Fermacell pro's and cons

[Nick1c]

I am trying to get my head around the best way to line the house in the far, far, future when it eventually goes up. 

The wall structure, from the outside in, will be rainscreen (timber/render), batten, Proctor Wraptite, OSB (or something more breathable tbc), 300mm I-beam with warmcell, OSB, (?vcl), batten/service void, plasterboard or Fermacell. We will probably go for either a shadow gap to the floor or flush skirting/ architrave with a shadow gap to the walls. 

As far as I can see Fermacell is a superior product, but you pay for the privilege. Does anyone know what the real premium for using it is? Some of the extra cost must be set off against not needing to plan/ put in extra noggins for hanging, is it quicker/ slower to put up, is taping and using the fine finisher quicker &/or cheaper than skimming? How do the finishes compare, does it feel more solid than PB, does it repair well if dinged? Anything else?

Other than cost the downsides seem to be weight when moving it around and unpleasant dust - any others?

Sorry for the exhaustive list of questions, but I haven't actually seem it in the flesh. 

 

[ProDave]

Fermacell is heavy, expensive, and much harder to fit.

 

But it is much stronger, far less likely to get dings, and has crisp sharp edges that should stay crisp and sharp, so I would say the logical choice for shadow gap details.

[Vijay]

can you mix and match between PB and Fermacell depending where you want/need it?

[PeterW]

3 minutes ago, ProDave said:

Fermacell is heavy, expensive, and much harder to fit.

 

I disagree with that ... it’s no harder than taper edge boards with a tape and skim finish. In some instances it’s easier as you can create clean edges with a router and bearing bit - especially on corners. 

 

9 hours ago, Nick1c said:

Some of the extra cost must be set off against not needing to plan/ put in extra noggins for hanging, is it quicker/ slower to put up, is taping and using the fine finisher quicker &/or cheaper than skimming? How do the finishes compare, does it feel more solid than PB, does it repair well if dinged? Anything else?

Other than cost the downsides seem to be weight when moving it around and unpleasant dust - any others?

 

Right .... depends is the answer ..!

 

Firstly it is very heavy - it needs two people to manage boards and you also need a board lifter to do ceilings. You can’t do it on your own ..!

 

One of the benefits is that you don’t need to join on a stud - you use JointStik to bond the edges together, this is a cross between D4 glue and Gripfill and comes with a custom nozzle that puts a bead on the edge of the board. These joints are strong, but you need to leave them to dry properly before you do anything else. 

 

There are two ways to fit Fermacell to timber, either using the correct screws or by using crown staples. Screws hold better when the timber is uneven but leave a larger hole to fill. Staples are quick and easy and leave a very small gap to fill - very easy to do but if there is stress on a board they may move with only staples. 

 

Fermacell is very easy to repair though. If you cut a hole in the wrong place with a hole saw, or even cut an access hole, you can just glue it back in place, filler in the gap, sand and it’s done - you can’t tell it’s been removed.

 

It is also surprisingly easy to cut. Fermacell sell a knife designed for the job and it works on the the score and snap method and is very good. It leaves a slight ragged edge but this takes filler really well so isn’t a problem.  When it comes to filling all the screw holes or edges, you will need their filler. It’s much better than anything else and sands to a fine finish too. It’s better put on with a wide spatula or trowel, and it goes a long way. 

 

FST - or fine surface treatment - is the oddest product I’ve ever used ..!! Fermacell show it being applied with a squeegee, I use a 12” plastering trowel and you can do a 5m wall in probably 15 minutes. You put the thinnest coat possible on - the boards change from light grey to a slightly darker grey and that’s it ..! A quick sand over with a 120grit sanding board and you can be painting less than an hour after applying. The wall will look like it’s full of filler and screws etc, but a coat of paint and it’s all gone and you have a perfect flat wall. I’ve gone from a stud wall to ready for paint in 24 hours - that’s impossible with board and skim, and pushing it with TE/taping. 

 

The downsides are that the dust will destroy any power tool that you use to cut it. Circular saws or jigsaws create a lot of dust, routers are magic for cutting holes for back boxes or making perfect corners but all of them will die in a ditch with the dust. Buy cheap Titan ones and keep going back for the warranty claims ..!

 

Fermacell is very good for perfect square and flat surfaces - anywhere that you want curves or anything that needs blended angles then you possibly need to look at something else or look at how to get skim coats applied to certain sections. 

 

I priced a job recently that would have been £4K in Fermacell, and was just less than £2k in plasterboard and skim in terms of materials. When it came down to it, the labour costs were double for the board and skim as there was a lot of curve and detail work but the whole lot came out about the same price in total. If you can DIY and have square rooms etc then you can get a very good finish with Fermacell that is comparable to a skimmed plaster finish with no wet trade delays. 

 

 

 

[jack]

We have a mixture of Fermacell and plasterboard. You can skim over it like plasterboard, which we did for a consistent finish.

 

28 minutes ago, ProDave said:

Fermacell is heavy, expensive, and much harder to fit.

 

Yup. Compared to plasterboard, it's extremely heavy (45kg for a standard 12.5mm board) and expensive. You need to use special screws, which are several times the price of plasterboard screws (the guys who put ours up skimped on this and had a really hard time). Subjectively it's probably twice the physical effort to install - unless you're using the small one-person boards, there's no way a single person is going to be installing standard sheets by themselves, they're just too heavy. 

 

When it's up, it gives a much more solid feel to walls than a single sheet of plasterboard. You can hang heavy stuff without drilling into studwork, although I still prefer to drill into the wood behind if I can.

 

You may also struggle to find people willing to install it. Most plasterers either haven't used it or hate it with a passion. You might find commercial guys who have experience with it, but they'll be expensive.

 

In the end, we used Fermacell in places where we knew we'd be hanging things - kitchen, plant room, garage. Everywhere else, we doubled up on standard plasterboard to give extra weight to the walls more cheaply. I can't really tell the difference just by knocking on the walls.

 

There are other boards that are somewhere between Fermacell and plasterboard in terms of density and strength. For example, I believe habito and duraline are heavier and somewhat more impact resistant than standard plasterboard. I don't know to what extent though, and I'm sure there are other products.

 

[nod]

44 minutes ago, jack said:

We have a mixture of Fermacell and plasterboard. You can skim over it like plasterboard, which we did for a consistent finish.

 

 

Yup. Compared to plasterboard, it's extremely heavy (45kg for a standard 12.5mm board) and expensive. You need to use special screws, which are several times the price of plasterboard screws (the guys who put ours up skimped on this and had a really hard time). Subjectively it's probably twice the physical effort to install - unless you're using the small one-person boards, there's no way a single person is going to be installing standard sheets by themselves, they're just too heavy. 

 

When it's up, it gives a much more solid feel to walls than a single sheet of plasterboard. You can hang heavy stuff without drilling into studwork, although I still prefer to drill into the wood behind if I can.

 

You may also struggle to find people willing to install it. Most plasterers either haven't used it or hate it with a passion. You might find commercial guys who have experience with it, but they'll be expensive.

 

In the end, we used Fermacell in places where we knew we'd be hanging things - kitchen, plant room, garage. Everywhere else, we doubled up on standard plasterboard to give extra weight to the walls more cheaply. I can't really tell the difference just by knocking on the walls.

 

There are other boards that are somewhere between Fermacell and plasterboard in terms of density and strength. For example, I believe habito and duraline are heavier and somewhat more impact resistant than standard plasterboard. I don't know to what extent though, and I'm sure there are other products.

 

Habito are about the best on the market In terms of impact and fixing to 

Also cost 

Don’t forget to allow 35 % extra for labour 

[Nick1c]

Thank you @PeterW  It's sounding quite positive, I didn't realise you could stop worrying about studs. 

Virtually all the corners will be 90 deg, but a couple aren't - do you just cut on an angle with a (cheap!) skill saw and glue or is that what the router is for?

If using beading fit shadow gaps will they work with FST or do they rely on a 'proper' skim coat?

Is it tough enough to be hoover proof at ground level, or are you better off fitting flush skirting with a shadow gap above? I have seen examples on here that looked good (criterion industries I think, but they were Australian). 

Can you hire board lifters?

Would pallet loads via TP be the best option & would you get the screws/ glue/ filler from there too?

Thanks again. 

 

[Mr Punter]

I found Fermacell expensive, heavy, difficult to cut and difficult to install electrics. I have recently used Knauf Soundshield Plus which is a multi purpose plasterboard so has improved sound, impact and fire resistance. I think GTEC Universal board is similar. Go with 15mm thickness and double up if you want more.

 

I think they sometimes use 2 x 15mm Fermacell for secure institutions as it is so tough, but unless you are planning to set about the walls with a club hammer it is OTT for housing.

[PeterW]

1 hour ago, Nick1c said:

Thank you @PeterW  It's sounding quite positive, I didn't realise you could stop worrying about studs. 

Virtually all the corners will be 90 deg, but a couple aren't - do you just cut on an angle with a (cheap!) skill saw and glue or is that what the router is for?

If using beading fit shadow gaps will they work with FST or do they rely on a 'proper' skim coat?

Is it tough enough to be hoover proof at ground level, or are you better off fitting flush skirting with a shadow gap above? I have seen examples on here that looked good (criterion industries I think, but they were Australian). 

Can you hire board lifters?

Would pallet loads via TP be the best option & would you get the screws/ glue/ filler from there too?

Thanks again. 

 

 

So you need to go to CCF direct for it - TP just buy it in and CCF (actually part of TP group) ship it to them. CCF are cheaper and do it all and deliver with a wagon with a Mounty - better than your average clown with a Hiab...

 

Fermacell doesn’t need a bead for a shadow gap as long as you use the factory edge. They are so sharp you can cut yourself on them..! FST just fills the surface of the board to “glue” down the newspaper fibres on the surface, it has no discernible thickness. 

 

Tough..?? Get a sample and hit it with a hammer and make a decision ... 

[jack]

26 minutes ago, PeterW said:

Tough..?? Get a sample and hit it with a hammer and make a decision ... 

 

True, although try using the wrong type of screws near the edge and you'll find it splitting all over the place.

[nod]

3 hours ago, nod said:

Habito are about the best on the market In terms of impact and fixing to 

Also cost 

Don’t forget to allow 35 % extra for labour 

Yes We are using them on a couple of jobs 

I slipped up on the first You shouldn’t use collated 

They need to go in in singles with an impact driver batterie circular saw and jigsaw for sockets 

I’ve spent 3 k on three kits 

Normally get around 35 per man as aposed to 50 plaster boards per day 

[epsilonGreedy]

How does firmacell compare in terms of heat capacity?

 

In other discussions on the forum the high heat capacity of regular plasterboard it cited as a significant contributor to the total heat capacity of a house inside the layer of insulation. I think @TerryEcalculated his plasterboard drylining had about the same heat capacity as his UFH concrete floor slab.

 

A few Google searches indicate plasterboard and firmacell have similar specific heat capacity but since firmacell is twice the weight that means double the heat capacity per m2 of wall.

[WillShields]

Very helpful post from PeterW. I'm about to line our new house (walls and vaulted ceilings) with about 700m2 of Fermacell, and I'm struggling to decide on the fixing method. Do I buy a crown stapler for speed and the minimum filling afterwards? Is there a cordless battery stapler with the oomph to get through 12mm Fermacell? Should I use divergent staples? (My other tools are DeWalt, so ideally something from them). Or do I go for a collated screwdriver and Fermacell screws - slower, more filling, but possible more secure? I'm only going to do this once in my life, and I want to get it right.

[Visti]

Screwing is hard work. Burnt through two impact drivers on about 300m2 and then got contractors in to finish the job

 

Are you planning on DIYing it?

[Mr Punter]

@WillShields why are you using Fermacell?

 

I suggest a trial just getting a few boards and doing one small room.  If that goes OK, then go for it.  Not for the fainthearted.  250 boards my goodness...

[WillShields]

I am DIYing it, but so far I've DIYed most of the house except for the oak frame and SIPs, so I'm reasonably hardened. I've put up 400m2 of Knauf Aquapanel outside, which is not dissimilar to Fermacell, but I got very bored towards the end. I like Fermacel for its strength and solidity (my previous build has it, although I didn't install it myself) and I'm better at screwing than plastering. I'll have some help from someone who has fitted it before, but they used an air stapler, which is noisy and a pain to lug around, so I'm hoping to streamline the process.

[Russdl]

Against all the wise advice on this forum I’ve had a go with it, with limited help and varying levels of success. Started with a cupboard area and progressed to larger and larger rooms. It got more and more difficult. We are now using plasterboard to finish off. Weak and feeble and as fragile as eggshells in comparison but what a pleasure!!!

 

Perhaps with your helper who has prior knowledge it’ll be ok. But I’d definitely go along with what @Mr Punter said, get a trial batch to start with. 

 

It does kill power tools, and it is bitchin’ heavy. 

[Visti]

Get the one man boards if you're only 2. I wouldn't want to try doing to full size unless you've got a decent crew. Experience helps, as does the right tools, particularly blades for the saws.

 

We've still got a few small unboarded areas we'll be doing in the next few weeks. You're welcome to come along and experience it once Corvid restrictions relax. 

 

Encon are a great supplier when it comes to price.

 

I love it once it is on, but goodness it is difficult compared to standard board. And the skimming isn't as DIY friendly as it's appear as there is little room for error.

 

Oh the dust!

[Russdl]

9 minutes ago, Visti said:

Oh the dust

 

Oh yeah. And the dust. 

[PeterW]

4 hours ago, WillShields said:

Do I buy a crown stapler for speed and the minimum filling afterwards?

I’ve got a BeA air stapler you can have if you want it. It is what I used and wouldn’t use anything else. Heavy bit of kit, you need a compressor but you can get away with a £70-80 one. 
 

Benefit of a stapler is you can put a lot of fixings in very quickly as long as the compressor can keep up. 

[jack]

I'd probably go with staples if I were doing it again. Screws are slow and labour-intensive. Use loads of staples along with the jointing compound between boards and I doubt you'll see much difference compared to screwing them on.

 

This is for walls - I'm sure staples would be fine for ceilings too if you use enough of them, but mentally I think I prefer the idea of screws holding up something above my head!

[PeterW]

23 minutes ago, jack said:

I'd probably go with staples if I were doing it again. Screws are slow and labour-intensive. Use loads of staples along with the jointing compound between boards and I doubt you'll see much difference compared to screwing them on.

 

This is for walls - I'm sure staples would be fine for ceilings too if you use enough of them, but mentally I think I prefer the idea of screws holding up something above my head!

It’s bizarre ..! I reckon when I did ceilings, we had about a dozen staples holding a 10mm 2.4/1.2 board onto the ceiling before we took the board lifter down and put the rest in at 150mm centres. Used Jointstik on the edges and it’s not moved since installing and no cracks. 

[jack]

3 hours ago, PeterW said:

It’s bizarre ..! I reckon when I did ceilings, we had about a dozen staples holding a 10mm 2.4/1.2 board onto the ceiling before we took the board lifter down and put the rest in at 150mm centres. Used Jointstik on the edges and it’s not moved since installing and no cracks. 

 

I don't doubt it's fine, it just feels like there's no way staples would be enough! 

[WillShields]

Thanks very much for the advice, folks. A stapler sounds like it's a route worth pursuing. Very generous offer, Peter, but unfortunately while I'm currently sitting the plague out with my family in London the build is in SW France, so probably better to get one there. Having used a DeWalt cordless nail gun very successfully on the interior and exterior battens, I'd love to find a stapler that didn't need an airline - anyone come upon one with the power to get through the Fermacell? Apparently it would have to be the equivalent of a pneumatic gun operating at 7 bar. Otherwise I'll bite the bullet and go with air. 

 

As to the weight, in France the boards are available in 12.5 x 2500 x 600 size, which is quite manageable in terms of weight and dimensions, and if necessary can be cut in half for even more convenience when doing tricky bits at height. 

[joth]

Thinking about these Pros and Cons in light of the current situation :

- Pro: National bagged plaster shortage means Fermacell has distinct benefit in avoiding wet plastering

- Con: Heavy two person lift  makes it impossible to work with full sized boards while following social distancing

 

Using half-sized Fermacell boards maybe a popular choice for upcoming projects. (Assuming there isn't a national shortage of these too)