FHB Logo Facebook LinkedIn Email Pinterest Twitter Instagram Plus Icon Close Icon Navigation Search Icon Navigation Search Icon Arrow Down Icon Video Guide Icon Article Guide Icon Modal Close Icon Guide Search Icon Skip to content
Subscribe

In every issue you'll find...

  • Expert insights on techniques and principles
  • Unbiased tool reviews
  • Step-by-step details to master the job
  • Field-tested advice and know-how
Subscribe Now!
Subscribe
  • How-To
  • Design
  • Tools & Materials
  • Videos
  • Blogs
  • Forum
  • Magazine
  • Members
  • FHB House
  • Podcast
  • Join
  • Log In
Subscribe

Discussion Forum

Discussion Forum

Anyone Tapcon Ply Subfloors into Concrete? Screw Spacing?

FinishedBasementGuy | Posted in Construction Techniques on February 7, 2022 12:18pm
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.

– 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.

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?
Reply

Replies

  1. catmandeux | Feb 07, 2022 04:31pm | #1

    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.

    1. FinishedBasementGuy | Feb 08, 2022 06:59am | #4

      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?

      1. catmandeux | Feb 08, 2022 03:01pm | #8

        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.

  2. kayakmsdt | Feb 07, 2022 04:33pm | #2

    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

    1. FinishedBasementGuy | Feb 08, 2022 07:02am | #5

      Interesting- thx. What do you use to nail them?

  3. calvin | Feb 07, 2022 11:32pm | #3

    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?

  4. FinishedBasementGuy | Feb 08, 2022 07:03am | #6

    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?

    1. kayakmsdt | Feb 08, 2022 09:03am | #7

      Depending on the thickness, 6-8" spacing would be secure.

  5. Andy_Engel | Feb 09, 2022 06:10am | #9

    Just do a double layer of plywood and skip the concrete fasteners.

Log in or create an account to post a comment.

Sign up Log in

Become a member and get full access to FineHomebuilding.com

Video Shorts

Categories

  • Business
  • Code Questions
  • Construction Techniques
  • Energy, Heating & Insulation
  • General Discussion
  • Help/Work Wanted
  • Photo Gallery
  • Reader Classified
  • Tools for Home Building

Discussion Forum

Recent Posts and Replies

  • |
  • |
  • |
  • |
  • |
  • |
View More Create Post

Up Next

Video Shorts

Featured Story

Durable Wide-Plank Floors Made From Hickory

The Earthen collection from Carlisle Wide Plank Floors combines a unique look with the advantages of an enduring material.

Featured Video

Video: Build a Fireplace, Brick by Brick

Get an overview of the process of creating a traditional-style fireplace that burns well and meets current building codes from experienced mason Mike Mehaffey.

Related Stories

  • Keep Craft Alive Podcast: Ep. 19, Jesse Neumann, Arborist
  • FHB Podcast: Special Edition With Neil Freidberg of Louisiana Pacific and Kyle Stumpenhorst of RR Buildings
  • DeWalt Recalls 12-in. Sliding Compound Miter Saws
  • Podcast 483: Recalled Electrical Panels, Drainage Behind Brick, and Lazy Additions

Highlights

Fine Homebuilding All Access
Fine Homebuilding Podcast
Tool Tech
Plus, get an extra 20% off with code GIFT20

"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.

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

BOOKS, DVDs, & MERCH

Shop the Store
  • Outdoor Projects
    Buy Now
  • 2021 Fine Homebuilding Archive
    Buy Now
  • Pretty Good House
    Buy Now
  • Code Check Building 4th Edition
    Buy Now
  • Shop the Store

Fine Homebuilding Magazine

  • Issue 309 - Aug/Sept
    • 10 Steps to Install Crown Molding on Cabinets
    • How to Get Sturdy Walls Without OSB
    • Choosing the Right Construction Tape for the Job
  • Issue 308 - July 2022
    • Pretty Good House Book Excerpt: Copper Farmhouse
    • 10 Dos and Don'ts for Electric In-Floor Heat
    • A Sturdy Rail for Outdoor Stairs
  • Issue 307 - June 2022
    • How to Raise a Post-Frame Home
    • Trimming Deck Stairs
    • Evolving an Energy-Efficient Envelope
  • Issue 306 - April/May 2022
    • Framing Stairs to an Out-of-Level Landing
    • Building a Zero-Energy Home for Less
    • Good-Looking and Long-Lasting Traditional Gutters
  • Issue 305 - Feb/March 2022
    • The Steady Surge in Residential Solar
    • The Fine Homebuilding Interview: William B. Rose
    • How Good Is Your Air Barrier?

Fine Homebuilding

Follow

  • twitter
  • facebook
  • instagram
  • pinterest

Newsletter

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Membership & Magazine

  • Online Archive
  • Start Free Trial
  • Magazine Subscription
  • Magazine Renewal
  • Gift a Subscription
  • Customer Support
  • Privacy Preferences

Taunton Network

  • Green Building Advisor
  • Fine Woodworking
  • Fine Gardening
  • Threads
  • About
  • Contact
  • Advertise
  • Careers
  • Copyright
  • Terms of Use
  • Site Map
  • Do not sell my information
  • Privacy Policy
  • Accessibility
  • California Privacy Rights

© 2022 The Taunton Press, Inc. All rights reserved.

X
X
This is a dialog window which overlays the main content of the page. The modal window is a 'site map' of the most critical areas of the site. Pressing the Escape (ESC) button will close the modal and bring you back to where you were on the page.

Main Menu

  • How-To
  • Design
  • Tools & Materials
  • Video
  • Blogs
  • Forum
  • Reader Projects
  • Magazine
  • Members
  • FHB House

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Account

  • Log In
  • Join

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Popular Topics

  • Kitchens
  • Business
  • Bedrooms
  • Roofs
  • Architecture and Design
  • Green Building
  • Decks
  • Framing
  • Safety
  • Remodeling
  • Bathrooms
  • Windows
  • Tilework
  • Ceilings
  • HVAC

Magazine

  • Current Issue
  • Past Issues
  • Magazine Index
  • Subscribe
  • Online Archive
  • Author Guidelines

All Access

  • Member Home
  • Start Free Trial
  • Gift Membership

Shop the Store

  • Books
  • DVDs
  • Taunton Workshops

More

  • FHB Ambassadors
  • Reader Projects
  • Podcast
  • Customer Support

Account

  • Log In
  • Join

Newsletter

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Follow

  • twitter
  • facebook
  • instagram
  • pinterest

Join All Access

Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.

Start Your Free Trial

Subscribe

FHB Magazine

Start your subscription today and save up to 70%

Subscribe

We hope you’ve enjoyed your free articles. To keep reading, become a member today.

Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.

Start your FREE trial

Already a member? Log in