What's your thought on installing 3/4" solid on concrete? Bad idea?
3/4" solid on concrete
- Thread starter Floorist
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Nick
In Remembrance
I do believe NWFA approves it above grade . But you won't catch me doing it.
Nick
In Remembrance
I would screed it if i had the height.
You cut your ply into 2' x 8' pieces E ?
You cut your ply into 2' x 8' pieces E ?
Would you fasten the plywood down or leave it floating?
Nick
In Remembrance
two layers - Float .actually be a floating nail down.
Agree Ernesto ?
Agree Ernesto ?
TNT
Well-Known Member
3/4" is approved on above grade concrete, you just have to glue it. Nick, why wouldn't you do it? If the substrate passes moisture tests and the home is temp and humidity controlled, not seeing a reason to pass on that ...
Tia
Tia
TNT
Well-Known Member
Traditional ¾ Inch Hardwood Glued. No Plywood Sub Floor.
For more traditional hardwoods or ones that are longer in length, the largest disadvantage of gluing has always been material that is not milled straight. This creates problems trying to close up gaps, whereas nailing to a wood sub floor forces gaps to close by the sheer force of the hardwood nailing tools used. Other common problems include wrong adhesives used or incorrect amount used.
For more traditional hardwoods or ones that are longer in length, the largest disadvantage of gluing has always been material that is not milled straight. This creates problems trying to close up gaps, whereas nailing to a wood sub floor forces gaps to close by the sheer force of the hardwood nailing tools used. Other common problems include wrong adhesives used or incorrect amount used.
Nick
In Remembrance
You answered your question with a answer Tia .
Some of the low end 3/4" i get to work with is tough enough nailing . Plus all that strapping to keep it tight . I inspected a lot of glue down failures that were not 3/4" I just think they are a accident waiting to happen . [Personal opinion].
Some of the low end 3/4" i get to work with is tough enough nailing . Plus all that strapping to keep it tight . I inspected a lot of glue down failures that were not 3/4" I just think they are a accident waiting to happen . [Personal opinion].
TNT
Well-Known Member
You answered your question with a answer Tia .
Some of the low end 3/4" i get to work with is tough enough nailing . Plus all that strapping to keep it tight . I inspected a lot of glue down failures that were not 3/4" I just think they are a accident waiting to happen . [Personal opinion].
See your point ...
Tia
Flaoting ply is cheaper and faster. I like two layer of 3/8 than one layer of 3/4 floated. I only did one 3/4 ply floater and all that ripping 2 ft strips was a PITA! Plus you have to deal with curling plywood. http://www.flickr.com/photos/13772863@N08/5479231068/in/photostream
Fastening the ply is not needed as the weight will keep it down flat.
I only do it if the consumer will pay for Bostik MVP4 and 6mil plastic as well. Just using plastic is also a problem waiting to happen.
Fastening the ply is not needed as the weight will keep it down flat.
I only do it if the consumer will pay for Bostik MVP4 and 6mil plastic as well. Just using plastic is also a problem waiting to happen.
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Nick
In Remembrance
You can have the plastic .
Won't mold grow under the plastic if you get moisture?
The plastic is just a precautionary measure. Lots...well even NWFA says 6 mil is all you need. To me everything they say is minimum guidelines. Even MVP4 is not fool proof. But add both together....no mold. I believe MVP4 has some sort of mold and mildewcide in it. Was that a word?
TNT
Well-Known Member
3/4" solid wood floors on concrete below grade ~ never! Excellent question by Floorist on mold beneath a moisture barrier. There are those that by some magic allow moisture to go down but not come up. "Breathable" is what they call them. Have yet to be given a very proper explanation, but in the event of having a warranty in my hand, will accept that.
Tia
Tia
Are you talking about my picture? Well that picture is of a job that was very rare in it's building construction. I did multiple types of testing, Wagner Rh, CaCl before and after Bostik app, even over the plastic as well. The home is pretty high end and had multiple expensive HVAC units that can hold the ambient temp within a ten degree zone. And the builder/architect did a fine job of protecting the slab even though that room was 3ft to 5ft below grade on 3 sides.
I went way out on a limb with that one but got paid handsomely for it. The owner didn't do his homeowrk and bought like 1500sf of solid 3/4 Beech no less and could not send it back.
TNT
Well-Known Member
No, not talking about your picture, as I wouldn't consider what you had going on there as a solid hardwood going onto a below grade concrete, as you essentially turned it into a below grade plywood floor.
Tia
Oh ok. Just thought you had read that on one of the pictures in my flickr account.
The manufacturer of that wood would disagree with your assement though. They would not agree with my method even though they agree with plain old six mil under ply shot full of holes. That IMO is way worse than what I did
TNT
Well-Known Member
I'm not sure the manufacturer would disagree with what all you did. It might give me some fun to ask a couple of the reps, but honestly, they mainly blow me a lot of hot breathe, at least the majority. I think you did great!
Do know that I'm on an upcoming which is only a couple inches below grade on concrete and told the guy if he told me he was insisting on 3/4" solid, he could just go somewhere else. It's a personal house for the owner of one of my hugest commercial contracts, and I still said it. He told me that he would never be convinced that engineered was better than solid - and, I told him there was nothing he was trying to be convinced him of, just something he wanted to do that was inappropriate and being refused. After that, he did listen. Geez, I do all his commercial work, he ought to think he's safe with me on his own house!
Tia
Oh I called the tech dept @ MUllican and he just kept regurtating the usual garbage about how it is you cannot install solid below grade. When I told him it would not be fastened down and protected with MVP4 and plastic with 15lb felt and he would not budge. I even asked about the method of floating with plastic shot full of holes which is in his guidelines, nothing! These guys need to think outa the box sometimes. The industry's installation guidelines are outdated.
Then I aksed him why his 5" wood was 1/32 up to a full 1/8 in difference in width out of the same box. He said thats just the way wide wood is. lol Heck I've had 8 inch wide wood ten feet long milled perfect before. It's all nonsense.
I wouldn't be afraid of installing a floater a couple inches below grade if you protected it like I did. It is quite common for a builder or architect to do that so the floor is even with the tile or stone on top of the concrete. Makes a nice even transition.
