Rain water penetrating verge

[denis0151]

Hi,

I've recently had my facia and soffit boarding replaced with UPVC. As part of the job the mortar verges were replaced with new mortar that had a waterproofing agent added to the mix. I've noticed that on one of the roof sections rain water seems to be penetrating the verge and the water runs down the inside of the verge and collects in the facia box end. It then tends to run down the wall, so not good.

Any thoughts about stopping this? Would a water proofing coating on the verge help?

 

[Mw Roofline]

Are you sure its getting in through the mortared verge? Even without a waterproofer, its pretty well waterproof.

It could be getting in somewhere else, running onto the existing roof felt and dripping off at the end inside the box.

 

[denis0151]

Thanks for your reply. I'm able to recreate the problem by applying a good flow of water from a watering can so that it runs over the edge of the tiles (Redland Cambrian imitation Welsh slate) and onto the verge. After a few minutes drips appear from the box. I can't rule out that water is getting through the tiles at some other point but getting water to spill over onto the verge seems to recreate the problem. Even though the mortar verge is new there are small cracks where it abuts the tiles and the under cloak, which could be providing a path for the water.