Mouldy silicon after just a few months

[WindowNerd]

Hi everyone,

I'm a homeowner and I've had the windows on my 4 bedroomed house replaced in May 2022. 

The old double glazed units were installed in the 80s and had seen better days. I oped for an installer that supplied and fitted Eurocell windows as I've had good experience with them in the past.

 

In some rooms, the silicon used to seal around the windows had already gone mouldy by January. It looks worse than the 40 year old silicone did when they ripped out the old windows. 

 

It's worst in my daughter's bedroom - see photos. The window is on the catch most days for the whole day so lack of ventilation isn't really an issue. There's no damp or mould on the walls. The walls are cavity insulated. 

 

I've approached the supplier/installer and they have so far ignored my initial email. Am I being unreasonable for querying this? It seems like an oversight and they may have used the wrong silicone as even the bathroom window doesn't look anywhere near as bad, in fact that looks much better.

 

I'm also wondering if they should have fitted trickle vents. I've read they became compulsory in June 2022 whereas my windows where fitted in May. When I asked about trickle vents at the point of purchasing they told me I don't need them.

 

Many thanks, 

 

Stefan

 

 

 

 

 

 

[JohnMo]

Did you watch them being installed, if so did the seal the gaps around the window frame and wall with anything.  If they didn't you may have a big thermal bridge, basically cold outside air one side and warm inside air the other side of the silicone.

 

If you don't have MVHR you need trickle vents.  Did the ones removed have them?

[Mr Punter]

Yes you need trickle vents, then replace the defective sealant.

[Sparrowhawk]

Trickle vents became mandatory (if no alternative ventilation) on 15 June 2022. I'm going to disagree with the two above and say you don't need trickle vents; you've "got the window on the latch most days for the whole day" which will provide adequate ventilation so I don't think that is the problem.

 

I note it's more the silicone at the top of the trim than against the window sill, so I'm thinking it's thermal bridging - in simple language there's a way for cold outside air to get behind the trim.

 

If you want to start with the easiest option I'd remove the silicone and redo with bathroom-grade silicone (i.e. known to be mould resistant). But it'd be worth taking the trim off and looking behind if you're up for doing that.

 

In my experience the supplier/installer will blame any mould on you and do nothing. Good luck but I feel you are on your own to sort this.

[ETC]

While there may be thermal bridging issues trickle vents should have been installed for background ventilation and may have helped with reducing mould build up.

[Marvin]

Hi @WindowNerd

 

In my humble opinion I think that peoples health should be the first issue. Use a cleaning product that has a small amount of bleach in it and clean all the window frame to kill the spores. There are many types of common mould that can cause serious health issues. Laying in a room for hours breathing in the spore riddled soup can damage a person for the rest of their life. I know this doesn't solve the problem, but please just keep cleaning off any mould you find in the mean time.

 

I'm no expert. I would guess it could be Stachybotrys or Ulocladium.

 

This should give you an indication as to what level of mask you should be wearing: 

 

https://www.familyhandyman.com/list/common-types-of-mold-in-the-home/

 

Typical cleaning material:

 

https://www.screwfix.com/p/no-nonsense-mould-mildew-cleaner-1ltr/31686?kpid=31686&ds_rl=1243318&ds_rl=1241687&ds_rl=1245250&ds_rl=1245250&gclid=Cj0KCQjwlPWgBhDHARIsAH2xdNdLOoG0lhEnvUK81YnbRoCED47isNirvpUt_ZbURA0k9KUB7RXDyDcaAp3iEALw_wcB&gclsrc=aw.ds

 

Good luck

 

M

[WindowNerd]

On 23/03/2023 at 15:56, JohnMo said:

Did you watch them being installed, if so did the seal the gaps around the window frame and wall with anything.  If they didn't you may have a big thermal bridge, basically cold outside air one side and warm inside air the other side of the silicone.

 

If you don't have MVHR you need trickle vents.  Did the ones removed have them?

Thank you. I didn't watch them being installed up close but recall seeing them seal the gaps. The fitters were very experienced and did a good job overall in my opinion.

Sorry, what is MVHR? The old windows did not have trickle vents. 
 

[WindowNerd]

On 23/03/2023 at 17:46, Mr Punter said:

Yes you need trickle vents, then replace the defective sealant.

Thank you. Are they easy to retrofit?

[WindowNerd]

On 23/03/2023 at 19:38, Sparrowhawk said:

Trickle vents became mandatory (if no alternative ventilation) on 15 June 2022. I'm going to disagree with the two above and say you don't need trickle vents; you've "got the window on the latch most days for the whole day" which will provide adequate ventilation so I don't think that is the problem.

 

I note it's more the silicone at the top of the trim than against the window sill, so I'm thinking it's thermal bridging - in simple language there's a way for cold outside air to get behind the trim.

 

If you want to start with the easiest option I'd remove the silicone and redo with bathroom-grade silicone (i.e. known to be mould resistant). But it'd be worth taking the trim off and looking behind if you're up for doing that.

 

In my experience the supplier/installer will blame any mould on you and do nothing. Good luck but I feel you are on your own to sort this.

 

Fair comment. I do agree that we can probably get away without tickle vents and that we may have a thermal bridge. Other rooms don't have this problem or at least not to this extent.

Edited March 27, 2023 by WindowNerd

[Mr Punter]

9 minutes ago, WindowNerd said:

Are they easy to retrofit?

 

Yes you can look it up on YouTube.  Just a series of holes drilled in the frame and the plastic vents fixed over.

[Marvin]

13 hours ago, WindowNerd said:

Sorry, what is MVHR?

Hi @WindowNerd

 

MVHR: Mechanical Ventilation with Heat Recovery.

 

How MVHR works. A mechanical ventilation and heat recovery (MVHR) unit will usually contain two fans; one to push fresh air through the heat exchanger and into the building and the other to pull the wet stale air through a separate circuit and out of the building. An MVHR system recovers about 75% of the heat that would otherwise have been expelled outside with the stale air.