In message , Andrew Gabriel
writes
If you are designing your own doors to take sealed units, it's
vital to understand the environment in which the units must be
fitted, as it's incorrect fitting that results in most sealed
unit failures over time. The main cause of failure is that the
unit ends up sitting in a puddle in the bottom of the frame.
In plastic frames, the unit should sit on a number of plastic
spacers along the bottom, which hold it above the drainage
channels in the frame. The drainage channels must actually
work and drain the water away from the bottom channels. The
rubber seals against the glass are not designed to be completely
waterproof (they're designed for speedy fit by less skilled
fitters instead) and water which gets through must drain out.

I don't know how it's supposed to work with timber frames.

I have just done some after criticising the builder's efforts. The
rebate is suited to the current dg width plus two lots of 3mm thick
arboseal. The glass is stood on plastic spacers as you describe. The
bottom bead is *L* shaped and stands on thicker rigid plastic spacers
thus leaving a space for water to escape and the *L* forming a weather
drip.

With first generation metal frames, the outer glass was sealed
to the frame to prevent any water ingress, and where this was
done properly, those units at now over 30 years old are still
fine. The snag is that fitting those units was a much more
skilled job than fitting today's PVC units is, which made them
both relatively more expensive and/or more prone to being
fitted wrongly.

regards


--
Tim Lamb