Board choice for lining fireplace builders opening

[fatmcgav]

Evening all,

So I'm currently renovating the living room in our victorian end terrace.

As part of this, I've removed the old gas fireplace that we never used, and have built the chimney breast out about 40mm in order to provide some more depth for alcove bookcases.

I'm now working on lining the builders opening.
I'd originally intended on using normal plasterboard; however I then had the thought about how to handle damp etc, as it's a capped chimney behind.

Is normal plasterboard suitable, or should I be aiming to use MR Plasterboard or cement board such as hardiebacker.

One side and rear is going to be fixed to studwork, but the other side is going to be sticky foamed onto the brickwork and screwed at the front.

This is what it looks like right now:


Once boarded, the fireplace is going to be plastered and painted, and left as an open space for ornaments or similar.

Thoughts?

Thanks in advance.
Gavin

 

[lostinthelight]

If your thinking damp, then Im thinking treated timber?

 

[JohnD]

a capped chimney should be ventilated top and bottom to prevent damp.

it may also help to dig the rubble out from under the hearth, down to oversite level, because it will not have a dpm so will draw damp up from the ground.

 

[fatmcgav]

a capped chimney should be ventilated top and bottom to prevent damp.

it may also help to dig the rubble out from under the hearth, down to oversite level, because it will not have a dpm so will draw damp up from the ground.

Wrt ventilation, I was planning on hiding a small vent in the top panel, so should be good there.

And Yeh, I was also thinking about the ground level and damp, and maybe pulling all the crap out and then putting some concrete in there to level up...

 

[JohnD]

If you have a wooden floor with a ventilated void beneath, you can open a ventilation gap under the floor once you have dug out the hearth.

The chimney must also be ventilated at the top. Both flues.

 

[fatmcgav]

If you have a wooden floor with a ventilated void beneath, you can open a ventilation gap under the floor once you have dug out the hearth.

The chimney must also be ventilated at the top. Both flues.

It was previously a suspended floor, however when I started this renovation I discovered that everything had rotten out. So had to replace with a concrete floor with. Took the opportunity to add wet ufh aswell.

 

[JohnD]

Did you find and rectify the source of water?

 

[fatmcgav]

Did you find and rectify the source of water?

So the issue was dry rot rather than damp in the floor.

There was also very poor ventilation which was probably the primary cause.

 

[dontbelieveawordofit]

hardiebacker covers all bases. but if your confident it’s dry just use vapour board. (foil back board)