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Downlight/spotlight on pitched roof with insulation


richie9648

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Hi

I am having a pitched roof extension a bit like the pic attached

i want spot lights in the roof but the electrician is saying that I will need to lower the ceiling by 5-6 inches so that the insulation isn’t compromised.  Is this right - I’ve seen loads of pics where the spot lights are installed in the roof that way. 

F29AD99E-E52B-4B51-BAF4-BEDF752194CD.jpeg

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Have you considered ceiling mounted rather than sunken spotlights?

 

Personally (having inherited about 55 from the person who built this house and gone through the gantlet of making them all LEDs back in 2013) I think recessed spots are evil.

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Just now, Iceverge said:

5-6 inches sounds like someone who hasn't updated their understanding of the world in some while. 

 

20mm slimline LED spotlights are readily available. 

 

doesnt matter the depth if its a warm roof then the vapour barrier (not that there is evidence of one) needs to be protected and not pierced.

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3 minutes ago, Dave Jones said:

 

doesnt matter the depth if its a warm roof then the vapour barrier (not that there is evidence of one) needs to be protected and not pierced.

Yes, 

 

Its seems to be totally forgotten by most builders and designers with everyone hell bent on achieving one u value or another. U-Values are long forgotten when the roof is full of fungus and the timbers are rotten.  

 

I was almost going to point it out but i think 3 of my last 4 replies are on similar topics so the tune is wearing thin. 

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it’s a warm roof - 100mm of insulation 

23 minutes ago, Dave Jones said:

Is it a warm or cold roof ?

It’s a warm roof with 100mm insulation installed 
 

Ok so it sounds like that I can’t have spot lights without having to lower the ceiling a bit further which I don’t want to do. 
 

what about pendants ? Could I install a pendant without lowering the roof space 
 

so will look into surface mounted 

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9 minutes ago, richie9648 said:

it’s a warm roof - 100mm of insulation 

It’s a warm roof with 100mm insulation installed 
 

Ok so it sounds like that I can’t have spot lights without having to lower the ceiling a bit further which I don’t want to do. 
 

what about pendants ? Could I install a pendant without lowering the roof space 
 

so will look into surface mounted 

100mm of insulation won't meet regulations. 

 

Do you have any architects detail drawings of the roof structure you can share?  I understand the pic isn't of your own roof. What stage of construction are you at? 

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1 minute ago, Iceverge said:

100mm of insulation won't meet regulations. 

 

Do you have any architects detail drawings of the roof structure you can share?  I understand the pic isn't of your own roof. What stage of construction are you at? 

 
i can’t remember how much insulation he mentioned. I don’t have drawings to hand 


just about to start on the roof that’s why I am asking about Downlights

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45 minutes ago, Dave Jones said:

if its a warm roof check what vapour barrier was used, there isnt any evidence of one at the ceiling junction in which case the ceiling needs to come down and it be installed or you will have problems.

 

 

 

Capture.JPG


Does the foil on the PIR boards act as VCL?? 
 

A second layer of inso' across the studs prevents any cold bridging through the studs thus preventing the risk of shadowing. (Would this be correct?? 

Read more: https://www.diynot.com/diy/threads/vapour-barrier-needed-on-pir-boards.547007/#ixzz74UKvpxlJ

Edited by richie9648
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Flush downlights in a 45 degree sloping ceiling will probably not shine the light where you want it to shine.  For our vaulted ceiling I used surface mount spotlights that you can point any way you want them to, and they work well.

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3 minutes ago, ProDave said:

Flush downlights in a 45 degree sloping ceiling will probably not shine the light where you want it to shine.  For our vaulted ceiling I used surface mount spotlights that you can point any way you want them to, and they work well.

Thanks Dave - any pics you can share? 

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19 hours ago, richie9648 said:


Does the foil on the PIR boards act as VCL?? 
 

A second layer of inso' across the studs prevents any cold bridging through the studs thus preventing the risk of shadowing. (Would this be correct?? 

Read more: https://www.diynot.com/diy/threads/vapour-barrier-needed-on-pir-boards.547007/#ixzz74UKvpxlJ

 

no it doesnt, you have no VCL so it will grow mould/rot as the water cant get out. drop the platerboard and do it properly, alutrix is very goof VCL.

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 Any construction details for the new roof was what i was looking for.

 

Something like this below. 

 

By the way this would be my preferred detail.  Swap out the 325mm engineered joists for 220x45mm timbers and include a 45mm insulated service cavity. U value slightly better than 0.15. 

 

You'll have a very vapour safe roof if you do a good job sealing the vapour barrier and use a good breather membrane outside. You will need to batten and counterbatten to have 50mm ventilation over the membrane under the tiles. 

 

If you can't find cellulose or it's uneconomical for such a small project use mineral wool instead. 

 

 

 

Cut / Vaulted Roof | Timber Frame Houses | MBC Timber Frame

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