LED downlights within Celotex insulation

[Jupiter01]

Hi,

Can someone please advise me on the correct process to install spotlights into a ceiling which I am planning to pack-out with Celotex insulation and then line with drywall and finish off with plaster. I have had a suggestion that I should leave a 150mm x 150mm gap in the Celotex wherever I plan to install a spotlight but such gaping holes will massively undermine the effectiveness of my insulation.

Thanks in advance.

 

[Taylortwocities]

Yes it will compromise your thermal benefit and if Building Control see it they will reject it.

If you want to put torchlights, sorry I mean downlights, in an insulated ceiling you need to specify a "warm roof" construction. basically the insulation is put in the ceiling, then you build basically a ceiling layer 100mm or so below it on joists, thus leaving a space for your lights.
This drawing shows it for a flat roof, but you'll get the idea.

Alternatively, use surface lights. That may also mean you can use something that will illuminate the room effectively.

 

[RF Lighting]

Use slim led down lights. Cutting massive holes in your insulation would be madness.

 

[Jupiter01]

Thanks guys. Even the slim lights will have a depth of around 60mm I assume which again means that I need to cut out holes in my insulation. Or are you suggesting that the 100mm celotex would only need to be notched out 60mm in this case? I didn't think it was acceptable to cover led spotlights?

The warm roof is a great idea but I am loathed to lose the ceiling space for what will just be an aesthetic addition to the bedrooms. I am arriving at a conclusion that I can either preserve the integrity of my insulation or cut out gaping holes to accommodate spotlights?

Isn't there such a thing as an insulation friendly spotlight?

Thanks again.

 

[RF Lighting]

http://www.ledhut.co.uk/spot-lights/ceiling-lights/12-watt-led-downlight.html

These are only 13mm deep. That's about the same as a skimmed plasterboard.

 

[Jupiter01]

Thanks. Is it permissible to cover the top of these with insulation?

 

[kingspandirect]

Hi, any lighting which adds heat into the insulation layer would have to have a gap around it to avoid any overheating. LED lighting produces less heat than halogen spotlights, but you will still be cutting a hole in the insulation and this will mean heat as well as moisture (from your room) can escape into the cold space above, cause condensation etc. We have a blog that covers a lot of the answers, so we hope that helps. It covers things more from an insulation point of view. Although we're from Kingspan Insulation, the same principles apply as if you were to use other rigid boards such as Celotex, Ecotherm, Xtratherm etc

 

[Jupiter01]

Thanks for the link. The false ceiling is not an option for me. Can I clarify option 2 and how it would work in practice please. Lets assume that my light has a depth of 110mm and is 100mm in diameter. I understood that I would need to create a round 200mm hole in the insulation and this would pierce right through in my case as the thickness of the insulation is 100mm. I then fit in the light as normal, fit the cap (from the roof space above I assume) and then throw insulation on top of the 200mm hole. Is that correct?

Also, I've noticed that there are fireproof led's which I assume will not require the cap. Finally, if the above is true, am I not best to find slim fireproof led's, lets say 50mm deep and then only notch out 50mm from my 100 insulation?

 

[Taylortwocities]

The manufacturer of the downlights will have a specification for the clearances needed. What does it say?
You mention a "cap" where did that come from?
Is this a new space that requires Building Control approval?

PS I am not sure why you might need "fireproof" fittings…?

 

[Jupiter01]

I've not purchased any lights as yet, hence the questions to understand the feasibility and viability of this. The cap was mentioned in the kingspan link posted earlier. I am considering this in my existing upstairs accommodation.

 

[Taylortwocities]

OK, so I gather you have space above the Kingspan?. If you must, why not cut out your clearance hole for the torchlight and then secure another slab of Kingspan on the top of it? Allow at least 100mm overlap round the hole. That would maintain your 100mm insulation throughout.
You'll need to make sure the moisture barrier is not compromised though.

 

[Jupiter01]

Thanks for the response. I have clearance above the insulation; it's the roof space. Presumably the vapour barrier will be compromised as soon as I cut the bottom side of the insulation?
Not withstanding the above and the narrow loft space that I have, I could potentially do what you have suggested. I'm still unclear on whether I can definitely cover the lights in this fashion. If the answer to this is yes, why not get a slim LED lets say 50mm and then only notch out 50mm from my insulation board which means I still have 50mm insulation above each light?

 

[theprinceofdarkness]

I have not seen any reference to fire protection. What I did was to build 6" square X 8" high boxes out of plasterboard with a piece of 5" wide aluminium which runs inside the top surface of it then has a 24" extension which rises upwards from the side. All joints were sealed with intumescent sealer. So the theory is, its fire proof, the vertical bit pokes through the insulation to get rid of the heat. This was for LEDs, I measured the temperature of their housing and it was 40 degs C which does not seem too high. It will get a lot hotter in summer. still the £20 LEDs (10 off) have paid for themselves over the old filament types in power used a year ago and don't loose so much house heat overnight.
Frank

 

[DetlefSchmitz]

I'm not sure I'd want to lie in bed with spotlights shining down from above.

 

[Iggifer]

I'm not sure I'd want to lie in bed with spotlights shining down from above.

I put some in before christmas into a bit of built in wardrobe above the head of the bed (can't remember the name for the thing I'm talking about) tried to talk them out of it, but they wanted them as 'reading lights'. I too, cannot think of anything worse