I've an early C.20th house where a fireplace has been removed. The job is to re-instate it. The problem is that the chimney stack has been dismantled down to joist level in the roof. The chimney stack would have had two pots, one for a bedroom fire, one for a downstairs fire. I will only need one flue, so I guess the bedroom one could be left out.
What is the best way to rebuild some sort of chimney? The roof is slated. The timber work is in good condition. I suppose I could just go through the slates with a new stack... ideas? What will I need to do? Any ideas much appreciated!
If the new chimney is taking the flue gases from a gas fire, then you can build a proper flue stack through the house and out to above the roof, like a long upright flue from a normal gas boiler. The only other thing is, you will need to build block work around it to protect it from damage and you from a hot flue stack. The light weight aeroblock system will do for this, and is an easily shaped method to fit in with the rest of the house. Once it is all plastered over and finished it should look like it has been there since the house was built.
An open fire for coal or logs is a different matter and the chimney will need to be fully reinstated with the correct type of brickwork to take the heat and soot that is exhausted by burning these types of fuel. That would have to be left to a good structural engineer and builder to get that right.
The gas fire on the new flue stack will also need proper air-flow from a constantly open venting system, which can be as simple as a hole through the wall with insect deterrent grilles fitted, or a hole in the floor if you have enough ventilation in the void below to supply a good flow of new air into the room.
It's not going to have a "gas fire". I am re-instating an early
20th. century fireplace. It will take coal etc.
Why should I need a structural engineer to build a new stack? "The correct type of brickwork"? That's just a pile of commons with a pot on top! I don't know how the leadwork goes, though.
I don't think that extending a normal chimney will prove difficult. You need to open a lot of the roof in order to work on it though. Nothing you couldn't cope with with a slate rip on a catladder.
The brick is the same as the brick in the rest of the house. Use a chimney liner and a weakish mix between the bricks and the liner. Ordinary 6 to 1 for the brickwork is fine. You only need to go as high as the other chimneys in the area. If they have all gone, get hold of old photos of the area. You don't have to put any fancy corbelling in. (But that is not difficult either on a small 2 or 3 foot high cube.)
What you need to do is "bench" up around the smoke stack to prevent rain settling on the chimney. Just build up a slope around the stack.
If you are not going to use it constantly, put a net over it to keep out birds. You buy the net (a chickenwire basket) at the yard where you get the lining and the other stuff.
Don't light a fire for a few days afterwards to allow the cement to set. Then have just a smouldering coolish fire at first. It helps minimise cracking.
You will need to put a lead apron around the chimney where it meets the slates. Bear that in mind when pointing it. You bend 3/8ths of an inch into the brickwork and wedge it in with rolled lead strips, hammered into a tight fit with a small boulster. You can't do that on fresh brickwork.
You will need building regs for this, so the cost is 10 times what you would do a DIY boge for, and about 10% better cimney will result from the extra cash. If its a DIY get a real decent working platform up there, I lined my own chimney a while back, and spent time on the roof wishing I had hired a cherry picker.
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