Opening up fireplaces for log burners

[AndyBaillie]

Hi guys,

I am currently in the process of opening up two chimney breasts in the dining room and living room for log burners to go in. I am trying to do as much of the works as I can to keep costs down. I have a couple of queries relating to both fireplaces so I will explain both issues separately with pictures below:

LIVING ROOM
I have an oversized fireplace surround to set against this opening and board up to. As the opening in the fireplace surround is a bit wider than the brickwork at either side of the opening, I am having to take an additional bricks width out of each side to then be able to build out the fireboards to butt up flush to the inner edge of the surround as this opening sits proud of the chimney breast. I have installed a new 1400mm lintel 2 courses of brick higher than the original opening height. My question is that there is an additional staggered course of bricks gradually narrowing to the top at the rear of the fireplace behind the course I am breaking out. Is it safe to break out all of this rear brick to make a squared opening to be fire-boarded? Please see photos below:-

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I also have a concrete hearth that is an irregular height. I wish to extend this beyond where it currently sits so that it would be almost the width of the chimney breast on either side and protrude a bit further into the room. I believe it needs to extend around 400mm beyond the chimney opening but I am thinking of making this more like 450mm . My question in relation to this is can I build a mould and cast concrete directly on top of this existing hearth and directly over the top of the floorboards around the existing hearth? This hearth is then going to be tiled.

DINING ROOM
In the dining room we are having a smaller ACR Malvern burner which is a slimmer model front to back, which should sit relatively far back in the opening and shouldn't protrude as much in the opening as the ACR Rowendale we are going to install in the living room. We are looking to retain the arched opening. I found 2 blocks of wood wedged in either side of the first brick at the start of the arch. I have removed both of these as they were quite loose and have bricked up the holes both sides with tight mortar joints. I am wondering whether I need to do anything more to reinforce this arch or will it be safe to work with as it is? What would be the best way to finish this on the inside around the flue pipe and will I need some form of special heat proof bonding coat/plaster? I am looking to bond and plaster the face of the chimney breast back to the picture rail and I will be installing a floating mantle and corbels retrospectively.

I want to flush tile the hearth to meet my LVT flooring. Due to originally installing the LVT up to the previous fireplace surround, I will have to remove and lay new tile up to the edge of the new tiled hearth, and I want to have a border strip of squared LVT tile which the herringbone will intersect with. I have dug out a lot of concrete/brick/toy cars and general crap and it is gradually getting more earthy. How much rubble do I need to remove to cast a good solid constructional hearth? Also wondering what the most appropriate layering of concrete would be, presumably a heat resistant ratio of foundation concrete plus a heat resistant self leveller taken to approx. 16mm below surface level so I can account for a good bed of adhesive and the thickness of the tile? Please see photos of this fireplace below. Thanks in advance for your advice guys!

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[big-all]

havent got a clue about the actual question
are you aware off part j
https://www.gov.uk/government/publicati ... document-j
and the need to employ a hetas or registered installer to install to the regs and certify
or go the building regs route where you apply before you start' work to standard including liners ect and they pass at your cost if to standard

[wes56]

what are the ref numbers for the stoves? you need thestove install instructions forbuilding openings size.

your hearths joists are trimmed around the hearth and somtimes sit on the fender wall. the fender wall is below the concrete level and filled with soil and stuff. the trimming joists often rot out.can you go below the floor and look .and probe from above.

dig below the trimming or fender plates level.dig out the front andback hearths to same depth and use a membrane pouch then fill it with concrete to just below the finished surface eg leave room for tiles.
why do you want to extend the hearth?300mm is regs.
hearths have to beso many mm's above the ffl coverings. see blg regs or local council regs.

the sticking out bricks in the opening are part of the flue throating but i cant see whats goin onup there. should be safe to cut them backbut im not sure.have you removed a brick arch?

clean up opening and hearths and post new photosplease.
dryfit the new surround and photo.

[AndyBaillie]

Hi,
Thanks and apologies for my late response. I am aware of the need for solid fuel fires to be signed off by building regs and I am also looking to do as much of the building works myself as I can to keep costs down.

I was looking to extend 400mm in the dining room to maximise on our tile choice and to give more clearance before LVT tile starts. As this would be flush tiled, it wouldn't infringe on the usable floor space in the room any more than making it 300mm.

In the living room, I have indeed removed the brick arch which was a couple of courses lower than the new opening. I used 3 acrow props/strongboys to support chimney breast and installed a new concrete lintel. I will finish off the builders opening cutting back the flue throating here, clean up the mess and take some new photos including a dry fit of the new surround. Please await new photos. Thanks again.