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mf_111759
foam attic insulation application

I live in the panhandle of Texas, where we can have several 100+ days in the summer and temps below 10 in the winter.

My attic currently has blown-in fiberglass insulation about 5-6 inches deep. The attic is ventilated with soffit vents and an attic fan that operates when the attic temp exceeds 90 degrees.

I would like to remove the fiberglass insulation and replace it with a spray-in foam like Icynene (icynene.com). From what I've seen, it appears that the foam products are usually applied in the rafters of the roof.

So, my first question is this. Is it ok to intall the spray-in foam in the ceiling joists and if so, does any of the wiring or ductwork or electrical boxes have to be protected from the foam? I would prefer this type of application to hopefully eliminate a bad dust problem that appears to originate in the attic.

If a celing application is not recommended and the foam is instead applied in the rafters of the roof, would I then need to seal off the attic fan and plug the soffit vents so that the attic would be a closed environment? Would the fiberglass insulation in the ceiling joists need to be removed - what is the best/easiest way to remove it?

Thanks for any help and guidance.

canuk
Re: foam attic insulation application
mf_111759 wrote:

I live in the panhandle of Texas, where we can have several 100+ days in the summer and temps below 10 in the winter.

My attic currently has blown-in fiberglass insulation about 5-6 inches deep. The attic is ventilated with soffit vents and an attic fan that operates when the attic temp exceeds 90 degrees.

I would like to remove the fiberglass insulation and replace it with a spray-in foam like Icynene (icynene.com). From what I've seen, it appears that the foam products are usually applied in the rafters of the roof.

So, my first question is this. Is it ok to intall the spray-in foam in the ceiling joists and if so, does any of the wiring or ductwork or electrical boxes have to be protected from the foam? I would prefer this type of application to hopefully eliminate a bad dust problem that appears to originate in the attic.

If a celing application is not recommended and the foam is instead applied in the rafters of the roof, would I then need to seal off the attic fan and plug the soffit vents so that the attic would be a closed environment? Would the fiberglass insulation in the ceiling joists need to be removed - what is the best/easiest way to remove it?

Thanks for any help and guidance.

Two things with your current setup that can be easily resolved more economically than spraying foam into the attic.

First thing is the mention of a dust problem orginating from the attic.

By this I'm getting you mean dust from the attic is an issue within the living space below.
What this says is there are openings between the living space and the attic which freely allows your heat to escape into attic during the colder temps.
Also during the hotter temps. heat is allowed to enter the living space making it more difficult to cool the home.
This would be the first thing to relsove before insulating and make an immediate difference. Air seal all the pentrations to keep heat loss / gain to a minimum and keep the dust out.

Secondly, 5-6 inches of insulation in the attic ?

You barely have an R10 at best which is not nearly enough to do much of anything as far as insulation.for heat transfer.
If you ( after air sealing all penetrations first ) blow in 12 - 18 inches of cellulose into attic , combined with proper venting , would provide you with a very good insulation level and temperature relief for a modest cost --- biggest bang for the buck.

Yes, spray in foam can be applied to the bottom section of the attic instead.
If you like , have 1-1/2 inch spray foam applied between each ceiling joist , then blow in 12 - 18 inches of cellulose. The foam will seal the pentrations and provide some R value---- the cellulose provide the rest of the R value.
The attic venting is also required here.

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