On 24/11/2016 13:23, Chris J Dixon wrote:
There seems to be a move to retro-fit plastic dry verges these
days, with plenty of firms touting for business.

My cement tiled roof is due for some attention, and I don't do
aerial clambering.

Are they a good idea? What are they screwed into?

What sort of prices are reasonable? I am in a semi, but next door
is lower, so I effectively have two gable ends.

Unusually for me, I was curious enough to allow a caller at my
door to give me a price, which started at £550, then dropped by
£100. I've just had a flyer for another outfit (devoid of street
address) which would be £298.

What dodges do the unscrupulous use, about which I should be
wary?

They're screwed into the ends of the roofing battens.

We've had anthracite (colour) cement tiles (look like thick slates) on
the extention and the plastic dry-verge of the same colour looks spot-on.

The best thing about them is where cloaked(?) tiles aren't available
which they weren't for our tiles is they get rid of the need to have the
tiles mortar-fixed but.... as a retro-fit item on an old roof, the
mortar-fixed perimeter concrete tiles won't be nail-fixed as I believe
is the requirement for current roofing standards so I'd be wary of the
fact that
a) Your tiles won't be drilled for nail (mechanical fixing)
b) They'll be removing the only form of secure tile fixing on the
leading edge of the tiles.

Yes the dry-verge should prevent the wind from catching the tiles and
ripping the whole lot off but I'd want more than a bit of plastic and 1
screw doing this job especially in a windy location.

The following might help:
klober.co.uk/media/uploads/56fd46cb14bbf.pdf