Leveling old ceiling with GypCeiling MF

[Annker]

Bit of a niche question.

On my renovation project I have stripped back all lath and plaster ceilings to bare joists, in preparation for new plasterboard and skim.

 

The underside of the existing joists are up and down, and in some areas two rooms have be knocking through to form one bigger room.

Therefore I need to level the underside of the joists for the new continuous ceilings.

 

I've previously installed MF ceiling in new build project however unsure of how to go about it in a renovation job.

 

My plan to maintain ceiling height, is to screw the MF7 primary support parallel directly to the existing joists.

Essentially the MF7 will be within the joist void and therefore the ceiling height will only be lowered be the thickness of MF5 top hat section.

 

Is anyone familiar will the system and know if this an accepted arrangement?

 

 

[crispy_wafer]

Would it be easier to just batten with 3*1 or 4*1, using the lowest spot as your zero point, and shim out the battens at the high spots.  

[Annker]

7 minutes ago, crispy_wafer said:

Would it be easier to just batten with 3*1 or 4*1, using the lowest spot as your zero point, and shim out the battens at the high spots.  

I've sometimes used that method in the past but it is considerable more work and harder to achieve a level finish (I'm a carpenter so experienced at this sort of work)

 

The other alternative is sister along the joists with 3x2, possibly could get away with using 2x1/12.

This would be a little less expensive material wise (vs MF system) but more labour.

I have 2x row of solid bridging therefore x3 sistering pieces per joist.

Less work than counter battening below the joists but still more work than MF system options. 

[Annker]

Just to add in another question for opinions.

 

In one room the 1st floor joists are running 30mm off level front to back.

There is no subsidence and it seems they were just installed this way; they aren't bowed down too much and otherwise the ceiling is flat.

 

The ceiling is about 3m high and 30mm fall is along a 4.7m long run.

I wonder if such a fall would be noticeable and should I go to the effort of level out this ceiling?

 

30mm is a decent amount to have installed a joist off level but I'm not certain this will be noticeable in the finished ceiling.   

(I may level the floor above though).

[nod]

1 hour ago, Annker said:

Bit of a niche question.

On my renovation project I have stripped back all lath and plaster ceilings to bare joists, in preparation for new plasterboard and skim.

 

The underside of the existing joists are up and down, and in some areas two rooms have be knocking through to form one bigger room.

Therefore I need to level the underside of the joists for the new continuous ceilings.

 

I've previously installed MF ceiling in new build project however unsure of how to go about it in a renovation job.

 

My plan to maintain ceiling height, is to screw the MF7 primary support parallel directly to the existing joists.

Essentially the MF7 will be within the joist void and therefore the ceiling height will only be lowered be the thickness of MF5 top hat section.

 

Is anyone familiar will the system and know if this an accepted arrangement?

 

 

Gypsum do a system where you don’t need a primary bar 

The gypclips fit to the side of the joists with an arrow shape pointing downwards The gypliner simply clicks onto these 25 mil minimum void 

 

[Annker]

16 minutes ago, nod said:

Gypsum do a system where you don’t need a primary bar 

The gypclips fit to the side of the joists with an arrow shape pointing downwards The gypliner simply clicks onto these 25 mil minimum void 

 

Thanks Nod, I wasn't aware of that system. I'll have a look around their website, sounds like it could be a very good option.

[SteeVeeDee]

30mm is too much to leave, plus the plasterers won't manage to get a good finish. All the systems mentioned are good. You've got enough height to go old school and do a 3/2" frame as well if you want. You've also got enough space for resilient bars if you want to make an acoustic ceiling, just make sure you don't fix through the resilient bar and the subframe. You know all this anyway so I'm not trying to teach you how to suck eggs. I battened a ceiling out recently to avoid losing too much space and I quickly remembered why I stopped doing that years ago. What a pain in the backside messing around with the shims. 

[nod]

2 hours ago, Annker said:

Thanks Nod, I wasn't aware of that system. I'll have a look around their website, sounds like it could be a very good option.

We use them quite often 

Usually housing associations as part of the soundproofing 

Simple system 

[Annker]

16 hours ago, SteeVeeDee said:

30mm is too much to leave, plus the plasterers won't manage to get a good finish. All the systems mentioned are good. You've got enough height to go old school and do a 3/2" frame as well if you want. You've also got enough space for resilient bars if you want to make an acoustic ceiling, just make sure you don't fix through the resilient bar and the subframe. You know all this anyway so I'm not trying to teach you how to suck eggs. I battened a ceiling out recently to avoid losing too much space and I quickly remembered why I stopped doing that years ago. What a pain in the backside messing around with the shims. 

I actually think the 30mm is borderline ok.

The only place I believe it could show up is any margins around joinery fitted in the alcove. And as the alcove are ~ 1/3 of the width of the room the ceiling in each of them will only be running ~10mm off.

Can't see any issue for the plaster finish either, the ceiling is a flat plane.

 

I don't care to remember how many concrete soffit/ceilings I battened out in the past.

We did a lot of apartment blocks that way. 2x2 battens fixed to the soffit with express nails and then counter battened again with 2x2(without nail guns).

Dusty, noisy, over head work. I hated it.  

 

[Annker]

16 hours ago, nod said:

We use them quite often 

Usually housing associations as part of the soundproofing 

Simple system 

I found the BG spec sheet for the system. GL6 is the bracket.

It's exactly the system I want. Simple, fast solution and easy to get right👍

 

Just to add for future reference BG only list the GL6 which has long leg, other manufacturer & suppliers offer a GL5 with a shorter leg which is a better option when looking to keep tight to existing timber joist.  

Edited Friday at 10:31 by Annker

[nod]

You simply cut the top of the leg off 

If it’s in the way 

[Annker]

4 hours ago, nod said:

You simply cut the top of the leg off 

If it’s in the way 

Say with MF5 tophat section the primary support channel goes in a maximum 1200mm c/c.

 

Can I ask what is the maximum c/c of support that GL1 requires, and therefore spacing of the GL6 support bracket?

 

My plan is to install the GL1 perpendicular to the existing joist, and therefore put a GL6 bracket on every 4th joist which works out a little less than 1200mm c/c