chimney breast short cuts.

[omeg3]

hi
need some help with chimney breast please.
ordered a nice new fire place, took old botch job out, to find four inch unfilled unrendered unplastered hole in wall.

so I want to plaster and render
he wants to use plaster board and skim
the latest idea is to fix the plaster board to the wall via scree on the floor (there is a gap where the ash felt ends, and fill in the gaps around the edges of the board and leave it un skimmed and unrendered as the thing will be hid under our new fire place.
The best one was just fit the board in the wall and leave it, the fire place will hide it.
I need arguments against the above please other than It seems a bit dodgy.
or is he right will it be ok!

 

[Richard C]

As this comes up so often, I’ve put together this generic post; read the links but not all may apply to you.

You can DIY but you need to understand the Building Regs (which changed in October), submit a Building Notice & pay a fee. Your LABC will inspect &, assuming everything is OK, issue a compliance certificate; the BI may want to witness smoke & spillage tests. No compliance certificate may lead to difficulties when you come to sell your property; if cannot produce a compliance certificate in the event of a problem, your insurance company may invalidate your policy & reject any claim.

Lots of archive threads on this, & other things you have to watch out for, here a few links for you to read:
http://www.stovesonline.co.uk/stove_building_regulations.html
http://www.hetas.co.uk/public/certificates.html
http://www.solidfuel.co.uk/pdfs/buidling_regs_consumer leaflet.pdf
//www.diynot.com/forums/viewtopic.php?t=183614
//www.diynot.com/forums/viewtopic.php?t=211524
//www.diynot.com/forums/viewtopic.php?t=242738
//www.diynot.com/forums/viewtopic.php?t=224751

& some more sobering just in case you think it’s all a load of old tosh:
http://www.solidfuel.co.uk/main_pages/news.htm
http://www.dailymail.co.uk/news/art...wood-burning-stove-leaks-carbon-monoxide.html
http://www.eveningnews24.co.uk/news/warning_over_heaters_after_norfolk_couple_s_death_1_811099

Also get at least 3 quotes from local independent HETAS installers:
http://www.hetas.co.uk/nearest_member

You might be pleasantly surprised & you should ask yourself if you really want all the hassle & risk getting it wrong; climbing onto the roof with an 8M stainless steel snake on your back is not for the feint hearted!

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As far as your concerned, if your fire has any serious heat output then board & skim is out & even Render plaster won’t work unless you use the right stuff; lime render & no Gypsum plaster, you need a specialist heat proof plaster but it’s all there in the links; read & take in the info & come back with questions if you need to.

 

[omeg3]

hi
thanks Richard
I should have explained that the fire we have chosen is a surround with stand alone electric fire which you plug in (i think). there is no flue or gas needed, theres no hole in the wall fire, wood burning or anything like that. but I take your point about heat out put which I am not sure about.

 

[omeg3]

Hi
heat out put is 1kwand 2kw settings. and we are paying for fitting I thought all this would be covered in the fitting but have been told if any extra work needs doing they will charge, all this covers is placing against the wall hence the diy, bought normal sand cement mix and a normal plaster board which I am now going to throw and use fire proof ones.

 

[Richard C]

The critical factor with using Gypsum based plaster or plasterboard (including Fireline) is the amount of heat transfer into the surrounding wall. Gypsum based products will only tolerate a maximum of 49C, regularly exceed that & the plaster will crack & eventually disintegrate. I’ve no idea how your particular fire will translate to the temperature in the surrounding wall as I only have experience with wood & multi fuel burners.

From the links, a sand/cement/lime render mix will give you a good heatproof base coat but if you want a smooth plaster finish then you will need a specialist heatproof plaster such as Vitcas. Render & plaster will give a more soild & robust finish but be careful which fire proof board you choose if you go that route; the cheaper ones are still Gypsum based & are only designed for a “one off” exposure to high temperatures, they are not suitable where the temperature will regularly exceed 49C to any great degree.

Building work is never covered unless you ask & they specifically include it in their quote.

 

[ajrobb]

It may be covered in RC's first post, but I think you'll need to keep an open vent for the chimney. Someone suggested stuffing some loft insulation up the chimney, I don't know if that is a good or bad idea, but I'll be doing some work on chimney breasts so would like to find out. I've seen that an open chimney can add 1400W to a room's heating requirement. I assume that a properly vented chimney will still lose a few hundred watts. Some ventilation is required for the inhabitants (4 litres/sec per person according to Building Regs?), so it might as well go up the chimney.

 

[Richard C]

It may be covered in RC's first post, but I think you'll need to keep an open vent for the chimney.

No it’s not actually as the post is mainly concerned with solid fuel & open fires so good point for the OP.

Someone suggested stuffing some loft insulation up the chimney, I don't know if that is a good or bad idea, but I'll be doing some work on chimney breasts so would like to find out.

Would be an extremely bad idea IMO.

 

[bogies]

hi can I ask what the ingredient is in the heat resistant plaster? is it asbestos do you think, if so would be a bit dubious about using.

 

[Richard C]

hi can I ask what the ingredient is in the heat resistant plaster? is it asbestos do you think, if so would be a bit dubious about using.

Can't recall exactly what's in it, possibly mica, silicotes etc. basically I think it's finely powdered rocks with binding agents; absolutely no chance of it containing asbestos, the stuff is banned & it would be illegal.