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peach680
attic insulation

We bought a home this year built in the 60's. For some reason the previous owners thought they need to put a floor in it for storage. They did put some r-13 if that under it. I am going to blow 18 to 24 inches in to the attic. The question is do i need to pull the floor up? id rather not but been told it could trap cold/hot or moister up there. Any thoughts?
Thanks.

MLB Construction
Re: attic insulation

you should pull up the floor. leaving a gap between the ceiling and 24" of insulation above will be the perfect habitat for moisture to accumulate.

MtMan54
Re: attic insulation
peach680 wrote:

We bought a home this year built in the 60's. For some reason the previous owners thought they need to put a floor in it for storage. They did put some r-13 if that under it. I am going to blow 18 to 24 inches in to the attic. The question is do i need to pull the floor up? id rather not but been told it could trap cold/hot or moister up there. Any thoughts?
Thanks.

Hi, Adding 18 to 24 inches of insolation will not be enough if it is not the full depth out over the walls. You will see that when they installed the roof, they attached it to the top of the walls not leaving the full 24 inches of space needed for the insolation but this can be fixed. Thanks

keith3267
Re: attic insulation

The answer is really simple, if it isn't trapping moisture now, it wont trap moisture unless you add another vapor barrier. Just blowing insulation over the existing floor will not cause a moisture build up, in fact it makes moisture less likely to condense in the cavity because the cavity will be warmer. Moisture condenses on cooler surfaces, not warmer surfaces.

Make sure to address all other issues in the attic before you blow in the insulation. Look for "chimneys" that form in interior walls. When interior walls have holes in the top plates for plumbing, wiring or venting, cold attic air falls into the uninsulated wall cavities and forces warm air up and out. It can be a huge heat loss that homeowners are just not aware of. If you don't fix these, then the added insulation will not do you a lot of good.

Don't worry about insulation over the exterior wall. Make sure that the soffit vents are not blocked by the blown in insulation and that the attic remains well ventilated. You can use baffles under the roof sheeting over the exterior walls to insure that the ventilation is good.

Chuck58
Re: attic insulation

One thing to keep in mind is the attic access hatch itself which often goes without insulation. One of the reasons is because roll insulation is wider than the space between the joists - this is so that it will fit tightly between them but also prevents it from coming down with the attic hatch or attic door when you lower it into place. There is a product made specifically for the attic hatch and roll insulation - also called batt or blanket insulation. You can find it at www.ScuttleBuddy.com.

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