Andrew Gabriel wrote:

You sit them on plastic spacers so the bottoms are lifted
well clear of the bottom of the frame. This is so water
which inevitably leaks past the weather seal can drain away
from the sealed unit bottom edge, and out through the frame
drains. If the sealed unit ends up sitting in a puddle of
water in the frame, it will not be a sealed unit for long.
You can buy packs of mixed thickness spacers from about 2mm
to 10mm from uPVC suppliers (and probably somewhere like
screwfix, although I haven't actually looked for them there).

For bigger frames it is also worth packing the units such that they tend
to resist the desire of the frame to sag at the free edge - i.e using
the spacers to add diagonal rigidity to the frame.

If you have a uPVC door, the units and spacers play an
important role in bracing the door against dropping, by
heeling and toeing the bottom corner of the hinge side
against the top corner of the lock side, so the unit is
acting a bit like a diagonal timber you find on a slatted
timber door or gate.

I should have read that bit before typing the above... ok just ignore me
- too tired!



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/