I’m thinking more and more it’s a good idea this winter to blow some cellulose in my attic. I have a walk-up attic, used as storage, and insulated in the rafters, but I think it’s still a source of heat loss, b/c there is no insulation in the floor of the attic. The attic floor is old ‘true’ 2×4 joists, covered in T&G flooring on top. It’s sturdy, b/c the plaster ceiling has no cracks given all the stuff we keep up there, and the recent work that was done to install the Central A/C unit.
So to blow cellulose into this 16″ x 4″ x 20′ long cavity, do I need to cut holes in the floor to do this or can I start at the opening on either side (near the eaves where there is no no flooring) and blow it in that way? If I don’t stuff the hose in the cavity very far, will the cellulose get packed in enough with the rough underside of the plaster/lath? Should I try to stuck the hose in all the way and do a dense-pack and risk damaging the plaster? I don’t really want to cut holes either b/c of the difficulty patching them. Any tips are appreciated.
Thanks,
PJ
Edited 11/21/2005 6:00 pm ET by pjmcgarvey
Replies
Learn how to remove pieces of flooring.
happy?
Learn how to remove pieces of flooring
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It's the 'replacing' of the flooring I'm more worried about. It's already a low-headroom, obstacle course there already, don't need mini speed-bumps trippin' me up.
PJ
There are various tricks to removing and reinstalling T&G flooring without excessive damage. If this is your typical rough T&G used in old attics then you can either use a saw to cut off the tongue (if not nailed through there) or you can do a shallow cut to cut off the top of the groove. Another option is to simply slice down the middle of the plank (avoiding nails, of course).With any of these techniques (and probably one or two more) you should be able to remove a plank or two without excessive damage, insulate, and then reinstall the planks, face-nailing to secure them. If you can find some matching planks somewhere to patch in, so much the better.
If ignorance is bliss why aren't more people
happy?
Before I blew in 4 in. of cellulose in that attic floor, I'd be thinking of foaming the roof deck. Yeah, that's pricey, but 4 in. of cellulose, even though I'm a big fan of the stuff, isn't a lot. What sort of insulation is there now? Batts? And the gable walls?
Andy Engel
Never try to teach a pig to sing. It wastes your time and annoys the pig.
Other people can talk about how to expand the destiny of mankind. I just want to talk about how to fix a motorcycle. I think that what I have to say has more lasting value. --Robert M. Pirsig
None of this matters in geological time.
Even if I could afford that right now, which I can't (new heater last month, large prepayment on heating oil, xmas coming) wouldn't I still be effectively trying to heat the attic? I would also be putting as much cellulose as is needed in the eaves, behind the knee wall, so that might help a little more. I know that doing this myself will be *alot* less than paying someone to do the foam, after I pull down all the FG I put up a few years ago.
I would probably pay the same or less money to put cells in the exterior walls and ceilings than do the foam in the rafters, and that seems to make more sense to me.
Right now it's just FG in the rafters and gable ends.
PJ
Yes, you'd be heating the attic. But remember, it's not the volume of the heated space that matters so much as the surface area. You can go either way, but it seems to me that if you've got a nice board floor in the attic, then it's useful space, even if just for storage. That makes me want to insulate the roof, and the best way to do that is with foam. But I do feel your pain in terms of cost. And yes, insulating under the floor would help. How's your air sealing, though? Frequently, I find that houses have huge air leaks their owners aren't even thinking of. Fixing air leaks is usually cheap and easy, and pays great dividends. Is there an internal chimney? Is there a gap around it? Close that off with sheet metal. What about the attic door? Is it weatherstripped? Any hole in the upper ceiling plane is costing you energy.Andy Engel
Never try to teach a pig to sing. It wastes your time and annoys the pig.
Other people can talk about how to expand the destiny of mankind. I just want to talk about how to fix a motorcycle. I think that what I have to say has more lasting value. --Robert M. Pirsig
None of this matters in geological time.
Yes, you'd be heating the attic. But remember, it's not the volume of the heated space that matters so much as the surface area. You can go either way, but it seems to me that if you've got a nice board floor in the attic, then it's useful space, even if just for storage. That makes me want to insulate the roof, and the best way to do that is with foam. But I do feel your pain in terms of cost. And yes, insulating under the floor would help. How's your air sealing, though? Frequently, I find that houses have huge air leaks their owners aren't even thinking of. Fixing air leaks is usually cheap and easy, and pays great dividends. Is there an internal chimney? Is there a gap around it? Close that off with sheet metal. What about the attic door? Is it weatherstripped? Any hole in the upper ceiling plane is costing you energy.
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Andy, thanks for providing your expertise in this thread...
Air sealing of the house is much better, especially the 2nd floor, since I've redone alot of the rooms, caulked, new windows, outside is vinyl siding over 1/4" foam, over heavy building paper, over original claps, not too bad for an old house. But I'm thinking the attic is a lost cause, it's too low to ever be a finished space so doesn't warrant the extra expense, has the soffit venting and ridge vent, with baffles, to let plenty of outside air "do its thing", balloon framing and all the little nooks and crannies don't make it an ideal 'envelope' IMHO. There is a chimney, with a recent top-mount flue, but it doesn't come through the attic space. Attic door was weatherstripped when we got the A/C put in.
Slight change of topic, I've already closed them off, but is there a better way to seal the supply/intake vents in the ceiling for the a/c system, the magnetic material I've used on other vents in the house doesn't stick, the vents are aluminum...
PJ
So the vents for the AC aren't used for heat?Andy Engel
Never try to teach a pig to sing. It wastes your time and annoys the pig.
Other people can talk about how to expand the destiny of mankind. I just want to talk about how to fix a motorcycle. I think that what I have to say has more lasting value. --Robert M. Pirsig
None of this matters in geological time.
Forced air heat vents are near the floor, one per room, original to the house. New Central A/C supply vents are in the ceiling, unit is in the attic. 2 per room.
PJ
Since the A/C unit and ducting are in the attic, make it a conditioned space. In the Building America Program and as recommended by Joe Lstiburek, many new homes with attic HVAC equipment are being airsealed/insulated at the roof sheathing/gable ends with spray foam. The foam is quick and easy for a contractor since it is quite finicky work in tight spaces that many labourer types don't wish to do or will not do well. So for quality and time savings, the foam is used. The foam price (contractors get better prices than the general public) is hidden in the overall price of these upgraded homes so the buyer does not see it.
You can do similar in performance terms using a combination of fiberglass, foam board, cellulose, extra framing (maybe re-cycled) and a sealed air/vapour barrier over a period of time and cheaper than the foam at $4-$7 per sq ft.
So how does the ridge venting play into this, how would I make sure the attic gets ventilation in the summer, but make it a conditioned space in the winter, without alot of work and maintenance.
I don't feel like making a project out of this attic, I simply want to save some energy in the cheapest, easiest way possible.
PJ
Block of the ducts for the A/C for the winter.
Airseal all larger penetrations of ceiling.
Build a drop in/down insulated, weatherstripped hatch for top of stairwell or blow walls of stairwell/ under steps; install insulation and weatherstrip door.
Blow floor cavities by removing strips of selected boards about 8-10 apart (depends on blocking/cross bridging) for ease of hose insertion.
Or: Drill 1" holes about 3' apart into individual cavities and blow like walls
Related discussion from October.
http://forums.taunton.com/tp-breaktime/messages?msg=63867.1
You can pump in the cells from the eaves, but use an extension pipe setup. You'll probably have to add the pipe a 4' length or so at a time since you'll be inside the eaves area.
Use 2" diameter PVC pipe, some glued on threaded male and female connectors. Push in the first piece, screw on the next piece (not too tight), attach/slide more until the pvc pipe assembly end is mid point, start pumping cells. Pull back and uncouple the PVC sections as you fill the bay. Go to other side and do the same.
When the sound of the cell blower machine changes pitch, you'll know to pull back on the pvc. When you see the next coupling, shut off the machine, uncouple attach hose again start blowing again.