How to Close the Top Opening of a Chimney Breast

[Kellysalmo]

Hi All

I've tried to google this - but can't seem to fid the correct terminology....so can't find any advice!

We've opened our fireplace up to the original builders opening and now want to create a feature fireplace (basically a plastered hole in the wall without a fire).

We have had the gas safely capped (below the floorboards).

We will be employing a plasterer to come in to do the plastering, but we would like to do all the prep work ourselves.

We will use plasterboard for all the sides including the top - but here is the question I am struggling to get answered...Do we need to block/seal the top of the opening in a special way?

Thanks in advance for any advice.

 

[ree]

OP,
1. FWIW: The original opening went much higher. The higher infill looks unsteady?
2. The present lintel is supported on a loose brick.
3. The corner metal angle beads are rusted & need replacing with plastic angle beads.
4. Theres no need for plasterboard - your plasterer can use solid plaster on the face of the c/b?
5. By "top of the opening" do you mean the flue? Read up on Register plates - you could fit a metal plate or a Backer board plate?
6. The flue should be swept, & any remining soot in the fireplace scrubbed off with a dry scrubbing brush.
7. The fireplace can be lined with p/b or Backer board.
8. The debris in the fire opening is from the back hearth - remove it all. Then consider what you want for the decorative opening "floor"?

9. The recess back walls on either side of the c/breast show defective signs of moisture - or chemicals from the flue?
10. The sheet floor boards you've laid need lifting & laying correctly.
11. The old front hearth is humping the boards.
12. Front hearth fender wall construction often leads to damp.

 

[Kellysalmo]

Thank you so much Ree for your detailed reply.


1. FWIW: The original opening went much higher. The higher infill looks unsteady? To be fair they are pretty solid, with only one loose brick - which you can see.
2. The present lintel is supported on a loose brick. It looks loose, but solid - although not well fitted originally.
3. The corner metal angle beads are rusted & need replacing with plastic angle beads.
4. Theres no need for plasterboard - your plasterer can use solid plaster on the face of the c/b? Ok great.
5. By "top of the opening" do you mean the flue? Read up on Register plates - you could fit a metal plate or a Backer board plate? Yes we were thinking of a Backer board plate...so good to hear someone else think it!
6. The flue should be swept, & any remaining soot in the fireplace scrubbed off with a dry scrubbing brush.
7. The fireplace can be lined with p/b or Backer board.
8. The debris in the fire opening is from the back hearth - remove it all. Then consider what you want for the decorative opening "floor"? Great advice.

9. The recess back walls on either side of the c/breast show defective signs of moisture - or chemicals from the flue? I'll have another look.
10. The sheet floor boards you've laid need lifting & laying correctly. Lol I will tell the fitter....only joking, they have been lifted (gas capping from original fire underneath) and I have taken the photo before they have been refitted properly. Love the honest critic though.
11. The old front hearth is humping the boards. It was, but we've dug it out.
12. Front hearth fender wall construction often leads to damp. Yes we had damp in this area - now we have taken out the whole old hearth, which has rectified the problem.

Another question for you - the CB has no air vents, would you put one in?

Thanks again Ree

 

[ree]

OP,
You can choose from a wide variety of decorative or plain white plastic 9" x 3" H&M vents.
Install it on the c/b face above the Register plate height.
The flue at the chimney stack terminal also will need a redundant flue cowl for top ventilation.