Heat resistant plaster

[Tobiasisno1]

Hi. I'm about to install a multifuel stove and have already seen various posts on the above with 2 names cropping up-Envirograf and vitcas, but I've recently spoken to someone who's used heat resistant plaster-not sure if 1 of the 2 mentioned-and he said his has still cracked. My question is therefore " how well do these plasters work?" I assume they must otherwise they wouldn't be on sale but the chap I spoke to has put a doubt in my mind. Perhaps he just didn't follow the instructions.
If they are ok where do I need to use it-just inside the fireplace or on the chimney breast as well? The flue will be lined and I'll try to get some vermiculite down the chimney but there won't be a lot of room.

Any advice and tips will be welcome.

Thanks
Keith

 

[PrenticeBoyofDerry]

Never used them sure not sure, I am sure if you googled them you would come up with some info about them, but to be honest best to use a cement render around the stove.

 

[Richard C]

Was the base coat he used also heat resistant? Vitcas also do a heat resistant render
http://shop.vitcas.com/vitcas-heat-resistant-plaster-16-p.asp
but you can use a sand/cement/lime render which will withstand the heat or even lime putty. Don’t know if you’ve seen it already but here’s a useful archive post;
//www.diynot.com/forums/viewtopic.php?t=211524&postdays=0&postorder=asc&start=0

Properly applied the Vitcas stuff is supposedly good up to 500 degrees which is far more than you should experience; I have measured temperatures well into the 90’s on the wall surrounding my own multi-fuel cassette stove. You certainly need something like it inside the opening if installing a free standing stove but not if installing a cassette; you also need to use a heat proof base & finish plaster on the wall around the stove within around 500mm either side of the stove & 800mm above. I had an initial failure with Gypsum finish plaster but it's been fine since re-done.

I assume you are aware that installing a stove is subject to several Building Regulations & is notifyable work unless you use a HETAS registered installer who will issue a certificate of compliance; you will in all probability be asked to produce one when you come to sell.

 

[Micilin]

Best additive for sand and cement in fireplaces is fresh cow dung. A lime/dung/ sand mix was used years ago, sometimes with a small bit of cement

I rendered the sides of my fireplace (back is bare brick)about ten years ago. We have fires in it every winter (not every day), not a sign of any cracking. 4:1:1 scratch, 5:1:1 coat, onto bricks that were cleaned of soot.

I can't guarantee it will work for you, mind, so go with the recommendation above. The important thing is to have the background well prepared, so that the render will not pull away when it expands.

I would be inclined not to use a skim coat anwhere near it, just sponge it up nicely, and if you like run a trowel over it when it is gone hard enough to take it without marking it

 

[PrenticeBoyofDerry]

Best additive for sand and cement in fireplaces is fresh cow dung. A lime/dung/ sand mix was used years ago, sometimes with a small bit of cement

Bullshyt

No seioriously , I have heard of this kind of application before, but not as a heat resistant one, more themal.
But that don't mean it don't work

 

[Tobiasisno1]

Thanks for the replies folks and sorry for the delay in getting back to you, access to computer not possible over the week-end.

The best bet seems to be the lime render which I assume will be cheaper than the branded product which seems bit expensive. This is in the kids house and I think they'll probably want to give the cow dung a miss-in any case we haven't got a cow! My daughter does have a horse-will "hoss muck" do??

I'm aware that building regs apply and I'm not trying to avoid them-just want to get the job done at best cost by doing some bits myself and getting my plasterer to do some, but might still get a specialist in to actually fit the fire.

I'll print off the stuff on the lime render to discuss with the plasterer-he's rendered the cellar stairs recently and that finish would be ok I would think, but need to hear what the kids think.

Thanks again
Keith

 

[Richard C]

I'm aware that building regs apply and I'm not trying to avoid them-just want to get the job done at best cost by doing some bits myself and getting my plasterer to do some, but might still get a specialist in to actually fit the fire.

I found the cheapest & best option was to source my own independent HETAS engineer; i.e. not linked to a stove shop! You can download a list of local installers from their website but get at least 3 quotes & make sure they are happy for you to source & supply your own fire & do any other building work, under his guidance if necessary.

My guy did the initial flue survey, supplied the liner & all fittings at cost (I had to order & pay over the phone), spent a long day installing & commissioning the stove & provided the notices & a certificate of compliance. You probably won’t save much if anything on the liner, fittings & insulation so if you knock off the £100+ LABC fee for inspection/test & all the hassle of having to climb on the roof with an 8m stainless steel snake on your back, attempting to stuff it down the chimney, install a new pot, register plates & then having to satisfy LABC! As a % of the total cost, I thought the extra £300 it cost me for someone to actually do all of this for me was a no brainier!

 

[Tobiasisno1]

Yes, Richard I see what you mean but I've found in the past that contractors, of whatever type, usually want to do their standard job, not just the parts you want them to do. I'll try a few tho' and see what response I get.

Keith

 

[Sharpey]

Hello all. Sorry to bump this but I feel I have a relevant question.

Looks like we might be getting a wood burning stove fitted in the downstairs lounge. Will the chimney in the above bedroom need heat resistant plaster?

Also, is it absolutely imperative for the chimney in the actual lounge where it is fitted to have that sort of plaster? Only just finished having the room done up so the thought of hacking off render and skim and having it all replaced is worrying. If so, would it have to be the entire chimney breast?

Thanks for any help.