Hugo Nebula wrote:
Bear in mind that these type of joists have their limitations....

minimum depth is over 240mm, which causes problems in loft conversions
where headroom is usually at a premium. AIUI they can't be chamfered
nor can they can't be simply supported by resting on a wallplate, they

There might be a plan C....

conversions where the joists have to be inserted between the existing
ceiling joists on top of the existing wallplate under the existing
roofing felt.

The new joists may be able to go perpendicular & under the existing joists.
Loft headroom is maintained at the expense of first floor headroom, of
course a new ceiling is also required. This route seems to work quite well
in standard Victorian / Edwardian terraces at low material cost although
arguably greater disruption.

--
Toby.

'One day son, all this will be finished'