Suspended Floor Air Duct (Vent) through Concrete floor I'm relaying

[mattwaddy]

So I'm about to dig out my solid kitchen floor which has an air duct/pipe going under it and comes out on the external kitchen wall. This is because there is some suspended flooring in the property, and there is also the same duct/airbrick at the front of the property. I've dug out a small core and can see it looks like some sort of cast pipe under the DPM that connects somehow to the external airbrick.

Now I was going to dig out the floor to around 40cm on Saturday, but I'm just wondering how I can deal with this pipe/duct before I redo the floor. At the moment it's under the DPM sunk into the hardcore layer. I'm assuming it would need to be the same again when relaying, so I was thinking of perhaps using the plastic telescopic type to bring it down on the internal wall and up again on the external wall, with the main connecting pipe placed into the hardcore layer before the sand/dpm goes down. Is that going to be feasible, i.e. the telescipic part sitting on the inside of both internal wall and external, or do they need to be recessed? Obviously I want to do it properly to maintain correct airflow and prevent future issues but I've not dealt with something like this previously.

I've seen the following which is pretty much what I was trying to describe

https://www.emerysltd.co.uk/Files/117936/Img/12/timloc-1205-in-use-big.jpg

 

[23vc]

How come you need to move the duct at all? Why are you digging the floor up? Changing the finished level?

 

[mattwaddy]

How come you need to move the duct at all? Why are you digging the floor up? Changing the finished level?

So I'm retrofitting insulation throughout and also putting in wet underfloor heating. In addition I've taken some internal walls out to make a larger kitchen which were at different finished floor levels so needs to be sorted and wanted to max the benefits of ufh with insulation as an overlay would be poor performing and door height would be an issue in this property. It might be the duct can stay depending what it is and how it's supported but I'll need to redo layer of Mot1, sand, dpm, concrete, insulation and screed. I believe the air duct should ideally be under the DPM, but perhaps it could go through the insulation layer maybe

 

[noseall]

. At the moment it's under the DPM sunk into the hardcore layer.

If it's that deep, do you really need to mess with it?

But yes, you are on the right track. Manthorpe sell a range of telescopic vents, reducers connectors etc, that will convert say 110mm plastic drain into the rectangular telescopic section.