Our plastic front door is “leaking” rain (a damp patch) under the sill, The cement is in large part missing or loose. Tissue becoming damp/wet when pushed into the gaps. Will replacing the cement stop this or is there further action needed?

John Barrett, December 2006

Cement will do the job but with movement of the upvc (expansion and contraction ) it will likely fail again.
Fill with cement then rake out 1/8th inch directly under the sill.. Once the cement has hardened , after a couple of days, fill the gap with silicone sealant and finish off leavind a fillet.

Pete., December 2006