Cover concrete(?) Chimney breast

[Stephiepea]

Hi, a little bit of background, myself and partner bought a 1920s property which was very dated and so we've spent the last two months renovating.

Unfortunately when we started on the bedroom we noticed the chimney breast (which had been covered at the front with some mdf on a frame) was damp on the left hand side. We called in a roofer to take a look at the flashing and believe that this (plus the fact it doesn't have a cover at the top) is the reason there is damp. The roofer however suggested that we should hack off the old plaster as it was no longer in a repairable shape.

After many hours of chipping away, we were surprised to find the chimney breast seems to be made of a mixture of brick and concrete? This has now left us in a quandary as to how best to make good again. (Were going to put the fireplace back in as a feature but leave it unused)

We would prefer to use plasterboard but are then worried about the surface. It's not smooth due to the concrete so will we be causing ourselves problems in the future by not sealing the surface?

Could we cover it with a coat of waterered down PVA to stop any bits falling away?

Should we use a special type of plasterboard? Can we dot and dab directly on the surface or should we build a frame?

Or is the best thing to plaster, but then again what type should we use?

Any help would be much appreciated! Thanks

 

[vinn]

The brick starts where the chimney stack becomes exposed to outside view and the stack begins.

Is this a complete chimney breast coming up from the ground floor in one piece?
Your fire opening and flue should be swept.
The flue needs through ventilation with a vent at the bedroom fire opening, and one at the stack terminal.
Do you intend to block up the flue again or make some kind of feature of the fire opening?
What about your other chimney breasts and flues?

After removing all the old plaster, prep by removing the suction with two coats of SBR (second coat tacky) not PVA.
Use a render of sand and lime and board finish: dont use gypsum plaster or dot and dab. Keep it simple.

 

[Stephiepea]

Thanks Vinn, we never thought of the bricks being the exposed part of the chimney! That's one mystery solved!

Yes there is a fireplace in the lounge underneath, we haven't yet stripped that back, but there was a gas fire installed there which we have now disconnected. Ideally in the future we want to put a log burner in the lounge, though for the moment we'll just tidy up and leave an exposed gap.

In the bedroom we intend to put back the original fireplace, but never use it. Therefore, do we still need to do something extra for ventilation?

Do we need to do a render of sand and lime, or could we skip that and just board over the SBR?

 

[vinn]

All flues need sweeping and venting. Have them all swept at the same time.
Abandoned gas pipes should be capped off where they branch off the main gas supply pipe.
Dont leave a live gas dead leg.
Always remove any Restrictor Elbow or isolating valve - they can be knocked and leak.

Nothing extra is needed for ventilation as long as some kind of vent or venting is present.
Unless you render the chimney breast you might find problems when fitting back the original fire surround. Nothing flammable, for instance can be within 150mm of the fire opening. There's also the possibility of soot chemicals bleeding through.
Read previous posts about these issues.