My recent addition in Maine has a full basement. The poured concrete walls have 2 inch foam applied on the outside. The floor joists are 2 x 10. I have radiant heat, with aluminum plates applied to the underside of the sheathing. Below that is that thin quilted foil stuff, then fiberglass batts. The heat works fine, but seems to use more propane than we expected. The big puzzle is that the basement is almost always very warm, about 75 degrees. I insulated all the pipes. Any ideas?
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What's above the "sheathing" (subfloor). Sounds like watever is below the subfloor is not insulated enough when compared to the insulation value of what's above the subfloor, so the heat radiates down into the basement more than you'd like.
The solution is to reduce the insuation above (probably pretty hard to do) or increase the insulation below -- how thick are the batts? Is there drywall on the basement ceiling, or is the FG exposed?
Mike Hennessy
Pittsburgh, PA
Above the sheathing (3/4 Advantec) is thin set (I think that's what the tile guy used), Ditra, thin set and 1/4 slate tile. No ceiling in the basement.
The FG batts are either six or eight inch, kraft faced, shoved up and held with those wire things.
I spoke to my contractor this AM and he'll be coming by to take a look. I told him that I think the installation of the insulation may be part of the problem, in that the foil looks to be too close to the radiant pipes. with no or very little air space.
Thanks for the response.
For the foil to be effective you don't need a lot of air space, but you want to avoid direct contact. Half inch is good if it's reasonably consistent.If the FG is just secured with wires then likely it's not particularly tight in the openings. Probably lots of gaps along the edges and at the ends.Also, presumably the FG is unfaced, meaning that air can flow through it with ease. Any sort of ceiling barrier will eliminate that air flow.
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Above seems fine. Below -- methinks you need an air barrier. If you can drywall the ceiling, that'll probably help a lot.
Mike HennessyPittsburgh, PA
Do you think Tyvek would help? Drywall is an option, although maybe not right away. Thanks.
Anything that will stop the air currents, thus promoting radiant heating of the floor above, rather than convection heating of the basement below, will help.
The problem you may face is that I'm not sure Tyvek is approved for exposed applications, like basement ceilings, for fire purposes. How big is this addition and is the ceiling relatively unencumbered by ducts, plumbing, etc.? If it isn't too big, and it's pretty clean, I'd throw some drywall up -- no need to finish it if you don't want. Heck, even a lawyer could do that! ;-)
Mike HennessyPittsburgh, PA
PS: I just noticed my profile indicated I was in "Arts & Entertainment". Huh? For the record, the above smart comment about lawyers is privileged, since I am one -- sometimes. Profile fixed.
Edited 12/10/2007 1:40 pm ET by MikeHennessy
Heck, even a lawyer could do that
A lawyer probably could hang drywall, perhaps has often done so in the past, but said lawyer may hate drywall more than any other building material :-)
The basement is about 1000 square feet, no ducts, just a relatively small number of plumbing pipes, etc. As for tyvek approval, no building inspections to worry about, but I don't want to create anything hazardous.
Heck, rent a lift (best $60 you'll ever spend), have 35 sheets delivered -- done that day! With a lift, ceilings are almost fun!
I'd rather hang it than finish and paint it. Any day.
As for Tyvek, try burning a piece. If it doesn't, go ahead and wimp out and staple some up. I'd consider gluing/caulking the perimeters to keep it pretty airtight.
Mike HennessyPittsburgh, PA
Several folks here (including this folk) have done ad hoc flammability tests on Tyvek and found it to be (in their judgement (judgment to you legal beagals)) safe for this sort of application. It will ignite, but burns very slowly/poorly and will not support a fire but eventually self-extinguishes.You don't want to use clear plastic because it will allow a fair amount of IR through, and black plastic would radiate IR. White Tyvek (printed side up) would be ideal from an IR radiation point of view.I suppose you could also use "fan-fold" -- the foamboard they use behind vinyl siding when going over existing. It's cheap, light, and generally reflective or a light color, plus it adds a modicum of insulation. Don't know about its flammability, though.
If your view never changes you're following the wrong leader
I don't know about your design considerations, but a friend of mine put galvanized barn siding on his ceiling, and if you like the style, it looked very good.You could also use ply or osb I suppose.I put up a suspended ceiling, even though I dreaded it, DW helpd keep me motivated, and it was siprisingly fast and easy.A medium to large guy named Alan, not an ambiguous female....
NOT that there is anything wrong with that.
Arts and entertainment.
Now that's weird. Mine did that yesterday.
Gremlins?
since yur using the carpenter's helper...
wouldn't that be more like Artful Entertainment???
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!Forget the primal scream, just ROAR!!!
don't I wish...
I got sloted for home maker....
ROAR!!!
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!Forget the primal scream, just ROAR!!!
So who's the joker??
And how??
giving odds???
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!Forget the primal scream, just ROAR!!!
got no clue...
as usual...
we move to Seattle and nobody let us in on it???
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!Forget the primal scream, just ROAR!!!
Maybe Taunton's trying to give us a hint on maybe rethinking our carreer choices? ;-)
Mike HennessyPittsburgh, PA
If you don't have a ceiling up, install one. Preferably drywall, but even Tyvek would do. Don't use clear plastic, though, or anything black.
You need to cut down on the air circ and radiation from above.
Thanks.
We put up Tyvek or similar all the time in cases like yours. It will block the flow of air which is what it taking the heat out of your floor system.
Wish I could complain about my basement being too warm! Winter seems to have come early this year.
When I saw this yesterday, my first thought was hmmmmm:
1. Very well insulated new basement.
2. Using more propane than expected.
Possible conclusion: very low heat loss from basement to ground, plus room above losing a lot of heat so heating system is on a lot. Despite insulation between the radiant heat and the basement space, some heat does migrate down through that whole floor area, and the temperature down there rises a few degrees until the the heat loss through the basement walls and floor equals the gain from the ceiling, low as it may be.
Of course, air movement through the ceiling insulation could be the problem, as others have suggested. I have to wonder what the driving force for that would be, since the lighter hot air would tend to stay up in the cavity. Perhaps the slightly cooler air next to the walls gives rise to slight thermal currents there. Maybe. Then covering the bottom of the insulation to prevent the thermals should indeed work, provided the covering has no leaks near the walls.
But tell us what is above the heated floor. If you are using a lot more propane than expected, you have heat loss up there, and the floor is staying hot all the time to keep up with it. Some must go downward to the basement, however little.
This thread reminds me of another (Breaktime or JLC, don't remember), where someone was wondering about putting radiant floor heat into a basement slab with very well insulated walls and XPS below the slab. Others said forget it, since the heat from above would keep it plenty warm. This thread seems to confirm that, doesn't it?
I expected that this addition would not be cheap to heat, because the first floor is an open room with a ceiling that is open to a cupola up about 27-28 feet above the floor. The ceiling has FG insulation in the rafters ( if I knew then what I know now, I would have opted for foam, perhaps) and, as you see from this photo, lots of south facing glass. We get great heat gain on sunny days, but that may screw up the heat in some way because there is no call for the boiler to run from about 10 AM to 5 PM on sunny days. Of course, even though we have good windows (Marvin) we certainly lose heat through them. The radiant heat works fine, in that we are comfortable and there doesn't seem to be much heat rising in the space, in that the top of the stairs isn't any warmer than down below.
I guess my main concern is that we are clearly paying to heat the basement somehow and we'd rather not do that.
My contractor came by yesterday (the project was done in early spring 2006) and he looked at the insulation in the basement ceiling and thinks it was properly installed, with an air space between the foil and the heat pipes. He asked some heating gurus and seems to think that the well insulated basement may be heated just by the excess heat from the boiler.
I have partitioned off a small room (about 10 x 20) under the section with all the windows) in the basement and insulated and sheetrocked the wall between it and the rest of the basement. Once I put the door on, it should be pretty well isolated from the rest of the basement, and if that room is still too warm, that should tell me that the heat is from the radiant heat in the ceiling, and not from the warm boiler.
Thanks to you and everyone else for your comments and suggestions.
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The small room you describe has no real way for heat to escape, and hence it will tend to the temp of the rest of the area, regardless.
If your view never changes you're following the wrong leader