Drop ceiling construction

[mrsplodge]

I'm planning on creating a drop ceiling for our living room (1970s house), so that we can have a shadow gap + LED strips around the edge, install some LED downlights, soundproof insulation, and a couple of ceiling speakers. There's a bedroom above and you can hear the TV when it's loud. I was thinking a drop ceiling would be easier as I can get everything in without worrying about compromising the acoustic / fire performance of the existing ceiling. The room dimensions are roughly 6.5m x 4m, and I'm wanting around a 120 - 150mm drop to accommodate the lights / speakers / acoustic insulation (I've got 50mm insulation).

I'm trying to decide on the best way to do it. The ceiling is textured at the moment (tested for and confirmed free from asbestos). So I'm thinking either:

a) 47mm x 125mm timber, edge on, screwed up through the existing plasterboard into the joists above. I'd put these in at right angles to the existing joists, after scraping the texture off the existing ceiling. The joists run along the 4m width, so I could run about one and a half-ish 4.8m lengths along the 6m direction of the room. Then I guess run a length along each end of the short side and screw some noggins between the timber at 400mm(?) intervals. Then plasterboard onto that.

or

b) Install a MF ceiling. I did a quick price up and the framing for an MF ceiling would come in around the £200 mark, plus I could pay a bit extra for acoustic hangers to help the sound insulation. The timber for just the long runs in option a) was coming out at around £300, plus I'd need timber for the ends and noggins. I can then plasterboard onto that. I'm leaning towards this as it seems like an easier, quicker, and lighter way of doing it, and the weight is spread between the existing joists and the walls. I also wouldn't need to bother scraping the existing ceiling, just the small areas around where I'd attach the hangers.

My questions are:

For option a)
- Does that seem like the right way to go about it? It would let me have as much shadow gap as I need to get LEDs in and get access to them as needed. My main concern is that all the weight of the wood + plasterboard is just on the joists above, not onto the walls.

For option b)
- How would I go about creating a big enough shadow gap to get LED strips in? As far as I can see, the MF6 perimeter sections are around 28mm wide, and you need to screw the plasterboard to them so there'd be no space to have a gap. Plus they're at the same height as the MF5 furring sections, so the depth of the gap would only be the width of the plasterboard (i.e. 12.5mm). Would I need to add wooden battens to every furring section and around the perimeter to drop the plasterboard down, giving me some extra depth between the finished ceiling and the perimeter sections to fit the profile / LED strips?
- Because the size of the room is bigger than the 3.6m the sections come in, I'll need to overlap them to span the full width / length of the room. As far as I can tell, this creates a slight bump where they overlap, which I guess would also mean the plasterboard wouldn't be exactly level. Would it be noticeable? Would the skim coat hide the slight bump, or would I get a bit of a shadow?

 

[Wayners]

I can't answer all your questions. I've boarded loads of ceilings and I'd go spend £50 on a board lifter that you can hire for a week.

I'd also consider pulling down ceiling to strength with timber if required and level out. I like timber on all the edges of plasterboard. You can then run wires and sort out any plumbing above.
I've only ever seen one ceiling like you discribe. Starred out being a mess and new people were contracted to put right. The critical light around the edge shows all the imperfections so needs to be well constructed

 

[Deleted member 174758]

In the days of yore we framed ceilings like this (and the opposite, coffered ceilings) in shops, restaurants and bars, etc in timber. It wasbvery heavy and the framing ideally need to be suspended on timber drops bolted through the sides of the joists above, which doesn't do much for your soundproofing or your fire rating/compartmentation. MF is a lot lighter and I think easier to install , especially given that there are various edge and stop beads available to help form the outsides of your dropped ceiling centre and that the extra tool kit over a basic home tool kit isn't huge - basically tin snips and a (green) self- levelling laser level). Doing this job "old school" with spirit levels, a water level and string lines is slow and frustrating and to be avoided

The centre (dropped) section of your ceiling needs to be supported from the underside of the joists above - there are several methods, but fundamentally you should look at fixing steel angles (hanger section) across the joists, then fixing your angle drops beneath these. The mains are levelled and fixed to the drops and in turn carry the top hat sections, which are cut to stop short of the outer walls (making the reveal for the lighting). C-section wall profile is fixed to the ends of the top hats using wafer head screws. infill framing between the upper side of the top hats and the original ceiling can then be added, if needed (for a 100mm drop or a narrow gap it probably wouldn't be as the revealed old ceiling could simply be painted-out matt black before boarding out). Any wiring should also be run before boarding out. That's one way - there are others

 

[mrsplodge]

Thanks for the replies. It definitely seems like MF is going to be the easier and lighter way to do it. I'm still not sure about how to fix the C-section wall profiles though, as they won't be fixed to the wall. I'd need some way to support them. I'm thinking something like this might work:

I'd fix angle brackets every 600mm along a wooden batten at the top of the wall (something like these) and fix the C section to that. That would give me a 50mm gap, which I could overhang the plasterboard slightly to make a space to fit the LED strips. I know the C-section perimeter is supposed to be fixed directly to the wall all the way around to give support to the rest of the frame, I'm just concerned about it not being rigid / supportive enough. I think the hangers are supposed to be spaced 1200mm, so I'd do that for them. I just haven't had any experience with MF and a full ceiling's worth of plasterboard, so not sure if it's going to be super heavy and needs more support, or if it's not actually that heavy and supporting with the brackets will be fine.

Also, I have a red laser level. Is there a reason to get a green one?

 

[freddiemercurystwin]

Plenty of solutions eg https://www.google.co.uk/search?q=g...CODz1eCR-4ADFQAAAAAdAAAAABAH&biw=1592&bih=764 but none of them particularly easy or cheap.

 

[Deleted member 174758]

Looking at the OPs drawing it is plain that they do not understand how MF is installed, what the various profiles do and anything I wrote previously...

Unless someone else does it I'll tidy up my sketch and publish it in the morning, when I am less tired. Unless someone else beats me to it (I hope)

 

[mrsplodge]

I was working from this guide: https://mf-ceilings.co.uk/how-to-install-mf-ceilings/
From that, the main steps are:
- Install the MF6 perimeter
- Install the hanger angles down from the joists (in a 1200mm x 1200mm grid)
- Install the primary channels (MF7) across the room in one direction, bolted on to the bottom of the drops and resting on top of the MF6 at each end
- Install the MF5 (top hat) sections onto the underside of the primary channels (at right angles to them) going across the other direction of the room and slotting into the MF6 "C" section on the wall.

From what I understood of your description, it's basically the same as that but you said to install the MF6 as the last step instead of the first, I guess because it's not actually attached to the wall in my case. My diagram above was just showing a way of attaching the MF6 perimeter to the wall so that it's supported. I left out the primary channels, hangers, and furring sections from the diagram.

 

[mrsplodge]

I've added the rest of the parts to the diagram. Side view:

Front view:

 

[mrsplodge]

I'm struggling to find an angle bracket of the right size to use to support the C-sections around the perimeter. Would something like this be enough? https://www.screwfix.com/p/magnodur-nailing-plates-matt-steel-100m-x-2-5mm-x-35mm-10-pack/416jf

 

[freddiemercurystwin]

It would, though that's not as per your drawing, though a flat would suffice. How will you finish the edge of the plasterboard and ensure it remains a nice clean line even after faffing about fitting the lights and perhaps having to change them etc? What you've drawn is pretty delicate.

 

[mrsplodge]

I'm not sure about finishing the edge. I'll be getting a plasterer in to skim the ceiling. Is there some kind of beading or profile or something I can put around to keep a clean edge before it's skimmed? I don't think the gap would be enough to see up the side unless you were really looking up the walls.