How to get airtight seal around services?

[Novice]

What is the best method/product to get an airtight seal around the services coming in and out of an airtight building? These include water pipes and electrical ducts entering through the slab in a 110mm pipe, with one containing 3 x 32mm water pipes (rainwater harvesting). I have also got to seal around the flow/return pipe on the ASHP, these are in a ducts that pass through the wall.

Your ideas will be gratefully received, thanks.

[Crofter]

One neat way is to use a silicone rubber flashing from the likes of Dektite (other brands are available).

[Onoff]

Although I'm as far from airtight as its possible to get I was worried about maybe stagnant smells or even gas coming in via the 63mm duct I ran my 25mm water pipe in. I forced some 22mm pipe insulation down there (a metre), pushed it into the duct by a couple of inches and topped off with Wiska Magic Gel. I reckon you could, in a larger duct with multiple services, squirt some expanding foam in followed by gel when dry.

 

 

 

[Jeremy Harris]

I sealed our ducts up this way:

 

First poke a ball of expanded metal down as a rodent barrier.

 

Next shove a plastic bag round the cables/pipes, deep into the duct, with the open end upwards.

 

Finally, squirt expanding foam deep inside the plastic bag, trim the top flat and add a bit of airtightness tape for good measure. 

 

This sealed things up very well, and also had the advantage that it could be undone.  I needed to pull the length of 25mm² SWA further into the building, when I decided to relocate the CU upstairs, and found that it was easy enough to pull the foam-filled plastic bag out of the duct, because the foam hadn't been able to adhere to the cable or duct.

[gravelld]

There are special purpose grommets made like http://www.ecomerchant.co.uk/walls/airtightness-products/service-grommets.html

 

Any good?

[Novice]

Thank you for your responses, I will go with the JSH option.