Cold vs Warm roof. Should I care?

[Mmark]

We are doing an L shaped loft conversion, we have two flat roofs. Halfway through someone advised me to make sure we have a warm roof - I had no idea there was cold or warm roofs. Builder says we have cold roof, too late to change now.

Should I care? My concern is we have down lights, so lots of cavity holes and two steel beams. I don’t understand why he 1) wouldn’t have given us this choice. 2) now we are down this path, should I really care and just learn to live with it.

 

[Notch7]

cold roofs and downlighters dont mix well.
Ive seen jobs where the hole goes through the insulation into the ventilated void -not good.

Was this not detailed on the building regs drawings?

have the flat roofs been felted already? -what stage are you at?

 

[Alastairreid]

Cold roof will need ventilated above the insulation and should be factored in at planning/construction stage.

Warm roofs requires rather deep fascias.

 

[^woody^]

Customers dont get a choice of what roof they get, it's all down to how good the designer is.

If it's ventilated, then it should not really matter and whoever advised you to "make sure you have a warm roof" should be crossed off the Christmas card list

 

[Mmark]

Here are some photos. Turns out architect specced warm roof, builder ignored - see attached spec from my architect diagrams. Also included photos of what builder has done.

So I now need to decide if I leave things, or push to make them implement what architect specced.

 

[Mmark]

Customers dont get a choice of what roof they get, it's all down to how good the designer is.

If it's ventilated, then it should not really matter and whoever advised you to "make sure you have a warm roof" should be crossed off the Christmas card list

Yeah sometimes ignorance would be easier if it wasn’t mentioned to me, I’d have no idea builder was implementing what he wanted and not what was specced. Problem is I don’t have knowledge to know how much I should or shouldn’t care, if the cold roof, insulation and lights are installed correctly. Hopefully photos might help people advise on that.

Thanks, appreciate people’s time.

 

[Notch7]

Turns out architect specced warm roof, builder ignored

You need to find out if the cold roof has been built correctly, theres another thread on here showing condensation problems with a cold roof due to inadequate ventilation.

Other thread....
"I wish it was a warm roof but didn't know much about cold and warm roofs when the builder did it, and now it's too late"
Read more: https://www.diynot.com/diy/threads/...-flat-roof-condensation.534597/#ixzz67FCDqLhL

 

[^woody^]

Yeah sometimes ignorance would be easier if it wasn’t mentioned to me, I’d have no idea builder was implementing what he wanted and not what was specced. Problem is I don’t have knowledge to know how much I should or shouldn’t care, if the cold roof, insulation and lights are installed correctly. Hopefully photos might help people advise on that.

Thanks, appreciate people’s time.

Regardless of what is specified, the builder should be doing what the plans say and not freestylin'

 

[johnny2007]

Warm roof is easier to build and rarely creates problems.
A cold roof must be built properly to the tiniest detail, otherwise it becomes a problem.

 

[Mmark]

I’m since reading else where that flat cold roofs with downlights are a very bad idea and potentially not passing building regs, if theY digged deep enough - due to all the swiss cheese holes in the PIR..

 

[^woody^]

I’m since reading else where that flat cold roofs with downlights are a very bad idea and potentially not passing building regs, if theY digged deep enough - due to all the swiss cheese holes in the PIR..

Where are you reading all this? It might be best to ignore those sites.

If a cold roof is built properly and the correct materials used, it can be splatterted with downlights and it will be OK.

 

[Mmark]

Where are you reading all this? It might be best to ignore those sites.

If a cold roof is built properly and the correct materials used, it can be splatterted with downlights and it will be OK.

It is true, I can only find that in DIY comments, nothing official. All I could read in Part L was "should not be compromised", but I guess that is guidance for achieving the minimal U value.

I have found a lot of stuff around BS 6229, that says warm roofs are recommended over cold.
https://www.bauder.co.uk/getattachm...verviewOfChanges_BauderMay2019.pdf?lang=en-GB

I'm more worried now on why they cut such huge holes, recommendations seem to be twice diamater of LED light (Enlite Pro E6). The squares they cut are huge, hoping to speak to them today, about how they plan to fill those (suspect they were now). Does this look bad, or am I worrying about nothing?

 

[Notch7]

If

most important word, 'if'

 

[Notch7]

Enlite Pro E6

90mm deep cut out.....

Ive recently fitted enlites -Im very happy with them.

PS: buy some spares so if one goes wrong in the future you can replace with a matching fitting.

 

[Mmark]

90mm deep cut out.....

I'm assuming you mean 90mm circles? I need to measure but the squares they have done look almost the width of the joists. So it's 300mm squares. I cannot see how they can effectively fill those in, I bet they weren't planning to. Is this just lazy or standard?