Leaking shallow pitched tiled roof

[Cobnut]

I could do with some advice/info regarding a problematic roof please…

My mid 18th century cottage has a 1980’s extension, and that part of the roof has a very shallow pitch. I’m not sure of the angle but it’s not steep enough for the tiles to do their job properly according to the roofers who’ve seen it.
The problem I have is that the rain has managed to get under the tiles and has come through the ceiling underneath . This obviously needs fixing but I’ve had 2 FMB approved roofers say different things; one said he could take the tiles off and replace the old felt with more water resistant modern stuff, then replace the tiles. The other said that wouldn’t work and I’d need to treat the extension as though it has a flat roof, which in my opinion would look horrid.

Since the two roofers visited I’ve noticed that when it rains hard some of the water flows over the top of the guttering from the main roof and splashes onto the extension. Could this be the cause of the problem?
I’m now confused about my options as I need a water tight roof, but I want it to be in keeping with the cottage. Help!

Thanks

Cobnut.

 

[biffvernon]

Huh, I've got a steep pitched roof and it has leaked several bucket-fulls today. I hear the gentle tinkle of our new indoor water feature as I write.

 

[Lime]

What is the pitch?

 

[Schoolmarm]

Ooh your problem sounds identical to one we had with a stone roof.

We ended up altering the pitch and having the roof taken off and redone.

We did it by knocking 12 inches off the wall at the bottom of the roof. Huge job, looks good but still having problems. :roll:

 

[andrew gayton]

strip off the roof covering, fix a ply deck, 2 layers of mineral felt, counter battens, battens then the tiles - this provides (almost a) flat roof structure on a pitched roof ('traditional' flat roofing uses 3 layers).... so if the tiles don't do the job, the underlying felt will................. i have done this twice on shallow pitched norfolk cat-slides. works well (be mindful of insulation, interstitial condensation etc) the roof over sounds like it needs the guttering realigned/cleaned.

 

[Anna]

Just to agree with your roofers & Andrew, though I don't know the details of flat roofing:

As I understand it, tiles need a certain minimum pitch to work correctly. If you go below that then you need what is in effect a flat roof underneath those tiles (which are really just decorative on shallow pitches).

 

[andrew gayton]

i have also seen the use of o*duline (lapped over 4 rolls), battens, then roof covering.... saves using plydeck and counterbattens......................... presents an odd eaves detail....... but ok on 'high' roofs.

 

[Cobnut]

Thanks everyone for your replies. I would post a couple of pictures to show what I’m talking about but I can’t, but at a guess I think the pitch is about 15 degrees. Also, there’s grass growing between the tiles which is a little alarming...although on a positive note, it means I have more garden :wink:

 

[Penners]

At that shallow a pitch, I don't believe that just solving the leaking gutter problem above would solve the problem. Remember that wind can also blow rain up underneath shallow-pitched tiles.

Andrew's an expert in such things - I would go with his solution.

 

[andrew gayton]

Pen - steady on, thats another £5 i.o.u ; - ) - Andrew

 

[Nemesis]

Yes - this love/love relationship will have us all talking - although we know you aren't his CO...

 

[andrew gayton]

i know where he lives; so i bet he wishes i was. hee hee.

 

[Penners]

Thinks - how to answer that without putting my foot in something, somewhere.

I would be delighted if you were my CO, Andrew, although I have no complaints whatsoever about my current one. He's been extremely helpful to me with guidance and advice.

Thinks - phew, I think I got away with it.




PS: Actually, I'm telling the truth!

 

[NT]

Some types of tile are rated for shallower roofs than 15 degrees, some arent.

Fixing the overflowing gutter would improve the situation, whether that alone is enough only you'll find out.

Removing the moss might help the between-tile spaces drain freer.

NT

 

[NT]

If you do sark under the tiles, fibre cement sheet would last better than felt.

That was not a sarky comment

 

[chuckey]

With roof tiles there is this magic parameter called "headlap", the amount the tiles on course 1 overlaps course 3 (from the fixing hole). As the pitch comes down, the amount of headlap increases. As a cheap start I would search on the web on tiling documents appertaining to your sort of tile to see what the head lap should be. This should be your guide as to what to do next, but at 15 degrees it looks too shallow for most tiles.

If the head lap is OK then the fault is somewhere else if its too small, but your slope has a quoted head lap. Strip the roof re-felt and batten it to get the correct or greater headlap. At this time it would be a good idea to put in eave ventillation etc.
Frank

 

[wasiyku]

We have a similar problem with a shallow roof on the porch of our property, which is a C17th listed cottage with an extension added in the 1990s. The cottage is a real hotch potch of materials with old brick on one side, and stone on the other and pebbledash render on the extension. Sounds awful but it has got quite a charm to it!

There is currently a leaky corrugated roof on the porch, apparently containing asbestos. We would like to replace this but have been told the roof is too shallow for tiles - other than very modern ones that would not be in keeping with the original plain tiles.

One roofer has suggested a that a leaded roof would be most in keeping with the house. This might be expensive but would hopefully be long-lasting. I find it hard to imagine what this would look like but it probably would be preferable to the wrong tiles or more corrugated stuff. Any thoughts?

 

[Penners]

wasiyku - if you could post a picture of the porch, I think this would help.

 

[wasiyku]

http://emma594.fotopic.net/c1314641.html
[/img]

 

[Penners]

Have you actually measured the pitch on the porch?

It's not easy to see in the picture, but it does look a bit shallow for peg tiles to match the rest of the roof (by the way, you have a slipped one on your lean-to extension!).

But what about slates or pantiles? I believe you can comfortably use slates down to around 25 deg., but pantiles can go even shallower than that.

Alternatively, there appears to be some free wall above the porch roof. You could rebuild the roof structure at an increased pitch, at not much cost.

You'd need LBC, though.

That's an interesting gable detail on the end of your neighbour's thatched roof, which oversails your own roof. Presumably it's designed to give added protection to the joint between your roof and their gable wall?