Enlarge fireplace - right approach?

[EvilDonut]

I've started demolishing my fireplace (old open fire in 60s house) with the intention of rebuilding it using new bricks, wider than before.

Here's a top-down section:

I'd like to rebuild the inner skin of bricks 1 brick wider on each side, to accommodate a log burner.

My worry is that I might find it impossible to remove the existing bricks without compromising the load bearing capacity of the wall. 215mm worth of bricks each side need to go.

Is the inner leaf of the recess likely to be supporting anything further up the chimney?

The first floor joists are bearing down on this wall too, if I remove a 1.1 metre width section of bricks am I likely to destabilise things?

Here's a pic of my progress:

I can see that the centre two columns of bricks are fine to remove, but the sides may be a different story!

Thanks!

 

[Doggit]

I think you're trying to take out too much: why does the opening need to be so wide, and what's the current width of the chimney breast. But some pictures taken from further back would help.

 

[EvilDonut]

The current width is 500mm - this is a bit limiting for log burners, so I want to expand it to 725mm (ish). The 1100mm I mentioned previously is the new lintel width.

But even if I kept the 500mm opening, I'm still looking to replace the old bricks with new ones, so I'd have to remove part of the existing wall.

Here is a pic from further back:


And here's my sketch plan:


Here's the sort of thing I'm trying to achieve:

 

[EvilDonut]

Here it is with all the infill excavated...

 

[vards01]

Have you considered a cassette stove type.......my dad had one installed as his opening was insufficient for a conventional log burner.

http://www.stovax.com/stove-fire/riva-wood-burning-multi-fuel-inset-fires/riva-40/

 

[EvilDonut]

Yep we've considered it, and it certainly would make things easier, but both me and the mrs would like a free standing one.

 

[EvilDonut]

What a total pain in the arse this is turning out to be! Removing bricks from the middle of a wall is hard even with an SDS. Is there a better way? Like angle grind out the mortar? Will a 9 inch disc do that?

My problem is all the bricks I need to remove are keyed into the bricks that need to stay, and this is in a 330x330 square pillar arrangement so not just a basic wall. Plus the pillar has corbelled bricks above it for the gather.

Progress:

 

[vinn]

OP,
You should stop cutting out brickwork now, & set your lintel - when its 24hrs installed & dry, cut back up to the lintel.
Use a brick chisel or a cold chisel to crack/split the bricks prior to removing them.

 

[EvilDonut]

Ah yeah splitting the bricks would be much easier.

Unfortunately I can't install the lintel yet as it is intended to be fully supported by the new bricks that I'm going to lay. Can't lay those until the existing ones are out. The wooden frame you can see around the fireplace has a heavy duty angle bracket. It's a DIY strongboy!

I think I'll build up some supports at the far back of the fireplace recess, to take any weight of the corbelled gather if it tries to sag a bit after I remove what's under it

 

[Newboy]

Put a lintel in that is long enough to span into the existing brickwork past the point where you want to lay your new bricks, remove the old brickwork and then lay your new (cosmetic?) brickwork up to the lintel. Your DIY strongboy may have a piece of angle iron but it's all held up by four woodscrews.

 

[Doggit]

As this is a flat wall, where exactly is the chimney. If it's on the outside of the wall, how wide is it, as you don't want to open up the front and find you've opened up a hole in the wall to the outside. That's not to say that you can't overcome it, but let's check the structure sooner rather than later.

 

[EvilDonut]

I've stopped at the outside wall - that's the back wall you can see in the latest pic. The outside chimney is 1370mm wide, inside is 500mm, so I've got plenty of masonry either side.

 

[vinn]

OP,
Unfortunately you are doing it back to front, so to speak.
What should happen before you knock out a single brick to enlarge the opening is that the lintel should be set.
Then you work down from the lintel opening up to your dimensions.
Note that when the lintel is in position it takes care of your concerns about "compromising" higher up the flue.

The wooden propping arrangement is unnecessary & can be removed.

But keep going, you wont burst through an outer wall - just remove bricks up to the soot covered fire back wall.

You want to consider removing any metal bits (damper etc.) from just up the flue - the flue will have to be clear all the way to the stack terminal.
Then have the flue swept.

 

[Doggit]

What are the dimensions of the stove you're going to fit, and will the flue be able to straight up, or will it need to bend backwards. If the latter, then you'll need to allow a bit more height for the 45 degree bends, so take this into account before you fit the lintel.

 

[EvilDonut]

A while has passed but thought I'd post pics for reference of people in similar situations in the future...

I did as advised and installed the lintel before proceeding.
Then I poured the constructional hearth, which extends a metre from the wall.

Then I excavated 225mm brick pillars either side, cutting half bricks as required.

Then I dot and dab fixed some hardibacker to the rear wall. Was going to use bricks but would have pushed the log burner out into the room too far.

Next job pour the visible hearth and build up the new bricks (110mm width either side)