Subfloor Questions

Remember to glue plywood floor to joist to prevent squeaks!

 

wood screws or deck screws?

With all the screws I will be using do I need to drill pilot holes for the screws that will go through the subfloor into the blocking?
For the screws through the joists into the blocking?
For the screws used to laminate the subfloor?

 

Deck screws will work .

Probably no need for pre drilling for the blocking unless you find it prone to splitting .,

On the plywood to plywood screws , just make sure there is no bridging ( the plywood not sucking together ) when you screw it together , if there is , pre drilling will eliminate that , or use a screw that has no threads within the top 1/2" of the screw

 

deck screws!!!! ...way superior to regular wood screws IMO, bite into wood better, hold good, stronger, better drive system in the head (go w/ the star-drive), ...worth the extra coin..

i'd probably just put one or two screws down through the existing subfloor sheet into each "block", ...then add your extra plywood layer B-C or A-C grade, w/ better side up... run the grain crossways to the existing subfloor grain, and make sure joints overlap by 1/4 width if possible.. do 4" spacing on the perimeter of the sheets, 6" in the field...

 

Robertson screws FTW

 

Deck screws it is.

But there seems to be two different ways described for when to add the blocking and plywood.

OZ method is to lay the plywood over the existing subfloor then add the blocking and screw through both sheets of ply and then into the block.

Wiley method is to put the blocking in and screw through the existing sheet of plywood. Then add the new sheet of plywood on top. overlapping the seams at a quarter width.

Which one is correct or is this just a personal preference? I feel Wiley's method would look neater when finished but oz's method ties all layers of the floor to the blocking.

 

1. I talked about "smart block placement" previously. You are installing 2x8 anti-roll blocks, correct ? 2 runs, right ?
Align those block runs with your existing plywood joints that are presently unsupported. Now the block serves 2 purposes, anti-roll (stiffener) and backing for your plywood. It is in a smart location.
Add "flat" 2x4 blocking as needed in areas not covered by the 2x8 blocking.
The 2x8 blocking is positioned vertically, by the way.

2. I previously mentioned that you should not "stack" plywood joints.
Stacking is when you match the joints on the second layer of plywood with the first layer.
Some lay the sheets perpendicular to each other, but it is actually better to go the same direction so that your plywood continues to be perpendicular with the joists below.

But we don't want to stack....so what to do ?
Slip the 8' side so that it is 16" away from the existing seam. Slip the end so that it is 32" from the end.
So you're 16" offset on the long side and 32" offset on the short side.
Depending on conditions, you may have to cut a sheet to get started.

3. So now we have unsupported plywood edges....what to do ?
Since this is a small area, locate the new seams below and add flat 2x4 blocking for backing as discussed previously.
On large areas or underside inaccessible areas, sometimes special laminating screws are used in lieu of the added flat blocks.

Space your new plywood a shy 1/8", use construction adhesive and screws to avoid squeaks. Pull any screw "shiners"....screws that don't find backing.

Edit:
The area is small and is going to have a tile covering so you could break some of these industry standard methods without ill effect. Just make sure that the floor doesn't squeak and is stout.

 

Personally, I'd want the top layer of plywood screwed into the blocking. I don't see how it'd make a difference whether the blocking is installed before or after the top layer of plywood is put in place. Wait for OZ or Wiley, that's just my $0.02 (I'm also taking notes from this thread because I have a tile job coming up and there seem to be a lot of pointers in here)

 

I can't really say it any better than OZ-T or jflan. Follow either or their methods and you will have yourself a rock solid floor. For what it's worth I have had great success with Schluter-Ditra. I am old school when it comes to construction means and methods, but Ditra is one of those new school methods that just plain works.

PS: Don't skimp on the construction adhesive, 2 words: PL Premium.

 

Nope! I have 3/4" ply, 1 1/2" of concrete, plus 3" of crushed Jeeps and Silverados, 1/4" Schluter Ditra then tile!

 

Jflan that makes sense. If I do this right the one wall I will need to rip a 16" long strip and use special laminating screws for this because I will not be able to block under this section because it will be 16" off the center beam for the house and coverd by duct work. After that I should be in the clear. Also do I need to worry about 2x4 flat blocking the perimeter after the new sheets are added.

 

Just do it already

 

We're picking fly shit outta pepper now .

Bottom line :

Add blocking to stiffen the floor
Make sure all plywood seams in your original layer are supported

Use PL Premium subfloor adhesive on any plywood to blocking or plywood to plywood connection

Screw through both layers of plywood into the blocking and joists

Use Ditra , read and follow the directions carefully

Tile

Enjoy

 

Haven't heard that one before...

 

Thanks guys this thread now needs to die as I dont believe there is much left here to discuss with out you showing up and doing the job. And 323 sq ft of ditra is on its way to my house as we speak. Thanks for the help really didnt want to botch this job and have to re-tile.

 

Are you kidding? After 5 pages of prep and advice, this thread doesn't need to die, it needs pictures of the final product!

 

yeah i didn't just read this whole thread for nothing lol.