WBP Plywood Urgent Query!!

Lumi

I'm laying some 12mm WPB plywood on wooden floorboards at the moment. Do I lay the smoother side up or down. Any help much appreciated

bothyhead

From a structural point of view, there shouldn't be any difference. For anesthetics, I would put the smooth side up - though I assume you're going to cover it with tiles or lino, so in this case it would really make no difference. IMHO

RKQ

Just in case you didn't think of it, mark the position of all the joists before you lay the ply. Use a chalk line to mark there position on the ply and screw every 200mm to 350mm centres.

If you don't have a chalk line, mark joist on wall with perm marker, ( will be hidden by skirting) lay ply on floor, then put a screw at junction of wall and joist - tie string and go to other end of joist. Place screw at wall / joist junction. Tighten string and screw along string at centres.

( Sounds slow and complicated but works well and gets very fast as you get into a rythem! One length of string per room. Put loops on ends of string to increase speed)

Also check existing floor for cables or pipes, prior to laying & screwing ply! Don't want to burst a pipe or screw into an electric cable!

311

RKQ wrote: »

Just in case you didn't think of it, mark the position of all the joists before you lay the ply. Use a chalk line to mark there position on the ply and screw every 200mm to 350mm centres.

If you don't have a chalk line, mark joist on wall with perm marker, ( will be hidden by skirting) lay ply on floor, then put a screw at junction of wall and joist - tie string and go to other end of joist. Place screw at wall / joist junction. Tighten string and screw along string at centres.

( Sounds slow and complicated but works well and gets very fast as you get into a rythem! One length of string per room. Put loops on ends of string to increase speed)

Marking the ceiling is dead handy for hanging stuff on the wall. Figure out where the stuff you want is going and mark the ceiling with anything.

One or two screws in a stud(:eek::D) is worth far more than anything from a tile.

pixbyjohn

If you are laying the ply over existing floorboards I dont think you need to worry where the joists are. Sure you can screw to boards.:D Both sides should be similar of the WBP Ply but it wont make any difference really .

Hotblack Desiato

pixbyjohn wrote: »

If you are laying the ply over existing floorboards I dont think you need to worry where the joists are. Sure you can screw to boards.:D

Exactly. I've had to do this on kitchen and bathroom recently before they were tiled. Use a screw which isn't long enough to go right through the boards, and you don't have to worry about buried pipes/cables. Get a good cordless drill/driver unless you want to have a right arm like Popeye and use self-drilling screws at 20cm centres in all directions, forget about the joists.

If one side of your WBP is slightly rougher, it might be as well to have that upwards, to give a slightly better grip for the tile adhesive. You need a tile adhesive for wooden subfloors (flexible.)

Edit: for tiled floors, OSB is cheaper than (good quality) WBP ply, and just as good if not better. There is a lot of rubbish cheap Brazilian ply on the market at the moment.

builditwell

Exacly right for RKQ,

You should be hitting the joists as they are the most rigid part of the floor and will only provide a more solid base once the top layer of plywood is screwed into this, you still of course use the 200mm centres but hit the joists also. light screws are ok for this but you should be using at least 3.5x50mm for the joist fixing and 3.5x30mm for the rest. As for the surface rough side up gives a good key for spreading of adhesive (flexible type)


Regards
Builditwell