laying reclaimed floorboards on to screed

[Sachakins]

Should be fine at 400mm.
I don't think there's going to be any "nice screw heads" they'll all be glaringly obvious, especially Philips, posidrive or torx heads.
Maybe brass slotted look more authentic, but that's going to be a ball ache to do.
Not being t&g likely need extra too.

I'd dry lay half a dozen boards to walk on and see how they sit without fixings, that way it will show if they're going to bow, and adjust centres accordingly.

I'd consider skew nailing boards through their sides to hide all fixings.

Any surface fixings will likely catch when final sanding the boards before finishing.

 

[Bob008]

Hi, I am looking at flooring a 20 year old ground floor extension with reclaimed floorboards (timber tbc as I am literally at investigation stage). the floor is concrete screed and will be finished level.

I am thinking a base layer of thermal underlay, but then not sure on fixing the boards them selves. I am aware of leaving an expansion gap around the edges of the room which the skirting will cover.

I would really welcome the forum's wealth of knowledge on this subject!

Level floor
Install Dpc membrane (visqueen)
Install underlay
Use engineered planks and just have a floating floor it’s the easiest way

 

[Bob008]

Hi, The boards are 20mm thick so would 400mm centres be fine for these? What type of screws would you use as we don't want ugly screw heads but we want them to be secured without too much movement? I was suggesting 40mm screws as the boards are 20mm and the battens we are fixing too are 25mm. What are your thoughts please.

Use these from Screwfix there made for fixing flooring and they hold well and are hidden
Tongue-Tite TX Countersunk Floorboard Screws 3.5mm x 45mm 200 Pack