*
I have a cottage with a very cracked concrete floor. I am going to be remodeling and busting some holes in it for plumbing also. I would like to pour a couple inches on top of the existing and I’m concerned about what mix to use, what mesh to use, if any, and any bonding agent requirements.
Thank you.
Phil Cyr
Whether it’s already in your house or picked up at a flea market, vintage hardware almost always needs help.
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial NowGet instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now
Replies
*
Phil-
Sounds like you'd be better off with P.T. sleepers
over a vapor barrier and a t&g subfloor.
The concrete doesn't need to bond to the old floor
as with any concrete floor solid tamped soil is the key.
With sleepers say 2 x 4's on the flat, you can shim
etc. and have a flexible floor that won't crack.
Pour any concrete 2" thick over cracked unstable
substrata and you are going to get more cracks.
I bet that a wood system is cheaper in the long run.
Upon inspection, you may find that you only have a couple of inches of concrete now. You could bust it out and do a real 4" floor but you may want to let sleeping dogs alone. good luck, Cal
*
and you could bust it up, dig it out , put a 2" foam under it and repour it with a radiant slab....
the possiblities are endless....
if you can knock it thru with light sledge, its probably not worth saving....
*Mike,Just curious. You've mentioned two inches of foam under a concrete foundation a couple of times lately, but you didn't expand on the reasoning. I've read of using foam around foundations in certain places to prevent frost heave (this has been described in FHB), but what is your reasoning for putting it under a basement floor before it's poured?Thanks in advance.
*Steve, in this case it is the living envelope floor surface....but the two inches under the basement slab is a throwback to our solar heating days.. every basement i've ever built since '76 has 2inches styro -sm, or foamular, etc..when we were trying to save every BTU we collected from the sun.. it was fairly obvious that the ground temp. being 45 deg. year round and the inside design temp. being 70.. gave us a delta -T of 25 deg. 24 hours a day.. since we had already drastically stopped the BTU loss in all the other surfaces. .. the basement and slab became the last frontier....we have very warm floors with very little heating loads.... so its just one of our standard responses for heating strategy..now this is fairly standard procedure with radiant floor heating systems..when you go into a nice dry basement, and the homeowner starts talking about a family room, its kind of nice saying.. no problem. we 've ALREADY got an insulated slab, and heating this is going to be a cinch.....we are developing some plans for retirement homes, which will be slab on grade, 100% handicap accessible, the slabs will be insualted to a minimum of R-10...
*Steve: While heat losses per square foot are much higher to the side of a foundation (colder shallow soil temps in winter), there is also heat loss below. So the 2" of foam is for energy conservation. The older perspective was that once you got the soil underneath warm, it would stay warm, which is partial true. But even after the soils have been warmed, heat does continue to conduct downward and to the sides. Much more important up here (38F soil temperatures) and requried for energy rating. At some point (Key West? Panama?) the soil gets to 70F and there's nothing to insulate from. So I think there ahould be a map of (roughly) latitude versus economic foam recommendation (1" in Lexington, 1.5" in Spokane, 2" in Fargo, 4" in Barrow) but I haven't seen it. Fuel costs play a role too. Use electric heat and insulate more, have cheap natural gas and insulate a little less. -David
*Thanks, Mike.That makes sense. My wife has always hated basement floors, or worse yet, the bottom ones in tri-levels, because they were cold to her tootsies. We're in zone 4 for growing plants, if you're wondering. The LL Bean fleece-lined mocs I gave her for Christmas have helped, as has carpeting and rugs.
*
I have a cottage with a very cracked concrete floor. I am going to be remodeling and busting some holes in it for plumbing also. I would like to pour a couple inches on top of the existing and I'm concerned about what mix to use, what mesh to use, if any, and any bonding agent requirements.
Thank you.
Phil Cyr