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Roof flashing


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3 hours ago, tonyshouse said:

Thanks !

 

10mm in for a porch , I often use 100mm lead 

 

NHBC shows a stepped Flashing going as close as 65mm minimum to the tile line. The first link below shows older NHBC guidance which said 85mm minimum but that seems to now be 65mm. This is all for stepped flashing. I can't find anything for chased in at an angle but some logic (dangerous) dictates:

  • Could be 85mm (or 65mm) measured across the flashing (e.g. 110mm tucked in ~25mm)
  • Could be 150mm measured vertically which on a 45 degree wall is 106mm across the flashing

Normally wouldn't be so fussed and they've used 150mm lead chased in (now). Above the bay window on the front of the house I want it tighter and fancy 100mm across the lead. Does anyone have a copy of the LSTA Complete Guide and able to see if they specify something for straight chased flashings?

 

I know NHBC aren't building regs, but I haven't seen a building reg related to this and the warranty providers must meet or exceed regs (surely).

 

I think a lot of roofers just have 150mm minimum in their head as that works pretty much everywhere. It's 75mm minimum lead upstand at a horizontal pitched roof abutment.

 

image.png.4fac7d896d9f39b9e7f420d3719270ee.png

https://nhbccampaigns.co.uk/landingpages/techzone/previous_versions/2011/Part6/section1/default.htm

image.thumb.png.24f3c79cb020593920707ad81b0374f1.png

image.thumb.png.e39e25a89f9e3d92c0b1d8b7ee92976b.png

image.png.bfd526ba30a1ec9a76123eba9adc1811.png

https://nhbc-standards.co.uk/7-roofs/7-2-pitched-roofs/7-2-20-weathering-details/

 

 

 

image.png.d74e453d866c49cfb99b9e5358f55497.png

https://www.associatedlead.co.uk/wp-content/uploads/2018/06/Guide-to-Rolled-Lead.pdf

Edited by MortarThePoint
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On 21/10/2020 at 15:58, tonyshouse said:

 

sorry but that looks awful. 

 

Should be stepped properly, clipped into the cuts then morter or lead sealent. 

 

No more than 1.2 m lengths as well.

 

DIY bodge job.

Edited by Dave Jones
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27 minutes ago, Dave Jones said:

 

sorry but that looks awful. 

 

Should be stepped properly, clipped into the cuts then morter or lead sealent. 

 

No more than 1.2 m lengths as well.

 

DIY bodge job.

 

Ouch!

 

I presume you are more keen on chasing in lead at an angle if it is to be under render. If so do you have a spec for the thickness of the lead strip? 100mm?

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read the NHBC guidelines on how to do it properly. You should really have a lead saddle on that ridge as well.

 

the upstand is a min 75mm but dependant on the roof pitch and weather its going to take it can be more.

 

https://nhbc-standards.co.uk/7-roofs/7-2-pitched-roofs/7-2-20-weathering-details/

 

also give it a wipe over with patination oil as well.

 

 

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22 hours ago, Dave Jones said:

read the NHBC guidelines on how to do it properly. You should really have a lead saddle on that ridge as well.

 

the upstand is a min 75mm but dependant on the roof pitch and weather its going to take it can be more.

 

https://nhbc-standards.co.uk/7-roofs/7-2-pitched-roofs/7-2-20-weathering-details/

 

also give it a wipe over with patination oil as well.

 

 

 

That page only covers the ridge abutment and stepped flashings though.

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