richie9648 Posted August 24, 2021 Share Posted August 24, 2021 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. Link to comment Share on other sites More sharing options...
Dave Jones Posted August 24, 2021 Share Posted August 24, 2021 Is it a warm or cold roof ? Link to comment Share on other sites More sharing options...
Ferdinand Posted August 24, 2021 Share Posted August 24, 2021 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. Link to comment Share on other sites More sharing options...
Iceverge Posted August 24, 2021 Share Posted August 24, 2021 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. Link to comment Share on other sites More sharing options...
Dave Jones Posted August 24, 2021 Share Posted August 24, 2021 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. Link to comment Share on other sites More sharing options...
nod Posted August 24, 2021 Share Posted August 24, 2021 He’s right you shouldn’t be cutting into the isolation Service mounted are a better option Link to comment Share on other sites More sharing options...
Iceverge Posted August 24, 2021 Share Posted August 24, 2021 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. 1 Link to comment Share on other sites More sharing options...
richie9648 Posted August 24, 2021 Author Share Posted August 24, 2021 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 Link to comment Share on other sites More sharing options...
Dave Jones Posted August 24, 2021 Share Posted August 24, 2021 (edited) 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. Edited August 24, 2021 by Dave Jones Link to comment Share on other sites More sharing options...
Iceverge Posted August 24, 2021 Share Posted August 24, 2021 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? Link to comment Share on other sites More sharing options...
richie9648 Posted August 24, 2021 Author Share Posted August 24, 2021 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 Link to comment Share on other sites More sharing options...
Iceverge Posted August 24, 2021 Share Posted August 24, 2021 If you find them stick up a cross section and I'm sure the collective brains here will present the optimum solution! If not maybe you could put together a sketch yourself. Link to comment Share on other sites More sharing options...
richie9648 Posted August 24, 2021 Author Share Posted August 24, 2021 20 minutes ago, Iceverge said: If you find them stick up a cross section and I'm sure the collective brains here will present the optimum solution! If not maybe you could put together a sketch yourself. Here you go. Link to comment Share on other sites More sharing options...
richie9648 Posted August 24, 2021 Author Share Posted August 24, 2021 (edited) 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. 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 August 24, 2021 by richie9648 Link to comment Share on other sites More sharing options...
ProDave Posted August 24, 2021 Share Posted August 24, 2021 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. 1 Link to comment Share on other sites More sharing options...
richie9648 Posted August 24, 2021 Author Share Posted August 24, 2021 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? Link to comment Share on other sites More sharing options...
Temp Posted August 25, 2021 Share Posted August 25, 2021 There are some guides but not great.. https://www.lightingcompany.co.uk/blog/light-a-sloping-ceiling-lighting-from-a-different-angle/ Adaptors are needed for some lights to cope with the slope. Link to comment Share on other sites More sharing options...
Dave Jones Posted August 25, 2021 Share Posted August 25, 2021 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. Link to comment Share on other sites More sharing options...
Iceverge Posted August 25, 2021 Share Posted August 25, 2021 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. Link to comment Share on other sites More sharing options...
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