LED Downlights

[DiyDONOT]

Hey All,

I've an attached garage with a pitched roof 3/4 up the side of the house

Planning on plasterboarding the inside of the roof and sticking 100mm or rockwool between the joists

I've space to put in 8 LED downlights but unsure of the regs a) for heat b) for insulation

Assuming since there is no insulation and that it is a garage it won't matter about keeping it 'insulated' but I do want it warm as it will be my gym!!

Can I drill a hole for the light, stick it in & wire it up and layover the rock wool or should I leave space?

Will the wire be alright aswell ?(either under or above the insulation)

Thanks for help - I've searched but couldn't find an answer.

 

[ban-all-sheds]

Planning on plasterboarding the inside of the roof and sticking 100mm or rockwool between the joists

Any vapour control layer, or are you OK with risking the roof timbers rotting?

Assuming since there is no insulation and that it is a garage it won't matter about keeping it 'insulated' but I do want it warm as it will be my gym!!

Actually, the regulations say that if you do put insulation in it has to meet performance standards.

Can I drill a hole for the light, stick it in & wire it up and layover the rock wool or should I leave space?

How will you get access to do that?

You need to see what the manufacturer of the lights says about clearances, and you really should try and prevent warm moist air from getting through the ceiling. Making lots of holes in it is a bad way to start.

Will the wire be alright aswell ?(either under or above the insulation)

Depends how big it is.

• //www.diynot.com/wiki/electrics:mcbtocable
  
  
• http://www.tlc-direct.co.uk/Book/4.3.1.htm
  
  
• http://www.tlc-direct.co.uk/Book/4.3.11.htm
  
  
• http://www.tlc-direct.co.uk/Book/5.3.1.htm
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/cableselection_web.pdf
  
  
• http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html
  

 

[DiyDONOT]

Planning on plasterboarding the inside of the roof and sticking 100mm or rockwool between the joists

Any vapour control layer, or are you OK with risking the roof timbers rotting?

Assuming since there is no insulation and that it is a garage it won't matter about keeping it 'insulated' but I do want it warm as it will be my gym!!

Actually, the regulations say that if you do put insulation in it has to meet performance standards.

Can I drill a hole for the light, stick it in & wire it up and layover the rock wool or should I leave space?

How will you get access to do that?

You need to see what the manufacturer of the lights says about clearances, and you really should try and prevent warm moist air from getting through the ceiling. Making lots of holes in it is a bad way to start.

Will the wire be alright aswell ?(either under or above the insulation)

Depends how big it is.

• //www.diynot.com/wiki/electrics:mcbtocable
  
  
• http://www.tlc-direct.co.uk/Book/4.3.1.htm
  
  
• http://www.tlc-direct.co.uk/Book/4.3.11.htm
  
  
• http://www.tlc-direct.co.uk/Book/5.3.1.htm
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/cableselection_web.pdf
  
  
• http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html
  

Hi thanks for your constructive none provoking reply & things to consider

I was thinking about letting the timbers rott, would quite enjoy replacing my roof. Im going to resist being a keyboard warrior for the rest of the post.

PLEASE explain what you mean by your answers / what to implement as its obvious I havnt thought of everything so would appreciate a bit more advice.

 

[ban-all-sheds]

If you insulate as suggested, the roof will be cold, and the inside of the building warm.

If air from the inside gets onto the roof there will be condensation, which over time could rot the timbers, and/or cause mould to grow.

You need a vapour-tight seal between the warm and cold spaces, e.g. plasterboard with a VCL backing. The problem is if you cut holes in that for downlights it will stop working. It is very difficult, if not impossible, to install recessed lighting when you do not have access from above to fit sealed enclosures around them.

 

[DiyDONOT]

Thanks
Deffo never thought of that

I might be able to install it into theboard lose from the ceiling / plug it in

But that doesn't get past the moisture problem :-O

 

[seasickstevie]

You fit the fittings in the hole in the plasterboard after its boarded & skimmed.

First clip the cables leaving a loop close to each light position, but so as your hole cutter when cutting the light apertures doesn't go through the cable - that wouldn't be good.
Then when you cut the holes, fish out the cable.

None of this gets around the vapour barrier issue, but if you use fire-wall type fittings, maybe that might help (others will disagree).

 

[stem]

I've fitted these lights made by Astro in my Kitchen (5 years ago) and Bathroom (3 months ago) There are other types about that have similar features.

Untitled

• stem
• 24 Jan 2013
• 3

They take a standard GU10 lamp so I've installed 7W LED versions (light output equal to 50W halogen) There is a neoprene seal between the glass and the fitting, which is compressed when the glass cover is twisted into position. This prevents the transfer of any moisture from room to loft space.

The LED lamps do get warm (not hot) so the insulation is just cut back by about 5 cm so that it's not in direct contact with the fitting.