Cold flat roof bathroom extension spotlight / insulation conundrum

[Jujuman]

Hi guys,

First time posting on this forum so please be gentle

So the Mrs wanted spots in the bathroom so I took down the 2 layers of old ****e ceiling (the underneath layer was mouldy from the old flat roof - we now have a fibreglass roof) and got sparkies in to move the light switch and install 4 spots (read as downlighters) in main bathroom and 1 in the vestibule/entrance cubby.

The sparkies have done their first fix and wires are dangling.... they said celotex is fine for insulation aslong as i leave a gap around the lights - so my intended solution was to cut the board to fit between the rafters and push it flush to the underside of the rafters leaving an air gap behind it and where the lights are to leave a gap so i would cut board leave gap, then new section of celotex - rather than cutting holes out of it which i hear is unadvisable. I also intend to use the plasterboard with the vapour barrier to stop damp/moisture permeating into the cavity.

However i am concerned that there may be "cold spots" around the light fittings where there is an absence of celotex potentially causing condensation and a hazard.

To be honest I'm pretty flummoxed by this and kind of wish i'd stuck to my guns and gone with the standard ceiling light we had before which was relatively new and not a downlight but surface mounted.

Builders ive spoken to seem to be very slap dash in their approach ie just put some insulation in there and next... but this surely cant be right.

Basically i dont want to burn the extension down or kill anyone in an ideal world so any assistance in this would be a huge help.

Tried attaching pics but the accepted size is set too low

Wife now bugging me to "get on with it" but i think safety and not invalidating our insurance is slightly more important than rushing in and making a potentially expensive and dangerous error.

Looking forward to hearing from you guys and sorry if ive rambled.

 

[winston1]

In the second picture there is a non maintenance free junction box in an area where it is clear maintenance won't be possible. Your sparks should have picked this up. It needs changing to a maintenance free type.

Of course it is not too late to "stick to your guns" and say what she wants is not achievable.

 

[securespark]

Looks like two JB's.

 

[Jujuman]

Hi guys, thanks alot for replying so quick - not sure how to quote but ill just use bold for now:

In the second picture there is a non maintenance free junction box in an area where it is clear maintenance won't be possible. Your sparks should have picked this up. It needs changing to a maintenance free type.

The sparks didnt pick them up - they have literally just installed them - ill tell them these are not the correct typ do to lack of access (they could have set these back in the cavity which actually has an acccess hole....

Of course it is not too late to "stick to your guns" and say what she wants is not achievable.

No of course, but I've now spent almost £300 with the electricians so would be painful to just get them to undo the work.

Looks like two JB's. (okay i googled and this means junction boxes but puzzled as to how to utilise this advice in relation to the questions posed).

Any ideas about insulation once ive got the maintenance free junction boxes instead of current ones.

Thanks guys!!!

 

[ban-all-sheds]

There is no conundrum.

You may not have lights recessed into that ceiling and that's all there is to it.

 

[Jujuman]

Oh, that's not what i wanted to hear

Why would a qualified sparky be prepared to do it without question and issue a certificate for it if that's the case?

Also what is/are the specific reason/s it's not allowed - this would be very useful to know (a building code/link would be great) - it seems this is something many builders and electricians appear to have no knowledge of whatsoever.

If anyone can tell me why its a no no i can go back to the sparkies and tell them that it is not okay and why then we can renogotiatate - although i have to say im thoroughly ****ed off that theyve done this when it is not something you should do, afterall thats exactly why someone like me gets a professional spark in in the first place to avoid such issues.

I'm now very happy I joined this forum and for the pointers so far - learnt more here in 20 minutes than i have from any of the 3 dozen tradesmen I've discussed the project with (some builders some sparkies some bathroom fitters) all of whom have been on site and seen the situation but all have said its okay how many downlighters do you want type thing...

 

[Jujuman]

It appears there is a conundrum.

Local building control (southampton) have just said the new fire rated LED downlighters are fine in this type of pitched roof extension and to leave a gap behind the insulation and the roof for air flow/ventilation.

#confused

 

[ban-all-sheds]

Why would a qualified sparky be prepared to do it without question and issue a certificate for it if that's the case?

Because he is not very conscientious?

Because he neither knows nor cares that he has to comply with the Building Regulations and not just ignore anything not specifically electrical in what he does?

Also what is/are the specific reason/s it's not allowed - this would be very useful to know (a building code/link would be great) - it seems this is something many builders and electricians appear to have no knowledge of whatsoever.

Because of the requirements of Part L, and (as it's a bathroom) Part C of the Building Regulations.

Basically you may not have holes in the insulation and you may not have holes in the vapour control layer which will allow air through to where the moisture in it will condense. You said "the underneath layer was mouldy from the old flat roof" - there are no signs in the photos that the old roof was letting the rain in, so £ to a p the mould was because warm moist air was reaching a cold surface and condensing on it.

 

[ban-all-sheds]

Local building control (southampton) have just said the new fire rated LED downlighters are fine in this type of pitched roof extension and to leave a gap behind the insulation and the roof for air flow/ventilation.

Fire-rated lights provide nothing in the way of a vapour barrier, and you don't need them anyway.

Also you don't look to have enough space for lights, insulation, and then an air gap.

Given that you've pulled down the ceiling and had the waterproof layer replaced, you would have been much better off replacing the roof in its entirety with one better constructed.

 

[Jujuman]

Thanks for your responses guys.

Mould in old roof was because it was a felt roof that was letting water through, the boards you see in the pics are ones the builder put under the new fibreglass roof so these are newish.

Yes totally agree with you ban-all-sheds in hindsight a warm roof would have been a much better solution. Wish i would have come here first before getting real life builders opinions - none of whom suggested it.

Anyway - long story short, im going to put celotex in the void leaving an air gap behind and make allowance for space/clearance around the fire rated led units. Then I'm going to use vapour board (the plasterboard with foil back) to create vapour barrier.

As we're only having 4 downlights i will seal these with sealant around them so I cant really see how the moisture will penetrate from 2 showers a day in a bathroom with an airbrick and 2 windows with trickle vents that never gets very damp in the first instance. Also the cavity vents into a larger space with air bricks.

Thanks again for everyones contributions.

 

[ban-all-sheds]

Anyway - long story short, im going to put celotex in the void leaving an air gap behind and make allowance for space/clearance around the fire rated led units.

Have you checked that that will comply with the Building Regulations? Sounds iffy to me. Building Regulations approval is required - did you apply for it before the work started?

Then I'm going to use vapour board (the plasterboard with foil back) to create vapour barrier.

That will be a vapour barrier with holes in it, will it?

As we're only having 4 downlights i will seal these with sealant around them so I cant really see how the moisture will penetrate from 2 showers a day in a bathroom with an airbrick and 2 windows with trickle vents that never gets very damp in the first instance.

It will go through the lights.

Time will tell - if you'd rather risk damage to the roof in order to have recessed lights, that's up to you, but IMO that would be [polite term]barking mad[/polite].

 

[333rocky333]

Im no expert on building regs, but you can get thin leds that look like downlights and are barely as thick as two sheets of plasterboard, that may be suitable even with insulation over them, these run off drivers that could be put in that void you say has an access panel

 

[ban-all-sheds]

And many of them are of a decent diameter.

 

[phatboy]

https://www.ledhut.co.uk/spot-lights/ceiling-lights/6-watt-led-downlight.html

Fit these, you can insulate over the top and they are the thickness of the plasterboard. Just need a tiny hole to pass the cable through, and can have the transformer on the other side of the insulation. May be a good idea to cut out the insulation along with the hole for the light, and then refit the removed piece so that you can replace the transformer if ever required, or run it to somewhere that is accessible.

Your electricians are not real electricians if they fitted those junction boxes, I would be searching for a new one.....

 

[winston1]

https://www.ledhut.co.uk/spot-lights/ceiling-lights/6-watt-led-downlight.html

and can have the transformer on the other side of the insulation.


so that you can replace the transformer

According to the specifications it runs off 240 volts.