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Deleted member 174758
Hear! Hear! On cost grounds there's a lot to be said for T&G chipboard, which is 2400 x 600mm and so can be installed by one man working alone. My own feeling is that it it is probably as good as a lot of the low cost T&G softwood we see these days, but it costs less, is far quicker to install and is probably stronger because it has less defects. Yes, access can be an issue with poorly-planned installs, but one that can be dealt with using a tool such as the Routabout or the solid board access cover. Plywood has exactly the same "disadvantages", yet nobody ever mentions it in connection with ply - nor the fact that plywood comes in 8 x 4ft sheets (making installs a 2 man job) and needs to have grooves routed in the edges and loose tongues glued in place for a bulletproof installation.Chipboard gets a bad press but people don't help themselves. I regularly see people using 18mm standard P4 boards, not glueing the joints and then using the wrong screws - and even using nails which is ridiculous.
My advice is always use 22mm P5 moisture resistant board - and even better we have recently started using Weatherdeck which is a lot denser than ordinary and has higher moisture resistance still. The boards should be glued together at joints and glued to the joists. The nails should be at least 2.5 times the thickness of the board. If the joists are the correct size you should not get problems with this spec.
I'm not saying I wouldn'yt install T&G softwood, just that it's a lot more expensive. At home my bathroom has 25mm H/W plywood flooring whilst the attic was refloored with 22mm T&G chipboard about 20 years ago Both floors were properly glued and screwed on 150mm centres. Neither squeaks, both were installed with appropriate access panels from the off