Roof help!

[bigi]

I’m just replacing fascias and soffits on our extension. It was built in 1990 and didn’t get building inspections done during its build - not the same size as plans, or more importantly roof pitch (long story, council doesn’t care now!)
Rafter angle is 15”, and they have used Marley Ludlow major tiles (I know min pitch is 22.5). They appear to have used 25-20mm battens(!) and have a 120mm overlap. The main roof tiles are running at 9” and the last one was about 18” because of resting on a same size batten. To bring this up to the same height, I need a 35” upstand on the fascia, which I can get away with on 250mm fascia and vented trays. But I’m concerned about how shallow the tiles are sitting, and not 100% sure why they are so much shallower than the rafters. I’m suspecting due to the insufficient batten size and overlap, but would appreciate some advice from some experts!
I can’t afford to change the tiles (they are matched to the main house tiles as well), but if I need to replace the battens then I’ll do that while I’m doing this job as I’m fitting a new dry verge as well, so could stretch to a dry ridge was well if I pulled them off too.

The batten spacing is around 260mm (eaves one was 230 but I’ve removed that to install trays and will support tile on new full fascia).

 

[ree]

OP,
I'm not sure how to help you but:
If you post the span and your proposed rise it might help?
The Marley site will give you complete fixing specifications for Ludlow major tiles eg. it suggests using 38mm x 25mm battens.

 

[noseall]

I’m just replacing fascias and soffits on our extension. It was built in 1990 and didn’t get building inspections done during its build - not the same size as plans, or more importantly roof pitch (long story, council doesn’t care now!)
Rafter angle is 15”, and they have used Marley Ludlow major tiles (I know min pitch is 22.5). They appear to have used 25-20mm battens(!) and have a 120mm overlap. The main roof tiles are running at 9” and the last one was about 18” because of resting on a same size batten. To bring this up to the same height, I need a 35” upstand on the fascia, which I can get away with on 250mm fascia and vented trays. But I’m concerned about how shallow the tiles are sitting, and not 100% sure why they are so much shallower than the rafters. I’m suspecting due to the insufficient batten size and overlap, but would appreciate some advice from some experts!
I can’t afford to change the tiles (they are matched to the main house tiles as well), but if I need to replace the battens then I’ll do that while I’m doing this job as I’m fitting a new dry verge as well, so could stretch to a dry ridge was well if I pulled them off too.

The batten spacing is around 260mm (eaves one was 230 but I’ve removed that to install trays and will support tile on new full fascia).

Your post terminology is confusing and it isn't clear what's going on with the roof...?

If the roof is 15 degrees, and you are stripping the roof, then it should be furnished with say smooth Marley 'Mendips' tiles and 100mm head-lap on say 25mm x 50mm battens. Not sure how a 15 degree pitch roof can have the tiles running shallower than the rafters..? Has the roof been counter-battened?

We stripped and binned an entire lean-to roof in the summer because it was slightly under-pitched and the the roof tiles were not suitable for the pitch. I would not take the risk.

 

[^woody^]

If the roof was not a problem and leaking due to the lap for the past 35 years, there's no reason why it should be a problem if the tiles are refitted.

You may need to replace the felt/membrane if replacing the battens.

There is a recent thread about shallow angles at the eaves.

 

[stevie888]

I did building regs drawings many years ago for a friend-of-the client-architect's approved planning drawings. They were a joke but the planners didn't realise or didn't care and had passed them, so I'm faced with a 15deg roof pitch and plain tiles needing 35 deg to work.

After a chat with BC we adopted a composite roof with ply covered with 2 layers of built up felt then counterbattens, battens and tiles. The thinking waqs that the function of the cap sheet of felt to protect the others was provided by the tiles and the felt was ample to keep out any driving rain that got through the tile. All looked good. worked and everyone happy.

In your case if things are marginal and have workedso far then perhaps a doubling up of the felt would be enough.

 

[bigi]

Sorry if my post doesn’t make sense!

I’m replacing the rotten wooden fascias and soffits on the roof of an extension which was built in 1990. It had planning permission but they never inspected it during build; I have the plans and the initial plan was for a larger extension with a roof at 30 degree pitch.
I’ve pulled the tiles back and the pitch of the roof frame is 15 degrees, but the tiles are at an angle of 9 degrees and I’m not sure why the difference between them. The battens used are actually 20mm(d)x25mm(w) which I believe are too shallow, so not sure if that’s part of the problem?

I’m not planning on stripping the entire roof as funds don’t stretch to new tiles at the moment. Felt is reasonably ok, I’m fitting vented support trays so will be trimmed back anyway.

I’ve checked the req’s for Marley Ludlow major and the min angle is 22.5 degrees, so it’s way out of spec. It doesn’t appear to of leaked (except at the wall meeting the main house, I think because they felt has dropped and isn’t supported) the tiles are running with a 120mm headlap, and most of the battens are at 300mm spacing.

My question is why is there a 6 degree angle difference between the tile and roof frame/rafter pitch? Would changing the battens to, say 25x38 help at all?

Thanks for the replies and hopefully this makes a bit more sense!

 

[noseall]

My question is why is there a 6 degree angle difference between the tile and roof frame/rafter pitch? Would changing the battens to, say 25x38 help at all?

No.

Incidentally, the reason I was so fussy about our job was that it fell under BC scrutiny, had new Velux's fitted and became my responsibility. As Woody has said, if you have had no issues then carry on.

 

[catlad]

My question is why is there a 6 degree angle difference between the tile and roof frame/rafter pitch?

My guess! its the kick of the fascia board.

 

[danfre]

If I understand you correctly, the difference between the roof angle and tile is because the tile bottom is resting on top of the tile below it,

 

[datarebal]

The tiles will read a different pitch to the roof ..
Ppretty logical really . And irrelevant.
The rafter pitch is what you should be interested in .
Putting different batten size won't help .
Post above is correct if I understand your post.