And........so, this Other Thing is Happening - Page 13

MrSurly · #**181** 07-11-2017, 06:52 PM

I now have an appointment with a spray foam insulation company for next Tuesday. Now, I've got to decide which option I'm going to go with:
1" of closed cell, roof and walls;
3.5" of open cell, roof and walls;
A combo of of those;

Or 5.5" open cell on either or both.
Or (more options) 2" of closed cell.

I do wish the reasoning behind the material type selection were more clear.
Different sprayers disagree on which type is better for my application.

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Fe Butte · #**182** 07-11-2017, 07:40 PM

Would something like mold grow on open cell more readily than closed cell? Or are both equally resistant to such things?

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Backroad Mike · #**183** 07-11-2017, 08:04 PM

How does the insulation choice affect the potential for trapping moisture against the inside of the steel? I'm assuming with the spray application it coats the inside of the steel. Does this eliminate the moisture potential?

Fe Butte · #**184** 07-11-2017, 09:13 PM

^^^^ That Also...^^^^

MrSurly · #**185** 07-12-2017, 08:10 AM

Those are among the questions I've asked.
First, source of moisture:
1. condensation
The claim: There won't be any; since the foam (either type) adheres directly to the metal just like paint, there is no space or void available for warm (moist) air to contact the (cool) metal so condensation will not occur there. where warm moist air is available (inside the room) it will only contact foam which will be the same temp as the air, so, no condensation can occur there, either.

2. intrusion (leaks)
The first thing is that there seems to be a consensus on one point: metal roof attached with screws *WILL* have water intrusion, sometime, somewhere.
Now, what happens next is about which type of foam you have.
This is where the answers are not as clear.

Short term/ immediate indication:
Closed cell: You will have no indication that any intrusion has happened; the CC foam provides a barrier itself so any water that gets through the metal can't go any further so no leak through. (sounds like we have the perfect answer....but wait)

Open Cell: Water leak through the metal is absorbed into the OC foam because it's just like a sponge. It's actually virtually identical to the foam in couch cushions. You'll notice a wet spot on the foam that might be a couple of square feet and eventually a drip if the leak is very large.

Long Term:
Closed cell>
PROS: Virtually leak-proof, should last ages, air/water/vapor barrier; excellent thermal barrier @R7pi, hard surfaced, rugged, provides structural bond and structural support.

CONS:can eventually be damaged by water that is in contact with it, leading to foam rot and rusting metal that occurs out of sight until eventually discovered (perhaps much later).
Removal of product and metal for repair is extremely difficult. Not effective as sound insulator or absorbent. Cost to install (per inch of thickness) is three times greater than OC.

Open Cell>
PROS:
Leaks can be noticed, the leak located and repaired before any damage occurs and the foam will simply dry out (slowly). Less costly (per inch) than CC.
Provides good air seal (considered an air barrier and vapor barrier) Superb sound barrier. Good thermal barrier @R3.5pi.

CONS:
Easily damaged by incidental contact (one can easily jam fingers into the stuff and rip out fist-sized chunks; got kids or cats around?) Not a water barrier; Leaks that occur in hidden areas could be very ugly. Takes more thickness to achieve similar R value.

Dinero · #**186** 07-12-2017, 08:13 AM

Contractors are going to recommend the type they sell. Find a couple of builders, kit makers or other manufacturers and see what they think when they don't have a dog in the fight.

Spray foam insulation does "seal" and protect the steel, but it does require someone who knows what he is doing.

BenBoosted · #**187** 07-13-2017, 12:35 PM

Nice progress Ricky!!!

MrSurly · #**188** 07-15-2017, 11:26 PM

I have decided on an approach to get the best bang for the buck with the foam; there will three ways the foam is installed all at once, on Tuesday. Now, I have to really crank it up to get all the metal and trim and a jillion screws all finished beforehand.
Here's a peek at my weekend.