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Hi guys.

I'm in the unfortunate position of trying to source a long-standing leak on a roof which has no visible clues to the source.

Previous roofers slapped a lot of mortar over an awkward area round a soil-stack so I followed their lead and spent a lot of time making that area watertight (removed crumbling mortar/cut tiles to sit flatter/apron to shed water away etc).

Leak persists so went back into loft and found it was much nearer the ridge than the soil-stack.

I took most of the ridge tiles off and a lot of tiles and could find nothing wrong apart from a very large gap between two of the ridge tiles if all the other joints were up tight.

The system is Marley ventilated dry ridge and property is about 40 years old. Tiles interlocking concrete (Marley Double Roman?). Assume original roof.

Did some reading tonight and the PDF advises to fit appropriate ridge filler unit onto head of tile. There is no filler unit on this roof at all and it's very shallow pitch.

Only part of house affected is West-facing roof and apparently prevailing wind in this area (East Kilbride, near Glasgow) is South Westerly or Westerly.

Anyone think the absence of the filler units could be allowing water to be blown into the throughs of the tiles, up to rear face of the plastic batten then dribble back down under the tiles?

Or put it another way. Do many ppl omit the filler units? as 'they're not necessary mate'


Marley ventilated dry ridge battens



some water getting in somewhere



no broken or missing tiles but we have a leak



tiles removed to check for problems

Well I headed off to my local SIG roofing outlet without a sample tile and asked if they had such a thing as ridge filler units for Marley double-roman tiles.

The guy was very helpful and they had then for about £1 each. I bought 3 thinking that would be sufficient to cover the ridge at the area that's leaking.


ridge filler units for Marley double roman

I was a bit worried the things might not fit as I didn't know for sure what the tiles were.

Went to the job today. You guessed it they don't fit. I don't actually think they'd be the cause of the leak anyway as looking closely at the interface today I can see the tiles are hard up against the face of the plastic ridge batten. Having said that they must be necessary or why would they be produced.



Anyway I thin I may have found reason for leak. It's very minor but one column of tiles isn't quite overlapping correctly and it is above the area that's leaking. The tiles can't be jostled back into place so they must've been spaced badly or something so all I could do was flashband down the joint and wait for next spell of rain

NB. I found out the tiles are Marley Bold Roll and it seems they didn't do a ridge filler unit for them or it isn't now available

So. No broken or missing tiles or gaps on dry ridge. Filler units not present but unlikely to be cause of leak in one area when missing from whole roof.

What are we left with?

Well after going in loftspace and measuring from wall to leak-spot then transferring that distance to the outside of the roof (allowing for the eaves and thickness of wall) I find one slightly suspect column of tiles not overlapping their neighbours properly.

They can't be manipulated back into position as they are locked correctly on their other edge.

So it's out with the flashband. I don't like sticking tape on roofs but no other option just now and at least we'll see it it changes the situation


do we have a problem here?



close-up



taped-up

How much water was getting in? Tbh you shouldn’t really be getting any water in if the felt is in good condition. Is the roof properly vented? The felt,counterbatten and tile batten are certainly not 40 years old,I’d hasten a guess at 20 years max. Do you have eaves/soffit vents?
Have you ruled out condensation?

Hi steviejoiner74. Thanks for the reply.

The leaks are bad enough for the owner to have buckets underneath. I've not actually seen them dripping cos not been there when it's been raining heavily but I think it's more than condensation.

I've not looked at eaves and soffits for vents but the leak is bang in the middle of the house and near the ridge so I didn't suspect those items.

Am pretty sure it's the original roof that is on the house and the scheme was built in pre '83. Will ask owner if it's had a new roof but I doubt it