Are you a subscriber but don’t have an online account?

Register for full online access.

+ Reply to Thread
Results 1 to 11 of 11
  1. #1
    Bill S. Guest

    Default Subfloor screw down questions

    I have a framing business. Recently, a builder asked if I would screw down the floors when home buyers request that. I told him that I would consider it and get back to him. Since I have never screwed down a floor I have several questions to those that have. We normally frame with 2X10's or I-joist and 3/4" plywood subfloor. Houses range from about 2000 SF to 3000 SF. What screw size is best? Cordless screw gun or corded screw gun? Should we glue and nail as we always do and then screw down the floors later or just use screws? Is glue required when using screws? How much extra do you charge for screwed down floors? What screw spacing works? Is there anything else that I should know about this that I didn't know to ask? Thanks in advance for any and all help with this.

  2. #2
    benny Guest

    Default Re: Subfloor screw down questions

    don't be tempted and leave off the glue , you need that gasket badly. one of the big buiders tried by me once in the mid 90's it didn't work so good sometimes the threads would keep the joist and ply from being forced together and sometimes the heads would snap of of stand proud of the plywood... maybe try it with a high quality screw but in my humble opinion ring shank nails and glue is by far the best and qickest route.

  3. #3
    Tim Uhler Guest

    Default Re: Subfloor screw down questions

    We screw down all our floors before carpet or finished surfaces go in. It usually takes no more than 3 hours. We use the Grabber. I'll try to find the website for you. The type of bit they use lasts forever. It doesn't take long to screw the floor down and it really makes a difference. We still glue our floors and nail them off as though we won't screw them down later. We have almost reduced squeaks to zero. We will still get some under walls sometimes, but we've started glueing the walls to the subfloor and that seems to be helping.

  4. #4
    Tim Uhler Guest

    Default Re: Subfloor screw down questions

    Here is a link. We have the superdrive. I think that tools of the trade has done an article on these tools before. The link to Tools of the Trade is at the bottom this page.


  5. #5
    Wayne Guest

    Default Re: Subfloor screw down questions

    Been screwing floors since '91 & have yet to have a call back for squeeks. Glue is intrinsic to a sound floor. 1 3/4" screws work best for 3/4" T&G plywood or OSB. Corded QuickDrive or equivelent (w/extension for standing up. Your back will appreciate it!). Six inch spacing on the perimeters & 8 or 9 inches in the field. The only nails I use, is to tack it down, then go back & screw the whole thing off. No extra charge as it's a helluva lot easier & time saving than nailing.


  6. #6
    Dwight Guest

    Default Re: Subfloor screw down questions

    Just need to make sure glue doesn't set up before you come back to screw it off.

  7. #7
    Todd Guest

    Default Re: Subfloor screw down questions

    The deck screw for the Makita auto feed gun work well. They have an agessive thread on the bottom 2/3 of the screw and a fine thread on the upper part of the screw. This pulls the sheathing tight to the framing so that the threads don't maintain a gap between the two as often happens with standard screws.

  8. #8
    Justin B. Jensen Guest

    Default Re: Subfloor screw down questions

    We've experimented with all means of attaching sub-flooring to joisting and we're now full-circle back to using either 8d ring-shank nails or 1 1/4" staples (engineers preference), always with adhesive (we formerly used standard sub-floor and construction adhesive. We now use one-component polyurethane foam with an American Plywood Association rating APA-AFG-01)

    The strength of the cured adhesive greatly enhances the assembly or diaphragm strength as well as eliminating squeeks or differential movement between components.

    As far as we could determine, screwing only increases your cost of construction, not your product quality.

  9. #9
    beezo Guest

    Default Re: Subfloor screw down questions

    I just saw, on This Old House, I think it was them using some type of foam for guling together some joists that had to be sistered onto. This product came with some type of a canister and a nozzle that went from can to can. I thought they said that each can was supposed to be something like 20 tubes of adhesive. Is this the type of foam that you are using? Any more information would be appreciated such as where you can get it and the pros and cons.
    Thanks, Beezo

  10. #10
    Justin B. Jensen Guest

    Default Re: Subfloor screw down questions

    Beezo -

    Yes, the system that we are using is, from your description, the same.

    The advantages are, as we have found: Greater yield per container translating into less cost per unit floor installed, no laborious, tiring and frustrating hand pumping of glue as the polyurethane is dispensed under pressure and, no tendency to have "glue shimming" which you can get with the old traditional form of viscous sub-floor glues.

    The down-side is the same for any adhesive: if you get this stuff on your hands, air-hoses or tools you will not be happy.

    There are several manufacturers, trade names include Dow Chemical EnerBond & EnerFoam, HandiFoam and PurFil. I purchase the products from Tek Supply (see link below) as I've found them to have competitive pricing. You will need to purchase a gun; Tek Supply sells one with a long nozzle so you don't have to bend over to apply the product to the joists. You may want to purchase a long nozzle and a standard short one for foaming penetrations through wall plates, etc.

    Be aware: the manufacturers offer products in three general product classifications: Adhesive, Low Expansion and High Expansion. You will want the adhesive for sub-floor and utility gluing, low expansion for windows and doors and high expansion for general building envelope sealing. One other note: the guns work great and require little or no maintenance so long as you keep a cartrigde screwed onto the dispenser. This material cures by moisture from the atmosphere; never leave the gun without a cartridge (even an empty one) screwed on or the foam will cure in the gun, ruining it.

    Hope I've answered your questions.


  11. #11
    Chris Martin Guest

    Default Re: Subfloor screw down questions

    We also have come full circle with screwing subfloors. I haven't found an auto screw gun that holds up to the rigours of my framing crew. Screwheads not sunk below subfloor and broken screws not pulling material tight have created more problems without any less squeaks than a properly laid subfloor. All sheets are set into wet glue and hand nailed with an aggresive ring shank nail. Special emphasis is made to head-up nails pulling materials "toight". As far as labor costs go, when an auto-screwgun is working properly it takes not much more time than using a nail gun. Hand nailing is most labor intensive.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts