On 22/03/16 18:38, John Rumm wrote:
On 22/03/2016 14:17, Dave wrote:
Two questions or thoughts on this topic which I started.

I have a bungalow and wiuld not be too worried about roof climbing and
don't
need extra long ladders. Would it not be at least a help if I put
ventilation in the two gable ends at oppodite sides of the ridge as I
will
be leaving a couple of feet or so between the ridge board and the
insulation
board which of course leaves a good coupling space between the eaves.
To my
mind ventilation only happens with air flow and opposite side of a
roof will
have different air pressure during any breeze or wind which should drive
some air through even without ridge ventilation. I know that warm
moist air
will rise due to convection and can condense depending on dew point,
but I
think any breezy day would clear stagnant air. How often do we get a
totally
calm set of days in the UK?? I sometimes think building regs are a bit
over
the top and are dreamed up for job creation.

Yup if you have coupled all the rafter gaps to a big space at the top,
then you can just ventilate the big space and do pretty much the same job.

Notwithstanding because my rof timbers are at risk, does anyone know of a
semi-round ridge tile replacement with ventilation built in. I'm sure
I've
seen rooves with the odd ventilator on the ridge and not a continuous
strip.

When I did my loft, we just took off the exiting ridge tiles and then
bedded them back on with some cavity wall weep vents installed under
them at a downwards slant... investigation with a smoke match showed
they worked nicely.

These kind of things:

http://www.builderdepot.co.uk/cavity...erracotta.html





Clever - and much more subtle than tile vents.