Molynoox
Established Member
Seems to be three factors for the flooring materialThank you Martin it’s very reassuring to get someone else’s view, is chipboard as strong and water resistant as plywood?
I will draw up another diagram for the roof when I’ve given it more thought.
I would dig down to reasonably hard soil and use 4-6” of hardcore.
1 strength
2 damp resistance
3 water resistance
Chipboard is strong enough... Its tongue and groove design means that once it's glued and screwed down it acts like one massive sheet. An advantage of that is you don't need to worry about finishing the board edges on the joists so you get better utilisation of the boards and also minimised cutting.
On wet and damp I wouldn't trust chipboard anywhere near water, as James mentioned, but on damp I think it's only the edges that might be at risk as the underside is usually a shiny plasticised surface that I would expect to do pretty well with normal humidity. The exception would be if you have an unusually large amount of humidity / condensation in which case you have other problems you need to solve. I think ply is probably more expensive but it's certainly an option and plenty of people use it. OSB3 too. Ply comes in lots of flavours and some are more water resistant than others so if going that route it's worth thinking about that side before buying.
On the foundations thing it's a tricky one because, as you alluded to, the ultimate factor is the soil underneath the foundations! So the fact you are aware of that and are assessing soil conditions and not just blindly throwing in 100mm of type1 on top of decayed leaf sludge is probably the most important thing Its a judgment call at the end of the day and I think my concern was that its dependant on factors you can't really control or measure I.e. the soil 'strength'. For that reason I would be digging down a bit further than I felt it needed and adding slightly more hardcore than I felt it needed.
It's the main reason I prefer groundscrews over piers actually, but I do like the pier foundations... they are cheap and fast which are big selling points
Martin