New Roof Leaking Water

[vinn]

Your tile gauge should be 100mm approx. - that means a 100mm exposure of the tile and a 165mm cover by the tile above.
Your full tile will be 265mm in length. Tops and eaves tiles are shorter.

Tops tiles typically need a double batten because they are an overcourse.
Eaves tiles sometimes also need a double batten as they are an undercourse.



If you have the top battens wrong you possibly also have the bottom/eaves battens wrong - you possibly have the whole roof batten gauge set out wrong?

 

[vinn]

As above, your chase should be approx. 22mm into the brickwork. Do not go cutting in a higher cover flashing.

There is no need to climb and measure the flashing overlap - it can clearly be seen in photo 1.

 

[vinn]

OP,
why not "get up there with" a camera, and lift the flashing or pull it away from the render, and also show how the top abutment & eaves tiles and battens are arranged?

 

[chappers]

as it's running down the wall it's clearly coming in right at the top can you take a picture of the outside where it is dripping down.
Those look like interlocking concrete tiles so shouldn't need any top courses, though nor should plain tiles if gauged properly. Both should be flashed down according to the manufacturers lap(for single lap tiles) or head-lap for (double lap tiles). I would check the overlap at the joins in the flashing as that looks the most likely

 

[stuart45]

The felt or membrane should go at least 3 inches up the wall on an unvented roof, so this would normally stop any leaks.

 

[Devonish]

as it's running down the wall it's clearly coming in right at the top can you take a picture of the outside where it is dripping down.
Those look like interlocking concrete tiles so shouldn't need any top courses, though nor should plain tiles if gauged properly. Both should be flashed down according to the manufacturers lap(for single lap tiles) or head-lap for (double lap tiles). I would check the overlap at the joins in the flashing as that looks the most likely

Ok, Firstly they are interlocking tiles. I carefully measured out the distance to the internal leak and transferred that to the outside. It falls directly over the lap joint.

I have just been up with a hosepipe and sprayed the wall just above the lap joint, the lead and the tiles. Again water came through. So I guess the issue is at the flashing.

 

[catlad]

If you can lift the lead flashing to expose the one underneath you could fold a small welt on the end of the lead, if thats were the water is coming in then its worth a try.

 

[chappers]

if you flood the lead from right to left is it still coming in. The lead mate looks pretty sound, whioch only really leaves water tracking back under the joint in the lead or through cracks in the render. I would tomorrow do your water thing again and get it leaking then carefully bend the flashing up and see where the highest point it has been leaking in is.
As Catlad suggests you can try rolling the edge back on the lower lead.

 

[Devonish]

if you flood the lead from right to left is it still coming in. The lead mate looks pretty sound, whioch only really leaves water tracking back under the joint in the lead or through cracks in the render. I would tomorrow do your water thing again and get it leaking then carefully bend the flashing up and see where the highest point it has been leaking in is.
As Catlad suggests you can try rolling the edge back on the lower lead.

But if it's getting through the render, the lead can't go in far enough, can it?

 

[vinn]

I was wrong, & stand corrected, in thinking (seeing) plain tile, they are indeed interlocking.
My monitor simply doesn't show clear detail until the screen pixels have "matured" or some digital thing - definitely nowhere near the detail you can somehow see.
But I accept what you say, plus it would be an extraordinary gauge for plain tile

Most all plain tile roofs that I've fixed have had tops and eaves tiles (or slate as the undercourse) - the gauge has always been 100mm as far as i can remember.
Note: I've just checked this with the: Clay Roof Tile Council specs, and they agree.
And FWIW so does John V 2.0's Ref: The lead sheet assn. pic shows double battens and top tile.

 

[chappers]

100mm is about the right gauge which would give you a 65mm head lap. You would use top tiles on a ridged roof where the ridge tiles won't make the head lap.
But on an abutment provided you slightly alter the gauges so that your last course butts nicely to the abutment then your cover flashing forms the head lap and would normally be extended beyond the normal 100mm cover. Most roofers would only use top tiles at an abutment if the gauge would have to be drastically increased above 100mm

 

[chappers]

But if it's getting through the render, the lead can't go in far enough, can it?

no that's why the flashing should be cut in beyond the render into the brickwork

 

[vinn]

I know its 100mm for the gauge because thats what I've always used.
Tops always give the roofer a bit of room to play, and eliminate any possible difficulties even with 150mm of flashing cover.
Abutments dont always come in nice neat lines - they have variations:
tops can usually, easily & neatly, take care of these things.

 

[Devonish]

Well I have left it a few days, we have had some really heavy rain but no leak. Surprised I went up with the hosepipe again and soak the area and no leak.
I have tried soaking the wall, soaking the overlap and where it is chased into the wall. No water is getting through.

I am baffled by this but will keep an eye on it and see if it leaks again.

Thanks for your advice guys.