spray foam insulation - dangers and downfalls

[mound]

I found this interesting:
https://vtdigger.org/2023/05/22/i-wanted...omeowners/

[Snipe Hunter]

I've inspected a few homes where the spray foam was an issue. Personally, I'd never put it in a wall. Between roof rafters... maybe.

BTW, there are several class action suits aimed at spray foam manufacturers.

Most homes are built where the walls can breath a little and provide a means to dry out. The siding is designed to breath, house wrap is designed to breath. Sheathing will breath some. Even brick facades have an air gap between it and the wall and weep holes so it can dry out. Stucco has an air gap. This is necessary to prevent mold and water damage.

The issues I've seen are rotted sheathing, rotted wood trim and uncured foam. You could smell the uncured foam as soon as you entered the home. We didn't know what it was but after a little investigation, we (including a spray foam contractor) figured it out. The exterior walls had to have the drywall removed and the spray foam removed. Fortunately, the buyers were able to get out of the contract. I haven't seen it personally but roof sheathing will also rot if the roof leaks as foam traps the water and the sheathing can't dry. Another home 9not my inspection) had MDF siding. Looks kind of like Hardie Siding. Not sure why anybody would make siding out of MDF. In that case, the wood 1x trim around the doors and window looked fine but it pulled right off the house. The MDF siding was basically mush behind the trim.

I think there's a fundamental flaw with how spray foam is installed. The same flaw with how EIFS was incorrectly installed causing lawsuits. There is no open area between it and the structure. I'd like to see some sort of rigid porous board in the cavity against the siding and the studs before spraying. There are rigid fiberglass insulation panels that would work but that would probably negate the labor savings of spray foam.

They claim the newer spray foam is "open cell" and it is... except where in contacts the structure. It creates a seal.

[Cabinet Monkey]

They claim the newer spray foam is "open cell" and it is... except where in contacts the structure. It creates a seal.

Not to be argumentative, but.......................................

if it creates such a tight and permanent seal, how does water or air get through in the first place ?

[Snipe Hunter]

Not to be argumentative, but.......................................

if it creates such a tight and permanent seal, how does water or air get through in the first place ?

Moisture moves in and out of walls all the time. Modern walls are designed to allow the transfer of air and a means to shed water. Air has water in it. It's slowed/controlled by siding, vapor retarders (House wrap), paint etc. If they can't breath, moisture gets trapped inside the wall. When moisture gets trapped, wood rots.

Water in the air will condense on the 1st thing it sees cooler than itself. The last thing we want is a "tight and permanent seal" on an exterior wall.

The new thing is "Spray On Vinyl' siding. It's already causing problems.

[Bill Wilson]

Moisture moves in and out of walls all the time. Modern walls are designed to allow the transfer of air and a means to shed water. Air has water in it. It's slowed/controlled by siding, vapor retarders (House wrap), paint etc. If they can't breath, moisture gets trapped inside the wall. When moisture gets trapped, wood rots.

Water in the air will condense on the 1st thing it sees cooler than itself. The last thing we want is a "tight and permanent seal" on an exterior wall.

The new thing is "Spray On Vinyl' siding. It's already causing problems.

My Dad worked in construction most of his life.  He used to say all the time that houses had to breathe.  This was in the 70's & 80's when contractors were trying to make homes more energy efficient by sealing them up.  It's amazing to me that the industry is still learning that lesson.

[vernonator]

We are building a new home right now and our Contractor will NOT use sprayfoam as the primary insulation. Before getting into custom homes they did alot of remodel work. They said in they saw more mold/moisture issues in foamed houses than in those using more traditional insulation. For our house they did spray the sill plates and all the penetrations in the top/bottom plates, etc. For the walls they did the system (I cannot remember the name) where they put up mesh on the walls then blow in loose fiberglass fill (its REALLY densely packed), while the attic is traditional blown in insulation.

Cabinet Monkey - the sheathing leaks and then the water cannot migrate thru the insulation and so it sits and rots.

[Cabinet Monkey]

Cabinet Monkey - the sheathing leaks and then the water cannot migrate thru the insulation and so it sits and rots.

If it leaks , then the insulation couldn’t have possibly “sealed” the panel, right ?


There’s nothing inherently wrong with the product. The issues arise because the product is improperly specified or applied.  

What works for a dwelling in New England doesn’t work so well in central Georgia, and neither works great in the Pacific Northwest.  

If the conditions are right ( poor specification and or install technique) issues occur in wall assemblies insulated with fiberglass, cotton, cellulose, and rock wool ……I’ve seen first hand.  Does that mean all those products shouldn’t be used or considered ?

[vernonator]

If it leaks , then the insulation couldn’t have possibly “sealed” the panel, right ?


There’s nothing inherently wrong with the product. The issues arise because the product is improperly specified or applied.  

What works for a dwelling in New England doesn’t work so well in central Georgia, and neither works great in the Pacific Northwest.  

If the conditions are right ( poor specification and or install technique) issues occur in wall assemblies insulated with fiberglass, cotton, cellulose, and rock wool ……I’ve seen first hand.  Does that mean all those products shouldn’t be used or considered ?

The sprayfoam does not penetrate the seams in the roof/siding. Water can still migrate thru those and get trapped, or as said above you get condensation on the underside of the panel. Trapped water = rot.

[blackhat]

The take away should be that spray foam isn’t  the miracle many touted it to be. It can be very effective. It is less forgiving then conventional products if misused or improperly applied.

[FireWood]

The take away should be that spray foam isn’t  the miracle many touted it to be. It can be very effective. It is less forgiving then conventional products if misused or improperly applied.

This.

Spray foam on a tightly sheathed house, like properly applied zip system with all joints and penetrations sealed and taped, works very very well.

spray foam on the back of sheathing or roof decking that has gaps and unsealed seams can be problematic because water can get into the gaps and wick through the fibers of the wood along the back side of the sheathing and siding.

That water WON'T get into the house, so the homeowner is fat, dumb, and happy while the sheathing around their house is rotting.

I suspect this is especially problematic with houses sided in composites or vinyl.  Around here, any house with wood siding and paint will clearly show problems via peeling and sagging paint, long before the sheathing rots.