Anyone mounted a Ubbink UB48 MVHR vent from above?

[Alan Ambrose]

… and made it an airtight seal with the roof. This guy:

 

https://www.ubbink.com/gb/products/building/roof-terminals/pitched-roof-terminals/roof-terminal-insulated-ub48-180mm-black/

 

Best idea we have is to cut the pipe, install in the roof, and then use a SC200 rubber pipe connector to join the stuff above - assuming we can get to it.

[MikeSharp01]

Nope but I am going to - in the near future. So I can perhaps share the journey. Let's hope we can get advice. 

 

In our case we don't yet have the slates on so that I am hopeful that will simplify things.

 

[JohnMo]

Why don't you use ubbink foam duct? Ubbink website states

 

Designed to fit Aerfoam 160 mm & 200 mm, with adaptors available for 150 mm and 180 mm

[Nickfromwales]

3 hours ago, Alan Ambrose said:

… and made it an airtight seal with the roof

Eh? You mean weathertight? 

[Alan Ambrose]

>>> Why don't you use ubbink foam duct?

 

I am, this drops into 180mm foam duct.

 

>>> You mean weathertight? 

 

I am mainly concerned about the airtightness of the ply box that is the roof (that has the foam duct running within) - there’s a membrane and a metal roof to go on top.

 

The main problem is logistical - I’ll take a few pics when I’m up there. Ubbink (who are not good designers imo and have clearly never installed their own products in anger) seem to assume the whole contraption pokes through into an attic where it can be joined to the duct afterwards. (Although how it would be sealed, I can’t imagine.) I have the duct in place and a hole in the right place in the ply and want to install from above. Unlike some Ubbink roof terminals, this one doesn’t seem to be designed to be installed sequentially from above. If the cowling could be installed last following the 2nd sleeve that would work. But that’s not how it’s designed.

[JohnMo]

3 minutes ago, Alan Ambrose said:

am, this drops into 180mm foam duct

Use ubbink joints then.

 

5 minutes ago, Alan Ambrose said:

mainly concerned about the airtightness of the ply box that is the roof (that has the foam duct running within)

Suspect the terminal is designed to go through roof from a cold loft that is outside the airtight envelope. If your doing some different you may have chosen the wrong product.

[Alan Ambrose]

>>> you may have chosen the wrong product.

 

Possibly, I think that’s the only Ubbink choice for the flow I need. But … I’ve found elsewhere that the Ubbink range doesn’t appear to have had a lot of thought behind it. Will see if I can cobble together a hack.

[Gus Potter]

On 20/03/2026 at 17:11, Alan Ambrose said:

and made it an airtight seal with the roof.

If you have corrugated steel profile roof sheeting something like this may be more suitable for the weathering detail.

 

 

Your air tight layer is further into the depth of the roof. The issue is sequencing of the build process. Weather proof steel sheeting is probably going to go on first before you start to introduce plasterboard and air tight layers. You probably need a second flashing to pipe gizmo that you can bond to your air tight layer. 

 

Your air tight layer is usually a plastic membrane so we need something that you can use to bond the plastic to the soil pipe. Remember that soil pipes expand and contract a bit when you empty the bath warm water for example, thus we need something flexible. Can we just rely on air tape or do you want something more " professional" looking.  Like this: