Warm roof

[geraldthehamster]

I understand the difference in construction between a warm (flat) roof and a cold roof. I've insulated both (cold and ventilated in the case of a loft conversion - ok, not flat but the same principle), and warm in the case of an outbuilding renovation.

But I'm having a rush of blood to the brain, I think. ... sitting here today, I can't get my head round the need for ventilation in a cold, flat roof, with an intact vapour barrier above the plasterboard. If warm moist air can't rise into the roof from below, and condense, and the roof covering is also intact, how can moisture get into the timber of the roof structure, and need to be ventilated away? What's the issue with packing the insulation between the joists, up against the top deck?

Sigh.

Cheers
Richard

 

[ban-all-sheds]

I can't get my head round the need for ventilation in a cold, flat roof, with an intact vapour barrier above the plasterboard. If warm moist air can't rise into the roof from below, and condense, and the roof covering is also intact, how can moisture get into the timber of the roof structure, and need to be ventilated away?

Maybe you can't guarantee that moisture will never get in, given that the structural elements will suffer from thermal movement all the time?

Are you planning to build a cold roof? I thought they were deprecated?

What's the issue with packing the insulation between the joists, up against the top deck?

No ventilation.

 

[freddiemercurystwin]

A vapour barrier, with the best will in the world is not impermeable to vapour, there are hundreds of fixing penetrations, and laps where they join, the perimeter to wall junction, and add some crappy workmanship in to boot.

 

[geraldthehamster]

Thanks both - that was the only reason I could think of.

I still want to know what you've got against sheds.

Cheers
Richard

 

[ban-all-sheds]

Sorry - meant to reply to that before.

I mean this:

not this:

 

[geraldthehamster]

Sorry - meant to reply to that before.

I mean this:

not this:

Ah, light dawns! Well I wouldn't argue with that.

Cheers
Richard

 

[freddiemercurystwin]

That's all very well but where am I going to get a plug socket on a bank holiday Monday or after work one day?

Convenience is the name of the game.

 

[ban-all-sheds]

... Convenience ...

Here are some more conveniences for you:

 

[freddiemercurystwin]

Thought that would be your answer!

 

[ban-all-sheds]

Well - on a more serious note there is absolutely no reason why a store which is open on Bank Holidays and evenings has to also be a store with insufficient and ignorant employees, which sells stuff that is utter s***e and which employs buyers to scour the world for the cheapest, nastiest tat they can find.

It's not their opening times which I object to.

 

[freddiemercurystwin]

Hmm, no reason to ban them though, plenty of retailers sell overpriced rubbish. Plenty of their stuff is OK, if over priced.

 

[ban-all-sheds]

It's too late anyway - they have successfully brainwashed the vast majority of people into thinking that when you buy timber it should be ready-shaped for making propellors, for example, or that an 8x4 sheet of 18mm chipboard should be light enough for one person to carry, and so on.

 

[geraldthehamster]

It's too late anyway - they have successfully brainwashed the vast majority of people into thinking that when you buy timber it should be ready-shaped for making propellors, for example, or that an 8x4 sheet of 18mm chipboard should be light enough for one person to carry, and so on.

But whenever we go to a builder's merchant we are still complicit in the survival of the sheds - Travis Perkins and Wickes, for example.

No-one is innocent

Cheers
Richard

 

[ban-all-sheds]

Those are sheds, not proper builder's merchants.

 

[geraldthehamster]

Those are sheds, not proper builder's merchants.

I meant that TP (ostensibly not a shed) owns Wickes (clearly a shed).

Which builder's merchant, that the average bod is likely to find in his town, is ideologically pure then?

Cheers
Richard