Help on roofing detail

[Adman101]

Hi,

I am undertaking an extension and currently on the roof. There is a detail which is puzzling me and i would like some advice on how to undertake it properly - not bodging as I would have done!

See the attached photo. The green felt is the existing roof which hasn't got baton on yet. The blue felt with baton is the extension and you can see there is a GRP dry valley which outfalls on to the new roof. There is a small section of wall where the tiles of the new roof end and then the existing roof will flow over the end of this.

I want to know how to join in the valley to the new roof, and how the water is channelled down to the guttering (soaker/gutter??) and whether i need to clad the small bit of wall with lead or some material?

The detail won't be visible so not worried what it will look like but I want it done right.

Any advice would be much appreciated.

Thanks

Adam

 

[noseall]

Lead soakers would be fitted under the (blue felt) tiles and lapped up and under the green felt tiles or behind the short run of fascia should you fit any.
Once you draw level with the valley you need to fit another lead soaker under the valley and onto the (third course) tiles.

You perhaps should have left the valley a wee bit longer. We wouldn't have fitted the valley until we had laid say the first three lower courses of tiles. However, a lead soaker slid under the bottom of the valley will deal with any shortcomings. Just make sure that it is about 150mm up the valley and laps a similar amount onto the tiles.

 

[^woody^]

I can't see it exactly, but it looks like you still have two pitches meeting lower down from the end of that valley, and if so there needs to be a valley there.

Looks like you will need a load of lead. Didn't your plan drawer detail this connection?

 

[Adman101]

Thanks guys. That makes sense. Woody, although it looks like a pitch where the blue meets the green is actually a wall - I will clad this with lead from the soaker to under the tiles. I'll be giving it a go at the weekend so might be on again then!!

 

[noseall]

I can't see it exactly, but it looks like you still have two pitches meeting lower down from the end of that valley, and if so there needs to be a valley there.

Looks like you will need a load of lead. Didn't your plan drawer detail this connection?

I've viewed it as a typical abutment detail and needs treating as such. A bit like where a pitched roof dormer exits a main pitched roof with the blue felt being the main roof and the green felt being the dormer.

 

[freddiemercurystwin]

Bit of an awkward looking junction from the photo, but the angle from where photo has been taken maybe to blame, can you take any more? Can you take a pic from where you'd be if you were in line the guardrail looking perpendicular back at the roof?

 

[Adman101]

Hi,

Just to clarify things a bit. Noseall had it correct when he said it was a dormer type setup. The GRP valley isn't fixed yet so can be moved down someway as i left a big overlap with the upper valley. I have had a go at marking up the attached picture which will hopefully show the situation. the green and blue arrows show the direction of tiles. Just wondering how i should use the lead correctly. i think i need a bit of lead at the end of the valley to make it fall on to the tile ( maybe leave a half tile out on the blue roof so the valley comes out flush with the top of the tile below) then have lead on every tile up the wall to under the tile on the green roof as in detail A shown on the picture. I orginally thought detail B but this would involve cutting baton out and is overkill i think.

Sorry about the crudeness of the picture but i only have Paint.