Low pitch on new roof

[Onions1066]

Hi I'm new here, I'm not a roofer but I am doing a loft conversation at home and really need some help. I had the structure built by a joiner who informed me the pitch was 20 degrees, so I invested it some Marley eternit tiles which go down to that pitch. I fitted the tiles myself All finished looks good. No signs of leaks and we have had some pretty severe weather. Now to the problem, another friend of mine came round and said the pitch looked low and measured it and it actually 16 degrees . Will I get away with this there aren't any leaks I have laps of 110mm tripled up top and bottom rows and all fitted with the copper disc rivets to hold them down, this has really worried me as I have invested all my money in this and really can't afford to rip it off. Any help would be really appreciated. Thanks steve

Just to add I live in midlands so no severe weather really and the tiles are 600 by 300.

And also it is a simple one sided roof no valleys or anything like that

 

[Alastairreid]

Marley eternit smooth go down to 17.5 degrees at 100mm headlap.

i wouldnt lose any sleep over it.

 

[Onions1066]

Thanks for the reply, I don't seem to have sprung any leaks yet.

 

[Alastairreid]

Your,e not likely to as the felt will keep it out....till it perishes

Seriously at that pitch and headlap i would go worry about something else.

 

[Onions1066]

I'll go back to worrying about money instead. Thanks

 

[Roofer]

Marley eternit smooth go down to 17.5 degrees at 100mm headlap.

Minimum pitch for 600x300 slates at 110mm headlap with Moderate Exposure is 20 degrees.

With a pitch 20% less than that I would be concerned if not worried; keep a close watch on it.

 

[Onions1066]

Will do thanks

 

[freddiemercurystwin]

Be sure to let the 'joiner' know he cocked up!

 

[Alastairreid]

Marley eternit tiles

Is it these tiles?

Minimum Pitch:

22.5° Smooth (75mm headlap) / 17.5° Smooth (100mm headlap)

 

[upstairscharly]

If I'm correct the rafter pitch will be steeper than the tile angle due to the tile below slightly raising the bottom of the tile. Tile specifications of minimum pitch are done to the rafter pitch, so the true pitch can only be found out by removing a section of the tiles to get to the rafter & measure that, not the the tile. So may be worth asking what angle was measured.

 

[Onions1066]

Thanks for your help guys this roof is really stressing me out now, it's half 12 and I'm still thinking about it, yes they are the tiles I've done 110mm laps. Yes he cocked up big time but the problem is I'm the one left without a seat when the music stops because I have to live with this not him. Anymore help would be appreciated

 

[Onions1066]

If I'm correct the rafter pitch will be steeper than the tile angle due to the tile below slightly raising the bottom of the tile. Tile specifications of minimum pitch are done to the rafter pitch, so the true pitch can only be found out by removing a section of the tiles to get to the rafter & measure that, not the the tile. So may be worth asking what angle was measured.

And to be fair joiner did measure rafter not tile, roofer has measured tile not rafter. I'm so confused

 

[Roofer]

Marley eternit tiles

I have laps of 110mm

tripled up top and bottom rows

and all fitted with the copper disc rivets to hold them down

and the tiles are 600 by 300.

I think we are pretty safe in assuming they are Eternit slates!

16 degree pitch is not enough and I don't think that measuring the pitch of the slate rather than the pitch of the rafter is going to make too great a difference

 

[upstairscharly]

If you think about it though even if the angle is 2.5 degrees different between rafter and tile measurement its the difference between correct and incorrect, so I think what was measured would make a whole lot of difference. If the tile angle measure 16 degrees its more than likely the rafters (even if not 20 degrees) are above the specifications of 17.5 degrees if they're smooth.

 

[Roofer]

But the correct specification is for 20 degrees minimum

I have scaled it out on paper and the difference between the pitch of the slates and the pitch of the rafters is only about 1 degree (effectively each slate is 8mm higher at its tail than at its head)