mlennox
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| 03/20/2009 8:14 PM |
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Hello,
We are in final planning stages for a new home that will have hydronic radiant on all floors. We like the idea of having a concrete floor finish for most of the open main floor.
To this point we were planning to put Gypcrete over the radiant flooring, but as I understand Gypcrete cannot be used as a finished floor.
Does anyone have any recommendations or advice for alternate thin-slab options that would allow us to achieve a polished cement floor on a suspended engineered floor with radiant tubing? |
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jimmy48
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| 03/22/2009 11:40 AM |
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| peastone concrete |
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Blueridge company
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| 03/25/2009 8:57 AM |
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We have provided light weight cement 7 1/2 sack pea gravel mix followed with an acid wash for this type of application. however you will need at least 2 1/2 inches and be prepared for some cracks. scoring joint lines across the floor field on all hard external corners can minimize it but you will have cracks. I have seen Some jobs with this idea have come back with a concrete saw and cut 1/4 lines 3/8 deep on a 4'x4' grid, looks good but still you will ave cracks, also the structure underneath will effect the amount of cracks.
Dan |
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Dan
BlueRidgeCompany.com |
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jmagill
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Posts:237
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| 03/25/2009 9:48 AM |
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| We did regular concrete 2" thick over a plywood deck. We beefed up the joists. Ours is acid stained and our finished floor. We love it. |
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pinkrobe
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| 03/25/2009 10:21 AM |
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| If/when I get radiant in our basement, I was hoping to use 2" of regular concrete with a high fly ash content. I really like the look of plain old concrete, so we would probably skip the acid wash and just polish and seal. How big will the cracks be? Can anything be added to increase the strength and reduce cracking, like "fibre mesh" or something? |
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mlennox
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| 03/25/2009 10:25 AM |
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Posted By jmagill on 03/25/2009 9:48 AM
We did regular concrete 2" thick over a plywood deck. We beefed up the joists. Ours is acid stained and our finished floor. We love it.
Was this over radiant tubing? How much did you have to beef up the floors to support the cement load?
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jmagill
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| 03/25/2009 10:38 AM |
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| Yes over radiant tubes. It has been a several years so I don't remember the exact specs we upgarded from but we went with a 12" on center joist and a couple inches taller. |
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mlennox
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| 03/25/2009 2:52 PM |
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Posted By jmagill on 03/25/2009 10:38 AM
Yes over radiant tubes. It has been a several years so I don't remember the exact specs we upgarded from but we went with a 12" on center joist and a couple inches taller.
It seems there is a general negative opinion about concrete over a wood floor, based on my discussions with various contractors. In fact, when I mention the idea they look at me funny like I'm some sort of idiot. I wonder if this is just a false perception amongst contractors because on the surface it sounds unusual.
But if I understand you correctly you had a plywood sub-floor over a floor joist system and you poured a 2" regular concrete mix directly on the sub-floor which had the radiant tubing stapled into to?
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jmagill
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| 03/25/2009 3:01 PM |
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Posted By mlennox on 03/25/2009 2:52 PM Posted By jmagill on 03/25/2009 10:38 AM
Yes over radiant tubes. It has been a several years so I don't remember the exact specs we upgarded from but we went with a 12" on center joist and a couple inches taller.[/quote]
It seems there is a general negative opinion about concrete over a wood floor, based on my discussions with various contractors. In fact, when I mention the idea they look at me funny like I'm some sort of idiot. I wonder if this is just a false perception amongst contractors because on the surface it sounds unusual.
But if I understand you correctly you had a plywood sub-floor over a floor joist system and you poured a 2" regular concrete mix directly on the sub-floor which had the radiant tubing stapled into to?
Yes, joists,plywood subfloor, radiant tubes and then concrete(acid stained)
We have been living in this house now for 7 years. The floor is a breeze to clean, looks great and provides a thermal mass that makes the radiant very efficient.
All in all it makes for a very cost effective floor. |
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Blueridge company
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| 03/28/2009 10:31 AM |
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Staple pipe to the sub top of floor and top with light weight cement (though it still comes in at 16 lbs +/- per sq ft 1 1/2 inch thick) check your structural load on joist system. this is still sub floor, finished concrete needs to be thicker or you will have more cracks.
Normal system, tell the contractors to relax, breath deep.
Dan |
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Dan
BlueRidgeCompany.com |
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Brawler
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| 03/29/2009 9:10 AM |
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| mlennox, I have just gone through the same decision process you mention. After posting here and speaking with my concrete guy and my engineer i decided to go with 1.5" of concrete over my subfloor. I spent an extra $240 to reduce my truss spacing to 12" from 16". My biggest concern was creep, which is long term settling of the trusses. My concrete guy told me even with a highly engineered concrete i would still get cracks so i have decided to go with 1.5" with slate or travertine. I would love to use cork or marmoleum in the kitchen but i am afraid it would insulate my slab to much, even at such a thin thickness. It would be a shame to go to all this trouble for concrete to diminish effectiveness with the floor finish. Just set trusses this past week. Ill let you know how th rest goes. |
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Blueridge company
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| 03/29/2009 11:21 AM |
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put down the cork or marmoleum, with a 1 1/2 heat sink you will have no problems, these are both thin products and attach with direct contact to the slab.
Dan |
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Dan
BlueRidgeCompany.com |
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NRT.Rob
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| 03/29/2009 1:12 PM |
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| cork performs like a wood floor. Marmoleum should be less resistant. |
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-=Northeast Radiant Technology=-
NRTradiant.com |
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mlennox
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| 03/29/2009 1:39 PM |
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Posted By Brawler on 03/29/2009 9:10 AM
mlennox, I have just gone through the same decision process you mention. After posting here and speaking with my concrete guy and my engineer i decided to go with 1.5" of concrete over my subfloor. I spent an extra $240 to reduce my truss spacing to 12" from 16". My biggest concern was creep, which is long term settling of the trusses. My concrete guy told me even with a highly engineered concrete i would still get cracks so i have decided to go with 1.5" with slate or travertine. I would love to use cork or marmoleum in the kitchen but i am afraid it would insulate my slab to much, even at such a thin thickness. It would be a shame to go to all this trouble for concrete to diminish effectiveness with the floor finish. Just set trusses this past week. Ill let you know how th rest goes.
Thanks for this. Please keep me informed how things work out.
I'm curious though, if you're going to put slate over top anyway, why did you go concrete and not gypcrete?
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Brawler
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| 03/29/2009 2:30 PM |
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| I checked into gypcrete and it was much more expensive. The people with Maxxon here in charlotte were very helpful but you cant DIY gypcrete. They only sell to distributors which is understandable but i only need about 3.5 yards for my main living area and maybe 2 for the loft if i go concrete up there. They have a minimum amount and if i remember correctly my job was just below that level. |
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mlennox
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| 03/29/2009 2:36 PM |
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Posted By Brawler on 03/29/2009 2:30 PM
I checked into gypcrete and it was much more expensive. The people with Maxxon here in charlotte were very helpful but you cant DIY gypcrete. They only sell to distributors which is understandable but i only need about 3.5 yards for my main living area and maybe 2 for the loft if i go concrete up there. They have a minimum amount and if i remember correctly my job was just below that level.
We're doing about 1800 sqft of poured underlay, probably 1.5" thick. When the time comes I'll compare concrete vs. gycrete and see what the price difference is. |
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jmagill
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| 03/29/2009 3:42 PM |
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Our two inch slab had some cracking. It happened in doorways or hallways where the two rooms met. We had no cracking in the larger rooms. It seemed to crack where it was narrower and two larger rooms met.
We fixed the cracks by using the flexible concrete repair grout and painting it to match the floor.
In the end it was a much cheaper option than tile or concrete. I think cork would be a good option over unfinished concrete.( and one I am considering for our next build) It is not enough of an R value to make any huge effect on your heating costs. |
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Brawler
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| 03/29/2009 4:08 PM |
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| Here are some pictures of our project, called the "bomb shelter" by the inspector. We decked this with 3/4 huber advantec, so this past three days of downpour have hopefully had litle effect. Thanks for the responses, they are invaluable for a layman like me. |
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Blueridge company
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| 04/01/2009 8:33 AM |
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Nice looking structure,
anther note about gypcrete VS concrete and surface covers. You can tile directly to concrete, If you are doing a traditional nail down floor you can place 2x4 sleepers flat and pipe in between, 12 inch pattern is usually fine in fill with ether product. If you are doing a sheet good product or floating wood floor product gyp in some ways is easier as it lays flat like a pancake bater, if you chose concrete the flat workers involved will need to know where the sheer good or floating floor products are so they can be sure there are no peas or ridges left on there finish.
Dan |
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Dan
BlueRidgeCompany.com |
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sayre3
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| 04/03/2009 9:22 PM |
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| I'm currently doing a job estimate for marble tile that is to go over this type of radiant floor (1 1/2" concrete over 1" plywood subfloor) There are small cracks throughout the concrete floor. I am concerned about the cracks continueing through the tile. There are too many cracks to preform a repair. Has anybody tiled over this type of subfloor? |
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