Chimney Flue Condensation

[alprod]

Hi,

I have had several roof conpanies round to inspect these huge damp patches that have appeared on the attic walls, around the chinmey stacks. Two companies said i needed some flashing and pointing done but the 3rd guy told me he was sure it is condensation off the chimney flue and there is nothing he could do to fix it.

The flues are no longer in use, the fire places have been plastered over. If this is the case does anyone have any experience of how I could fix this problem as the damp patches are pretty substantial.

Thanks

 

[Richard C]

If you’re sure it's condensation & not water penetration from above, try fitting a vent to the bottom of the flue where the downstairs fireplace used to be & see if it cures the problem. A disused flue should always be vented & not completely sealed; a small positive draught will prevent damp air entering from outside & stop any condensation forming. If the top of the pot is still open, fit a vented cap to prevent rain entering.

 

[Shytalkz]

It could be water penetration via a failed flashing, or condensation in the flue - if the blocked-up openings aren't vented and the pot has been closed off - or it could be a bit of both. None of the advice you've had is potentially incorrect.

If the chimney is completely blocked, as Richard says, vent it; I would also recommend putting a cowled pot on the top as well, to let the air move around, but prevent water penetration. Oh, just realised Richard said that as well d'uh!

 

[^woody^]

Any damp patches from penetration from the roof are completely different to stains from condensation from the flue. Also condensation from the flue (or penetration from the flue) will be confined to or emanating from the line of the flue.

And condensation is more likely to form lower down in the flue than in the loft, and bleed through the plaster in the rooms below.

Another (more obvious) sign is that if its penetration, then the damp is worse after rain. Have you checked following heavy rain?

If you could post an image then it may help to narrow it down

 

[alprod]

Hi Guys,

Thanks for response, sorry i was late getting back to you but was away on holiday last week. Anyway here are some pictures i took of the damp patches. Do they help narrow the problem down any?

thanks

View media item 942 View media item 943 View media item 944 View media item 945

 

[^woody^]

You've got a rain penetration problem, and need to determine where its getting in.

Most likely related to the flashings, but also check the chimney capping or flaunching.

If the chimney is not capped, then consider getting it done and then ventilate the flue from bottom to top

 

[alprod]

cheers mate, will get it sorted.

Flue is actually on neighbours side so wont be able to vent it but will ge the flasdhing fixed and some re-pointing.

 

[JohnD]

I have a feeling you could drill a hole in your wall.

 

[ta88ycat]

I'm new here, how do I view Alprods pictures mentioned above?

And how do I tell the difference between water penetration and condensate in my stack?

Thanks
Paul