Fireplace questions: stove, cast iron insert

Leif

I opened out the fireplace today by removing the fire back, and the rubble, to reveal an opening 23" wide, by 14.5" high and 28.5" high (measured to the lintel). The inner hearth is a mess, and the sides are brick, with holes in the mortar, minor damage to the bricks, and bits of mortar on the sides of some bricks.

My options are a cast iron insert, slabbed granite hearth and wood surround, which I think I can fit with help from a friend to lift the bits, or a stove fitted by a local shop (Focus Stoves).

For a stove, how should I prepare the fireplace? I would put a slabbed granite hearth on the constructional hearth. The walls around the opening are plastered (presumably brick, with ~1cm undercoat plaster and ~3mm finishing plaster. My concern is that gypsum based plaster does not like heat, and I suspect it would fall off. So could I hack away the plaster on the wall around the opening, and apply a plaster like substance, and then paint with acrylic emulsion to blend in with the rest of the wall?

Also, as the inside of the fireplace is a bit messy, is there a suitable render I could apply, and paint? I suppose I could have a go at tiling, using cement based adhesive. I presume that tiles are not suitable if burning wood in a grate, but they are okay with a stove as the temperatures are lower.

I assume concrete is okay for the inner hearth, as the existing one is a mess.

Lots of words, some questions! Thanks.

w50nky

Your post has given 2 sizes for hight, I assume that 14.5" is the depth.
I found that rendering the inside of the builders opening with a mix of one part cement, one part lime to six parts sharp sand worked well. This was applied in 2 coats and allowed to dry out slowly over several days. This was then given 6 thin coats of lime wash over 6 days and has stood up well over the last 2 years. You can lime wash each year and this will penetrate any small cracks that may develop. A concrete screed for the inner hearth would be fine to in my opinion

Each stove will have a minimum clearance advised to side and rear etc so this could dictate your choice.
Have you calculated your stove output requirements?
A stove over 5Kw needs an additional air supply to the room in which it is fitted.

Your suggestions for the granite hearth seem fine to me. Remember that you need 300mm Minimum in front of your stove, more if the door is wide and would allow ash to fall onto your carpet when opened! You are right regarding gypsum plaster although I have approx 9 inch clearance at each side of my stove and have not had any problems so far. You can get high temp plaster and render ready mixed but it is quite pricey. I have never used it so can not say how easy it is to use. Look here: http://shop.vitcas.com/vitcas-heat-resistant-plaster-16-p.asp

Lots of useful information and regs at this site too. http://www.stovesonline.co.uk/stove_building_regulations.html

Leif

Thank you very much, that is very helpful. Yes, 14.5" was the depth, and I already have a vent in the room for use with an open fire. I doubt I would need more than 5kW though, since this is more of a 'nice thing to have' and a safety back up in case the combi croaks e.g. power cut.

I will get the local shop (round the corner) to do the survey (they charge a small amount) and they will confirm how much front hearth I need, and no doubt flag up any issues.

w50nky

Glad to be of help. I would try to obtain a few quotes and arm yourself with your questions written down prior to their visit.

Enjoy!