Vapour Barrier

[Jupiter01]

Can someone please put me on the straight and narrow for this please. I'm reading lots of conflicting advice. I have a cold loftspace above my bedrooms. I will be replacing the insulation and plasterboards. How do I approach this?

Some of the specific questions:

- are spotlights a no-no
- if I wanted a hollow ceiling below to support the downlighters, I would still have to screw battens into the above
- how do cables penetrate this
- how do we stick it to joists
- what happens at the edges
- what gauge
- what happens when the plasterboard gets screwed into it
- any details on overlapping sections of it

My sense is that most people don't bother with it. Agree and what tends to be the typical outcome of this?

I will be doing it as I am pulling the whole thing apart anyway.

Thanks in advance

 

[^woody^]

Sorry, I can't see what the drama is. Replace or overboard. Screw the boards. Lap any joints. Use fire rated spotlights or fit fire hoods

 

[Jupiter01]

My questions relate to the vapour barrier that goes on before boarding. So for instance, if the vapour barrier is up and we then put the plasterboard on, can we penetrate this to support downlights. This is just one of the many questions I have raised in my initial post. Hope that makes sense.

 

[WabbitPoo]

why are you so sure you need one? Ceilings don't have them, as a rule.

 

[^woody^]

No vapour barrier required

 

[Jupiter01]

If I have a warm place (first floor of my house) and a cold space above it (the loft), wont that cause condensation and mouldy ceilings/rot trusses? Sorry if I'm barking up the wrong tree?

 

[^woody^]

Not if your loft is ventilated. Like it should be

 

[Jupiter01]

Loft is ventilated as the soffits are vented. I ahve chosen not to insulate between the rafters so there is plenty of airflow but keeping this very simple, will there not be condensation when hot meets cold and hence the need for a vapour barrier?

If not, when are vapour barriers ever required with ceilings?

 

[^woody^]

When there is an unventilated space above. Or if the room is one where lots of moisture will be produced.

 

[Jupiter01]

Thanks for your help but everything I am reading suggests that there is a need for a vapour barrier in this situation.

You may well be right but I would appreciate some additional views on this topic

 

[^woody^]

but everything I am reading suggests that there is a need for a vapour barrier

Where are you reading all this?
Nhbc? BRE? BSI?

 

[freddiemercurystwin]

There is no need for a vapour barrier here.

 

[Jupiter01]

Hi Guys,

Thnaks for the confirmation. It's references such as this that had me doubting
http://www.ehow.co.uk/how_8731671_install-vapor-barrier-ceiling.html

Out of interest, woud the situation be different if I had no vented soffits and hence the ventialation was poor or absent in the loft?

 

[freddiemercurystwin]

ehow? FFS!

If you had no ventilation in the loft any vapour would condensate on the underside of the roof.

 

[Jupiter01]

Sorry, sinful I know.
So in the above situation (just trying to establish a principle), would the VCL be required?