On 07/06/2015 11:09, WeeBob wrote:

I'm about to start laying some engineered hardwood flooring and before I
start, I'd welcome opinions.

The current floor is patchy quality old floorboards. My plan is to lay
plywood down on top of them. From what I read, I should nail or screw
the plywood to the existing floor... but also leave an expansion gap.

Surely there is a contradiction here? If I fix the plywood, then it
won't be able to expand. So what would be the right thing to do (and why)?

Also, I've enough underlay to do the room twice and I could put a layer
of underlay under and over the plywood.

i.e. floorboard, underlay, plywood, underlay, hardwood-floor.

Are there any advantages or disadvantages to this?

Thanks
Bob




If it were me .... screw fix plywood down at reasonable spacing (no more
than 200mm) through floor boards into joists.

Put a later of closed cell foam underlay and lay the engineered floor
floating with glued t&g joints.

Scribe in the first row, then put 10mm packers behind it, so top can
cramp up each subsequent row to it.
After floor complete - remove packers and some put in 10mm cork
expansion pieces .. not really convinced its necessary.