Chimney breast damp patch.

[tommos43]

Hoping someone here can help me.

Had a combi boiler fitted two years ago and the chimney capped at the same time.

A damp patch appeared at the junction of ceiling and chimney breast about a month later.

Checked in the attic and all seems dry and dusty.

Stack has been pointed a few years prior so no issues there either.

I still have my old de-commisioned gas fire in the hearth so as far as I am aware there is air moving within the chimney?

[wongers]

have you checked the lead flashings around the chimney breast

[tommos43]

I have given them a cursory glance yes and they do look all OK?

I am struggling to see any ingress of water anywhere?

[rayjay]

i would go back into the loft because it being at the point of ceiling and stack would point at above that point or lateral to the point above the joist, we are sure to have another down pour in next few days give it a few hours after rain and check again. this hot weather is capable of spot drying thus thus false positives.

[tommos43]

Thanks guys I will check when I have some rain likely tomorrow.

Just too add though I also have salt deposits on the chimney breast further down on the same side as the damp patch.

I live in a bungalow so checking the flashing from the ground all appears to be fine.

[lagerland]

Only one way to do it properly m8 ladder out then your know for certain,that all your flashing and pointing is up to the job..................

[tommos43]

AS all of this has coincided with capping off the chimney does anyone think it may be poor air circulation and if so would it be of any benefit to perhaps drill one of the bricks in the chimney with several air holes ?

[lagerland]

You can get these for about a score ....................

[jcgrumbles]

most of the time its your lead apron around the stack.any sign of condensation in your loft,i would put a few air bricks in anyway.have you got any vents in your soffits or facias as you need a good air flow...

[flyingpig]

Whoever capped off your chimney stack needs to have a word in their ear....

Your chimney stack provides natural stack ventilation to your property. As all air contains moisture, when the air cools down in the stack if it has nowhere to go it will deposit the moisture from the air as 'condensation' on the brick on the inside of the chimney breast. This then transmits through the brick and will show up as a damp patch on plaster work. Put an airbrick in and heat the room (or use a dehumidifier) to get rid of the damp patch. Once gone, repaint and all sorted.

Trapped air in any chamber in a house will cause damp, people dont realise the importance of ventilation and heating of air to prevent condensation and mould growth.

I hope this helps.

[tommos43]

Have asked my plumber to call up this week and see if we can fit a breathable cap rather than block off the chimney as he has done.

Will keep you posted.

Thanks for all the help and advice guys.

[binary]

If you have ridge tiles check they are pointed a good wind would push the water under and into the fabric of the building