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.

January Update - Slowly we are proceeding.

I am getting a few questions as to where I am at on the build and so will provide this short update.

We are getting there! OK, that may have been too short.

Currently, we are waiting to hear if our development variance will be approved.  The notice went out to the neighbours between Christmas and New Years (Many Thanks to Erik at the District of North Vancouver for getting this out so quickly).  The neighbours had till Wednesday to respond with only one neighbour providing official comment (positive).  The next step is for staff to write the report to Council and for Council to deliberate on the application at the next available meeting.  This currently is scheduled for Feb 17 (I today found out it is too tight to make the Feb 3 meeting which is disappointing but totally understandable).

Back in November when I was discussing this Variance with staff, I was under the impression that they would allow me to apply for the building permit in advance of the Variance permit approval and proceed on the condition the variance is approved.  I found out this week, that I had it wrong, and that I cannot apply for the building permit until after, and if,  the variance has been accepted.  This news filled me with disappointment as I was budgeting 8-10 weeks for building permit approval based on previous conversations.  However, the kind District Plan Checker has advised they will do their best to fast track the application and could complete the process in as little as 2-4 weeks.  This would end up putting me slightly ahead of schedule.

The District staff have also confirmed I can apply for the demolition permit at any time.  This will again help, as regular readers remember, I plan to dismantle the existing dwelling by hand and reuse, sell, give away, or recycle/salvage as much of the materials as possible.  I estimated this process was going to take a month to complete.  Current plans are to move out the first few days in March, spend a couple of weeks dealing with all of 'my stuff' in the garage and attic and storage shed, and then start tackling the dismantling of items like flooring, cabinets, end the like, all stuff not controlled by a permit.  I would then schedule the services to be cut near the end of March and then start on the official 'demolition'.  These efforts would all take place in advance of the building permit and further improve my schedule.

I am also nearing completion with Tacoma, the structural engineers I hired.  This process has gone on longer than I believe both Tacoma and I expected, but we have made excellent progress and I believe are getting to the final drawing edits, having been through all the drawings at least once to date.  There has been a struggle with my desire for a thermal bridge free envelope and Tacoma's desire to ensure the dwelling stays standing for decades to come, that has been worked out with lots of 1 and 0's flying through the internet email pathways, and I am grateful for Tacoma and specifically Heather's patience through this process.  In the end, it is difficult (impossible?) to build a thermal bridge free structure utilizing 2x4 wall construction, and while complying with zoning requirements, and I have had to compromise in several areas in order to allow us to proceed with permit drawings in any reasonable time frame.  There are a few areas I will try to 'upgrade' after the permit process, but will only be able to do so if ROXUL is able to provide some compressive strength testing results for their insulation in a 6" wide configuration (what I will have as continuous insulation on the exterior of the sheathing).

As you recall I recently completed a proposed plumbing waste pipe design and am now waiting for the licensed plumber to approve or adjust as required.

I also recently commissioned EcoLighten Energy Solutions to complete a room by room heat loss calculation that I will then use to design my radiant panels.  I will speak to this a lot more in the future, but it is my feeling that the method I was taught as part of the TECA Residential Hydronic Designer course, is too crude for high performance homes.  I plan on doing a comparison between that which EcoLighten provides and that completed using the TECA method, and will post the differences here.  The preliminary model from EcoLighten shows that I will use around 50% of the energy used by a 'code built' home.  With the levels of insulation and air tightness I planned, this is actually a disappointing result, as I was hoping for something closer to a 70%+ reduction. I will go over the model in the upcoming weeks and see if there are any assumptions that can be tweaked to represent what I believe will be the final reality.

I have also commissioned HoneyComb Creative to build the project website.  HoneyComb created my home inspection website and were an obvious choice to approach for my build needs.  The website www.theEnclosure.ca should be 'live' in approximately 4-8 weeks with at least the basic functionality, and then will be fleshed out as the project proceeds.  The site will include 'live' video, time laps photographs,  a link to this blog, a daily project diary, special component installation videos, dwelling design details, sponsorship links with promotional literature for sponsored products, and finally information and basic instrument readings for the science lab (once the dwelling is complete).  I am looking forward to the site launch and have been very pleased with the initial artwork provided.

Well, I believe you are caught up.   I will be posting documents pertaining to the variance application and the permit application, including all drawings, as I get through those hurdles.

As always, thanks for reading!  Please drop me a line if you have any questions or comments.

  

Thermal Bridging and Dew Points

Anyone who has heard me speak for more than 10 minutes has probably heard me talking about dew-point potential.  It is at the heart of good building science principles.  Move the dew-point to somewhere outside of your assemblies, and your assemblies will have a built-in safety regardless of any air movement through them.

But for many, this dew-point conversation is esoteric and abstract, they can not usually visualize a dew-point occurring (that they are aware of, the condensation on the outside of a glass or can of cold liquid is a demonstration of dew-points) and so cannot appreciate the importance of reducing its potential in building enclosure construction.

Well by happenstance, I had an excellent example present itself to me at my home this afternoon.  I was coming back from my neighbour’s house after ‘supervising’ the dismantling of some scaffolding, when I observed condensation on the inside of the window near my front door.  Now, I generally have single pane heavy aluminum frame windows throughout my home, so condensation around the frame margins of the windows is not an unusual occurrence.  However this window had a wood frame (site built) and did not usually suffer from condensation.

Why the difference?  Insulation and air films!

Condensation spotted on the inside of the window.

Inside of window is condensation free except behind some mail propped up against window.

Condensation is definitely on the inside face of the window.

General window surface temperature 56.5° F

Surface temperature drops to below 51°F behind the mail.

Temperature in nearby region is 68.1°F

Temperature behind mail 56.4°F with an RH of 64%

So, what does this all mean? 

I have to admit, that this took a lot longer than it should have to figure out.  On the first round of measuring, I had RH levels well below 50% and temps of 66.3°F ‘near’ the window (my office is at 44% and 72°F on the other side of the house and benefiting from all the heat being pumped out from the computer equipment). At these windows temps and RH, the dew-point should have been around 47°F which was clearly well below my initial recorded window surface temp of 53°F behind the mail. 

So why the condensation? 

It then occurred to me that this was a delicate microclimate and by removing the mail for too long to do the testing and photos,  I had inadvertently changed the local conditions and disturbed the air film that would have been against the surface of the window.  So, I put the mail back to let the conditions come to equilibrium again and reran the measurements to get the figures in the photos above.  As you can see, the temperature within a couple of ‘ft’ to the window was now over 68F and the humidity that was building up behind the mail was over 64%.  This works out to a dew-point around 56°F and with a window surface temp of just under 51°F, I was well below the dew-point and had condensation.

The mail was creating enough of a barrier to heat loss (acting as insulation), that it was lowering window surface temperatures over 5F and at the same time was creating a micro-climate where the humidity was ‘trapped’ by still air and building up well above the rest of the house.  

This demonstration highlights how delicate the balance can actually be and why heat-bridging in assemblies is so critical.  Whenever you have isolated conditions that allow a small area of your assembly to cool in relation to the assembly as a whole, or that allow the build-up of humidity, you have the recipe for  liquid water formation and when hidden inside an assembly, that can and often does lead to disaster!