On 22/03/16 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.

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.

YOu are perfdectly correct. What causes ROT is water that persists for
long enough to get spores established. That's not a soaking from a
shower or a week of winter condensation (dew). Its months of damp that
can't escape.

Almost ANY vent will do.


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