Opening up of fireplace for stove (Gas not wood burning)

28 Feb 2017
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United Kingdom
I have a 60s house with an internal chimney through the centre of the building. Strictly, i'm not installing a wood burner, as i'm putting a gas wood burner style Yeoman CL3 in there.

Having knocked the old one out, and pulled away the plaster, I can see that the lintel is doing very little at supporting the front wall so I need to sort that, and i'm planning to take 2 brick courses out to raise the height of the cavity however, I also would like to widen the aperture. It looks like the course to the left could be taken out fairly simply but i'm unsure as to whether I can make it any wider? Can it be done and would it need further supports in place to protect the side walls?

I must add that I wont be doing this myself as its a job too far for me, I dont want the internals falling down around the chimney!
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Whilst a gas log fire is much easier to light, it's not a lot more efficient that an open coal fire. As to opening up the chimney opening, and decent builder will be able to sort that out. They'll hold the chimney up, take out the bricks below the support, for an arch or a lintel far enough across where the new opening will be, then remove the bricks to widen the opening, and then corbal the throat of the chimney.
Whats the exact name of the appliance that you have or intend to buy?
The Mfr should supply dimensions for builders opening installation - you should work to them.
If you clean up the area and remove all chattels, including the carpet, & then post a pic showing the whole c/breast from floor to ceiling it would help?

You appear to be removing, and lowering, the soil in-fill inside the c/breast fender wall - do you intend to lay down a membrane, and then bring the front and rear hearths back up to the required level in poured concrete?
Are there any issues with damp or any rot in the trimming joists - have you been under the floor to inspect the timbers?

The flue needs a powerful sweeping.
Is the gas pipe still active?
Is there a chimney breast in the room behind?
Vinn, we are looking to buy a Yeoman CL3 or CL5. Its a work in progress at the moment and having removed the old fireplace, gives me an opportunity to see what we have to play with.

The floors have been up as there was some water ingress from the front of the house but that appears to have been failing mortar and has since been sorted. The soil infill was filled in with concrete but it was broken under the old hearth and the supporting timber seemed to have failed. Some of the old cast iron from the infill had broken away. I'm open to ideas on the best way forward on this, did think of spanning the joists with 4x2 and then laying boards parallel with fireplace opening and then using supporting timber again to refill the void with poured concrete? This would then give me a level base to lay down a new stone hearth? If that breaches combustible material guidelines then i'm all ears on the best way forward.

What made you consider rot in the trimming joists? I have checked the timber and apart from a joist on the opposite side of the room showing some dry rot (which will be replaced), the others look good.

Gas pipe is still active, was a gas fire that was taken out. Chimney breast is on the back of this into the dining room but there's no opening (I did consider having it opened through but like to keep the noise separate between the two rooms). The width of the breast is 1500mm.
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I cant locate installation dimensions for either of the appliances you mention - perhaps the dims come with the appliance.
Why not call Yeoman and ask for dimensions?
Removing the "lintel" bricks and any infill will be fine but unnecessary until you know the dims, and what you intend the finished c/breast to look like.

The fender wall is typically a brick surround in-filled with soil - sometimes the trimming makes contact with in-fill earth moisture and rots. If your situation is different then come back here.
You can dig out, and do as I suggested above for fit for purpose hearths. The stone hearth goes on top proud of FFL.
No wood to be in the hearths footprint area.
If any timber is resting on brickwork then slip a bit of plastic underneath as a DPC. There should be no earth to timber contact.

Still waiting for a photo?
Is this what you're intending to fit then for the CL3, and this for the CL5. It's got the dimensions Vinn, but not the distance to flamable materials.
In my first search and in my second search ref your post I only found the appliance dimensions - and FWIW they come with the caution "sizes not to be used for any building preparations."
The dimensions required are installation dimensions as I specifically mentioned in my two posts.
Sorry Vinn, didn't spot the "installation". It's odd that the Yeoman site doesn't give and installation dimensions anywhere.
Thanks for replies, sorry not had chance to take any photos. I've tidied it up today, but theres no lighting in there now. I'll get some tomorrow with a bit of luck.

On the Yeomans website, it suggests 150mm either side of the burner hence the requirement to take at least the course out to the left and a further half a brick width out to get mimimum distance. The hearth only requires a depth of 12mm and our decorative stone is 20mm thick. The chimney liner needs to be 127mm wide
So coming back to this, this is what the fireplace looked like. Lintel not actually sat on anything.

void to left hand side with back boiler pipes.

A bit of digging further:

Left hand side looking up

Gather to right hand side

Currently opening is 580mm and I'd like to remove course to left opening the void and half a brick course to right. Neighbour has identical house and has similar opening doing same. Just want to be sure that I can continued to remove the chimney upwards another couple of bricks and then open up. Advice required please.
Just to add, that I'm now looking to fit a wood burner, so I'll be building a new constructional hearth below this once the opening is complete.
Before anything else you need to install a lintel at the height required by the appliance installation dimensions.
The lintel must be a min of 200mm wider than the required installation opening.
After the lintel is installed you should be able to open up the side brickwork jambs to the required opening dimension.

But your best bet would be to bring in a HETAS to give you a heads up - the HETAS would be able to see if more work is needed.
Cheers Vinn, got the lintel and not planning on smashing any more in until that is fitted. Lintel is 1500mm wide as is the total width of the brick chimney. Should I just span the lot instead of cutting it down? I've sorted a HETAS engineer to come out at the end of next week for some advice before he comes with the burner itself.
No, dont install the lintel at all until the HETAS has arrived on site for a heads up.
Whatever kind of lintel you have its a simple matter to cut it to length with an angle grinder.
Stick with what I've suggested above or, better yet, wait until the HETAS arrives.

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