22mm floorboards up....now what?!

[WabbitPoo]

Refurb of bathroom.

Tatty broken boards removed (all of them)

Electric heating mat in self levelling, all under vinyl click together flooring, to go on top.

What's the preferred filling between the joists and the SLC? I have 25mm ply arriving tomorrow but on reflection they will create too thick a result compared to the floorboarded landing outside the room, so what is the best option? Would 22mm (harder to find here) or even 18mm work?

 

[big-all]

21/22mm is a wood yard/timber merchant/builders merchant size `18/19 is a diy shed size

 

[WabbitPoo]

Thanks. This is Wales, so normal rules don't apply! Anyway, would 18 be ok if I nog every edge?

 

[Deleted member 174758]

Round here 22mm generally indicates Scandinavian or Russian redwood, which is generally less knotty and stiffer (in same thickness) than white wood. 18mm is generally lower grade Russian whitewood, although not always

Why would you need to "nog every edge"? Sheets and planks should both be laid at right angles to the joists and if need be be cut to length so that the ends of the boards/planks coincide with the middle of joists. Plywood needs to be laid "brick pattern" (so the joints don't line up). Are you aware that plywood for flooring comes in 15, 18 and 22mm as well as 25mm and that 18mm is the most commonly used thickness? Also 18mm or 22mm T&G P5 chipboard is (was?) considerably cheaper than 25mm plywood - although you may need to support unsupported end joints with noggins. Ideally sheet materials need to be glued D4 (flooring glue) down and screwed in place at 150mm centres. If your joists are further apart than 400mm/16in you will need to go to thicker flooring than 18mm