Damp walls around blocked up fireplace

[matt808]

Hi,

a year or 2 ago when i had my old back boiler removed and an new combi installed i also had my old fireplace removed. i built a small wooden frame inside the fire opening, covered it with plaster board then plastered it.

over the last few months i have noticed the paint starting to bubble and peel off where i covered the fireplace. after giving the whole area a good inspection i've also found signs of damp at the base of all of the walls that surround the fireplace.

As the problem is confined to the area around where the fire used to be i'm assuming that the chimney is responsible for the problem. i've had a look at the chimney (only from ground level), the joints on the brickwork seem to be in good condition and the flashing seems to be ok.

can anyone help me with a few questions.

1. if the damp is coming down from the chimney, is it normal for the damp to be at skirting board level?
2. whats the best way to cap the chimney?
3. will i need to install air bricks or some other kind of ventilation and if so where?

thanks for any advice

[welsh brickie]

Its best to brick up the fireplace and install a sliding vent,Even if you cap the chimney its best to keep the flue ventilated as warm air rises it will encourage condensation to form and cause dampness in the chimney breast.

[collectors]

You never block a chimney completely. I sounds like you need a cap or cowl on top of the chimney & a 4x9 hole at the base with an air vent placed over it.