Heatproofing the wall behind wood burning stove

[Simon Langford]

Hi,

I've recently had a 3-11 kW woodburning stove installed in our kitchen. It's basically free-standing with a flue going up next to the wall and out through the roof. The back of the stove is probably only about

3"-4" away from the wall, and the plaster on the wall has started to crack quite badly. When you tap it, it sounds a bit loose and hollow.

The stove was installed very recently (end of November) and the installer said it might need some heatproofing, but we "could always do that later if needed".

So now I'm thinking we'll need to do something before the wall crumbles and comes away - is that likely to happen? If I put some tiles on the wall will that stop the problem? Do I need special tiles, or special adhesive/grout?

I'm hoping I won't have to take the existing plaster off and start again. The installers are coming back again this week to fix the leaning chimney and do a better job of the bodge they made where the flue goes through the ceiling. Can I get them to fix it as part of the original job on the grounds that they should have known that the plaster would crack?

Sorry if a similar question has been asked before -- I did search with google for similar problems...

Thanks,

Simon.

[The Natural Philosopher]

Th easy route is to whack up some heatproof board - asbestos replacement stuff. Gypsum and glass strand. Multiboard and masterboard are two names that come to mind.

If you paint it, it will need to be heatproof paint.

Other possibilites are tiles and metal sheets or plates.

At least you don;t have opne gartes ti cintend with - we've just split an expesniove cast iron fireback from bottom to top due to thermal stresses..

[keng]

You ask what 'you' can do to fix it. Don't even go down that road. It is not what 'you' can do but what 'they' should have done in the first place.

You state they are coming back to fix a "bodge" then include everything that has been bodged.

If they are "installers" then it should have been installed properly. Your contract (can be written or verbal) with them has not been fulfilled until they carry out their part of the agreement. I just hope you haven't paid for the 'bodge'.

[jacob]

Probably a bit too near the wall. I did mine by adding a brick back panel about 700mm wide, floor to ceiling with 25mm kingspan behind, the brickwork tied as per cavity wall but with more ties as there is no edge constraint or corner. Am thinking of painting the brickwork - any suggestions for heat resistant paint?

cheers

Jacob

[bill]

It's also worth pointing out that this sort of installation requires building regs approval. Professional installers have the option of a self registration get out along the lines of Fensa double glaziers and Part P for electricians. The building regs covers distance from walls and suitability of materials. Sounds as if your fitter either wasn't registered, or if he was he shouldn't have been!

Bill

[Simon Langford]

Indeed, the installers make a big thing in their publicity of how convenient it is that they can self-approve their work since they are registered.

I'm interested to know about the minimum distance in the building regs. I've found Document J:

far as I can see, on page 32 diagram 2.10 says that there should be at least 150mm around the stove (or to a suitably heat resistant wall). It seems that my wall is not suitably heat resistant, and my gap is not

150mm.

Have I got the right reference?

Sounds like a stroppy phone call is in order.

Simon.

[Pete C]

Hi,

A good way is with some cement board, sheet of metal, or similar with a 1" air gap behind and well ventilated at top and bottom. Some foil stapled or glued on both sides of the gap would help.

The advantage with cement board is that it can be tiled easily if desired.

cheers, Pete.

Or a sheet of aluminium

[sylva]

I think this could end up being a discussion between the installers and Simon on what constitutes a non combustible solid surface not requiring protection.

I was thinking along similar lines as a temporary expedient, a wire frame with baking foil set ~15mm off the wall with an air gap top and bottom.

AJH

[lyn rivers]

We've just done the same, and were advised by the stove suppliers that the stove should either: (a) be positioned 3 x the diameter of the flue pipe from the wall behind or (b) the wall behind must be made from heatproof materials.

In our case we got the builder to use the heatproof plasterboard mentioned in another reply. (Our stove is also freestanding.) Your installers should know about this stuff, but it sounds like they've made a bodge of so many aspects of the job that you must be able to insist on them putting the whole lot right at no further cost... Good luck :-)

Lyn