old dormer window timber repairs

foy9999 · Post by **foy9999** » Tue Oct 19, 2021 9:33 pm

Hi there

I do roof & gutter repairs but have been asked to make a customers wooden fascias etc look nice again.

I've explained to them a whole lot of work is needed on the wood before any paint brushes come out.

I can see there have been poor repairs in the past to the wood trims above the window

My question is really: is there any set design for the framing around these windows and names for each piece? I don't want to be calling them 'that bit on top of the bit that is nailed to the front' for example.

I'd also like to establish if the newer bits of trim are the same as what would have originally been fitted as it all looks a bit random to me :dunno:

all in black so difficult to differentiate but I see rafters/fascias/sarking but don't know name of 'fascia' inboard of rafters

previous repairs (including blocks at side of rotten front rafter ends)

is right-angled trim above fascia a common addition?

same trim viewed from other side. possibly used to stop edge slates lifting in high winds

big-all · Post by **big-all** » Tue Oct 19, 2021 9:49 pm

the trouble with that idea is the water cannot fall off it has to hit the wood then bounce back toward the building fabric wouldnt surprise me iff its hiding lots off rot behind it cause by it existence ??

foy9999 · Post by **foy9999** » Tue Oct 19, 2021 10:12 pm

Yes I would agree. Even on normal slate roof edge I don't like the wooden trims that are used. Theoretically they shouldn't cause a problem as the slates underneath should keep the water out but the seem to trap damp.

I have a barn with no trims on it and the slates have come off over decades (due to wind) but not had any issues after repairs.

I worked on a house which had a modern slate roof and it had these trims on each edge. all rotten as a pear. there was no need for them as the slates were much larger and double-nailed so unlikely to lift in wind anyway

slates at gable can be vulnerable to wind if no wood trim on top

new version of a traditional roof has these trims on all edges

big-all · Post by **big-all** » Tue Oct 19, 2021 10:22 pm

the "L" shaped timbers are greatly different they cover and trap/deflect the water back almost like a wall where as the plastic trim is under the tiles aiding the water on its way causing no resistance no restriction and no diverting water in a direction where any momentum built up coming down the roof will be converted into a spray or flow going exactly where you dont want it :dunno:

foy9999 · Post by **foy9999** » Tue Oct 19, 2021 11:04 pm

The plastic is something different. I just recently added them to my barn - as a workaround - as whoever re-slated the roof, in the 80s, left the sarking and slates short off the masonry then battened-out the gutters by about 2" so there was even more of a gap.

These are actually felt-support trays and I have just used them the bridge gap between last row of slates and the gutters

but yes I see your point. However the fact remains that the wooden strips on top of the slates (on any roof) are not there to deflect water. They are there to hold the slates down and if the slates below are in good order there should be no water ingress.

I only read yesterday tho that air pressure can cause water to go up behind slates if the gaps between slates are very small so it can get a lot more complex than you might think

slates and sarking fall short of masonry

fascias also battened-out from masonry

felt-support trays used as temporary fix to cross gap