Dropped Ceiling over Kitchen Island / Light Box Construction

[Cej238]

I am looking to build a dropped ceiling - approx 25cm over my kitchen island. This will allow a vented extractor to be installed above the hob situated on the island and house hald a dozen downlights. I want to construct it so that a shadow gap remains so I can lay LED around the edge and have light glowing outwards.

This is the sort of thing I am talking about:
https://i.pinimg.com/originals/85/08/f2/8508f2462660856c22eb0cbe1100f48b.jpg
https://i.pinimg.com/originals/90/45/b0/9045b0842b137f67339fdb162d0a070c.jpg

I've looked a a few construction guides and youtube videos. There seems to be real variation in how they are constructed. Some seem a bit more sensible than others... Can anyone advise as to how they would do it?

It will be constructed under a new, flat roof extension - regularly spaced wood joists but also a steel running the breadth of the room that will bisect the dropped ceiling. As it stands, I've just got bare joists - no plasterboards fitted.

Thanks!

 

[Deleted member 174758]

The lightest way is to frame-out with metal studding (fixed to the underside of your existing joists) then clad with either plasterboard or MDF. Alternatively a timber framework could be built and the cladding applied to it. There's a long-running thread about it here and here (there's a lot of stuff in there, too much to repeat, hence the links). In terms of fire compartmentisation you may want to consider boarding out the ceiling before building your dropped ceiling, depending on design. FYI it is possible to get dedicated shadow gap beadings for plasterboard these days which take LCD strips.

 

[foxhole]

I did a 8ft square unit , used 4x2 frame and plasterboard . Quite heavy so used chains to hang mounted about a foot in from edge so they could not be seen at edge . Also helped with mounting as hooked up one side and let it dangle too sort out the lighting before offering up the other side.

 

[Cej238]

Thanks for the replies on this. Our project got a bit delayed, but we are finally ready to start doing this dropped ceiling. I'm slightly starting to have second thoughts about it, as it seems a bit big, heavy and expensive - but we were banking on having a bunch of downlighters in it, and it would also hide a 30cm 'ceiling' mounted extractor i.e. the extractor is mounted in the box.

I've read the threads above. Our island is 3m x 1.2m and to fit the extractor it needs to be 30cm deep. That feels like it would be really heavy made out of 2x2, mdf etc. So out of the options in the thread above, I'm wondering about the Metal Framing / Metal Furring / MF. There is discussion in the thread, but not a great deal to go on as for how I'd actually go about building it. I'm not really clear which sort of profiles I'd need to buy, how I'd connect them together, how I'd connect to the joists.

I've also see this system called Kinook:
https://www.kinook.biz/dropped-ceiling-kit-c2x14604554

Looks pretty light and comparatively easy to build. Has anyone used it?

If I was to go with that - and presumably a MF option as well, then I think I would need to build a separate wooden drop-down support for the extractor fan.

Grateful for any advice.
Thanks!

 

[foxhole]

Fire rated plasterboard is quite rigid and would hold fan unit with a little bracing behind.
That kit looks quite easy to use .

 

[Deleted member 174758]

The main components in MF are the studs, C-sections (or channels) and top hat sections (for soffits/hoizontal pieces). Places like Selco will sell these components individually.

The MF is held together using self-drilling wafer head screws

and the plasterboard is screwed-on using fine-thread drywall screws and a drywall screw adaptor for a cordless screwdriver

Your drill driver needs to be able to run at 2500rpm (approx.) and you should use 25 to 30 mm drywall screws for the PB. As Foxy says, that kit does look easy to use

 

[Cej238]

Thanks - sounds like that kit is MF for dummies. Think I might go for that.

They have a video showing the construction of a light box with plasterboard sides and what looks to be a thin plywood or mdf bottom. Mine will end up being 3000mm x 1200mm x 300mm, so a bit bigger. Going by the specs on their website, I'll need to construct two adjacent boxes together. Here is the video:

A couple of questions/observations on the video if anyone can help:

- She fits the track to the ceiling using some sort of cavity plug. I would have thought they would have pulled out with the weight of the strips, plaster, wood etc. I was thinking when doing mine that I would want to ensure I screw into the wood beams when laying track across my beams. The way my ceiling beams are, the 1200 short sides will run across. For the long 3000mm sides, will I need to add more beam to screw into? I.e. break the current plastered ceiling and add a few connecting bits of wood between existing beams to screw into along the 3000mm length? Or is that overkill?

- The c profile track is screwed to the ceiling, but the plastic blocks just seem to be inserted into the profile and held by the lips of the profile itself (see 1:35 on the video). I'd be worried about the weight of the overall box pulling out of the profile. Any views on this?

- I want the box to look like the rest of my ceiling (which is painted, skimmed, plastboard). Inside the box, aside from the extractor (which is a big 20kg+ model so will need its own support so it just 'floats' in the drop box), I will have 6 down lighters, and a LED power supply - approx 2kg weight. Is that too heavy for plasterboard? Otherwise, I'll have to have plywood, then plasterboard on top? Trying to make sure the thing doesn't get too heavy.

Thanks!

 

[Deleted member 174758]

- She fits the track to the ceiling using some sort of cavity plug. I would have thought they would have pulled out with the weight of the strips, plaster, wood etc. I was thinking when doing mine that I would want to ensure I screw into the wood beams when laying track across my beams. The way my ceiling beams are, the 1200 short sides will run across. For the long 3000mm sides, will I need to add more beam to screw into? I.e. break the current plastered ceiling and add a few connecting bits of wood between existing beams to screw into along the 3000mm length? Or is that overkill?

I don't think it is overkill - as I said above I'd connect into the existing ceiling joists wherever possible and where it isn't then strutting between joists as you surmise would be ideal

- I want the box to look like the rest of my ceiling (which is painted, skimmed, plasterboard). Inside the box, aside from the extractor (which is a big 20kg+ model so will need its own support so it just 'floats' in the drop box), I will have 6 down lighters, and a LED power supply - approx 2kg weight. Is that too heavy for plasterboard?

You've doubtless seen, but probably not noticed, those big heavy Hitachi aircon units in shop ceilings - they are often supported on threaded rods into Unistrut which is bolted into the joists and are completely independent of the main ceiling structure, be that MF plasterboard or suspended ceiling (the lightweight grid variety). In general MF will easily carry quite a few downlighters, etc but the heavy stuff is always supported individually