Would I need to get building regs approval to knock out our chimney breast from the dining room and also take out the corresponding one from the back bedroom upstairs too?
Is there anything I need to be aware of when doing something like this?
If you're doing the work yourself (as we have just done)....
First floor joists 'may' be resting within the chimney breast - not uncommon. These might need to be secured before the bricks under them are removed, or they might be cantilevered enough by the rest of its length that you can remove the chimney below and then extend the joists. A carpenter should be able to tell which is necessary.
Tape up any vents or large door gaps to stop dust from escaping. Best to empty the room and roll back carpets if possible. Put cheap lining wallpaper on the floor and tape down, I found this easier than getting huge dust sheets. The thin poly dustsheets are useless for this kind of work.
Use an SDS drill or similar to do it brick by brick, and have an assistant that can take the loosened bricks off your hands, especially if you're having to go up and down a ladder, as it will reduce downtime of the drill. Any time saved by using a lump hammer will be lost in the clearing up of the lump hammer debris.
A lump hammer is definitely not a good idea if you're looking to keep some of the remaining bricks - if you're removing the front and sides of the chimney breast then presumably you're going to want to keep the back bricks, which probably form the dividing wall into the next room/external wall. If you're lucky you can drill/hammer the half bricks you need to remove from the back wall, if not then an angle grinder may be needed but these can be lethal if you've never used one. (I would never use one)
The remaining bricks along the back of the chimney may be decayed from soot - make sure you're able to make a judgement call on whether some of them are worth replacing. They'll need to be cleaned with a wire brush (and possibly other stuff) before plastering, else the plaster will adhere to loose brick/soot, and/or the black soot may seep through the plaster.
Concrete hearths can be broken up with a few well-positioned drill fractures. Not sure about stone ones.
Have a contingency fund for getting someone to come in and do the finishing bits when you run out of patience - after taking out a chimney and getting builders to remove the dividing wall, I've spent about two months gearing up for the final touches of plaster and wallpaper, whereas an extra bit of cash would have had it all sorted professionally within a week.
We removed ours totally, as the bit above the roof had already been removed by the previous owner, but if you're looking to keep your chimney stack then it does need supported somehow, building regs and engineer calculations, and if this was the case with ours then I would have got the whole thing done professionally.
Oh, and try to work out where you will put two rooms worth of furniture and belongings while the work is done.
