Leaking roof - best sealant to use between clay tile joints/gaps?

[LikeMyHome]

Dear forum members,

Our flat roof above car port attached to bungalow developed a leak - 1l/hour in heavy rain.
The part of the car port ceiling where it drips - is below clay tiled roof of the house, so water must somehow penetrate beneath the tiles.

What I plan to do is to fill all the gaps/joints between the tiles I can reach standing on the car port roof with a proper sealant and I'm considering three options available at home:
- mortar
- Black Jack All Weather Roof Coating (liquid bitumen with fibres)
- lead flashing tape.

DO you think this will work and what would be the best option? If none of the three - please suggest an alternative?

Looking forward to your help
Thanks a lot

P.S. Photo of the house and car port roofs attached with approximate location of leakage spots encircled in red. All tiles appear intact and the gaps between tiles are small ( 7-8 mm at worst, most are smaller)

 

[blup]

Is the water penetrating from the tiles, or is it leaking from the felt roof covering that you say is under the clay roof at these points?

Blup

 

[LikeMyHome]

Water is dripping from part of the ceiling which is underneath the tiled roof.

 

[JohnD]

.

 

[John D v2.0]

the pitch is very low. the tiles are only a rain screen, not water tight. The underfelt/membrane is the waterproof layer.
it's common that the felt is ponding near the bottom, you can strip a few rows and put some eaves trays to bring th felt back up to a slope. Don't bother trying to seal the tiles, it's impossible as they'll just move in the heat etc and break the seal.

 

[datarebal]

i dont think the tiles are the problem. there is a sprocket at the bottom of the roof giving a shallower pitch. In this case the roofer has compensated by closing the tile gauge... looks around 3.5 -3.75 inches
but, the first course of tiles dont appear to over hang the gutter as they should . i'm inclined to think its water droplets tracking back and missing the gutter at the rear.
pumping mastic isn't the answer here, underlay support trays might just help..... of course assuming there are no problems higher up the tiled roof slope

 

[LikeMyHome]

you can strip a few rows and put some eaves trays to bring th felt back up to a slope.

Thank you for the suggestion that sounds very reasonable. Unfrtunately that is a bit complicated for me as I have no experience, I'd rather pay a good roofer to do it.

Actually the leak has been "fixed" a couple of days ago by a gumtree roofer, but I think he didn't do it well. What he did was:
- Stripped a few bottom rows and put a piece of felt underneath and then replaced the tiles;
- He then sealed the bottom row with some rubber sealant (super powerful stuff as he said) and
- Put two strips of lead splashing tape on the 2nd row (from the bottom)

However, after haven given it a test - pouring half a bucket of water on tiles - the ceiling in the car port was still leaking (less but leaking).

He then put some of the rubber sealant and stuck some lead splashing tape ON THE CEILING (from inside the garage) which I thought was a bad idea. After he has gone, I added 2 more rows of lead splashing tape and also stuck a "Gorilla" tape (black) around the whole patch (see photo attached). But I still feel it's gonna leak - rain next week will show.

To cut the long story short - I will likely need a proper repair like you suggested (with eaves trays). I am based in Nottingham - can you recommend any good roofer?

Thank you

 

[LikeMyHome]

there is a sprocket at the bottom of the roof giving a shallower pitch. In this case the roofer has compensated by closing the tile gauge... looks around 3.5 -3.75 inches

I am not sure where you see a sprocket? The white at the bottom of the tiles is gutters.

the first course of tiles dont appear to over hang the gutter as they should . i'm inclined to think its water droplets tracking back and missing the gutter at the rear.

I think the bottom tile row does overhang the gutter maybe by ~2 cm or so. I will double check tomorrow but my recollection it does.

PLus the thing to bear in mind - this is the ORIGINAL tile roof (1928 built) and no visible change has happened to that roof since we moved in 4 years ago, yet the leak has recently developed. I think the leak source is more subtle than what you assumed. I might be wrong of course, but neither I nor the roofer were able to spot any obvious "tile shifts" or the like.

 

[datarebal]

Firstly, The sprocket I refer to is the change of roof pitch. (angle) at the lower end. Yes I can see the gutter is white. but 2cm over the gutter isn't enough.
probably the original gutter was cast iron I would guess. That being the case it usually sits tight to the fascia with no bracket holding it off the fascia, (depending on original profile)
I didn't assume a major leak at all. I can see its the original clay tile, the section in the picture looks fairly tidy and i doubt the tiling is the cause of the leak .Its been a long wet winter .
The gunk over the tiles sorting the issue is doubtful.

good luck

 

[LikeMyHome]

There was moderate rain this night for couple of hours - no sign of leakage. So what I'm thinking is that tiling itself isn't a problem, but in heavy rain when gutters get over flown excessive water rushes above the tiles and penetrates beneath them which creates leak. Does this make sense?

Looks like we need a roofer to fit in eaves trays and maybe and bigger piece of felt extending over a few rows. If any other suggestions please let me know.

Thanks

 

[blup]

Things are not always what they seem, and drip back of water from the gutter under the tiles seems the most likely cause, likewise the suggested solution of a gutter tray. Even though that was not apparent to your gumtree roofer, armed with this knowledge you are likely to get a more focussed opinion, and price, from a professional roofer, if you're lucky enough to find one who will do a relatively small job.

Incidentally, does the sloping roof have a felt underlay/membrane at present, apart from the one you had added to the bottom few rows (?).

Blup

 

[LikeMyHome]

Even though that was not apparent to your gumtree roofer, armed with this knowledge you are likely to get a more focussed opinion, and price, from a professional roofer, if you're lucky enough to find one who will do a relatively small job. Blup

There are quite a few that claim "no small job is too small", and all 3 from gumtree I contacted - replied, so I will find one no doubt, the question is still trust/quality, however.

Incidentally, does the sloping roof have a felt underlay/membrane at present, apart from the one you had added to the bottom few rows (?). Blup

I don't know for sure, but leak#2 above the transparent roof (see red circle) was fixed by our builder 4 years ago by fitting in a piece of felt underneath the tiles. Aslo the last roofer said something negative - like felt wasn't there (under leak #1) or was (heavily) deteriorated so he fitted a piece of felt too.

A question that I still have - do all the tile roofs have a layer of felt and membrane under the tiles? The house is quite old (1928), so I wonder if they didn't lay a felt at that time at all?

Another interesting (to me) observation is that there are TWO layers of tiles on our roof - the bottom layer has "middle" of tile underneath gap/joint of two adjacent tiles in the top layer. SO water that penetrates the joints in top layer drops onto tile surface underneath (bottom layer) and is carried down towards gutter by gravity (i.e. should not flow side ways, as this is against Nature/physical laws). So my question is - wouldn't this double-layer construction be waterproof even without any felt or membrane?? Please comment.

Thanks

 

[blup]

The reverse of no job is too small, is that many or most are too big. The small ad guys provide an important service particularly to the elderly or disabled who can't get a builder out, or are unable do it themselves; but there are obviously "cowboys".

The number of laps will mirror the batten spacing so as standard on clay tiles there is a double overlap like this:

Not aware of felt on 1928 roof structures but the pro roofers on the site will advise (I am a DIYER).

You can check both the above quite simply by going into the loft.

In theory tiles alone protected the roof from rain but in practice there is ingress of moisture as well as dust and dirt, because tiles can move or not be fixed correctly in the first place. The felt is a second layer of protection. I doubt the rain that penetrates in the way you describe will have caused that damp, but again you can look in the roof space

Blup

 

[John D v2.0]

blup has covered most of it pretty comprehensively, I'm also a diyer but here's mine:

should not flow side ways, as this is against Nature/physical laws

not correct, the reason tiles have a minimum pitch is because of wind blowing the water uphill, plus capillary action drawing it up through the gaps.
If you look at old tiles being stripped off a roof, you can see the water staining all sorts of ways it shouldn't.
The minimum pitch of those tiles, if it had one specified, would be quite steep. Any subsequent additions (the flat roof) and the aging process would make things steadily worse. Even changes in wind direction would worsen things.

wouldn't this double-layer construction be waterproof even without any felt or membrane

No, old houses worked by absorbing water more slowly than they evaporated it, in general. The original loft would be very well ventilated, so any slight ingress wouldn't be an issue. Modern houses work by directing water away from the structure reliably, and being more sealed and windtight..

 

[LikeMyHome]

All clear guys, thank you very much for your explanations and input to the discussion!