Spray foam

I had heard that spray foam can make a building stronger "by 20%" which is a little bit, well that was way off.
Well depending on the specific test it can make the building several times stronger.





Pulled from here:
Spray Foam Strengthens Your Home and Enhances Overall Building Stability | Pentoir

Just something to think about.
This is the 2 part foam "A+B" foam, not the canned stuff.

 

Not surprised....the stuff is fairly rigid. But I'll also mention it burns like pine fat wood, with heavy black smoke.....so make dang sure you drywall over it, not wood.

 

The science of structures and their strengths are absolutely fascinating. A single 2-4 standing alone doesn't have much strength, it buckles or deflects and fails, take 2 of them and tie them together with plywood or foam or dry wall even, so they don't defect and they are much stronger. Likewise if you make a carrying beam out of 2 2-8's it is strong, but put even a 1/2 in piece of plywood in between and nail or glue them, and it is much stronger as the plywood resists defection and carries stresses across defects in the beams. Building a structure so it doesn't fail is both an art and a science, usually found out when a diy has the ceiling over a large window sag, or floors sag, etc. My limited take on foam may be obsolete now, but used to be a lot of bad chemicals used in placing , it was very difficult to clean up the application equipment and you had to use some pretty heavy solvents, its expansion after it was placed was impressive and could warp walls, push out plywood, etc, they out gassed for months, the smoke of the burning was toxic, and the dripping melted burning foam was perfectly designed to rapidly spread the fire and give off toxic smoke. It does seal all cracks and give you a very tight structure. My limited advice is if you are going to use foam beyond a couple small cans, hire a pro, don't reinvent the wheel and make all the mistakes over again.

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R30 for me.
Steel reinforced concrete over that, inside and out.
Finally the general Insurances companies recognize just the phrase "Concrete" Roof and or "Concrete" walls.
Our insurance just dropped by 75% and coverage increased by 25%.

 

3 inches of rigid foam insulation equals 10 inches of fiberglass batt insulation , in todays insulation codes , as of a few years ago . Back in the 70s when the foam came out , or when I became aware of it , it was highly regarded , but later found out that it emitted formaldyhyde fumes , and then it was widely prohibited , as it was making people sick from the fumes ,but not before numerous homes and businesses were insulated with this material . Today , they are using different chemicals in the foam used today , mostly water based , versus 40+ years ago . It does make a stronger , tighter building , but the cost , at my last usage , 2015 , was about 3 times the cost of fiberglass batt insulation . It has it's advantages , and disadvantages . In my opinion , if your going to use it , make sure your framing and exterior sheathing , walls and roofs have been properly built and exterior waterproofing is done correctly , Tyvek , etc , because tearing that stuff out to replace wet and rotted wood is going to be a pain in the a$$ job .

 

My A+B foam set costs $300 and only puts out like 10 cubic feet of foam.

 

Tell ya a real world story about Tyvek (house wrap for those unfamiliar with it).

1984, I built my house and used it...expensive at the time compared to regular tarpaper, but supposed to be 'great stuff' because it would allow water vapor to pass, but block air infiltration....so I sprung for it. Paper was extremely tough....no way you could tear it. I used about 50% brick on the house exterior, the rest was board/batten white pine, stained with Sherwin Williams exterior stain.

2006: Got tired of the pine siding, pulled it all off to replace with vinyl. The Tyvek was all to pieces...literally falling apart....couldn't find a solid pc bigger than my hand, and it ripped like tissue paper. Went back with 30lb felt, which I've pulled off 100yr old buildings looking like the day it was installed. No more 'high tech' building papers for me !

House late 80's


House today:

 

Personally I frame with only treated wood. The least anyone should do is on a slab use treated on the parts that meet concrete or all that are in the bath room or any place that has water piped in.

 

one of the big advantages of foam insulation - according to the "experts" - is the ability of applying it directly to the underside of the roof sheathing - great for something like a cathedral ceiling ....

 

That's the 1st time I've heard of this happening . They do have other house wraps that I've seen do that , bot not the actual Tyvek brand , but I'm not doubting your word at all .

 

The Tyvek failure,What do you attribute that to?

 

I'll agree with you on the treated to concrete , plus it's code for treated to be used anywhere wood meets concrete , block or brick . The only thing with using treated studs for framing around a bathroom is the high probability of warpage which will show in most finished walls . Treated joists is a plus , treated plywood will warp pretty bad as well . The number 1 thing I always try to do when building is if any way possible , is try to have quick access to all plumbing fixtures inside of walls , drains or supply lines in floors or ceilings, buy using decorative trap doors if possible . And check them frequently.

 

I would expect heat buildup with a lack of air between sheathing and siding , or just a plain crap product . That's just my guess.

 

Until it breaks the bond and falls.
On site expert.

 

A straight edge and well cured wood prevents the warpage.
Finished wood is only a figure of speech and a carpenter is in charge of straight edges and table saws.

 

True !! I guess I was basically stating that for your typical wet treated lumber you're going to haul home from Home Depot , it's going to twist . And very few of the framers you could hire off the streets bother to look down a board to see which way the crown is , or care's . But , in a DIY situation , you know it'll be done right .

 

Fireproof | Airkrete - All Green Spray Foam Insulation!

 

I buy a lot of treated wood.
I try to get the straight ones and let them dry for a few weeks. Some still warp.
If I find a straight dry one at the hard ware store, definitely get it.
I put it around doors and windows.
All water damage repairs done with treated so if it gets wet again it doesn't start rotting immediately.

 

The tarpaper is the garage.....it was just fine when siding removed. As for heat being a factor, I think not....since this wall (kitchen) gets only some sun in the morning, and is shaded by trees even then. I've actually run up on a discussion in the past on the Fine Homebuilding forum that talks about this very failure of Tyvek. I'd imagine the low number of reports are due more to lack of siding removed over the years to actually see it.....for example, those areas I bricked, it's STILL there, although in what shape I can't say of course.

 

No idea.....just know what I found....and I ain't getting fooled twice.