Pointing ridge tiles - what sealant to use?

Hi there,

Our house is 100 years old and has a pitched tiled roof. During recent storms we had a leak in a bedroom. About an inch in a bucket all told. I have scaffolded that part of the house and traced the leak to a couple of ridge tiles. The roof seems in excellent condition but the mortar is a bit worn round a few tiles. These tiles are stuck fast. Whilst it might be better to remove them and re lay with mortar that is going to be a devil of a job and, if I break any, they will be hard to replace.

So, I would like to re point. The question is what with? Should I use PVA and mortar. Could I use Jetcem. Equally is there a sillicon type mastic that would do the job?

I am seriously not keen to get a roofer in We are in the Isle of Man and they are scarce and pricey. Last quote as £500 per day . . .

Thanks for any comments.

what makes you think it's the ridge tiles that are at fault?

I played a hose round the roof and the water came in when I pointed it at the ridge tiles. My wife was watching from the room below.

The point is that the leak occurred during a westerly storm; it's rained since but the room has been dry. It all points to rain blowing under the ridge tiles and getting past the mortar.

Thanks for your interest.

ridge tiles dont often leak lots of water into a roof - being the highest point of a roof they have the least amount of water on them - very rare for a missing/broken ridge tile to leak large amounts of water as you suggest. So i would reccomend checking other areas again as well -flashings chipped tiles etc. It can sometimes be difficult to see a broken tile if the break is hidden by the overlap of another tile.

That said if the mortar needs some work then its best to rake out any loose cement and re-point with a 3 to 1 sand cement mix adding a bit of plasticiser to prevent it drying too quickly.

I usually lift and re-bed ridge tiles rather than just 'pointing in' but as long as you rake out the loose bits you should be fine.

Try to avoid pointing a thin layer of new cement over old as it will just peel off after it drys. Thicker the cement the better.