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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthordelprado
    • CommentTimeJan 11th 2018
     
    Pretty much everything they do looks great, anyone got any thoughts? I am gonna use it on my stud wall for the TV and speakers...
    •  
      CommentAuthordjh
    • CommentTimeJan 11th 2018
     
    Good product as far as I know, although sheets are heavy. I went with sheets of OSB with regular plasterboard over the top where I needed strength. Actually I forgot in one place - as a result of which a couple of wall cupboards fell off a wall covered with moisture-resistant plasterboard. Luckily it was an external store room, so I made some pieces of ply cut to the same size as the cupboards and screwed them to the wall before hanging the cupboards on the ply. Looks OK now and is plenty strong enough.
  1.  
    We have it, with normal plaster skim over the top. Seems fine now it's up, but the guys hated doing it as it is so heavy and difficult to cut.
  2.  
    Heavy and can't be scored/cut like plasterboard - we used a plunge saw/rails for our cuts which was quick and easy. Cutting out holes for electrical boxes was the biggest pain - used an oscillating multi tool but went through a lot of (cheap eBay) blades and it took ages.

    It does give significantly more robust feeling/sounding walls and being able to hang most things with just a screw is great. (supposedly 25kg from a screw).

    We used the fermacell surface treatment but found it hard to get a good finish, as did the team we then paid to finish it. If I used it again I'd just get a standard skim.
    • CommentAuthordelprado
    • CommentTimeJan 15th 2018
     
    DJH I did wonder whether OSB plus normal plasterboard would be better and cheaper?
    • CommentAuthorowlman
    • CommentTimeJan 15th 2018 edited
     
    I've used it on a couple of jobs, one of which was a curved wall on a mix of timber and steel studs, and I echo what others say, but for some jobs it's very useful.
    Plusses:-
    Strong; Fire resistance; Sound transmission.
    Minuses:-
    Heavy; Cutting; Fermacell edge/gap filling adhesive is a bu...r to remove when it sets; Fermacell ready mix skim leaves something to be desired IMO; Plasterers generally don't like finishing it.

    I've also used djh's method of OSB with PB on top and regular finishes, cheaper than Fermacell and less hassle.
    If it's only one straight wall with, easy to achieve, accurate cuts, where wall thickness is critical, then go for it, ( i.e.Fermacell). If you require a perfect plain plaster type finish then you can always seal and cover it with lining paper before emulsioning.
    • CommentAuthordelprado
    • CommentTimeJan 15th 2018
     
    Why can you just use multi finish on it like normal plasterboard?
    • CommentAuthorowlman
    • CommentTimeJan 15th 2018
     
    You'd have to ask a plasterer with experience of Fermacell for a definitive answer. They, Fermacell will no doubt want you to buy their, value added, products.
    It can work but good adhesion; either too much, or too little suction; may cause lightweight plaster to pull, or dry before a decent finish can be achieved.
    My plasterer did it for me on a small 2M x 3M area that I'd fitted, but cursed me. He did prime it with PVA but maybe an acrylic primer would work better. I guess lightweight plasters and plasterboard are designed as complementary products.
    • CommentAuthorRex
    • CommentTimeJan 16th 2018
     
    I used Fermacall throughout and my builder and myself, skimmed the whole with Fine Surface Treatment. Had no problems whatsoever.

    Neither my builder and most certainly myself, are not professional plasterers so I don't know what problem a pro has with FST.

    For cutting, I used the Fermacell knife thing. Scribe deeply a few times and snap. No worries. No need to reinforce external corners, just file flush. I didn't use the jointing tape and generally have had no cracks anywhere, but another time, I would use the tapered board and tape the joints. Only cracks I have after six years are joints above windows and a few doors. No big deal, very minor but tape would have strengthened the joint.

    Can't speak highly enough of Fermacell.
    • CommentAuthordelprado
    • CommentTimeJan 18th 2018
     
    Rex - why did you use it, and pay more for using it, over normal plasterboard?
    • CommentAuthorRex
    • CommentTimeJan 19th 2018
     
    A number of reasons. This is probably the only house I will ever build, and although timber frame, wanted it to feel as solid as possible.

    Tap on a plasterboard and Fermacell wall and the latter sounds considerably more solid. Plus, I can put up paintings/ shelves etc without wondering if the plasterboard will take the strain.

    I really dislike all the plaster corner bead that is obviously necessary. If it is damaged, it is quite a task to repair. Fermacell, no corner bead and very easy to repair.

    I wanted all internal and external corners to have a radius detail. With Fermacell, I achieved that on the external corners with a router bit; internals I skimmed with Fermacell Joint Filler and used a short length of 15 mm copper pipe to get the radius. I could have done the same with plasterboard on internal corners.

    I did not need any wet trades in the house as there was no skimming. Fermacell FST to seal the boards, light rub down, couple of coats of undercoat with rub down, two emulsion top coats. Job done, no experience necessary, easy peasy.

    The disadvantages are that it is heavy and very dusty when cut or machined. A plunge saw gives bloody wonderful cuts, almost too good as the joint stick works better with a raggedy edge.

    As for weight, the full sized boards are not really a one man job, so I bought a pair of board carries from Axminster (http://www.axminster.co.uk/wallboard-carrier-391025). One of the best tools I have ever bought; you will never want struggle with large sheets again.

    So yes, Fermacell may have been a bit more expensive but for me, it was win-win on all counts.
    • CommentAuthordelprado
    • CommentTimeFeb 26th 2018
     
    Hi all

    can anyone recommend what primer to use on fermacell if you decide to skim? Heard people mention blue grit but query how permeable that is. Having said that, how much of an issue is that? I had understood that in passiv haus you want the internal wall to be less permeable and the outside much more so.

    However I wonder if DG27 works instead?
    • CommentAuthorbogal2
    • CommentTimeJan 3rd 2019
     
    Any updates on where to buy Fermacell from?
    • CommentAuthordb8000
    • CommentTimeJan 4th 2019
     
    I got it from FGF in Bristol. They had the boards in stock and the fine surface treatment in order. I did a ceiling but required a board lift as they’re so heavy!
    • CommentAuthorMike1
    • CommentTimeJan 6th 2019 edited
     
    Personally I'd probably use a heavy duty plasterboard - for example Gyproc Duraline / Gyproc Habito / Knauf Performance Plus. They're much more substantial than regular plasterboard, but can still be handled and skimmed normally.
  3.  
    DG27 works well for clay plaster over fermacell.
  4.  
    Using Fermacell behind wall cupboards on an IWI kitchen re-fit. Never used it before. Thanks for previous advice as to where to get a couple of sheets - Nevill Long, Leeds were v helpful. Carriage more than the 2 sheets, but that's life!

    Job starting 4th Jan and I realise that I have not done my homework enough re cutting, fixing and finishing.

    I don't want the dust of power-cutting. Is the Fermacell knife the thing to use? @Rex, do you want to sell me yours? :bigsmile:

    Do I need special screws, or will dry-wall screws do? Does one need to drill pilot holes?

    I'll only be using 2 boards; the rest will be done in plasterboard. I had assumed I could have the plasterer skim it the same as the plasterboards, but again, no homework...!

    Any advice gratefully received.

    Thanks,

    Nick
    •  
      CommentAuthordjh
    • CommentTimeDec 29th 2020
     
    Posted By: Nick ParsonsUsing Fermacell behind wall cupboards on an IWI kitchen re-fit.

    What we did was put OSB behind normal plasterboard. Nothing's fallen off yet ....
    • CommentAuthorowlman
    • CommentTimeDec 29th 2020
     
    In this instance, why did you decide on Fermacell, was it because of subsequent tiling/fire retarding etc.? What thickness are you using?
  5.  
    Posted By: Nick Parsons

    Do I need special screws, or will dry-wall screws do? Does one need to drill pilot holes?

    Nick


    Yes, from memory. it was 5 years+ ago but I don't think standard dry wall screws will cut through it. (but for two sheets you could get away with pre-drilling).
  6.  
    djh said: ''What we did was put OSB behind normal plasterboard. Nothing's fallen off yet ....''

    Owlman said: ''In this instance, why did you decide on Fermacell, was it because of subsequent tiling/fire retarding etc.? What thickness are you using?

    Yes, I was going to use 25mm ply and then pl'bd over, but I am IWI-ing, boarding and having it plastered, then leaving it for the kitchen fitters *with strict instructions not to pierce the VCL*!!! I was concerned that a mere 25mm (24.9mm?) 'bite' might be insufficient, so I want the 'plasterboard' to 'do a bit' as well, hence Fermacell over 25mm ply (50mm PIR behind). This is only for the wall cupboards, which will contain heavy crockery.

    and Simon Still said: ''Yes, from memory. it was 5 years+ ago but I don't think standard dry wall screws will cut through it. (but for two sheets you could get away with pre-drilling).''

    Thanks. I need to try to get some then, or spend a while drilling and probably countersinking too.

    Any thoughts on cutting? Do I need 'the knife' (any Genesis fans out there?)?

    Thanks,

    Nick
    •  
      CommentAuthordjh
    • CommentTimeDec 29th 2020
     
    Posted By: Nick ParsonsYes, I was going to use 25mm ply and then pl'bd over, but I am IWI-ing, boarding and having it plastered, then leaving it for the kitchen fitters *with strict instructions not to pierce the VCL*!!! I was concerned that a mere 25mm (24.9mm?) 'bite' might be insufficient, so I want the 'plasterboard' to 'do a bit' as well, hence Fermacell over 25mm ply (50mm PIR behind). This is only for the wall cupboards, which will contain heavy crockery.

    Well our crockery cupboard and our tinned food cupboard and various others are all on 12mm PB over 18mm OSB and nothing's fallen off yet :bigsmile: OTOH, I put a couple of fairly big cupboards up on moisture-resistant PB and after SWMBO filled them, they fell off the wall (with a spectacular bang, but not too much damage). So I screwed some 25 mm ply in front of the PB and screwed the cupboards to that and they've been fine. They're in the "bin store" (a.k.a pantry/wine cellar) so appearance doesn't matter so much, but it looks fairly neat - just the edge of the ply shows flush with the edge of the cupboards.
    • CommentAuthorFred56
    • CommentTimeDec 29th 2020
     
    Nick.
    I will be upfront on this. I am an unashamed advocate of Fermacell.

    You have to get to grips with cutting though. I use a variety of tools. I have the Fermacell scoring knife. It has a tct tip. It’s not like cutting regular plasterboard. You have to go over the cut several times and the edge still does not break cleanly. When I use that I keep a small block plane handy to smooth the edge. I also use a circular saw with a tct blade. I keep a cheapo one anyway for getting into chipboard floor and other nasty jobs. Mine is one of the Evolution ones with a nail tolerant blade. I am not promoting that brand, they are just cheap and, based in the one I have, reliable but crude. Mine does not have a riving knife or any dust extraction port so not the best or safest tool around. If you use one like that, no riving knife, it’s best if you clamp a guide down the board otherwise the cut wanders.
    I do also abuse my Bosch Pro jig saw with one of the wood precision blades, fairly coarse works better than fine tooth. Stuffs the blades but cuts fast and fairly true. I have used a hard point handsaw. Bahco is my favoured brand for first fix wood and they have a good stiff blade. The wobbly blade brands and hopeless and the S &J ones often have differing set on either side which makes it hard to cut true.
    The block plane is invaluable for edges when it comes to door and window reveals. Fermacell is hard and does not need edge or corner bead. Instead you cut it to a good fit, plane it smooth and fill. I use one of those Stanley replaceable blade planes because I can just put in a new blade and carry on. I tried a surform but trashed the blade too quickly.
    We all have Fein Multimaster type tools now and I use mine for sanding and cutting backbox holes in Fermacell. I bought that tool in 2006 so it is obviously up to the job. Way to slow for cutting boards though and the price of blades is hideous.

    Health. I have good, face fit, FP3 respirators. You can get one for £25, cheap considering the potential alternative.


    Screws. You need the right screws. Fermacell screws have a different angle on the head. Normal bugle head drywall screws can neck off just under the head so do not use them. It’s getting hard to buy genuine Fermacell screws but excellent and cheaper screws can be found on eBay. On my last project all the screws I used came from eBay. There are other ‘hard’ board screws available which will probably be ok but I have not used them yet.

    Careful not to get jointstik on the face of the board. It reveals as a different texture that is hard to disguise. The joint filler shrinks dramatically so be ready to build it up in a series of coats. Fine surface treatment catches the last imperfections. Odd stuff, a bit like wet chalk. It seems to react with the board in some way but using it fills the pores and gives a good face once lightly sanded with a very fine paper, a bit like sanding drywall joints.
    Years back we experimented finishing Fermacell with Gyproc drywall primer instead of FST. It worked very well but the guy who did it was excellent and it may have been his skill that was at play.

    Disposal. It’s unfortunate that Fermacell is a body double for AIB. I think it would be a wise move for Fermacell to stencil the name, date and composition all over the reverse of every board.
  7.  
    Fred56, thanks! Will have a more thorough read in the morning. Cheers! Ordered screws tonight.
    • CommentAuthorRex
    • CommentTimeDec 30th 2020
     
    And I am another big supporter of Fermacell.

    As stated above, no need for corner trim; to give my house a slightly 'different' look, I used a 12mm dia router on all external corners to round them. Less prone to corner damage. Looks good, and a great finish straight from the tool. Only problem was the dust!!!!

    As for screws, i have used regular plasterboard screws but it is necessary to pre-drill and countersink first.

    The Fermacell screws are very very good, but if not countersunk, they do produce a raised surface. I found that with countersinking, the screw goes in, not sanding required, just filler over the top.

    The only issue I have had over the years is that as the house has dried and settled, some of the filler over the screws has kinda 'popped' out leaving an obvious raised area. Not a big deal and most people would not even see it. Rub down to level and dab of paint more or less solves the problem, but my better solution is to dig out and re-fill. My other small issue is the I did not use jointing tape anywhere and in a few places, (above doors; in some internal corners and also some external corners) there is a slight settlement crack. Again, only the 'anal' would probably see it!

    I have used paper joint tape to cover, smoothed with fine surface treatment, painted and problem solved.

    Great stuff, expensive but well worth the cost.
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