Vapour Barrier
- Thread starter Jupiter01
- Start date
OK. Thanks for your help. As far as my original questions were concerned, there doesnt seem to be any issues with having led downlights punched into the plasterboard. I know you can now buy downlights that can be covered by rockwool loft insulation so we shouldn't have any issues...
D
Doggit
I think you're looking at the problem the wrong way round Jupiter, and you're asking the wrong questions.
Do you actually have a problem with the bedroom ceiling, and are intending to take it down, and then reboard it, or do you just want to put in LED downlighters, and having read the eHow website, think you need a vapour control barrier.
As there is no living space above the bedroom, you can use ordinary downlighters without a fire rating, but they won't fit easily into a lathe and plaster ceiling - is this why you are thinking of reboarding it.
You don't need a vapour barrier as you've got a ventilated roof space, but you do need insulation in between the rafters and then over them - but cut out around the downlighters - or you're going to get a very cold bedroom.
Do you actually have a problem with the bedroom ceiling, and are intending to take it down, and then reboard it, or do you just want to put in LED downlighters, and having read the eHow website, think you need a vapour control barrier.
As there is no living space above the bedroom, you can use ordinary downlighters without a fire rating, but they won't fit easily into a lathe and plaster ceiling - is this why you are thinking of reboarding it.
You don't need a vapour barrier as you've got a ventilated roof space, but you do need insulation in between the rafters and then over them - but cut out around the downlighters - or you're going to get a very cold bedroom.
Hi,
There are a number of different factors at play here. Let me explain...
The ceilings need to come down (irrespective of the VCL situation) as they are in bad state. It will also make it easier to insulate from below (using around 300mm of rockwool). This will be layed in between the ceiling joists and then ver the top too. My loft is very shallow.
I also wanted to put downlights in places but based on the earlier assumption that I need a VCL, I was starting to cool on this idea as I thought that it would penetrate the VCL. Now that we've established that a VCL is not required, I am back on with my original plan of downlghts.
The theory with the coverable downlights was that I can pile on the insulation without making spaces in the insulation and losing thermal efficiency and then pop in holes for my downlights. This seemed like a sensible approach. Am I missing something?
There are a number of different factors at play here. Let me explain...
The ceilings need to come down (irrespective of the VCL situation) as they are in bad state. It will also make it easier to insulate from below (using around 300mm of rockwool). This will be layed in between the ceiling joists and then ver the top too. My loft is very shallow.
I also wanted to put downlights in places but based on the earlier assumption that I need a VCL, I was starting to cool on this idea as I thought that it would penetrate the VCL. Now that we've established that a VCL is not required, I am back on with my original plan of downlghts.
The theory with the coverable downlights was that I can pile on the insulation without making spaces in the insulation and losing thermal efficiency and then pop in holes for my downlights. This seemed like a sensible approach. Am I missing something?
I think you could be missing something, anyway there is no need for bloody a VB. Stick some plant pots or similar over your bloody spots, insulate as normal. Job done. You're over-thinking it. End of thread.
D
Doggit
You're going to have fun and games trying to get the insulation put in from below, and getting downlighters in as well. Having taken down the existing ceiling, you'd be able to put the insulation over the joists, and then using netting, put the insulation between the joists, before you put the plasterboard up. You'd have to work out where the wires come through the ceiling for the existing light, and then pull the wires through the hole with a pull wire as you put that piece up.
If you're putting in downlighters, then you need to wire up the ceiling before the insulation goes in, then work out where the downlighters are going to go in the plasterboard, and cut the holes, and then tie a pull wire to the wires so they can be hooked through the holes as you put the plasterboard up.
Not going to be easy, but hopefully, someone might come up with a simpler method.
If you're putting in downlighters, then you need to wire up the ceiling before the insulation goes in, then work out where the downlighters are going to go in the plasterboard, and cut the holes, and then tie a pull wire to the wires so they can be hooked through the holes as you put the plasterboard up.
Not going to be easy, but hopefully, someone might come up with a simpler method.
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The normal way would be pre plan wiring, 1st fix for lights and fit all cables, then fit PB, this is where things can differ I always drill for downlights at this point but lots let the plasterer come in here. Insulate in the loft laying onto PB and over joists depending on depth requirement.
Fit downlights and fix any issues of lost cables
. I have in the past made little hats for the downlights using PB to stop cold air but since most downlights are now LED most people just lay the insulation over the top as the heat is minimal.
Am I missing something, possibly some brain cells, fit the plasterboard, sit the insulation on top using that thing gravity. Why all this talk of suspending the insulation? 
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The normal would be to replace the ceiling with foil backed plasterboard, the foil will act as a 99% VCL. Cut your holes for the downlighters and fit them. Now the fun begins, they must not get too hot when you put your insulation over them and it is good to put in fire protection as well so a house fire in one room does not spread or affect the loft. At this stage you MUST use LEDs, because they pay for them selves in two years or so then for the next 10 years they use 20% of the electricity of a halogen bulb. As a beneficial side effect their cooling requirements are also 20% of that of a halogen bulb.
So a flower pot might do. I engineered boxes out of plasterboard (fire rating) and had an ali fin which was about 30 inches long so it stuck out above the insulation. There was a 6inches square bit of the fin inside the box to pick up the heat and transfer it into the loft. Once all this is done, just pile on the insulation allover to taste.
If you want to put your insulation beneath the ceiling joists. Rip down the old ceiling. Put in a suspended array of 2" X 2" hanging of the original joists and then do as above. Plasterboard, skimming,lights, insulation.
Frank
So a flower pot might do. I engineered boxes out of plasterboard (fire rating) and had an ali fin which was about 30 inches long so it stuck out above the insulation. There was a 6inches square bit of the fin inside the box to pick up the heat and transfer it into the loft. Once all this is done, just pile on the insulation allover to taste.
If you want to put your insulation beneath the ceiling joists. Rip down the old ceiling. Put in a suspended array of 2" X 2" hanging of the original joists and then do as above. Plasterboard, skimming,lights, insulation.
Frank
Hi,
I've been advised that I don't require a VCL so the foil backed plasterboard should nt be necessary, unless you are about to tell me otherwise???
I propose that get the cables in position, get a board up at a time and then lay the insulation, then the next board and the insulation above that and so on...
I then have the ceiling plastered and then punch in holes for lights and fish out the cables. I will of course make a plan of where the acables are before boardng up. On the lights, am I not better off just getting insulation covered led downlights instead of faffing aroud with boxes or any other measures?
I've been advised that I don't require a VCL so the foil backed plasterboard should nt be necessary, unless you are about to tell me otherwise???
I propose that get the cables in position, get a board up at a time and then lay the insulation, then the next board and the insulation above that and so on...
I then have the ceiling plastered and then punch in holes for lights and fish out the cables. I will of course make a plan of where the acables are before boardng up. On the lights, am I not better off just getting insulation covered led downlights instead of faffing aroud with boxes or any other measures?
You can get insulation with a vapour barrier stuck to it too you know?
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