View Full Version : Ok to screw flange/toilet to plywood?

05-31-2006, 01:57 PM
Hello Experts,

Drilled a couple nice holes through tile and the 2" mudbed underneath. Below that is plywood. No idea how thick but from a test hole it looks like 5/8" or 3/4". Is it ok to screw the 5/16" screws to hold a toilet into that plywood? If yes, what diameter pilot hole do you guys drill?

In our case it's a floor-mount rear-discharge unit but I guess the same would go for securing the typical flange of a normal toilet since a flange holds the whole toilet via its bolts.

Putting a brace underneath this one would be a bear. I'd probably have to lose 30 pounds or more just to be able to crawl to that spot.

Regards, Joerg.

Gary Swart
05-31-2006, 09:17 PM
That's the way flanges are attached to the floor. As far as a pilot hole for the screws is concerned, I'd use about a 3/16" for the 5/16" screw and then use a power driver to sock 'em down. The length should penetrate the sub floor since you have so much above it, so at least a 3" screw.

06-01-2006, 10:45 AM
Thanks, Gary. So I assume the plywood provides enough "meat" to anchor down things like toilets. I grew up in Europe where there is no wood in houses (except for the rafters and furniture), that's why I asked.

It's more like 5" screws in my case since the toilet base thickness adds 1-1/2 to the 2" of mudbed, plus tile. The amazing thing is that you can get stuff like that at the local ACE store. No need to drive into town.

Regards, Joerg.