On Jun 8, 12:18*pm, stuart noble wrote:
It's about time I upgraded the insulation in the back extension of my
Victorian terraced house, an area 16'x10'. No access from the loft at
the front for a normal sized human, and installing a loft hatch in the
back bedroom would give me barely 3' height down one edge. No idea how
the original 4" of fibreglass was installed unless child labour was
employed.

I'm thinking of maybe pushing an 8x1 chipboard sheet across the joists
via the limited loft access and hoping that a second sheet would shunt
the first one to the back. It should then be relatively easy to slide
celotex over the chipboard surface. A bit of a dog's dinner but it's the
only way I can see it getting done. Blown vermiculite would have been a
solution but it seems nobody uses that any more.

Anyone got any bright ideas?

If you have sufficient headroom in your extention,some kind of
additional ceiling/suspended ceiling below the existing with
insulation between the two?