Internal window reveals/Fermacell

[nod]

42 minutes ago, PeterW said:

You shouldn’t need to but I assume PVA

 

@nod have you had to skim Fermacell..???

Yes Peter 

I use quite a bit of Fernacell 

Mainly render 

I’ve D&D with them also But they still need to be mechanically fixed

I normally lay a three mil coat of car lite bonding on with 10% board finish mixed in Then render mesh laid on and flattened in 

and skimmed with multi the same day This method gives a 100% guarantee against cracking or blowing and leaves no trace of the knock ins 

 

Hope this helps Peter 

[PeterW]

@Russdl there is your answer ..!

 

Thanks @nod

[Russdl]

2 hours ago, PeterW said:

there is your answer ..!

You’d think so, wouldn’t you, apart from whilst I recognised pretty much all the words that @nod used, I don’t think I’ve seen them arranged in that order before! ???

 

I'm constantly amazed with how little I know. 

[Visti]

Yup, it is a learning curve!

Edited February 7, 2020 by Visti

[Mr Punter]

23 hours ago, nod said:

I use quite a bit of Fernacell 

Mainly render

 

Their standard board is no good as a render carrier.  They do a cement based board as well, but their normal boards are gypsum based and prone to mould.

[nod]

52 minutes ago, Mr Punter said:

 

Their standard board is no good as a render carrier.  They do a cement based board as well, but their normal boards are gypsum based and prone to mould.

You can render on most surfaces 

over the years I’ve two coat rendered plasterboard 

Even a fishing trawler 

[Russdl]

Sadly my Fermacell experiment has come to an end. 

 

We've found it very difficult to get a smooth flush finish to the boards with a less than smooth and uneven timber frame to attach the boards to. Where resilient bars were used it went someway to help but that hasn't been fool proof.

 

The precision required to ensure that endless filling and sanding isn't needed prior to the Fine Surface Treatment is very time consuming and has been problematic. As time was running out we ended up getting the first room skim plastered, which made me weep as all the time and effort to get it pretty good was then buried beneath a few mm of plaster. The plasterer hated the Fermacell but he's done a great job. 

 

I had a go with the FST in one of the cupboards and I didn't get on with it very well at all. With more practice and time I may have got to grips with it, but I don't have the time so the final decision was made. No more Fermacell.

 

I wished it had worked out for us because it's really quite disappointing to be introducing so much water into what was a nice and dry house but such is life.

 

As many advised:

 

It's heavy.

Dust created with power tools is hideous.

It does indeed eat power tools and their blades alive.

It is of course expensive.

 

 

[vivienz]

Sorry the Fermacell won't work for you, but you can move on now and you have a plasterer on hand, so all's not lost.  I used a commercial dehumidifier in my place to assist with drying, but that was in the very early months of the year.  Worth considering, perhaps.

[Dreadnaught]

@Russdl Yes, sorry you're changing direction. But its good that you can now forge ahead, renewed.

 

Will you be still using the remainder of your Fermacell boards and just skimming them, or flipping over to now using plasterboard?

 

Your experience has been instructive. It brings it home the importance in the regularity and uniformity of the underlying studs and battens.

[Russdl]

@vivienz it’s quite interesting really, the house has no heating but has never felt cold over the winter even though it’s been down to 10 degrees inside, now that we’ve added gallons of water 14 degrees feels cold. 
 

@Dreadnaught We’ll use what we have left to finish of the bathrooms and toilet where it will be tiled over, so much easier to use. 
 

Onwards and upwards...

[Mr Punter]

From unhappy experience I have consistently advised against using Fermacell and @Russdl's experience chimes with mine.  Very clever marketing, I think.

[Dreadnaught]

I am attending an official Fermacell one-day training course in Birmingham next Monday. Let's see if I the course sways me in favour. I will report back.

[Mr Punter]

3 hours ago, Dreadnaught said:

I am attending an official Fermacell one-day training course in Birmingham next Monday. Let's see if I the course sways me in favour. I will report back.

 

Try cutting in a few electrical sockets.  I will be very interested to hear your take.

[Russdl]

6 hours ago, Mr Punter said:

I have consistently advised against using Fermacell

You did indeed and with 20/20 hindsight I should have listened (but I’ve always been a bit pig headed).

 

The marketing does seem to gloss over some of the nitty gritty but I’m sure a well trained team would ace it, but probably best in an office block or something like that.

 

I’m very grateful to @PeterW for his help to allow us to get this far but as a one and a half man band I’ve admitted defeat.
 

Started with some plasterboard today - all ready broken 3 sheets, that never happened with the Fermacell ?

 

@Dreadnaught it’ll be interesting to hear your feedback after your course. 

[Visti]

I find the box cutouts to be a piece of cake with the right tools. 10mm steel drill bit for the corners and a jigsaw with the right bit does the job well.

 

The issue is it eats impact drivers and wrists.

 

Technique is critical to get a good quality install.

 

Also, need at least two people to make the job viable, even with one-man boards. 

 

It is a viable product, but not certain it is worth it for the extra cost and effort. 

[Russdl]

2 hours ago, Visti said:

It is a viable product, but not certain it is worth it for the extra cost and effort. 

I think that is ultimately where I am regarding Fermacell. I found myself putting noggins in today, never considered that when I was using the Fermacell.

 

 

[markharro]

We are around 40+ (full) sheets of Fermacell in now and are getting the hang of it.....cutting outside with track saw and extraction after (very) careful measurement to avoid carting a cut sheet back done the stairs for adjustment.....the walls it creates are bulletproof - it almost feels like a solid wall. 

 

I like how you can router corners to have a curve on them.

 

Cutting boxes is slow but not too bad - either jigsaw with cement board blade or multitool (steady hand) and cheapo ebay blades as they don't last long.

 

We are now starting to fill board joins and screw holes with the FC joint filler compound. 

 

Is there a knack to filling the screw holes? I either seems to have to use quite a thick layer of compound to dome over the hole (which will need more sanding) or else if I scrape the trowel hard to smooth off the excess it tends to leave the filled hole a little concave which isn't ideal.

 

Any tips on this welcome. 

[garrymartin]

1 hour ago, markharro said:

 

Is there a knack to filling the screw holes?

 

It's a two-stage process - even says so in the Fermacell guides on filling. It's nigh on impossible to do it in one go without excess sanding afterwards. But once done, as you say, it's bulletproof. My entire garden room (including the ceilings!!) is full board 12.5mm, and it's as solid as anything. When the boards are glued together, there's also zero movement, and there are no cracks visible anywhere after at least eight years.

 

[garrymartin]

1 hour ago, markharro said:

Cutting boxes is slow but not too bad - either jigsaw with cement board blade or multitool (steady hand) and cheapo ebay blades as they don't last long.

 

 

A template and a pattern-bearing bit in a router are also great for this.

[markharro]

8 hours ago, garrymartin said:

It's a two-stage process

 That's interesting - I don't recall reading this guidance. Where did you find that?

 

So just to be clear, is this 2 stages with the joint filler? Before the Fine Surface Treatment skim?

[Nick Laslett]

I picked up a 2nd hand Mikra Leros with dust extractor early in my build. 
 

The extractor works great on my tracksaw when cutting the fermacell.  It is essential to use the PDC blade, creates a lot less mess. 
 

https://www.makitauk.com/product/b-33685.html
 

I only finished one room myself to understand the process. I then engaged some tape and joint specialists with experience with Fermacell. 
 

Observing them and consistent with my own experience; the best method is multiple passes with joint filler, with sanding in between, then FST. 
 

They only used the Mirka for the final pass, and hand sanded most of the time. I think this is because they did not have access to the Mirka and it was a different person that did the finishing pass. When I was doing the one room I did myself, it was very quick to just run the Mirka over the wall. 
 

I actually found buying the most expensive Bosch multi material blade, was the best solution for cutting out the pattress boxes. 
 

EXPERT PAIZ 32 APIT MULTIMAX PLUNGE CUT BLADE

https://www.bosch-professional.com/gb/en/expert-paiz-32-apit-multimax-plunge-cut-blade-2867251-ocs-ac/

 

To echo Garry, the router is also very useful for finishing certain aspects of the boarding. I used the router for corners, door openings, window reveals. It means you can be less accurate with your cuts if you know that you are going to router the edges. A dust extractor is essential if you use a router, most mess from any Fermacell cutting process. 

Edited 9 hours ago by Nick Laslett

[garrymartin]

I have a guide pinned in my notes, but it seems very similar to this one online now https://fermacellplaksnes.lv/wp-content/uploads/2022/02/fermacell_Montazas-pamatprincipi-griesti-sienas-jumts-ENG.pdf

 

The 2 stages are the edges and the screw holes with joint filler, then the FST skim. It's difficult to tell from your photo, but is the problem related to slumping on the initial fill? If so, the FST should cover this; however, you may want to check your mixing on the edge filler.

[Nick Laslett]

As an aside, I did an estimate last week, and made my final Fermacell board order, we have 42 boards left to put up. 
 

I dread to look back at how many boards we needed for the whole house, my wife and I could only handle deliveries of 48 boards at a time. 
 

The wastage with boarding is just heart breaking. But I feel with Fermacell because of the boards integrity you do get to use a lot more of the board off cuts. Our bedrooms are in the roof, so many angle cut boards. 
 

I also stupidly made the dwarf walls 1350mm high, when I thought we would use 2700mm boards. At the time they seems to be hard to get hold of, so used 2400mm, but this led to a lot of half cut boards. 
 

Not sure we would have been able to manage 2700mm boards, so probably a blessing. 

[garrymartin]

3 minutes ago, Nick Laslett said:

Not sure we would have been able to manage 2700mm boards, so probably a blessing. 

I remember fondly bringing all the 2400mm boards from the front of the house to the back garden, and I *especially* remember the 12.5mm full boards on the ceiling! Even with a lifter, because we were gluing them, it was a challenge that required help from good friends, and there were many curse words that day!!

 

If we ever build, I'd be looking for min 2700mm ceilings, so as you say, the 2700mm boards would be ideal, but I'm with you on the manual handling - not sure I can face it 🙂 

[Nick Laslett]

Some interesting YouTubes of Fermacell finishing. The second video is a series from a French couple, more general, but interesting nonetheless. 

 

 

 

 

Edited 9 hours ago by Nick Laslett