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Replace Fiberglass Insulation with Foam

One more foam vs fiberglass question.

Other than the cost, any down side to replacing ceiling fiberglass batting with foam?

I know of a few issues in open vs closed cell: closed better R value and better if in contact with moisture/water. Any others?

As I mentioned in another post, I have kraft faced fiberglass insulation on top of tongue and groove ceiling boards. My concern is the loss of heat in winter, and heat gain in summer since the T&G boards do not make a air tight seal.

Would removing the batts and applying foam be a good energy efficiency plan?


Re: Replace Fiberglass Insulation with Foam

Spray foam insulation if applied correctly will also seal any penetrations and gaps preventing air movement ... something fiber glass won't do.

The problem with fiber glass bat insulation is the insulation performance is reduced in moving air ... in a static air environment fiber glass bat insulation will perform adequately.
The insulation performance is also reduced when fiber glass bat insulation gets wet .

Hope this helps.:)

Re: Replace Fiberglass Insulation with Foam

It does.

In your opinion, there would be not problems applying the foam directly to the T&G boards thereby sealing them form air movement up or down?

For a vented ceiling in NC would you recommend open or closed cell?


Re: Replace Fiberglass Insulation with Foam

I would say closed cell if you want to stop air movement. You might want to take a look at this http://www.foam-tech.com/products/urethane_foam/open_closed_cell.htm

Re: Replace Fiberglass Insulation with Foam

I would recommend the 2lb closed cell foam applied to the attic floor. Have 5.5-6" installed. this will give you an excellent r-value and make your home alot more comfortable and energy efficient.

the other nice thing about having 2lb closed cell foam installed, is you can walk just about anywhere without the worry of falling through... depending on your weight. I'm 170lb and have walked on many ceilings with 5.6-6" of 2lb foam installed.

Re: Replace Fiberglass Insulation with Foam

Excellent information! Thanks and just in time since I hope to have a foam installation company visit today for a quote.

One other question I overlooked. What about foam installation on a sloped ceiling?

The flat ceiling will be easy and the one being looked at today. The other half of the ceiling is sloped and consists of 2x12's with kraft faced batting between them. T&G boards on the inside/ceiling and roof decking on top (I hope there is a gap for venting). I am almost positive that it will be impossible to remove the batting and spray foam in the cavity.

The roof will need replacing in the future. My thought is to have the roof decking removed. pull out the batting, then spray foam to the ceiling T&G boards. Again this would seal the T&G board gaps.

So, it should not matter where the foam is sprayed in my situation, correct? Can the faom be sprayed to the ceiling boards vs roof decking, leaving a space for the cavities to vent?

Many Thanks!

Re: Replace Fiberglass Insulation with Foam

One of the great things about foam insulation is that i sticks to just about anything. You can spray it in an overhead and it will stay. One of the bad things about foam insulation is that it sticks to about anything.:D

Re: Replace Fiberglass Insulation with Foam

Report from first contractor:

Uses open-cell foam in the attic.

Would spray to R-20.

Was concerned with foam penetrating around T&G boards since foam is sprayed at 2,000 psi.

Was concerned about low slope of roof line. Installer needs to be back two to three feet to prevent foam blowing back onto installer.

Initially was wanting to spray the roof decking vs ceiling. I explained about the air gaps in the T&G boards.

Your thoughts?

Re: Replace Fiberglass Insulation with Foam

where are you located? the reason I ask is to make sure that r-20 will be enough. I wouldn't recommend open cell in an attic space because if the roof were to leak the open cell insulation will soak up the water and it is a nightmare to remove, plus the water damage is also a nightmare.

if you spray the back side of the roof, you also have to do the gable ends aswell

r-20 of open cell is about 7" thick

the 2000psi seems kind of high, we spray about 12-1300 and it doesn't come out at that pressure like a car wash gun.

call some more contractors.

Re: Replace Fiberglass Insulation with Foam

1] open cell foam soaks up water.
2]you can blow air through open cell foam
3]open cell foam is not solid enoug to walk on.

If you have large gaping cracks do what Canuk would do and tape the cracks where the foam is going with duct tape. If some does come through you can scrap and sand it off.

Suggest you talk to another foam installer, the one you had should have known better. Just my humble opinion.

Re: Replace Fiberglass Insulation with Foam

Location is North Carolina.

I agree on not using open cell in the attic due to roof leaks. At least the is what I have read.

Yes, the contractor did say spraying the roof deck would also require spraying the gables. But in my case, that would not cure the air leaks around the T&G boards.

I have watched a few videos from companies that sell foam applicators. TigerFoam for one. It did not appear to be spraying at a high psi. Also the spray gun was no more than twelve inches from the area being foamed.

Are there any tricks or special spray gun nozzles (long or curved nozzle) that allow you to get into tight areas such as where the roof trusses attach to the ceiling rafters?

I really do not want to DIY the type of work, but I may have to if no ones wants to do the work.

I have calls in to two more contractors.


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