I live in CT, in a 100+ year old house. We have hot summers and COLD winters. I believe that our attic floor was previously insulated, as our house winter temperatures are easily controlled. Still I cannot easily verify that insulation. nor amount/ depth - as there is hardwood flooring in place.
There is no insualtion, on the attic roof insides. I would like to add insualtion, and looking for guidance. What should I buy for insualtion, which side facing the roof. Do I need to take efforts, to provide any air flow ? (There is no roof peak vent). Should I use a vapor barrier, over the new insualtion?
Would there be any issue/ concern, if I then put drywall over the insualtion, to make the attic into a finished room?
From your description there will be no gain from insulating the rafters unless you're going to finish and occupy that space . I'd only insulate the actual finished space , that is up the rafters to ceiling height then across the ceiling . Use the plastic trays they make to go between rafters to insure convective airflow , and your current attic venting system should work just fine . I wouldn't finish all the way to the peak , leave a space for airflow to whatever venting you currently have . Most insulation carries a vapor barrier , which always goes toward the occupied space .
Your post isn't entirely clear. You plan to finish the attic off? If not then you should figure out what's in the floor. You may not need to insulate the rafters. If you are going to use the attic as living space you should have a ridge vent put in and soffet vents. (Or you can build knee walls and leave the eves unfinished. In a house that old there's plenty of draft so that you really wouldn't need soffet vents. But you should insulate the knee walls.)
Put in fiberglass batts and cover with plastic sheeting before the drywall goes on. I like to use the faced insulation and then cut some of the facing away so that moisture isn't trapped between that and the plastic. You don't need facing. It's just easier to put up that way.
There needs to be an air space between the roof and the fiberglass. You can plan the batt size for that, use the corrugated fillers designed for the purpose, or whatever makes sense. The idea is just that you need to allow for air flow. The roof is pretty much a moisture barrier. If you put another moisture barrier on the inside then you need to allow airflow under the roof. Thus the soffet and ridge vents. Otherwise it's likely the roof deck would rot over time.
It's unusual to have an attic floor done in hardwood, yet the rest of the attic is unfinished. Depending on the space, it may not be worth finishing, unless you wind up with something reasonable. Depending on the rafter widths, he may want to sister support wood for sheetrock to the existing rafters thereby giving more room for insulation. Otherwise, with say 2x8' rafters, by the time you put those plastic baffles for airflow in, you only have ~6" of insulation, which isn't much for CT. But of course with the sistering, you would lose more headroom.
Also, he said there is no roof peak vent. How about gable vents? Soffit vents? If it's an unfinished attic, there should be adequate venting consisting typically of soffit vents together with exit venting up high. You said his existing vent system should work fine, but he never said what, if any, there was.
Presumptive of me ... but there's surely some kind of venting , probably gable and soffit . And I'd like to change something - insulate only the new space , that is the wall framing and ceiling , rafters only if they become framing for the newly enclosed space . And still use the plastic channel thingies in any insulated rafter space . And if there is no venting , he needs to add some - typically turbines or peak vents and soffit vents in a retrofit .
Your first issues are to stop all air pathways from the heated space(s) to unheated. Insulation of the fiberglass type does virtually nothing if there's any air movement at all thru it.
There are real possibilities of introducing condensation surfaces by have double layers of insulation in attics in particular. Since you apparently have an insulated ceiling now/future floor, you need to be careful you don't turn that into one of those areas where cold infiltration along the edges of it allows condensation since if you finish above it will now also be heated space.
As another said, if you are going to finish the attic into heated living space, likely it will be more efficient if there's the height in sidewalls to build another ceiling rather than insulate clear to the roof line itself. If you're _NOT_ going to add heated space then you want to simply add more on what is now the attic floor.
You can guesstimate what's there pretty well by looking at the thickness of the opening to get up there. If it's a framed hole w/ a ladder, should be relatively easy to see what the ceiling/floor joists are. If there's a finished stairway, still should be able to get a measurement/estimate of the distance between the ceiling below and the floor above -- subtract for the flooring and ceiling thicknesses and you should be able to tell if 2x4, 2x6, 2x8 (nominal sizes) was used. Assume either blown or fiberglass or perhaps rockwool depending on when you think such insulation may have been added and whether know if the flooring was in place first or not and can get at least a reasonable guess of what the R-value will be...
Also whether you've got enough floor there to actually convert to living space without additional structural work...
I'm in Michigan, therefore, we may experience similar weather. I have a bungalow with finished basement and upstairs. Thus, I had my house (attic and rim joists) insulated with spray foam. I used open cell foam on the roof deck and closed cell in the foundation rim joist. There is probably a 3 to 4 degree difference from the basement to the upstairs in summer and winter. Hot air will always rise, but a 4 degree difference is nothing when it used to be 10 +. With proper insulated windows, my entire house went from an absurd out of range efficient drain to one of the top 4% in this region, based on a blower door test and infrared reading before and after.
Overall, I was shocked at the low cost to have this done (at least in my area). Just thought I'd share in case you want to consider a different route altogether.
From the many useful posts, in response to my post. I realize I did not fully describe my attic situation.
The house, being over 100 years old does have hard wood (maple? ) floors. The area with with over 8 feet ceiling clearance is a ~ 20 x
40 feet area , then with sloped sides.
I live on Long Island Sound. Tthe views from the attic are the best we have - which is why I may finish the room. I now use part of the attic, for a workshop (rest now storage). In the summer, it is often too hot to work there , indeed the heat permeates the entire house. I thought that the ceiling insulation would limit the summer heat issue, while improving the winter heating.
I agree that the attic floor boards are likely 2 x 8. where the current insulation is located. The roof rafters are 2 x 6 (note, these are near full demenions. vs current board standards).
| I thought that the ceiling insulation would limit the summer heat issue, | while improving the winter heating. | Yes. So maybe you want to insulate it. If there are further questions they can be answered, but you already have directions on how to proceed. Insulation in the floor won't hurt. It will just be sound insulation. If I were you, before finishing off the ceiling, I'd also consider putting in a ceiling exhaust fan for summer, so you can pull in cool air. Once you're done the attic won't cook the way it does now without insulation, but heat rises, so it will still probably be hotter up there than in the rest of the house. A good vent fan in the attic will also help cool off the whole house quickly on summer evenings.
I have our attic finished. First thing I do when I get home on summer evenings is turn on exhaust fans in the attic window and a second floor bedroom window. With windows open on the first floor the whole house then gets an air change.
If the new ceiling is going to follow the roof rafters, you have two considerations. One is the existing 6" rafters are only going to allow for about 4.5" of insulation, which isn't much. The rest of the space will be taken up by the ventilation baffles/channels that need to run from the eaves, where hopefully there is venting, to the ridge, where you'll have a ridge vent. The other problem is that nailing sheetrock to the rafters is going to increase the load and depending on the span, 2x6 may no longer be adequate. Both of those could be solved by sistering the existing rafters, giving you more strength, more room for insulation.
It's not surprising that it's too hot to work up there. It's a totally unfinshed attic and I would think even on a moderate spring day it would be 100F.
On 12/19/2014 1:23 PM, KenK wrote:> CRNG wrote in > news: snipped-for-privacy@4ax.com: > >> I went shopping for an auto battery this week and noticed that all of >> them once again have removerable caps for inspecting and adding >> distilled water when required. >> >> That is the way the batteries used to be many years ago, but then they >> changed to "fill-less" batteries some time in the past. The fill-less >> batts didn't have removal caps to add water. Now we are back to the >> fillable batts. >> >> What caused the change back? Anyone know? > > I didn't know there was a problem. None of the batteries I've purchased > have ever lacked removable fill caps.
Not enough information. First: You must find out _if_ you already have insulation under your flooring. Second: You must verify _if_ the area above the flooring is conditioned space.
Planning on how to insulate at this point, is wasted effort without the facts.
While I have never removed any of the attic floor boards, I am most confident that there is indeed insulklation. I can easily heat (cool) the 1st two floor's ambinet temps, with no excessive heat loss. I want to insulate the attic ceiling to limit the heat gain (summer) / Loss (winter).
Note: It is not my current intent to heat/ cool our attic area. If I ever finish the area, I do have ezisting heat and AC ducting available (now capped)
I have eight "swing open" attic window panels, that I open in the summer months. While using floor fans, the attic temp rise (hot day) can still be most uncomfortable - when I use it as my workshop.
If you decide to insulate the rafters. It is important to have adequate ventilation between the insulation and sheathing. If not, you will get condensation in the winter and rot the sheathing. There's no what if's, the fact is you will. By the time you see the condensation, it will be only after the sheathing is saturated and will no longer absorb the condensation.
If you're going to convert attic into occupied/living space might it make sense to replace the roof rafters with wider ones(2x6" repl with 2x8") to allow thicker batts and still have 1-2" of space between the batts and the roofing itself?
My roof is(at best) 2x6" rafter beams, so I couldn't get thicker than 4" fiberglass batts in there if I were preparing for occupation.
And a general rule for attic insulation: A tight upper-most ceiling plane(no cracks or gaps) plus sufficient insulation = the best cure for drafts.
I crack up when I see folks fall for that plastic saran-crap they place over their windows every autumn, or stuffed draft-stoppers they place at the bottoms of exterior doors! Stopping drafts begins at the top of a structure, not at the ground level.
Tony Hwang wrote: "- show quoted text - Hi, What is draft? Convection(venting) and air leakage. It is two things, No? Spray foam is an excellent for sealing and insulating. "
At first appearances, it is cold air leaking in to replace heated air rising through gaps overhead and or insufficient insulation.
Yes, spray foam could be used to plug those gaps, keeping heated air in and reducing stack effect.
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