Friday, 30 November 2012

SENWiEco continues their test run of the Prosoco R-Gaurd product line

SENWiEco continues their test drive of the liquid applied WRB/AB system called R-Guard from Prosoco. This is a 4 part liquid barrier applied to the exterior sheathing to form both the Water Resistant Barrier and the Air Barrier.

The first part of their system is called Joint & Seam and is used at the  interface between any components that can move (either from moisture or temperature changes).  You would use this product (that contains fibres to provide strength to the joint under movement) at the interface between the plywood sheathing and the stick structure around door and windows, to fillet around plumbing and electrical pipes, to fillet between the wall and floor or between two walls, and along all sheathing seams.

The next product in the R-Guard lineup is the Fast Flash product.  Fast Flash is used in place of a self adhered membrane on the vertical surfaces of the sheathing and rough openings that may see a higher volume of moisture.  Unlike SAM, it is vapour permeable so will not contribute to rotting around the rough openings that is so often seen with dwellings where a high volume of SAM has been applied.  Although the manufacture recommends its use on window sills, SENWiEco cannot at this time recommend this application and instead recommend a water AND vapour tight membrane like PS45 at the window sill.  We will discuss this issue more in a future post and provide our test results where we performed an extended inverted water test using the Fast Flash product.

Once the Fast Flash has been applied, you are then able to treat the field of the walls with the R-Guard Cat 5 roll on product.  The product has gone through extensive testing and can withstand the forces of a Category 5 Hurricane.

Finally, as the final part of the R-Guard system, when the windows are installed you provide a air seal and water shedding surface at the interior face of the window frame using R-Guard Air Dam.

SENWiEco subjected our test assembly to -4500 Pa (equivalent of 185 Mph or 300 Kph winds) and did not experience any leaks through the sheathing joints and HVAC/Electrical/Plumbing penetrations.  We did have two pinhole leaks around window clips and the window frame itself started to leak at that pressure.  We will provide a follow up posting with links to videos of our tests once they are available.

In the meantime, we invite you to watch a series of videos capturing our trial run of the R-Guard system.

1) Application of R-Guard Joint & Seam
2) Application of R-Guard Fast Flash
3) Discussing the application of R-Guard Cat5
4) Detailing an exterior Electrical Outlet
(In hindsight, I would detail this differently to make it more attractive by making the wood 'box' only the width of the electrical outlet plus 3/8" each side for a caulking joint)
5) Detailing an exterior HVAC Termination/Intake
6) Discussing the consideration needed when installing a box style window
7) Detailing Window Sill using a Back Stop
8) Discussing the Head Flashing placement and Head and Jamb Trim considerations
9) Detailing Jamb Trims
10) Installing Head Flashing
11) Seal Sill Back Stop, Window Clips, and install Backer Rod
12) Installing R-Guard Air Dam
13) Discussing Failure at clips and ways to re-detail in a water tight fashion
14) Building a Poly Enclosure to test the Air and Water control layers in a wall assembly 
15) Pressurized Smoke Test
16) Depressurized Water Test 
17) Discuss Failure at Window Clip
18) BCIT BLDC 3060 Water Test - Passed at -1200 Pa 
19) Site built differential pressure gauge
20) Mock up assembly is tested to -4500 Pa or 18" of Head Pressure!

This was phenomenal results for the R-Guard system and for the Cascadia windows.   The only leaks around the windows were are locations where old sealant remnants had not been removed.  We also suspect that the window frame joint was damaged when the window was cut out of the BCIT Mock-up.  Even if it wasn't, this is very little water for a -4500 Pa pressure which represents winds this dwelling will never see!

Wednesday, 28 November 2012

We hit 1000 hits

Just a quick note to thank all you readers for visiting my blog.  I reached 1000 hits today which is an excellent milestone considering the short period of time this blog has been up and the limited topics of conversation.

Thanks for reading and please let me know what you would like to read in upcoming entries. 

I can advise that my house design is moving forward  (slower than hoped but still at a reasonable pace).  I will soon be able to post floor plans and advise the factors that were considered in their layout.  I will then be moving on to the engineering of the floors and roof structures.  I am aiming for plans submission and permit applications for Late February of 2013.  I anticipate needing a couple of variances that I will discuss further in a future posting.  I am crossing my fingers that this can be approved faster than the 4 months typically quoted, as I need to start by late May, or very early June at the latest, if I am to have any chance of getting the roof on before the winter rains.  If this was not achievable, I would be delaying the start until the spring of 2014.

Once again, thanks for visiting and please check back often or better yet subscribe so that you are automatically notified of new postings.


The problem with architecture is architects!

Some of you who know me, know my general bias against the architectural profession.  I have built up this bias over many years for many reasons, but primarily due to the lack of respect many of their designs show to good building science.

Well today was grounds to again support this bias and I just can't keep my thoughts contained.  Against my better judgment, I attended the Sustainabuild conference in Vancouver which is geared towards the architectural community.  My draw was one of the speakers - Murray Frank - who I highly respect and was one of the only real rays of sunshine in an otherwise cloudy and stormy day.  Fortunately he provided a presentation on good science or my head would have exploded with all of the assaults to good building science presented throughout most of the day's balance.

Let me give you some examples.  I just about bit through my tongue when one of the early presenters discussed Chicago's Aqua tower shown in the photos below and advised "we can design buildings that are able to capture solar energy".. "and get rid of excess heat within the building".  

Are you kidding me? 

The Aqua tower is an abomination to all good building science practices and pretty much eliminates the ability to separate the exterior from the interior environment due to its extreme solar bridging and moisture transport by means of the extended floor slabs.  I can advise that in the heart of the summer, you still need to have the heat turned on during cloudy days (I have the unfortunate distinction of having stayed at the hotel during a recent vacation - my wife booked the place before I realized where it was).
The Aqua Tower in Chicago - Photo by your author Summer 2012
Thermograph image showing the extreme heat bridging present in this building (Notice the 20ยบ Celsius spread in temperatures) - Photo

But the tower won some awards and was designed by a women and is pursuing the LEED certification, so it must be a good thing - right?

Wiki states "Sustainability was an important factor in Aqua's design. Gang and her team refined the terrace extensions to maximize solar shading, and other sustainable features will include rainwater collection systems and energy-efficient lighting. The green roof on top of the tower base will be the largest in Chicago." 

Why not try and make the building enclosure bullet proof before worrying about small energy contributors like lights and rainwater collection. 

Green roofs have been proven many times to not be green (they often do not reduce storm runoff, make for poor performing insulation, often need to be watered to stay alive, are often poorly installed leading to leaks, and the list goes on).  The only reason for them is a visual pleasantry and no one is going to see this one being on the top of one of the tallest buildings in the area.

The same presenter then tried to advise the room, towers are less green than low rises because they use more energy per cubic meter due to the need to "pump all that water up all those floors".  A figure of 1100 units (believe it was kWh/m2/annun) was identified for the towers and a much lower figure was used in their example for low and mid rise units.  This person was advocating that we take up more land for buildings, make the buildings shorter, and that the result would be that we needed less 'green' space and parks because there would be less shading from neighbouring buildings and I guess indicates people would be more comfortable staying in their little cubby holes. 

Fortunately there was a presenter later in the day who represented the Marine Gateway project at Marine Drive and Cambie in Vancouver.  He had actual numbers from the modelling of the development which were down around 100 units which represent a very attractive target and a well run efficient building.  But what if he was not in the room.  The first presenter's assertion that towers equated to energy inefficiency would have prevailed and could have started a whole new push by the architectural community based on poor concepts using inaccurate data.

Besides Murray's presentation, the only other ray of hope in the room for me, was the fellow who presented on the Cambie Corridor densification project and specifically the Marine Gateway project.  This project appears to be a great step towards sustainable multi-family living.  There is only 50% glazing in the residential and 51% in the commercial spaces (compared to 75%-90%+ for many downtown buildings).  The presenter went on to say that the areas that are not glazed are heavily insulated.  Finally a team with their priorities straight.  Get the building envelope right and you will have a low energy and 'green' building.

An example was made early in the day that showed the lotus car and had the presenter discussing how beautiful the cars exterior was and the true marvel was how the engineers were able to fit everything that was NEEDED into that 'beautiful' shape to make that shape FUNCTIONAL.   

I see this process as being the biggest fundamental flaw with the architectural community. 

We need to abolish this process and instead first decide on our performance goals, define our building enclosure to meet those goals using good building science, and only then allow the architects into the fray to design the perceived 'beauty' into the buildings. But only up to the point that the client can afford, after committing to the performance objectives first, and only to the point that the architects design does not impend the designed enclosure that is needed to meet the performance objectives. 

Only then will our building start to become legacies instead of liabilities and truly be 'green'!

Tuesday, 20 November 2012

Why do we continue to drill holes into our buildings?

I was recently driving by yet another building with vapour ‘diffusion’ ports (VDP’s) and it got me thinking:

Why do we continue to let our buildings be drilled full of holes?

I have always believed that the ports did not work based on previous information I had reviewed, and they are certainly not a recommendation made in the Best Practices Guide published by the Home Protection Office (HPO) in collaboration with some of the best engineering firms in the North America, firms like RDH, RJC, and Morrison Hershfield.

So why do a limited number of buildings still incorporate these ports in their designs?

First of all, we need to try and understand the intent of vapour diffusion ports. As I understand it, the intent is to help walls ‘dry out’ by allowing the wall assembly to ‘breathe’ more easily.  The ports are intended to increase the breathability of the assembly by means of diffusion, over a solid sheathing base line. By ‘breathing’, we are referring to the wall’s ability to ‘lose’ moisture in a vapour form, by allowing that moisture to go ‘through’ a wall’s materials and evaporate into the outside air (low vapour pressure side). We say walls can ‘breathe’ if all of the materials on the low vapour pressure side (which can change direction depending on conditions) are vapour-open, or that they have a high permeability.  In simple terms, this means that the pores of the material are large enough to allow a water molecule in vapour form to pass through the material.  The mechanism of passing through the assembly is usually termed ‘diffusion’, but a review of Chapter 8 of Building Science for Building Enclosures by Straube/Burnett details that the actual mechanisms involved with moisture movement through a porous material are extremely complex and can involve surface diffusion, capillary action, evaporation, convection, absorbed moisture transport, etc.  Even today, the flow of moisture through materials is not fully quantifiable by scientists or fully predictable. What is a provable fact is that in order for vapour diffusion to take place there needs to be a difference in vapour pressure across the two sides of the material (or assemblies) in question.

So are these ports working as intended?   How wide a range does each port have? Are there other mechanisms at work?  Is this an effective drying strategy?

In researching this topic I came across two related studies performed in the late 1990’s after the leaky condo crisis.  The first study titled The Envelope Drying Rates Analysis Study looked at the abilities of various wall assemblies to dry out (in lab conditions) while changing up components like sheathing materials, capillary break depth, and sheathing membrane materials.  What I found most surprising was that none of the panels were dry to safe levels (below 20%) even at the end of the 2000 hour study.

The second study titled Evaluation of Vapour Diffusion Ports on Drying of Wood-Frame Walls Under Controlled Conditions utilized the same panels, but drilled out vapour diffusion ports on some of the panels and then re-ran parts of the experiment to look at the effectiveness of the vapour diffusion ports specifically.  What was again remarkable was that, although the VDP’s did provide a minor increase in the initial drying rate of the OSB panels (no change in the rate of drying in the plywood panels which was already higher than OSB with or without the VDP’s ), all of the panels (OSB & Plywood) again contained areas with dangerous levels of wood moisture at the end of the study (which repeated the first studies results).

After reviewing these studies and Building Science for Building Enclosures,  I now have a better grasp on the true mechanisms at work with vapour ‘diffusion’ ports, and only a little of the process actually involves diffusion.  Where the ports have been effective to any measurable level, some form of convection must take place in conjunction with lots of capillary movement. Let’s look at these mechanisms in a bit more detail.

Convection (or air movement) can occur because of air leakage through an assembly from the high to low pressure side.  It can also occur by means of the convective currents that can develop within each stud bay if a low density batt and fill insulation (i.e. fibreglass) is used.  Neither of these mechanisms is desirable from an enclosure performance standpoint. Convection forces within the wall assembly can deliver moisture-rich air derived from the ‘wettest’ parts of the wall assembly (studs, plates, & insulation) and deposit that moisture onto the back side of the sheathing (which can allow a generalized increased drying rate from the sheathing by means of diffusion to the outside air). Where that moisture is close enough to a port, there can also be a localized marginal increase in permeability over the base-line sheathing.  This can help dry an assembly if no additional moisture is introduced through the convection mechanism, but air leakage through an assembly can often bring with it high levels of moisture into the assembly from the interior of the dwelling.  And once in the assembly, that moisture can then condense on any of the wall elements with surface temperatures that are below the dew point of the leaking air. (See my July/2012 and March/2012 blog entries for more info on dew points and moisture in wall assemblies).  Stud bay convective currents often create ‘air pumps’ that can lead to cold interior walls and thermal bridging, causing additional heat loss (you are bypassing the insulation by delivering heat to the outside sheathing and taking it from the inside wall board).

Now lets look at capillary and diffusion forces in connection with these ports - as areas close to the ports dry out via diffusion through the holes in the sheathing (which have a higher permeability because the moisture has to only diffuse through the sheathing membrane and not though the membrane AND the sheathing), or by air leakage through the holes (because the sheathing membrane has been damaged or is not sealed as an air control layer), that moisture is replaced by wetter neighbouring regions.  The process continues until, over time, the moisture levels within the assembly equalize.  The assembly as a whole is also trying to equalize with its lower vapour pressure neighbours (so in this geographical region, usually to the outside).  The entire process continues until all regions have the same vapour pressure (something that in practice rarely occurs as there is always changing interior and exterior humidity and temperatures which lead to changing vapour pressures).

The problem however, with relying on the diffusion and capillary forces alone is that, although capillary forces are faster than diffusion, both forces will not dry a wall assembly out fast enough to be an effective deterrent to decay and fungal growth.   This was confirmed in both studies, where portions of every test panel still had wood moisture levels in the danger zone for promoting (not just maintaining) rot, even after close to three months, regardless if VDP’s were installed or not!  These studies only had one wetting period - What happens when you have repeated introductions of moisture (interior air leakage, exterior leaks, or plumbing leaks)?

What does all of this mean? Are these results important?

Let’s look at where moisture can originate and how effective VDP’s are at addressing that moisture source.  There are five causes that come to mind:
  • Initial wood moisture elevated during construction due to the rain forest we are building in, 
  • Bulk water entry (after construction) from the exterior around poorly detailed penetrations and even through vapour diffusion ports, 
  • Bulk water entry from water pipe and drain leaks within the assembly,
  • Air leakage through the assembly causing condensation,
  • Vapour diffusion into the assembly (usually caused by excessive RH% levels in the dwelling’s interior and/or inadequate vapour control layer)

The easiest way to address the first cause is to leave the drywall, poly, and insulation off the interior of the structure until the assembly dries out.  The problem is that construction schedules are so tight; we typically do not allow adequate drying time.  If we are unable to allow sufficient time for a wall to naturally dry out before boarding, then we need accelerate the process by adding heat and air movement to the mix (and in some extreme cases, de-humidification). If we rely on the VDP’s alone to allow the wall to diffuse the moisture out and close up the assembly in a wet state, we could be waiting many months for safe moisture levels within the assembly to occur, and by that time a healthy crop of fungi would most likely have already taken root leaving us with a sick wall assembly. 
VDP’s Score: F

The second and third mechanism only has one solution – stop the bulk water entry!  There is no effective strategy to manage bulk water entry once it has occurred. Even BC’s Rain-Screen requirements will not solve repeated bulk water entry into a wall
assembly.  You must stop it at the source. 
VDP’s Score: F

The fourth mechanism of moisture entry is also somewhat simple to address. Stop the air flow through the assembly by means of an effective air control layer.  Unless you stop the air flow and the resulting condensation, the rate of moisture input will again often overwhelm the slow drying rate of a wall assembly by means of diffusion only, with or without VDP’s.
VDP’s Score: C- down to F (depending on the incoming moisture levels and type of sheathing installed). 

The final mechanism also has an easy solution in most dwellings.  Control the interior humidity by means of mechanical ventilation and/or install an effective vapour control layer in the assembly.
VDP’s Score: C down to F (depending on incoming moisture levels and type of sheathing installed).

Let’s summarize this information.  If a VDP is sealed against airflow, we are generally relying on diffusion and capillary forces and possibly stud bay convection currents to help dry out a wall assembly.   However these processes are slow, and the VDP’s only account for a limited improvement of drying potential over base lines.  As a result the assembly would typically not dry out in time to prevent decay regardless of the presence of the VDP’s.  If we allow air movement to occur through the ports, the air movement that would occur through the assembly can often bring with it levels of moisture that are easily able to overcome the limited additional drying capabilities represented by the VPD’s.

Are there downsides to including VDP’s “just in case”?

Well, it turns out these holes are usually conveniently placed just below windows and other enclosure penetrations where any incorrectly detailed flashing or membrane (like the holes drilled through all the water-resistant layers in the photo - below left) could direct water along the surface of the sheathing and into the wall assembly through these strategically placed inward water highways!  Is this really a wise practice?

We need to stop this insanity.  I put a challenge out to all of the engineering firms that know better.  Please stop allowing your buildings to be drilled full of holes. Start taking the architects, building officials, and contractors to task to stop this poor building practice. Start educating the teams you work with and let’s start building smarter!


Figure 1 Vapour ‘Diffusion’ ports (holes in sheathing that act as inward water highways) on buildings under construction in North Vancouver, BC