Need help with an attic insulation project
Hi. I am considering re-insulating my new old (drafty in winter) home. We live in southeast PA . It is a ranch house about 987 sq ft. I am considering this project after finally inspecting the current attic insulation.
Apparently what the previous owners had done was simply install batts on top of what looks like the original batt insulation. Needless to say that original insulation has deteriorated to such a bad degree that it is disgusting. The old paper facing just crumbles to dust and the fiber glass is so matted down that we, in effect, have just one layer of somewhat newer R-19 on top of that old stuff or what’s left of the old stuff.
There were a few rolls of newer foil-faced Certainteed R-19 batts left up in the attic too. Would they be OK to use up? They are still rolled up as if just bought. Is foil-faced still an OK technology to use?
My plan is to remove all of the old matted batts that are under the newer unfaced batts and, while I am at it, find all of the ceiling air leaks I can and seal those per the instructions I’ve found on FHB. Then I will place new R-19 kraft faced batts down first and place, on top of those, the R-19 un-faced batts that are already up there (currently the ones on top of the old matted batts) to save some money. I have about 760 lineal feet of batts to deal with, 16 inch on center joists. BTW the ceiling joists are only 2″ x 4″ believe it or not. House was built in 1952. Has continuous soffit vents and a ridge vent (added later) plus it has two gable vents.
I’m going to use batts for their ease of installation and I read somewhere (maybe in FHB) that blown in cellulose is not so green and has problems if it gets damp. Plus isn’t cellulose an organic product and would be subject to eventual deterioration over the years, just like the old paper facing crumbling on those old batt insulation?
Should I close off the gable vents? I’ve seen that suggested in articles here by building scientist Joe Lstiburek. I’ve calculated the soffit vent area to be 5.8 sq. ft. total and the ridge vent to be approx the same. The soffit vent area I’ve calculated is based on the groove cut into the soffit being 1″ wide and 34.9 ft long (2 of them). I don’t know the effective net area of the vent covers that run along the groove or the net area of the ridge vent either so those calculation are most likely less. I’ve read that the ratio should be 1:300 for venting.
The soffit vents seem to be an old style, a thin bent sheet metal with perforations almost like expanded metal.
Thanks. Sorry for the long-windedness.
Replies
Since no one is replying to this problem I am having , could someone forward this to Martin Holladay at Green Building Advisor.com ? I tried to send this to him but for some reason I kept getting a "Failed Delivery message". Thanks
pizza
I sent him a link to your thread-it said it made it.
Best of luck.
pizza
and then this morning I get the "mail delivery system" email that Martin's address doesn't exist...........
I passed the note along
Hey guys,
I'll send a note to Martin saying you were trying to contact him.
You might also want to repost your question in the GBA forum—energy-efficiency questions get answered pretty quickly over there, and the forum is full of the biggest energy geeks (I mean that in the nicest way).
Here's the link: http://www.greenbuildingadvisor.com/qa
I'm not sure about this, but there's a chance that the username and password you use here will automatically work on GBA too. Try it first and then create a simple free account over there if you need to.
If you want to contact Martin (or anyone else at GBA) directly, use the email form on this page:
http://www.greenbuildingadvisor.com/contact
Martin and I see any editorial emails sent through that form.
Good luck!
Rob Wotzak, Web producer, finehomebuilding.com
Attic insulation
My e-mail address is martin [at] greenbuildingadvisor [dot] com.
Q. "There were a few rolls of newer foil-faced Certainteed R-19 batts left up in the attic too. Would they be OK to use up?"
A. Yes, as long as the foil facing faces the ceiling drywall.
Q. "Plus isn't cellulose an organic product and would be subject to eventual deterioration over the years, just like the old paper facing crumbling on those old batt insulation?"
A. Cellulose insulation is an excellent product for attic floors. Of course, if any insulation gets soaked by rain, it might get ruined. But unless your rooof has a major roof leak, your cellulose insulation will last for many decades.
Q. "Should I close off the gable vents?"
A. If you want a ventilated attic, the preferred method is to use balanced soffit vents and ridge vents. It's OK to block up your gable vents if you want. But there is no need to. Unless you have ice damming or mold problems, there really isn't any reason to worry about your attic ventilation. Nor is there any need to calculate the net free area of your vents. Just relax.