External Vent

[Dozer.74]

Hi, I'm after some advise. I will be filling a hole in my external wall that was once a vent for the old back boiler.
I'm happy with regards to rendering the exterior and plastering the interior, and not bridging the cavity.
My query is regarding the cavity. It has been filled with insulation, and when I removed a plastic tube from the hole, I can clearly see the insulation in the cavity that was around the plastic tube. Obviously where the tube was, there is no insulation. When I fill the hole, should I put something in the gap, like celotex? Or should I fill the external and internal sides with cement/mortar and leave the gap as is?

 

[^woody^]

Use the same insulation as the rest of the cavity.

At a push for such a small area and if it's fibre, you can stretch some of the existing out to cover the hole.

 

[Dozer.74]

Thanks Woody. It actually looks like grey coloured polystyrene balls, they seem set in place in a circle where the tube was.

 

[endecotp]

Expanding foam?

 

[Dozer.74]

Looking online, looks like something called EPS beads, basically polystyrene beads.

 

[Dozer.74]

I've thought about expanding foam. Should i leave the 'tube' in and fill, then make good the internal and external walls, or remove the tube and fill?