Polyurethane spray foam insulation in exterior cavity in brick veneer wall

Archive of Older Topics Archive - Product Discussions #5
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I had started this thread earlier this year, and now the topic has come up again on another project.

We have accepted the use of spray foam insulation on one project since I started the thread. . I was not directly involved in that project and just learned about it recently. Two problems/concerns were observed on the project where the spray foam was used:

  1. Environmental sensitivity - temperature and moisture at time of application…and even greater - wind conditions. The spray can be wind blown and it is not readily removable from items that it comes in contact with i.e. cars. So - this presents a problem with construction delay if waiting for ideal conditions to minimize liability risks.
    2)The insulation is “warm” when applied and curing (at least the product that was used on our project) and it curled the fabric coated copper flashing that was already in place.

Since the first post - this is the only project of ours that I am aware that spary foam in the brick cavity has been used. As I understand it, the project turned out well and there were no problems with the spray applied insulation itself once installed.

Since this time, I believe that we accepted a voluntary alternative for the use of a spray product again - but the application has not occurred as of this time.

We also recently specified spray foam insulation as an alternate in a masonry cavity wall application. This project is still in the bid process.

We have a current project - 8 stories in a city environment - where consideration is being given to specifying spray foam insulation as the cavity wall insulation (not as an alternate). It does offer substantial cost savings which is one of the prime reasons for its potential use.

I was asked to check on other potential concerns or issues that should be considered before taking this step. Summarizing primary concerns/considerations that we currently have:

  1. Experienced applicator required.
  2. Compatability of materials that the spray foam will be in contact with i.e. flashings.
  3. Environmental conditions / control of spray to prevent damage to adjacent materials, buildings, vehicles, etc. [This was not addressed in previous thread comments - is “experienced applicator” the major factor here along with waiting for appropriate conditions…or has anyone found other control methods/requirements?].
  4. Compliance with NFPA 285 / IBC code requirements.

Other concerns/critical criteria?

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Dale:I’ve had some instances of spray foam insulation pulling away from the edges of the installation, which means that the advantage of completely filling the cavity isn’t quite met. some of the foams get relatively stiff and if you have a building wall that moves a lot from either wind, seismic or thermal expansion, you can lose the seal between the insulation and the wall framing. (for this reason in cold climates, I’ve typically used a softer spray foam that stays flexible)

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Dale:

My firm uses closed cell, medium density spray-applied foam insulation on 99.9% of our projects up here in the Great White North eh?

We use this material for a number of reasons, including good Long Term Thermal Resistance ratings, integrated vapour retarder/air barrier and ease of installation in a variety of challenging spaces/details.

I would tend to agree with comments that experienced applicator is PARAMOUNT! We have an organization called the Canadian Urethane Foam Contractors Association (check out their website… www.cufca.ca …it has a wealth of information). Not only does CUFCA have a certification program in conjunction with CAN/ULC S705.1 (Product) and S705.2 (Installation) and contractor licensing, but also offers a no-charge, independent field inspection service.

With repsect to John Bunzik’s comment that “The foam will not stick to the surface of all manufacturers peel-and-stick flashings, so be sure to do the research as to whose flashing product will work. Has to do with the coating used on the surface of the polyethylene. Talk to the foam folks.”…we use peel & stick transition membranes and through-wall flashings without any bonding issues to the membrane. ONE WORD OF CAUTION HOWEVER, when the spray foam cures, it is an exothermic reaction (ie it produces HEAT) which can and will affect the bond of peel and stick membranes to their substrates. We have added in a provision to our master spec in Part 3 under APPLICATION that states “At base of exterior walls, where through wall membrane flashing is installed, build up required insulation thickness in maximum 25mm (1) thick layers to prevent adherance failure with membrane flashing caused by heat of curing of insulation.”. This has eliminated our couple of issues with peel and stick membrane adhesion.

Also, caution must be exercised in the application of spray foam where there is a possibility of ingress into the interior (or interior use) due to the nasty fumes created when the product burns (this is no different that any foam insulation). We specify deck closures to make sure the spray foam doesn’t end up where it isn’t meant to be. If there is a requirement for exposed interior application, you will need to specify a “thermal barrier” in your spray-applied fireproofing specification. Speak to your friendly SFRM tech rep about this and be sure to specify a primer for the thermal barrier to ensure a good bond to the foam.

With regards to bonding issues, the one caution I will give is with respect to the joints in glass mat gypsum sheathing; not only between boards but also at veneer tie penetrations. Small gaps are not a problem at panel joints or otherwise. We specify a transition membrane (peel & stick) for any gaps larger than 3/8". Also we specify application in multiple layers, with a minimum 5/8" and a maximum 2" thickness per pass. The alleviates some of the shrinkage issues Anne spoke about and also allows low spots to be brought up to specified thickness with subsequent passes. Finally, we detail pressure-treated wood bucks at all openings for increased bonding as well as to get the dewpoint of the window inline with the dewpoint of the insulation and for anchoring the window across the air space.

If you have a wind-bearing stud wall back-up, you may also want to consider a minimum 25% of the overall insulation thickness be inboard of the sheathing. if we have 2 1/2" or 3" of SPF outboard of the sheathing we will specify 1" inboard of the sheathing. This combats the majority of the remaining thermal bridging issues.

As far as the issue with wind blowing the insulation around, we have never had any issues (that I am aware of) with this. Typically, the sprayer is around 6" to 8" away from the substrate during application. Obviously if you have hurricane-force winds, there is probably a better time to apply SPF, but otherwise I am not aware of any epidemic problems.

Although the majority of the standards that I quote are Canadian (eh?)and the main units of measure are metric (with imperial equivalents in parentheses), I am willing to offer my master section to anyone who may find it to be of assistance. (EDIT…oh yeah, you’ll have to deal with MF95, although I have been given the “go ahead” by the CEO to convert to MF10 early in the new year)

You can contact me at paul.gerber@rogers.com with your requests or any specific questions.

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Thank you for the additional information and suggestions. I have started to review some of the materials on the noted website.

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One thing I’ve heard suggested is that there is a requirement that the applicator own the equipment.

This means that the applicator has invested money - and presumably, time - in becoming proficient at the application.

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I’ve always felt that having their first born held as hostage works well, frowned upon by modern society, but what the hay, it works.

There is more investment there than just in equipment.

Really!? Owning the equipment! Depending upon the business model the sub is working under, (assuming subs actually have a business model, which I realize is a stretch) they may be very good and NOT own (at least some) of the equipment. General contractors routinely rent tons of equipment. For example, scaffold, cherry pickers, etc. it doesnt mean they dont know how to use them.

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Crazy question. Thinking about using closed cell foam inside a sanitary sewer vault to block the future invert and bench from flow, using it to fill up the half-pipe shaped cavity to prevent the sewage from stagnating. We need something waterproof, easy to install but also easy to remove in 1,2, or 20 years, whenever the next phase gets installed. Is this crazy? I will not be offended

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What about mortar? I would think it can be chipped out if and when that invert is ever needed? At least you know it will be durable, and last as long as required.