Velux flashings for standing seam zinc roof

[Benpointer]

I thought I'd post this lesson I've learned, and disaster (hopefully) narrowly avoided, in case it helps anyone else.  Also, some of you may be able to clarify the mysterious world of Velux flashings in a way I can understand.

 

 

We are having three SK06 triple-glazed Veluxes fitted in our standing seam zinc roof - indeed they are already fitted.  When I ordered them, my local builders merchant (Sydenhams) offered a price as good as I could get on-line, so I went with them.  I explicitly requested flashings for a standing seam zinc roof but I could not work from the very poor Velux website what the Velux code for those flashings is, so I left it for Sydenhams to liaise with Velux (mistake no. 1).

 

The windows were ordered and I was told I needed EDW flashings at £112 each (wrong).  

 

Wessex Metal Roofing visited the site on 14th July for a pre-installation check and their rep Graham straightaway said, they're the wrong flashings, and that we needed ZWC flashings.  So I called Sydenhams who took the flashings back and credited me.  They then liaised further with Velux but this time Velux suggested the EDE flashing kit, claiming not to recognise 'ZWC'.  The EDE kits are an eye-watering £588 each, and also on a 22 day lead time.  

 

Worried about the lead-time, I failed to challenge this new code (mistake 2) and the order went in.  

 

Meanwhile the windows had arrived, been fitted, and the zinc roof put in place... crucially with soldered zinc upstands around the Veluxes.

 

Being that way inclined, I spent some time trying to understand the EDE installation process.  Not that Velux's website was any help.  Download the installation guide for your product it says, but EDE is not to be found... https://resources.velux.co.uk/technical-resources/flashings-installation-products-guides 

 

Eventually I did manage to track down a copy via an online supplier site (can't remember which).  It soon became clear that the EDE flashing kit needs to be fitted before the roofing but our zinc was already on 😱.  Roofers were unfazed: "don't worry the flashings just clip on". 

 

Eventually it dawned on me that I should have stuck to my guns and insisted the ZWC flashings (just £43 each, so £545 cheaper than the EDEs!)  Sydenhams were pretty good again, cancelled the still not delivered EDWs, and suggested I'd do best to get the ZWCs online.  Which I did.  

 

They arrived at 4:30pm on Friday, just after the roofers had left for the week.  I am praying that on Monday, "they just clip on"...

 

My conclusion is the EDE is a full flashing for a metal roof that is not going to have custom-made zinc upstands , whereas the ZWC is what you need if you have a custom-made metal upstands... but I honestly can't be sure.  

 

Here's hoping that Monday brings good news, and my flashing worries are over!  

 

Meanwhile, I would just like to say that the Velux website and online support is utterly *****!

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[Benpointer]

To belatedly close this off: Monday did bring good news; the ZWC flashing kits fitted perfectly over the windows and the zinc upstands.  

 

We are going to add a Velux BBX vapour collar to each window on the inside but because of the confusion we neither bought nor installed BDX insulation collars.  So, between the window and the zinc roof upstands is a gap which looks to be between 10-15mm all the way round.  

 

It's water tight because of the ZWC flashings and the vapour collar will make it airtight.  Most of the gap (80mm) is above the insulated envelope of the roof and we'll be fitting PIR around the reveals below the Veluxes before fixing the vapour barrier but...

 

It feels wrong to leave those gaps empty.  Should we just fill them with expanding foam? Or try to squeeze something squishy like a thin layer of rockwall into the gap?  

 

Any ideas?

 

Thanks