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KittenHD
Attic insulation - foil lining?

I have a walk-in attic. We use it for storage. It has blown-in insulation and a wooden deck. It is vented. I would like to put 5" of poly-styrene down. Should I put down a vapor barrier first? I also thought about putting down 2" of insulation that has the radiant barrier on both sides. Does this perform as good or better than putting down 5" of the other? If it is better, do I have to worry about moisture?

Also, would you use the white, pink or blue poly-styrene? What is the difference? I have hear the pink and blue are bad for your health.

Timothy Miller
Re: Attic insulation - foil lining?

Howdy first is the attic framing capable of bearing additional loading- weight of contents? Second what is your climate it makes a huge difference on what and where to add or not to add moisture barriers. Is there a wood floor in the attic? How many inches of insulation is in the attic? How much weight do you plan on adding to the floor?

KittenHD
Re: Attic insulation - foil lining?

Yes, the framing can support more weight. We live In Southeast Iowa. It gets hot and humid in the summer and really cold in the winter with humidity. There is a wood floor. There is 6 1/2 inches
of blown-in insulation. This house has the old lath and plaster
walls and ceilings. I don't know the weight of the poly styrene
but I don't think it will weight too much.

canuk
Re: Attic insulation - foil lining?
KittenHD wrote:

I have a walk-in attic. We use it for storage. It has blown-in insulation and a wooden deck. It is vented. I would like to put 5" of poly-styrene down. Should I put down a vapor barrier first? I also thought about putting down 2" of insulation that has the radiant barrier on both sides. Does this perform as good or better than putting down 5" of the other? If it is better, do I have to worry about moisture?

Also, would you use the white, pink or blue poly-styrene? What is the difference? I have hear the pink and blue are bad for your health.

No idea what you mean about the health risk.

Forget the vapour barrier -- it's not needed nor would it be correctly installed inside the attic space.

KittenHD wrote:

Yes, the framing can support more weight. We live In Southeast Iowa. It gets hot and humid in the summer and really cold in the winter with humidity. There is a wood floor. There is 6 1/2 inches
of blown-in insulation. This house has the old lath and plaster
walls and ceilings. I don't know the weight of the poly styrene
but I don't think it will weight too much.

is this blown - in insulation completely touching the underside of the wood floor? If there is a space between the underside of the wood floor and the blown-in insulation then regardless how much insulation you put on top of the wood floor will not have much benefit to the living space below.

Generally the difference between the white and blue/pink --- the white is usually EPS ( expanded polystyrene ) similar to foam coffee cups --- blue/pink is XPS ( extruded polystyrene )
XPS has more R-value per inch and usually more pounds per square inch compressive strength than XPS.

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