removing secret nails?

[craigthecoupe]

i have purchased some reclaimed maple flooring that was once a school gym.
it has been secret nailed and i need/want to remove them before i lay it but am at a bit of a loss a to how to go about it.
is it simply a case of using a punch and a hammer? the nails have all been cut off near flush with the wood so i can't get any leverage on them. i have a first floor flat and this floor will go in the kitchen/diner and hallway. the house is a turn of the century victorian terrace and the floorboards are rough. i plan to remove them and lay a ply subfloor. the problem is hot water pipes run very close to the surface and am scared stiff about nailing so plan to glue the floor. is this acceptable?
my main questions are:
what is the minimum acceptable thickness for the ply?
and i read on another forum about liquid batons. the have more give to unevenness in the subfloor, is this correct? where can i find more info on relevant products?
the wood is 500x70x21 mm equal lengths.
your help is greatly appreciated

craig

 

[mattysupra]

when you say they the nails are cut of can you put the wood together and have nothing sticking out any where?
I would leave the nails in place and grind back anything that is sticking out and then install wood using a fully bond method ( glue down ). I think if you try and remove the nails you may end up damaging the tongue which can cause the floor to creak etc.
As for the plywood, the thickness will depend on how cupped your old boards are. If perfectly flat you can use 4-6mm plywood, but if you have cupped boards etc you will need to step up the thickness to lose the un-evenness ( 12- 25 mm )
I like to sand the floorboards flat and then over board with 4- 6mm so you dont raise floor height and also if you sand the floorboards flat to start with you always end up with a perfect sub floor to start with
Plus when you sand your new floor at least you will of had some practise with the sanding kit!

 

[craigthecoupe]

thanks matty. i think i will adopt this approach and leave the existing floor where it is and just board over it.
can you recomend a decent product that i can use to bond the new floor to the ply?
also should i screw the ply over the old floor or nail?

craig

 

[mattysupra]

4-6mm plywood use ring shanked nails 19-22mm. If thicker you must screw it down. 6" centers. As for glue try styccobond b92 or b93. I dont use these but have been told they are very good. The stuff i use you wont be able to get hold of easy at all. Woodyoulike might be able to advice you better on glue. Try searching some of her old posts to see if you can find other glues.