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  1.  
    A colleague has just told me of his intention to use the pink 'fire-proof' plasterboard behind his soon-to be installed wood-burner. I think he should render, but I am not *certain* he can't use the pl'bd (it just would never have occurred to me as a safe option). My feeling is that if he pl'bds and skims, it'll blow off with the heat, and if he doesn't skim, the paper will char. Tell me I'm right, please! (or wrong, of course!).
    Thanks.

    Nick
    • CommentAuthorJoiner
    • CommentTimeJan 14th 2011
     
    The biggest problem is the expansion and contraction because the heating/cooling cycle will be pretty rapid.

    We used a fireproof board (can't remember it's name) which weighed a ton and cost sixty quid for an 8' x 4' board back in 2000. A mate skimmed it with a refractory cement and it lasted for about five years until we took on board the need to burn the stove at its maximum heat (and this was pre-Brian) and tried it for a night. Still have to get that patch fixed! Hidden it with a pile of logs to date.

    Would join you in welcoming advice as to the best stuff to use.
    • CommentAuthorowlman
    • CommentTimeJan 14th 2011
     
    I wouldn't use plasterboard in close proximity to a stove, I don't care what the manufacturers say about it's fireproofing capabilities. If he must use sheet material there are much better products on the market, designed for such high heat applications.
    • CommentAuthorJoiner
    • CommentTimeJan 14th 2011
     
    In my case, it wasn't the board material that was the problem but the render/skim. What I found was that most of the "fireproof" boards out there are designed to be resistant to fire, to stop its spread, under circumstances where its (minimal/marginal/insignificant) expansion properties didn't really matter and the loss of a skim of plaster was the least of your worries.

    Maybe Nick will confirm it, but I get the impression his concern is the same as mine was at the time of fitting the lining board to the fireplace, protecting the bricks, to which end we put in a layer of insulating wool (again, irritatingly, can't remember what it was, but it replaced the asbestos fibre stuff) between the brick and board - and I'm not exagerating when I said it was heavy; it took four of us to lift that single 8 by 4 sheet onto the trailer at the builder's merchants! With just two of us this end we cut the sections to size on the trailer. We thought the refractory cement (on the advice of someone who'd done it before) would have done it. Actually, to be fair, it probably did because after five years of alternating temps to have lost a 10" square probably isn't bad going.

    I'll post a pic later.
  2.  
    Our stove installer used cement render with fine sand to get a smoothish finish, when painted with emulsion it looks good, very minor cracks after a couple of years.

    Plaster skim on anything will only last a few weeks in my experience.

    peter
    • CommentAuthorjms452
    • CommentTimeJan 14th 2011 edited
     
    have done the job twice (two different houses).

    The first one was 1:1:6 (cement: hydrated lime: sharp sand) skimed with multifinish plaster.
    Was OK but covered in hairline cracks after a few weeks (hidden by another coat of emulsion).

    The second time on recommendation from our stove installer used 0:1:3 and skimmed with the same ratio but using plastering sand rather than sharp - Only one small crack so far.

    Neither was a disaster but if doing it again I'd do the second method. In both cases I think you should leave it a while before painting with emulsion (or not paint it at all).
    • CommentAuthorTonyt
    • CommentTimeJan 14th 2011
     
    I used supalux fire board available from travis perkins.
    It didnt need a skim as its a pretty smooth surface, fixed with dri wall adhesive and high temp silicone on the internal corners.

    No problems so far after 2 years

    Tony
    • CommentAuthorchuckey
    • CommentTimeJan 14th 2011
     
    I have a free standing wood burner which stands in a fireplace with lime mortar and sandstone back, no trouble at all. I did though put a couple of sheets of thickish aluminium foil sheets up just the size of the fire behind it with an air gap between them to reflect (or protect?) the heat back into the fire/room. Depending on your taste, three sheets of stainless behind the hob paneling type stuff could look terrific and throw a lot of heat back into the room. Three sheets?- fix a sheet either side, with one over the centre to cover the joint and to give a larger air space behind fire. Leave all fixings loose to accomadate thermal movement.
    Frank
    • CommentAuthorJoiner
    • CommentTimeJan 14th 2011
     
    Tony, is that 'supalux' the incredibly heavy stuff I was talking about?

    I did phone the builder's merchants I got my stuff from ten years ago, but they (or at least the person I was talking to) didn't know what I was talking about!
    • CommentAuthortychwarel
    • CommentTimeJan 14th 2011
     
    for my wood burner mounted in the corner of a room, I used a sand cement render over concrete block and then faced it with ordinary black ceramic tiles.

    The excess heat is absorbed by the tiles, render and blocks, and because of the thermal mass the wall not get excessively hot. The heat then re-radiates into the room for hours after the fire has died down.

    This probably would not be great for a poorly insulated external wall, but for an internal wall or a well insulated external wall it works a treat.
  3.  
    Thanks all. You reinforce my view that render is the easiest way to go. Well, perhaps Supalux (which hadn't occured to me) is arguably easier, but I remember the price as being gold-plated. On the other hand another friend has an offcut! I wonder if it's big enough...

    Nick
    • CommentAuthorevan
    • CommentTimeJan 14th 2011
     
    I was thinking about using some spare steel roofing sheet. Just fold a neat box to fit into the recess and put rockwool behind it. Dunno what it's painted / plated with mind you.
    • CommentAuthorfinny
    • CommentTimeJan 14th 2011
     
    Lime render every time.. 3 parts finishing sand, 1 part 2.5 hydraulic lime. one coat.
    • CommentAuthorJoiner
    • CommentTimeJan 15th 2011
     
    How heat resistant is that mix though, finny?
    • CommentAuthorCWatters
    • CommentTimeJan 15th 2011
     
    The building regs specify a minimium clearance of 150mm between stove and combustible materials. If closer than that I don't think fireproof plasterboard is the answer. Fire proof plasterboard is intended to provide temporary protection to steel beams in the event of a fire not for continuous protection near stoves.

    Perhaps look at the render suggested by others or perhaps..

    http://shop.vitcas.com/vitcas-heat-resistant-plaster-16-p.asp
    • CommentAuthorwindy lamb
    • CommentTimeJan 15th 2011
     
    We have a wood/coal burning Raburn which gets very hot and behind that we have the pink plasterboard with a standard plaster skim over. It's been fine for the last 8 years even when the flue from the Raburn started to glow cherry red! I now sweep the flue every month without fail.
    • CommentAuthorJoiner
    • CommentTimeJan 15th 2011
     
    I was getting tempted to remove all the heat shielding and taking the lot back to brick and just repointing that and doing running repairs as the mortar crumbles out from the heat over time. The 'rustic' look would probably be much better to look at.
    • CommentAuthorRobinB
    • CommentTimeJan 15th 2011 edited
     
    It's probably not that difficult to get the 150mm clearance and then, according to building regs you don't have to worry. Ours would have had that clearance except that the stove pipe had to run exactly midway betwen any two timber joists and I wanted to keep the flue straight up (cost, draw, ease of cleaning, aesthetics), and I had some spare stone so put that behind it. I think bare brick also looks really good and will continue to look good for a long time. I agree pink plasterboard not the right stuff for the job.
      sitting_room_stove.jpg
    • CommentAuthorfinny
    • CommentTimeJan 15th 2011
     
    Joiner..
    Heat resistant? Tried to light a lump of unused lime plaster in the log boiler..reckon 800 or more degrees..no joy tho, bugger wouldn't burn!
    :cry:
    • CommentAuthorJoiner
    • CommentTimeJan 15th 2011
     
    :bigsmile:
    • CommentAuthorpmusgrove
    • CommentTimeDec 5th 2011
     
    I noticed that the photo above shows the stove right up against the wall. I am about to put in a Woodwarm against a rendered block wall and would like to also push it right up against the wall and have all the pipes behind the wall (it has the saddle boilers). The dealer says that will be OK but has anyone here done such a thing and if so what was the effect on the wall and stove?
    • CommentAuthorRobinB
    • CommentTimeDec 6th 2011
     
    I did it! One year I can't see any problems. We've probably never had a fire going for more than 10 hours at a stretch. Building control signed it off when the house was built. Had forgotton I'd posted that pic!
    RobinB
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