On 31/10/2020 19:57, Tim Lamb wrote:
In message , pinnerite
writes
From around the beginning of February, Mrs P and I will be moving into a
bungalow that is in need of lot of work. I do not yet know how old it is
but I am guessing from between mid-60s to early 70s.

The loft has glass-fibre insulation and is only partialy boarded. I
intend extend the boarding. I boarded my current one with bits of
chipboard let over from work done years ago. Well that was 5/8" board.

Now (soon) I shall need to buy new. It looks as though 18 x 600 x 2400 is
the default today.

The thing is I always aligned board edges along the centre of the joists.
So that would require joists at 600mm.

My house wasn't completed until May 1972 and its joists are at
16" (406mm) centres. The "new" bungalow may be the same age.Â* Should I be
concerned if I intend to lay them at right angles to the joists?

No. I use polyurethane glue to bond the joints but you might need to
consider access for moving/re-wiring light fittings etc.

Might be good to top up the insulation while you are there. I prefer
Rockwool. Much less irritating for a similar performance.

Above the new 'flooring', or squeezed into the 4inch gap under the
flooring ? :-).

Wickes sell special extension supports that lift the boarding up so
that the requisite 300mm of insulation is possible. I made my own
from inch thick plywood, cut into 300 mm long by 100 wide strips,
glued and bolted vertically to the horozontal bars of the trusses
and with 50x50 slot cut into the top end allowing a 3.6 metre length
of 47x47 timber to be carried from side to side, spaced 600 mm apart
and fitted the loft boards to those new rails.

The electricians will be along shortly worrying about power cables
buried in insulation:-)