Recommendation for a SVP flashing for metal roof

[Kelvin]

I need to get my SVP up through my garage metal roof so have been looking at suitable weatherproof flashings. Something like this. Any other suggestions. My intention is to bring it up through the flat bit of the roof rather than the seam bit. Flagged @saveasteading 

 

https://www.drainagesuperstore.co.uk/product/dektite-premium-grey-epdm-100mm-to-200mm-external-pipe-dimensions.html?srsltid=AfmBOopCaz9ldi74y3SGI8z--US8RsMOhq3Md1p-hashII9ajMp5VtYtULA

 

 

[Conor]

Air admittance valve rather than going through the roof.

[Kelvin]

Don’t I still need an SVP somewhere in the plumbing? 

[Conor]

Nope. We've three stacks, all AAVs. No issues. Satisfies BC.

[Kelvin]

We have a treatment plant. Everything I’ve read states you can’t install air admittance valves instead of an SVP. 

Edited March 2 by Kelvin

[saveasteading]

Yes that's the thing. Choose a size that is mid  to high in the range of diameters for each size. The rubber is severely stretched due to the angle.

I've often had to go on the roof to do it properly after bad efforts by roofers or plumbers so ensure care.

 Make sure you use use mastic that is long term flexible.

Cut through the flat of the cladding, not a ridge, or all strength is lost., but also ensure the flashing doesn't fill the whole width of the 'pan'.

Cutting an oval in the cladding isn't fun and needs a recip saw or snips. Or best perhaps hire a nibbler.

 

Any hole in the roof is a compromise. Can you use an aav here and provide end of line venting elsewhere? It is to release blowbacks so could be a pipe off the end of line manhole. Even a manhole cover with holes in it. Away from the house of course.

[JamesP]

Have a look at this thread, similar issue as I did not want to put a hole through the roof.

 

 

[Kelvin]

Thanks for this. Very helpful. Like you I don’t want to vent through the house roof hence why the garage roof was a good compromise. The BCO has already approved this with an AAV in the house.  But I wondered yesterday if I could vent near the treatment plant or if the blower itself would allow venting. Mine is a Graf One2Clean. 
 

ETA Just read the installation manual and unlike the Vortex system it doesn’t specifically say you can spur off inlet or outlet and the install diagram shows a more traditional layout venting out of an SVP in the building. Shall contact Graf and ask them if it can be installed similarly to the Vortex. 
 

 

Edited March 2 by Kelvin

[saveasteading]

Our Marsh digester has a venting pipe socket  off the turret. It definitely works and we are going  to have to extend it to an innocuous position.

But we are still putting in an open vent at end of line.

 

 

[joe90]

7 minutes ago, saveasteading said:

But we are still putting in an open vent at end of line.

I did the same, AAVs in the house but the run extended past to a garage (with a loo) and vent pipe at the end of the run.

[Russell griffiths]

@Kelvin

i have a Graf unit. 
if you look at the riser for the lid of the tank it comes with additional 110mm rubber grommets to put additional pipes in. 
I have a 110mm vent pipe that vents the tank over to a shed and up the back wall of the shed. 

I also have a short external vent pipe on the beginning of the run, as long as there are no windows above it you can use a short stack. 

[Gone West]

3 hours ago, Kelvin said:

We have a treatment plant. Everything I’ve read states you can’t install air admittance valves instead of an SVP. 

We had AAVs in the house and a low level SVP in the flower bed near the treatment plant.