Drop/stud ceilings.

[Northbeach]

PM sent.

Forgot to ask again - would this (second) drop ceiling in the hall be such an issue if it was 12.5 PB? Concern with MDF ceiling is

a: I've never seen it in a domestic setting.
b: at least with PB the plasterer (for skim) can perhaps hide better any joins.
c: issue with lighting and heat (not guaranteed I'll be using LED's - and if we left the house, what would future occupants use....

BTW - I may use something like these lights below - at this stage, I'm not sure if they're actually fire rated or not?! Also, how I would install them through two ceilings!

 

[Deleted member 174758]

I've now placed 2x1 battens across the entire length(?) of the hall, at right angles to the joists?

Yep. A lot easier to level them up if the joists are not level. To check how straight they are stretch a piece of string end to end and you'll get a good idea (the proper way is to use blocks and a traveller but I won't get into that unless your battens are really wonky)

You say rip the two sheets into two wide strips? Why two - have you taken into account the length of the hall? By rip do you mean cut in two? Do these pieces join at cross ways to the battens?

Definition: Rip cut - longitudinal cut in timber along the grain, in sheet material normally means parallel with the longest edge. These pieces will join along the battens - which is why you may need to insert an extra batten straddling the joint to carry the joint (so that the joint won't be uneven). The reason I'm suggesting two rips is because you want to get a gap parallel to the wall on one side which is absolutely consistent, whilst at the other side, this being an older house, you're probably not going to find that the walls are parallel or necessarily all that straight. That will mean scribing the entire edge. Strikes me that you'll probably find it easier to handle smaller pieces and joint them. But it does depend on how confident you are feeling. If you reckon you can do it in one, then why not.

Chamfer (again, some of these terms I'm not particularly knowledgeable on) - sand down the edges slightly (slight curve) so the 2-pack has something better to 'nestle' in?

Chamfer, see this drawing. can be worked with a block plane, router and chamfer bit, even a bit of sandpaper stuck to a piece of MDF or plywood scrap. Don't sand to a curve at all - not necessary. What you are aiming for is a 2 or 3mm V-groove where two pieces butt up to each other - somewhere for the 2-pack to go.

Not even sure how I would scribe the other piece/s to the wall job...sorry...I'm not quite getting this bit (although I'm bang on up to this point).

The MDF/sheet material you are fixing to the ceiling will butt to the wall on one side. If on that edge the wall is dead straight, i.e. no really big gaps, then there's no need to scribe, however if there are big gaps you'll need to shape the edge to take-out most of those gaps because filling them will be potentially very unsightly. Have you checked how straight the wall is?

 

[Deleted member 174758]

Concern with MDF ceiling is

a: I've never seen it in a domestic setting.
b: at least with PB the plasterer (for skim) can perhaps hide better any joins.
c: issue with lighting and heat (not guaranteed I'll be using LED's - and if we left the house, what would future occupants use....

I suppose it depends on ventilation and how much heat you are putting in/extracting. Go into any bar with an overhead glass shelf above the bar and downlighting and it will be made from MDF (and veneered), same for many display units in shops (which are often lit for days at a time), MDF again as are the boxings above department stores with the big air curtain heaters hidden inside them (often MDF on a softwood frame). If you are happier with PB then go with it - the reasons I haven't used it doing these sort of things before is because it requires an extra trade and it adds 2 to 3 days to any job to get a spread in. I've also been left unimpressed by the spread's ability to keep an near knife edge on the soffits

Also, how I would install them through two ceilings!

Cut through the first skin with a jigsaw. Do the second (plasterboard) skin with a stab saw
Before putting your second skin in you'll need to mark where the joists are (tick marks at the tops of the walls) so that you aren't trying to cut out the bottom of a joist to accommodate your lighting units. Also as the lights are projecting into a ceiling void they must have something like a fire-rated sock like these installed above it to be compliant - although I'm no spark, so I'd suggest that you direct that question towards those guys

 

[Northbeach]

Concern with MDF ceiling is

a: I've never seen it in a domestic setting.
b: at least with PB the plasterer (for skim) can perhaps hide better any joins.
c: issue with lighting and heat (not guaranteed I'll be using LED's - and if we left the house, what would future occupants use....

I suppose it depends on ventilation and how much heat you are putting in/extracting. Go into any bar with an overhead glass shelf above the bar and downlighting and it will be made from MDF (and veneered), same for many display units in shops (which are often lit for days at a time), MDF again as are the boxings above department stores with the big air curtain heaters hidden inside them (often MDF on a softwood frame). If you are happier with PB then go with it - the reasons I haven't used it doing these sort of things before is because it requires an extra trade and it adds 2 to 3 days to any job to get a spread in. I've also been left unimpressed by the spread's ability to keep an near knife edge on the soffits.

Ah - ok...I'll have a think about that then. I bet I've seen loads of MDF ceilings in the stores I get dragged around with the missus and daughters...but presumed they were PB (admittedly I don't go around staring at the ceilings, but from a design point of view I often take a look ...besides, too busy gawping at the oh so pleasant assistants in these clothes stores!).
I know from previous research MDF (once filled properly) can be painted. There's a question over the sides of the MDF - I'll have to 'box' in the ceiling where the stairs are (so you aren't looking into the ceiling void as you come down the stairs. Can this just be painted as per the rest of the MDF or would it require a 'paint' of the aforementioned filler (unless MDF is the same all the way through i.e. no veneer?)

Also, how I would install them through two ceilings!

Cut through the first skin with a jigsaw. Do the second (plasterboard) skin with a stab saw
Before putting your second skin in you'll need to mark where the joists are (tick marks at the tops of the walls) so that you aren't trying to cut out the bottom of a joist to accommodate your lighting units. Also as the lights are projecting into a ceiling void they must have something like a fire-rated sock like these installed above it to be compliant - although I'm no spark, so I'd suggest that you direct that question towards those guys

Thought I might have to do that...that's straightforward enough.
I've already purchased a set of downlights (I've been in the 'yes' camp of these for years, albeit lower wattage lamps and mostly dimmed) which are the fire rated (come with their own enclosed units), and of course likely I'll be using LED's. I do like those multiple recessed downlights I posted above, but not 100% these are fire rated/enclosed...they have their own enclosure, but will make sure).

Many thanks.

 

[Northbeach]

I've now placed 2x1 battens across the entire length(?) of the hall, at right angles to the joists?

Yep. A lot easier to level them up if the joists are not level. To check how straight they are stretch a piece of string end to end and you'll get a good idea (the proper way is to use blocks and a traveller but I won't get into that unless your battens are really wonky)

You say rip the two sheets into two wide strips? Why two - have you taken into account the length of the hall? By rip do you mean cut in two? Do these pieces join at cross ways to the battens?

Definition: Rip cut - longitudinal cut in timber along the grain, in sheet material normally means parallel with the longest edge. These pieces will join along the battens - which is why you may need to insert an extra batten straddling the joint to carry the joint (so that the joint won't be uneven). The reason I'm suggesting two rips is because you want to get a gap parallel to the wall on one side which is absolutely consistent, whilst at the other side, this being an older house, you're probably not going to find that the walls are parallel or necessarily all that straight. That will mean scribing the entire edge. Strikes me that you'll probably find it easier to handle smaller pieces and joint them. But it does depend on how confident you are feeling. If you reckon you can do it in one, then why not.

Chamfer (again, some of these terms I'm not particularly knowledgeable on) - sand down the edges slightly (slight curve) so the 2-pack has something better to 'nestle' in?

Chamfer, see this drawing. can be worked with a block plane, router and chamfer bit, even a bit of sandpaper stuck to a piece of MDF or plywood scrap. Don't sand to a curve at all - not necessary. What you are aiming for is a 2 or 3mm V-groove where two pieces butt up to each other - somewhere for the 2-pack to go.

Not even sure how I would scribe the other piece/s to the wall job...sorry...I'm not quite getting this bit (although I'm bang on up to this point).

The MDF/sheet material you are fixing to the ceiling will butt to the wall on one side. If on that edge the wall is dead straight, i.e. no really big gaps, then there's no need to scribe, however if there are big gaps you'll need to shape the edge to take-out most of those gaps because filling them will be potentially very unsightly. Have you checked how straight the wall is?

Yes on the chamfer now (meant to say groove rather than the curving I alluded to).

Just spotted a message you've sent job, so I won't ask any more questions on this at the moment. Fine with the battens and packing out if necessary (if not level) but I'm a little tangled on the extra batten (why it might be required) and joints etc...might need to read it a couple of times and let my brain gargle it!
The walls may not be straight in all fairness (1947 house). I still may go with three sided gap now, one of them (around the door) needs a layer of PB anyway (took the plaster off as you can see from the pic I posted).
I might try and knock up a google sketch of what I think you're suggesting...you might see where I'm going wrong then!

Cheers - will now check pm.

 

[Northbeach]

Hi (jobandknock -I'll give you a bell later today - will text first).

I might go with three gaps rather than the original one.
I've added picture below...not perfect, but something I've quickly knocked up to demonstrate the shape of the hall. Effectively there are six sides to the ceiling due to the stair opening. I'll have to 'box' off (strip of either MDF or plasterboard covering the first PB ceiling and the floating ceiling below) - this is so when you walk down the stairs, you aren't looking into the gap at eye level (seeing the battens and any lighting).

I know of a firm who supply thin LED tape/strip - these are usually used for floating walls/behind TV panels...so I think they should be fine (I'll check with the seller beforehand). I had some on the back of my previous TV and they threw out virtually no heat, but lasted years).

Here's a rough plan/s (more blinking levitating rather then floating!):

 

[Northbeach]

Little update:

I'm going to make the size of the 'drop box ceiling' smaller than originally intended - 4'x2' rather than 6'3'. Mocked up a piece with some spare MDF and it works better at that size.

Quick question (someone who's been helping me no this is 'lockdown busy' at the moment!). Can somebody point me to a link/image of some drop studs?
I'm struggling to find anything on the net/forum to describe this graphically.
I'm assuming they would be fixed vertically rather than horizontally and would be attached to either the inside (inside in my case) of the existing joists via coach bolts (or ordinary large screws) and at each corner (to attach the frame too) then 400/450mm in between? The drop is only small - perhaps 5 - 6 inches tops.

Contemplating getting hold of/making a water level, but have a 6 foot spirit level - might this suffice for getting the levels of the drops right?

Many thanks.