Dear All,
In a late 50's semi with rooms built into the loft, we have
had the original wooden soffit boards replaced with PVC ones. These
soffit boards have several of those circular soffit vents, installed
on the 3 exposed sides of the house. Since this work was done the
house, particularly the floors of the rooms in the loft seem much
colder when there is a cold northerly wind blowing.

As I understand it, those soffit vents are needed to provide
ventilation for the loft space and are used because the PVC is not
breathable like the original wood. However there is hardly any loft
space left over from the loft conversion -- just enough for the water
header tanks etc.

This seems like a criminal waste of (ever more expensive) energy.
So what are my options?

TIA.
Tom Crane.
--
Tom Crane, Dept. Physics, Royal Holloway, University of London, Egham Hill,
Egham, Surrey, TW20 0EX, England.
Email:
Fax: +44 (0) 1784 472794

Do not block these vents,they are not there due to upvc they are for the
prevention of condensation on the roof felt,

I had to deal with the consequences of this condensation build up in many
properties last year due too the cold snaps we did have and it can cause
quite a mess and in the extreme severe wood rot.

Alex

wrote:
Dear All,
In a late 50's semi with rooms built into the loft, we have
had the original wooden soffit boards replaced with PVC ones. These
soffit boards have several of those circular soffit vents, installed
on the 3 exposed sides of the house. Since this work was done the
house, particularly the floors of the rooms in the loft seem much
colder when there is a cold northerly wind blowing.

As I understand it, those soffit vents are needed to provide
ventilation for the loft space and are used because the PVC is not
breathable like the original wood. However there is hardly any loft
space left over from the loft conversion -- just enough for the water
header tanks etc.

This seems like a criminal waste of (ever more expensive) energy.
So what are my options?

Block em up and don't tell the BCO.

My carpenters reckoned the best compromise was to shove rockwool
insulation down. They will still breathe but the flow rate will be well
down.


TIA.
Tom Crane.

Alex wrote:
Do not block these vents,they are not there due to upvc they are for the
prevention of condensation on the roof felt,

I had to deal with the consequences of this condensation build up in many
properties last year due too the cold snaps we did have and it can cause
quite a mess and in the extreme severe wood rot.

Alex


yeah but the regulations are way over specified, especially if you have
a waterproof roof, and vapour barriers in the ceiling.

Actually one thing I did that really helped was to board out the
loft..that stopped air blowing into the insulation.

the vents are not just to ventilate there loft space but the area between
the roof felt and the plasterboard/insulation it may be that no insulation
was used so investigate that first,how old is the loft conversion.

Alex wrote:
: the vents are not just to ventilate there loft space but the area between
: the roof felt and the plasterboard/insulation it may be that no insulation
: was used so investigate that first,how old is the loft conversion.

Thanks all, for the feedback. The majority of the cavity served by
the soffit vents does not include any roof felt. It is the space
between the floors of the loft extension rooms and the ceiling
(ie. plasterboard) of the first floor rooms. As far as I remember
underneath the carpeted floorboards of the loft extension rooms there
is just space down to the plasterboard of the first floor rooms.
There might be some vermiculite down there -- I can't remeber, but
that is all. It would be a real fag to take up all the carpets and
floorboards in the top floor rooms to put down insulation.

Isn't there sufficient ventilation to the cavity via the (rather
in-fitting) floorboards and the carpet on top of them, in the loft
conversion rooms?

The loft conversion must have been done in about 1969.

Cheers
Tom.

Ps. The idea of putting Rockwool behind the vents looks attractive.
It seems surprising that vents manufactured along these lines are not
available...

--
Tom Crane, Dept. Physics, Royal Holloway, University of London, Egham Hill,
Egham, Surrey, TW20 0EX, England.
Email:
Fax: +44 (0) 1784 472794