reinsulate or say good enough?
therealpeter
| Posted in Energy, Heating & Insulation on
A 1900 humble farm house with 4×4 rafters, bays filled with 3.5″ paper faced fiberglass @ R-11, new sheething and shingles and no no no extra headroom. The half story room is about to be re-drywalled so, A)take out the glass and put in 3″ board leaving a 1″ vent space B)add a 3/16 foil and foam layer C)save time and money, leave the glass D)a and b
E)b and c F) none of the above
Replies
A real lack of info here.
Climate is what/where?
A)take out the glass and put in 3" board leaving a 1" vent space
Vent what? You say new shingles, is there a ridge vent with soffit vents now through the FG?
My guess, and with zero info it is just a guess, spray the whole thing full with foam.
Joe H
Hey Joe, the lack of info was for the sake of brevity. We are in the Ithaca/Watkins Glen area of NY. The house is post and beam. No soffit vents, but there is a ridge vent. The rafter tails are morticed into the beam (top plate) with no opening into the eave/soffit area. Soffit venting would require drilling through the beam into each rafter bay after opening the eave. Also, keep in mind that 1900 is the newest part of a humble home. There are no vapor barriers anywhere, and quite a bit of air flow into the attic. To bring this home to contemporary standards throughout would be economically stupid. I am also leary of applying contemporary concepts to a home not designed to accomodate them. Inappropriate retrofits cause at least as many proplems as the solve. So, I am looking for compromises to keep this old car on the road for the next couple generations not to try and turn it into a brand new Prius.
Foam? It might be the best solution but what about the next guy (or me) when something goes wrong like a leak, ease of future access is an issue to which I am sensetive since it is a constant in my life.
What else do you need to know?
Answers to this post will be interesting for me, too -
So, there is a ridge vent that is allowing the conditioned air to exit.
I'd still say spray the whole thing including the vent.
That will get you the most R. Those 4x4s are going to conduct cold to your DW, you might consider strapping it to alleviate that as much as possible.
Roof leaks are another issue, you will have to deal with that no matter what you do. How good is the new roof?
Seems like you are going at this in the wrong order, but too late now. Couldawouldashoulda put a layer of foam outside the roof first to gain some R.
Joe H
Yep (or yup depending on war yur frum) we are backing into this problem from the wrong side. We should have taken the whole roof drywall to shingles and rebuilt it, but water damage became abundantly and suddenly aparent last fall...
The water problem was from bad flashing/step flashing on two dormers. It wasn't showing on the interior, we found the problem because we HEARD the carpenter ants gnawing the rotted mortise and tenons on the rafters... arrrg!
Almost all of the real problems I've encountered in the structure of this house are from areas getting and staying wet. The spray in foam seems, because of the completeness of its contact, to guarantee a soggy situation down the road. No where for the water to go? I realize the lack of air flow diminishes introduction of moist air from the interior of the house but water is mighty dang sneaky stuff...