Anyone Tapcon Ply Subfloors into Concrete? Screw Spacing?
FinishedBasementGuy
| Posted in Construction Techniques on
What is an appropriate screw pattern for affixing 4×8 panels to concrete? All the info I can find online refers to screwing ply to wooden joists, etc.- not to concrete.
The context:
I’ve got a “basement” room in a slab on grade bi-level house with partially below grade lower level.
I’ve got a “basement” room in a slab on grade bi-level house with partially below grade lower level.
– Pulled up 50yr old carpet, down to the concrete.
– Put concrete sealer across the exposed 11″x11″ area.
– Underlayment of DMX 1-step 2.0 dimpled plastic.
Now, I’m adding 3/4″ T&G Advantech 4×8 subfloor panels.
– Put concrete sealer across the exposed 11″x11″ area.
– Underlayment of DMX 1-step 2.0 dimpled plastic.
Now, I’m adding 3/4″ T&G Advantech 4×8 subfloor panels.
Using 1/4″ tapcons, fastening the panels into the concrete (thru the underlayment, of course).
I’ve seen recommendations for 6″-8″ spacing around the perimeter, starting 2″ in from panel’s edge. Also seen 12″, 19″ rec’d spacing.
Seems like a lot of the recommendations are for applications over wood- so I’m wondering if applications over/into concrete are different.
Has anyone else screwed ply into concrete through an underlayment? What sort of screw pattern did you use?
Replies
DMX 1 Step is intended as an underlayment for a finish floor directly over concrete.
Why the subfloor?
I expect driving screws through the DMX will defeat the waterproof barrier.
Thanks and yes- I've seen installers seal the drill holes with silicone before driving the screw, to maintain the barrier. I'll do the same.
Still, I need to confirm how many/what spacing of screws are needed. Any help on this?
Install requirements from other vendors of similar products:
Platon: Screws are 24" grid pattern https://www.spycor.com/v/vspfiles/templates/1/assets/Platon%20Subfloor%20Product%20Brochure.pdf
Delta-FL: 8 screws per panel, staggered pattern: https://www.dorken.com/media/docs/products/Installation-Guides/Installation-Instructions_DELTA-FL.pdf
You may want to check with the DMX support folks for their recommendation.
Try looking at Rawl anchors. You drill through the material, into the concrete, and nail the anchor like a construction nail. I use them exclusively to anchor my bottom wall plates when constructing walls. They might work for plywood. And they will not pull out! https://www.fastenal.com/product/details/50610
Interesting- thx. What do you use to nail them?
I’ve tapcon’d a lot of things to concrete.
I would certainly try my Hilti P.A.D. gun b/4 my arms gave out.
Have you thought of dbl layering floating ply?
Would love to dbl floating ply- don't have the room in my floor height- resulting floor would be too tall.
Still, I need to confirm how many/what spacing of screws are needed. Any help on this?
Depending on the thickness, 6-8" spacing would be secure.
Just do a double layer of plywood and skip the concrete fasteners.