior face (and the side faces of the internal webs).  The go/no go test will be to see if a piece of paper stapled to the inboard face of the block shows any signs of moisture over time.

I will of course post the results once they have been tabulated.  Here is a video showing the start of the test and another video showing 60 hours into the test.  At this point, there has been no horizontal travel of liquid towards the interior panel, which confirms the testing performed by the University of Toronto.