high tech insulation

joe beer

i have a 100 year old home that has very little insulation. the best that i can find is about two inches of cray faced batt that seems to be made out of hair and straw, in the walls and under the floor in the attic. note the attic is not vented through sofit. (yet)

also a tid bit of info needed for the reader is the roof line extends into the living space. or rather cutting through the closets on either side of the upstairs.

my plan is to rip up the floor in the attic remove the hair and straw and use blow in for that, as for the walls \ roof in the closets i'm thinking of removing the plaster, to access the outside walls where the wall meets the roof. creating a space for air to travel along the inside of the roof. by drilling some holes directly under the roof boards to the outside, then insulating with two inches of polystyrene, leaving approx two inches above that for air to travel upwards. then before replacing the sheet rock, i'm thinking of using a layer of reflective or reflecex as both a vapor barrier and as insulation.

of course every manufacturer will tell me the same thing. that useing their product will be the best ever. therefore im looking for the approval of some seasoned vets.

would r-5 polystyrene plus r -13 reflecex give me the money saving insulation that i'm looking for or will i be just sweating in the summer, freezing in the winter?
thanks

747

You can insulate a existing older home. find a insulating guy which specializes in spray foam insulation. For your type of house he will go with the foam which rises instead of expanding so the plaster won't blow out. It won't be cheap but it can be done with him just making a few small holes upper and lower between studs once completed they can be patched no problem.

bigMikeB

Spray foam is the best and an added benefit is not having to add a vapor barrier

joe beer

i have thought of those as a good alternative, however how would i then vent the roof line.

747

Thats over my head.

crecore

He means make sure the peak is vented so the air can flow through the soffit out the peak. You just remove the cap shingles (if it's shingled), cut back the plywood approx. 2" (varies by product), use a product like rolled roof vent, and install new shingled cap with extra long roofing nails. This creates an air gap on either side of the cap, wind flowing over the roof will create an area of negative pressure and draw the air in from the soffits and along the underside of the roof.

NateHanson

You won't get much airflow if the joists have expanding foam sprayed into the voids between them.

I'm not sure how this is handled with spray foam. I'd guess you need to put some sort of baffle below the roof deck before spraying the insulation.

joe beer

perhaps these images will shed some light on my meaning... you'll note that there is no soffit at all. but a place for one there is. within the space where you see the small window is a closet. the top of the window is at about four feet from the floor. my thinking is to remove the inside walls from the closet to acsess the exterior wall as to insulate it and then create an air hole in the area directly below the roof line so air can rise up. im thinking this will work, but i worry about weakening the roof itself...


thanks for all of the advice

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