Flat roof to stone wall sealing

[DavidFrancis]

We have a flat roof which connects to a stone wall as per the attached two images. The felt seems to have been "sealed" into a slot in the wall with mortar. The black sealant dabbed over the mortar was put there by me when there was a leak in some very heavy rain in the summer of 2012. The brown sealant was there when we bought the house (30 months ago). We had a second leak a few weeks ago in heavy rain and this was more to the centre of the wall.

I was thinking of scraping off all the mortar and sealant and "re-sealing" the felt. Would it be better to use mortar again or some sort of flexible sealant. If mortar, what kind of mix and with what additives, if any. If sealant, what kind of sealant?

Thanks for any advice.

PS the wall faces south.

Untitled

• DavidFrancis
• 24 Apr 2014
• 1

Untitled

• DavidFrancis
• 24 Apr 2014
• 1

 

[cotswoldbuilders]

Cut all the joint out, fit lead flashing, then re-point in sand/cement.

The joints to large for sealants.