New Roof and Valleys Not Pointed

philng

Just had a new Roof installed which has a number of Valleys. These have not been pointed with Mortar down to the lead from the tile. I am reading mixed messages online whether they should or shouldn't be pointed.

The roofer says he hasn't pointed valleys for a number of years so I'm wondering what stops the water from the valley getting under the tiles?

twopenny

Interesting question - my neighbour has just had an extension and it was one thing I noticed (I'm hoping to know when they've finished !)

The tiles haven't been pointed on the extension. I'm surprised as I thought he would at least do it to match the rest of the bungalow.

tacpot12

It's what is called a Dry Valley. This video shows you the valley tray and how it is installed: https://youtu.be/F2qHuNiHjDc?si=t7z4uzT1U_FoNIiu

It's gravity and the raised portion of the valley tray that stops the water flowing under tiles. 

rob7475

Dry systems are becoming more common now. We've just had our ridge tiles replaced as part of a dormer conversion. Our builders who I've known for years usually use "traditional" methods but they've gone with a dry ridge system on our roof as they think it's a better way to do the job and there's less maintenance.

philng

These are the pics just doesn't look right to me? Roofer has offered to come back and point the ridge area but is adamant the valleys don't need pointing?

HHarry

That doesn’t look like a dry valley so I’d expect it to be pointed.  However it probably would be Ok - I’ve only just pointed up my new valleys after nearly a year.  No signs of water ingress, in an exposed location.

casper_gutman

This article seems relevant:
Navigating the valleys: A focus on pitched roof valley construction – Total Contractor Magazine (total-contractor.co.uk)

The author makes the point that mortar is typically not used on a slate roof, and the practice in Scotland is not to use any mortar even on a clay or concrete single lap tiled roof. Any mortar should have no role in keeping water out. This is the job of the upstand and welt on the lead.

I'd personally find it reassuring that your roofer is confident the roof will keep water out without mortar. The example of "an extreme example of a poorly constructed valley" in that article does have mortar, and might well have looked okay to the untrained eye before the tiles were stripped off. 

If you do insist on your roofer adding mortar then note the guidance given:
"Mortar must be laid onto an undercloak of slate or fibre-cement board rather than be bedded directly onto the lead, otherwise the mortar will crack and dislodge as the lead expands and contracts" and "The mortar must not block tile interlocks".

It also says that the mortar "should be bedded and pointed up in one operation or be pointed up as soon as possible afterwards to ensure the bedding and pointing mortar set as one piece", but I suppose the ship's sailed on that one!