Opening fireplace and inserting lintel

[Carsoh]

Hi all. I need some advice on guidance on opening up a chimney breast. I want to end with a builders opening and plaster it up to either use for a wood burner or to store logs.

I have started chipping aware at the plaster and removed some bricks. I am worried about how far to the sides the irregular bricks go, and about the lack of an arch or full lintel. There is a small steel lintel spanning the few centre bricks, but the opening it covers seems to be too small to be the builder opening, and it sits on irregular bricks.

What I want to know is:

1) Am I safe to remove bricks all the way to the last 20cm where I am expecting to see regular bricks.

2) Is a 100mm x 65mm concrete lintel sufficient?

3) Do I need two of these (i.e. does the front need to be two courses deep) or is one sufficient?

4) Is half a brick on each side (100mm) sufficient for the lintel to rest on (I am going to pack under with steel or slate and nhl3.5 lime mortar?

5) Do I need to support this sort of width opening with acros or am I good to just knock the bricks out and insert the lintel?

6) Am I likely to find any asbestos or similar thing that I need to be worried about (would they have used it in any of the cement)?

I have attached some photos in case that helps.

Thanks in advance.

 

[vinn]

You need to determine now whether you want a wood burner or a place for storing logs? Otherwise you might have to re-do the work to fit the new appliance's dimensions.
If you store logs in the opening where, & in what manner, would they be used?

Your flue(s) will need smoke testing and sweeping, & the chimney stack examined for soundness & terminal suitability.
Whatever, the fire opening will need wire brushing clean of all soot and loose debris.

Gently hack off the plaster to give a clear view of the original opening and the, is it a steel lintel(?) and post another photo.

Do you have a solid front hearth?

 

[Carsoh]

Would I not be ok for both if the opening is big enough for a wood burner? I think it will be if I go to the last 20 cm on each side - I brought an installer in take a look a few weeks ago, and he seemed pretty relaxed about the opening size given my choice of a 4-5kw burner. Is there anything else I should be considering that I have not?

Regarding the hearth, I am not sure. I am assuming it is there, but the previous owners have laid engineered floors (you can see in the photo), so I am not really sure whats underneath. Can I not put down a new hearth over the top of the flooring?

Regarding the current lintel, it is a thin steel one. You can sort of see it directly above the sooty bit in the zoomed out photo. It starts half way from under that blue brick on the right and goes the same distance to the left, so it looks like it is sitting on infill rather than original brick work.

I'll have a go at removing more plaster, but it is extremely hard work, and almost impossible without damaging the bricks. They seem to have been cement rendered. I have tried both chisel and hammer and an sds. Any ideas what is the best method?

How far up and to the sides should I go? You can see the line of what I think is the original brickwork in the photos. Is it safe for me to open up to that point?

I will have to wait till the weekend to knock off more plaster to take any more photos unfortunately.

 

[vinn]

No, its not OK taking a relaxed attitude (was the installer HETAS?) and guessing dimensions for a CO producing arrangement.
Mfr's dimensions must be followed.
AAMOI: a CO alarm is Regs required in the room, and the room must also have adequate ventilation.

Regs dont allow hearths on wood, see: stovefittersmanual.co.uk and similar sites.

You would have no structural problems removing the infill to the original opening, and taking out the lintel - but you would be guessing the dimensions.

Given what you say perhaps its best just to do the above. and leave the plaster alone until things are finalised?

 

[Carsoh]

Thanks Vinn. The installer was HETAS. He essentially said that the opening would be more than big enough for a 4-5kw burner. It can't be too big can it? I am not planning on installing the burner myself - I will get a HETAS in - probably the guy who already took a look. There is adequate ventilation in the room. I asked him about an air intake system underneath the floorboards, and he said it was not necessary.

Thanks for the heads up about the no hearth on wood. I guess I will need to cut that bit out if I do decide to install a burner in there rather than it being decorative.

Regarding the structural point, do you have any thoughts on the lintels (size, how many) and whether 10cm on the brick on each side is sufficient?

 

[vinn]

If its "too big" you would perhaps be wasting efficiency - but back to the beginning: all Mfrs specify dimensions for their appliances.
Your lintels seem fit for purpose.
How high do you intend to go?

 

[Carsoh]

I still haven't decided what is best visually. Any thoughts? I am leaning towards keeping it square. So I guess that would mean removing 2-3 courses of brick above the current steel lintel. This would mean 80-85 cms high and wide I believe (need to find the tape measure).

You say my "lintels" are fit for purpose. Do you mean that I should use two lintels, one in front of the other, in order to supported two thicknesses of brick in the front? Or is the single lintel sufficient?

Thanks.

 

[vinn]

Two lintels for two skins of brick or one lintel thats wide enough to carry both skins.