Screws needed to screw 25mm wbp plywood into joists - TilersForums.com

[aled]

Hi,
I am removing floorboards in my bathroom and replacing them with 25mm wbp plywood which i will be tiling on. I know I need to screw the plywood down every 150mm with countersunk screws. What screws would you advise I use? As I will be screwing into the joists I am not sure what length screws I need. I have had a look at the Screwfix website and there are so many different types of screws that to me look exactly the same!! Any advice would be great.

Thanks in advance

 

[Alan.P]

Any galvanised screws will do really, I like the double threaded gold variety from screwfix, you'll need something of 40mm + I would be tempted to go 45mm, don't forget to prime the underside and edges of the ply with an sbr primer.

 

[aph257]

as above

 

[Wood's better]

The old guideline is 2 and a half the size of the thickness of material. Therefore, a 25mm plywood floor should have a 60mm (approx) screw.

I use 4.5 x 60mm spax flooring screws. They are not full thread as fully threaded screws often lead to a tiny separation between the joist and floor leading to squeeks. These are available from Screwfix part no 56431.

Although it says no pilot hole required I would always pilot with a 3mm drill to the full depth of the screw and a slightly shallower countersink than required (especially in hardwood ply)

Hope it helps.

Richard.

 

[cornish_crofter]

As Richard says, 60mm is good for the job in question, though 50mm would do the job.

Although the Spax are good, any decent screw that is not full threaded will do the job. If you can only get the full threaded ones, then just make the pilot hole a bit bigger so the thread is not binding on it.

 

[aled]

Thanks everyone. I think i will go for the screws as mentioned by Ruchard above.

 

[aled]

Hi,
I went to ScrewFix today to purchase 4.5 x 60mm spax flooring screws (part number 56431) and was told that they were no longer in stock and that they could not be ordered in. Could you please advise on other screws found at ScrewFix that could be used to do the job?

Thanks

 

[devonmark]

these are a good screw, self cutting counter sink, I have used them many times


Toolstation > Screws & Fixings > Torx Fast

 

[aled]

I was told this morning that I could use the following screws to carry out the job in question. Spax Decking Screws 4.5 x 60mm (96947) As they are outdoor decking screws would they be suitable for screwing 25mm wbp plywood into joists?

Thanks

 

[aled]

I have also seen these at ScrewFix Spax Flooring Screw Zinc & Yellow Passivated 4.5 X 60mm Pack of 300 (88716). WHat do you think about these?