new extension recurring roof leak

[SpecialK]

What isn't 17.5? His roof pitch? Would it cause a leak like this... I guess the membrane would run the water down and out, probably end up with rotten battens eventually?

They are 49s and it's not 17.5

 

[Celeronmanuk]

They are 49s and it's not 17.5

I thought redland 49s in smooth were 17.5 too? Assumes 100m headlap though.

https://redland.co.uk/settings/resources/files/documents/redland49_product-datasheet0.pdf

 

[datarebal]

I am saying the roof isn't 17.5 degrees.

You can not rely on the underlay keeping the water out, it'll fail before the batten.

I still say verge...

 

[Celeronmanuk]

They are 49s and it's not 17.5

The OP said it's about 18 degrees and it doesn't look less than that to me. You're the roofer though, so I'll take your word.

 

[masamune]

What tiles are they? Redland 49?

Hard to tell from the pictures - Are there cavity trays in the walls above the roofline when there are openings below? Does the staining line up with your existing wall cavity?

Thank you. Can you make this in layman's terms please?

I am no roofer, although by the time this is over I may need to turn into one

 

[masamune]

I am saying the roof isn't 17.5 degrees.

You can not rely on the underlay keeping the water out, it'll fail before the batten.

I still say verge...

It's an interesting theory to test, I have thought the same so perhaps I should cover that area.

The only lame thought is that should the pitch or headlap not be right, then we should be having spots of ingress in lots more places at the roof. There has been none in 3 years, only this darn part with the two roof types marrying up.

I can take some measurements if for sake of precision to determine pitch/headlap etc helps?

I am no roofer, although the ones I have had so far do not appear to be either...

The question is who is responsible to get this sorted now, as I keep forking out money and it does not get fixed?

 

[datarebal]

The OP said it's about 18 degrees and it doesn't look less than that to me. You're the roofer though, so I'll take your word.

I am and it's not.

 

[datarebal]

It's an interesting theory to test, I have thought the same so perhaps I should cover that area.

The only lame thought is that should the pitch or headlap not be right, then we should be having spots of ingress in lots more places at the roof. There has been none in 3 years, only this darn part with the two roof types marrying up.

I can take some measurements if for sake of precision to determine pitch/headlap etc helps?

I am no roofer, although the ones I have had so far do not appear to be either...

The question is who is responsible to get this sorted now, as I keep forking out money and it does not get fixed?

As I said before, test the verge simply tuck some plastic under the top apron flashing continued down to the flat roof covering all the mortar and under cloak.
See what happens . If it makes no difference then destructive investigation called for.

 

[masamune]

Thanks, it sounds like a plan and relatively straightforward to test.

I don't mean to stir up any arguments against the trade here but I want some views as to where I stand with roofer who undertook the latest grp works?

Since they did not address the leak and have not returned so far?

 

[catlad]

Those tiles look stretched to me.

 

[SpecialK]

When you are inside and look up at the water staining - Does it line up with you existing house cavity wall? Could the water be coming down your main roof and into the house cavity and down to the extension ceiling?

Thank you. Can you make this in layman's terms please?

I am no roofer, although by the time this is over I may need to turn into one

 

[Celeronmanuk]

It's an interesting theory to test, I have thought the same so perhaps I should cover that area.

The only lame thought is that should the pitch or headlap not be right, then we should be having spots of ingress in lots more places at the roof. There has been none in 3 years, only this darn part with the two roof types marrying up.

I can take some measurements if for sake of precision to determine pitch/headlap etc helps?

I am no roofer, although the ones I have had so far do not appear to be either...

The question is who is responsible to get this sorted now, as I keep forking out money and it does not get fixed?

FYI, the pitch is the rafter pitch, not that of the tiles. If the ceiling is vaulted you can measure that.

 

[masamune]

When you are inside and look up at the water staining - Does it line up with you existing house cavity wall? Could the water be coming down your main roof and into the house cavity and down to the extension ceiling?

The leak is happening in the middle of the ceiling. There is no connection between the extension roof and the cavity of the wall of the existing house. The extension roof joists/beams rest on joists/structure fixed against the outside leaf of the old house wall. I hope it makes sense.

Funnily enough the 80+ year old roof of the existing house has given no issues whatsoever so far.

Let me know if I got the wrong end on the question.

 

[masamune]

FYI, the pitch is the rafter pitch, not that of the tiles. If the ceiling is vaulted you can measure that.

Thanks!

Taking the above into account and assuming the vaulted ceiling plasterboard is fixed to the rafter above, I have taken a rise measurement of ~41cm and a length of ~130cm. Adding that to a pythogorean calculator gave me approx. 17.5° Allowing for some error then, the roof is borderline under-pitched.

*the figure under "c" was in the calculator by default, not taken into account for calcs above. It results automatically to rafter length of 136cm which I also measured on actual and is about right.

 

[Celeronmanuk]

Thanks!

Taking the above into account and assuming the vaulted ceiling plasterboard is fixed to the rafter above, I have taken a rise measurement of ~41cm and a length of ~130cm. Adding that to a pythogorean calculator gave me approx. 17.5° Allowing for some error then, the roof is borderline under-pitched.

*the figure under "c" was in the calculator by default, not taken into account for calcs above. It results automatically to rafter length of 136cm which I also measured on actual and is about right.

View attachment 210923

17.5 degrees is the minimum pitch of your tiles provided the headlap is 100mm.