Is this the right way to lay a floor?

[WoodYouLike]

What would I use to cut it? Just a tenon saw? Whats a Skil saw mentioned above...?

Plunge saw could do the trick (you can set it on specific depth). Please note, this solution will make the floor (where you cut the boards on the T&G's) have some weak links.

 

[Thermo]

if you want to take it up and re-use it, you could sacrifice the first line of baords and then take it up piecemeal, might be a bit difficult and time consuming, but you should be able to use them again

 

[WoodYouLike]

It might destroy all T&G's and then the only way to re0install it would be to A) clean all t&Gs as best as possible and B) glueing it down fully, wich means glueing it to the plywood that has been laid first to make the underfloor more stable)

 

[Sapper]

Was thinking I would stagger the plywood underlay and the T&G sections (ie have the cut T&G section hang over the plywood by 3-4 inches then slide the next slab of plywood under and then nail it down) I'm hoping this would give the joins more strength and less likelihood of big gaps opening up over time.

Was also going to get rid of the battens and styrofoam and just leave the DPM with insulating board over it and then the plywood sheets...

 

[Thermo]

it coild well do WYL, but it might be worth trying on the first run to see. If its not been laid correctly in the first place it may well come up easily. Worth a try before running it through with a saw

 

[WoodYouLike]

Right you are Thermo.