Skip to main content

Ready to hire?

Post your job in minutes, browse real reviews and choose who to speak to.Post a job

Need some tips or advice?

Ask a question
Plumbing

How best to seal condensate pipe going through brick and mortar wall

Anonymous user 16/03/2024 - 3.32 PM

I had a boiler fitted 2 years ago with a condensate pipe going from the boiler (inside an airing cupboard) through an external wall to the drain outside. The other day I found the cupboard soaked with an inch of water. Doesn't seem to be the pipe itself leaking because it only happens when it rains, and the mortar where the pipe enters the internal wall is wet. There appears to have been an attempt to seal the pipe using silicone gel on the outside - but there are gaps in that seal (there's not much room between the pipe and the wall). I purchased some basic silicone gel but I'm worried it won't adhere well or make a permanent seal on mortar / brickwork, and that would be made worse if I can't fully dry out the mortar. Is silicone gel OK - is there a better product I could pick. The pipe doesn't seem to move so it would be almost impossible to fit a rubber gasket without removing the pipe and making the hole bigger. What should I do? I'm not particularly good at diy, but I don't want to spend a fortune on this!

Are you a tradesperson and able to answer this question?

Log in

4 Answers

PDH Installations Ltd

Rating: 5 out of 5
Motherwell
Hi Adrian, the best way to solve this issue would be to dig out the existing silicone and replace with a suitable external silicone or mastic, we generally use a soudal frame sealant on the external holes as it is flexible, adheres if there is some dust and moisture and comes in various colours to match your brickwork
Answered7 March 2024
4

Luke stark

Rating: 5 out of 5
Falkirk
You could put more silicone round the pipe itself and then try get a flashing of some sort around it then seal that.
Answered7 March 2024
1

Christopher Plumber.

Rating: 5 out of 5
Norwich
Silicone or Mastic won't stick to anything slightly damp,so use CT1 it will be more suitable this time of the year ,as most outside areas ore damp and you won't have to dry the area first,it comes in clear/white.
Answered14 March 2024
0

Hall's Heating

Rating: 5 out of 5
Ryton
Are you sure there is no cracks or damaged joints in the condensate pipe it’s self? These pipes can become brittle and crack very easily. I suggest calling a local gas engineer to inspect the pipework and replace if needed and use a sand / cement mixture to seal from the outside.
Answered18 August 2025
0