Airtightness of large opening of back boiler piping

Yellow_Fern

Hi,

I am doing a project lifting floor boards upstairs in a 1980s house to improve its airtightness by sealing joist ends with paint, airtightness tape and orcon. There is a back boiler and its piping exits the wall and runs through the floor void. See pic. I want to seal this, to stop draughts entering the floor void but not sure how as its an enormous gap. Any tips? Maybe cement is the only option?

IMG_20240830_193621.jpg

10-10-20

The concerning issue there is the twin and earth, it needs to be put into trunking and then the hole can be filled with a variety of fillers.

Use what you have is probably wisest, but you have a choice of using 1 to 4 mortar, an airtight expanding foam or something like bonding coat, or even just a premixed large hole filler.

Yellow_Fern

https://www.boards.ie/discussion/comment/122564725#Comment_122564725

Interesting. It is very deep void. I am thinking 15 cm high so not sure how I will build up the hole. I presume, its very cavernous on the other side and plunges down to the fire place below. I will ask an electrician to do something about that cable trunking. I wondered about it, is it ok to have a cable running in a black boiler duct? I lit a fire in the house fireplace just to test if that duct gets warm during fires and it does. I felt a real mix of hot and cold draughts,

10-10-20

Maybe the wire is already trunked on the vertical section, hard to tell from the photo. I'd investigate it more if it was me and then try do a tidy-up. It might be one for a blast of expanding foam initially, then backfilled with mortar.

Calahonda52

show what it looks like from other side.

is it a cavity wall?

sleeve the cable as you cant let foam near it

DC999

https://www.boards.ie/discussion/comment/122597195#Comment_122597195

Dumb question - what do you sleeve the cable with? I'm guessing the foam must affect the rubber insulation of you're saying not to let the foam at it. Will a sleeve not also suffer?

10-10-20

PVC cable trunking. Cheap as chips. And no, it's non reactive to the foam.

Calahonda52

https://www.boards.ie/discussion/comment/122599103#Comment_122599103

In part the possibility of reaction, the other is that cables are designed to be air cooled when under load, this space is already warm/hot so important to keep cable air-cooled.

I use a flexible conduit which is split longitudinally and fitted over the cable and taped with good tape to keep it closed