# pouring concrete over wood in livingroom?



## woodwoman (Sep 11, 2008)

hello everyone

we are considering pouring concrete for our hearth pad in the livingroom.  how thick should this be? then next summer putting tile over is for looks.  it will be poured over heardwood floor.  corner install.
thanks


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## Hogwildz (Sep 11, 2008)

Why? Is this floor on a slab? Otherwise that is a lot of weight to pour on a floor that prolly is not supported for that kind of weight underneath (stove + concrete).
Why not just frame with steel studs, put some Durok over, then tile? Or get yourself some blue stone and lay that over the flooring. Still a bit heavy. Make sure you have the needed support underneath. Unless is is a concrete slab under the hardwood. Still overkill to pour concrete IMO.


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## coHoser (Sep 11, 2008)

I did this way back in the 70's when we were poor young hippies - I did a wood frame, a double layer of "visqueen" or heavy plastic as a moisture barrier, some chicken wire for mesh, and about 1 - 2  inches or so of concrete with nice flat stones nestled down into the concrete... looked nice and worked for as long as we lived there, and was cheap at the time. Other than a few bags of concrete, everything else was recycled or scavenged. No pictures have survived...


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## woodwoman (Sep 11, 2008)

what was the slab over? ours is over a cellar


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## Rob From Wisconsin (Sep 11, 2008)

Find out just what is required for your stove.
The manual should be specific on this.
Most modern stoves require only a layer of cement board, w/ tile on top of that.

Cement, on the other hand, is not a good inulator.
Neither are ordinary bricks.

Hope this helps.....

Rob


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## markpee (Sep 11, 2008)

This shoud be no problem, as long as your floor joists can support it - you should find someone you know who is a PE to take a gander at it.  My hearth is 18' wide, and I only poured concrete directly in front of the stove to insure no fire.  I also laid an aluminum strip under it in case the concrete separated and sparks might fall to the wood below.  At any rate, I build a wood frame for the rest of the hearth and covered all with concrete board.  I then covered with faux bluestone and culture stone.  It came out nice, I'll have to post pictures.


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## Corey (Sep 12, 2008)

At first I thought "that doesn't sound like a good idea'  but then I got to thinking about my hearth which is 16" thick brick - and setting on the floor.  Then there are water beds, refrigerators, and lots of other things that probably put as much load per square foot as concrete.  I'd say the big issue - as already mentioned - is not letting the moisture from the concrete get into the wood and also providing an expansion barrier between the concrete and wood.  This could probably be done with layers of plastic or maybe even a layer of durock properly taped an mudded.

Overall, I think you'll be OK - Concrete is about 150 pounds per cubic foot and I think most floors are designed for 80 lbs per square foot of load - so as long as you aren't going over 6" thick shouldn't be too much of a problem.  But as always, you may want to check into the finer details for your specific application.


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## KWillets (Sep 12, 2008)

This basically how shower floors get made.  

You can mix vermiculite concrete (I think it's about 1:4 portland cement to vermiculite) and get some R-value too.


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## Ken45 (Sep 12, 2008)

Eons ago, in another wood burning age, we bought a nice concrete slab with a exposed pebble surface. It was maybe 1.5" thick.  It looked good and was simple.  I had totally forgotten about that.

This time around, I made a hearth pad out of plywood, cement board and tile.  Now that I remember the way we had it years ago, I wish I had gone that route this time.

Ken


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## RedRanger (Sep 12, 2008)

Don`t know how many of you south of the border have ever watched "Canada`s Worst Handyman"??   While it is hilarious, unforunately, I could easily be a candidate for that show/..  Which is why I hired my sweep who is also a tq carpenter to do my hearth.  2 hours labour=$100 and materials =100, so for 200 it is done as it should be according to code.  Nice slate finish, where the carpet was cut away.  And I now have 20 inch clearance.

On the wood floor, he did give me an estimate (just incase I win the war about another wood insert on the 3rd floor)..  over the hardwood, using slate again, double the cost, so=400 and maybe some change. still less than the cost of some of those ugly hearth pads.

Bottom line is if you can`t get it done yourself, at least get it done right. ;-)


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## fraxinus (Sep 12, 2008)

The weight of the concrete is an issue, but support columns in the cellar can take care of this. Cracking of the concrete is likely to be a bigger problem. Wooden floors flex; this will stress the concrete and probably lead to cracking. Wire mesh in the concrete or polypropelene fibres mixed in would be important to (maybe) prevent cracks. All in all, I think there are many better ways of building a hearth.


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## the_dude (Sep 12, 2008)

Ken45 said:
			
		

> Eons ago, in another wood burning age, we bought a nice concrete slab with a exposed pebble surface. It was maybe 1.5" thick.  It looked good and was simple.  I had totally forgotten about that.
> 
> This time around, I made a hearth pad out of plywood, cement board and tile.  Now that I remember the way we had it years ago, I wish I had gone that route this time.
> 
> Ken



I don't know that I would go the concrete route, but if I did, I would do exactly what Ken is talking about above.  It is called 'exposed aggregate' concrete.  Basically, you use colored pea gravel with your mix.  As soon as the slab is finished and before it sets, you spray the top with a chemical (sorry - I don't recall what it was) that keeps the top 1/4" or so from setting up.  After the rest sets, you remove the top layer of concrete.  We used to do it with a garden hose, which I realize wouldn't work inside - perhaps you could sweep it off.  Any way, it exposes all of the colored pea gravel.  You seal it a couple of times to make it glossy, and you are done.  It looks beautiful, and you wouldn't have to mess with tile later.


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## billb3 (Sep 12, 2008)

Geez, how much do you think a [full] refrigerator or piano weighs ?


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## Hogwildz (Sep 12, 2008)

billb3 said:
			
		

> Geez, how much do you think a [full] refrigerator or piano weighs ?


Not as much as a 400+ pound heavy steel stove + the weight of the concrete.
A fridge at best is 1/2 the weight of a stove, the piano I honestly don't know, I assume its heavy, but again as heavy as a steel stove & concrete pad in one small area? I just don't agree.
That said, with basement underneath, I am sure its easy enough to add support underneath. But why go through all that hassle? way overkill.


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## Ken45 (Sep 12, 2008)

Do you think it's heavier than four 250 pound people standing in the same area having a conversation?

Ken


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