DIY Doctor

Condensation or damp?

Postby Alligator » Mon Jul 02, 2007 5:42 pm

This is my first post and I apologise for the long ramble, but I want to get all the details across. :)

I recently moved into a 1920s detached house which has two chimney stacks and I assume it used it to have fireplaces in the bedrooms and both downstairs rooms.

One breast has had both fireplaces completely blocked up but without any air vents in the breast or on the outside wall. I recently noticed that there are some damp patches on the bedroom wall, about 1/2 to 2/3 of the way up the outside wall to the side of the chimney breast and towards the top of the chimney breast itself. This wall was previosuly covered by a huge built in wardrobe so wasn't evident before I moved in.

I've had the chimney checked above the roof line with new flashing, pots rebedded etc and also had the roof checked. The roofer said he can't see any source of a leak and also told me that the pots on the chimney were full of water as the chimney had been completely sealed at the top and seemed to be there for decoration. He has since opened them up and placed an air vent type of fitting to the pots t stop water, but let air in.

I have also added put an air vent in the breast down stairs so I am hoping that this will prevent any possibility of condensation in the chimney and this seems to draw the air through, however I have only just done this so it may be too early to see any results.

Can anyone tell me if condensation in the chimney is likely you have been the cause of the damp patches or whether there could be another cause?

The survey on the house suggesting that the ventilation in the loft could be improved. Does anyone know the best way of doing this? and will it help stop the problem in the bedroom?

Also, would it be worth putting an airbrick in the chimney breast in the bedroom and if so, where should this go? should it go towards the bottom of the wall where the fireplace would have been or at the top and how would I know if I've put it in the right place to ventilate the flue? would it be better to have an airbrick added to the outside wall of the bedroom?

Sorry for all the questions, but I'm hoping that other have experienced similar and know what 's the best course of action.

Thanks in advance

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Simply Build It

Postby thedoctor » Wed Jul 04, 2007 8:13 am

See our project on closing a fireplace it shows where the airbricks should go. Put them in every closed fireplace. The roof can be ventilated by either putting in special ventilation tiles which simply replace a tile in the roof and allow warm air to escape through them. Two per side, 80% of the way up the roof are usually enough, or ventilation ridge tiles can be put on the top of the roof to do the same job. We prefer the vent ridge although it is more expensive.
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