ᐅ LAS pipe (exhaust pipe for gas boiler) installed externally – how to decouple it from the masonry?
Created on: 22 May 2026 18:28
N
naliainHello professionals,
I would appreciate some practical tips.
We want to install a simple gas boiler in our weekend house. Until now, heating has only been done with a fireplace. A heat pump doesn’t really make sense for this house, either financially or functionally.
My question concerns the LAS pipe. It should pass through the wall and be attached to the exterior facade. Since I am quite sensitive to structure-borne noise and buzzing sounds, I want to avoid vibrations being transmitted into the masonry through the LAS pipe as much as possible.
Of course, I will pay attention to rubber-coated pipe clamps. However, I’m uncertain about the wall penetration itself: What is the best way to route the pipe there to prevent the formation of a sound bridge?
As far as I understand, the pipe should not be rigidly set in mortar. Instead, I often read about using a sleeve pipe or an elastically sealed annular gap. I would be interested to know how this is implemented in practice and which materials are commonly used for this, such as mineral wool, Sylomer, or fireproof silicone.
One more question: If the LAS pipe has an outer diameter of 10cm (5 inches), what diameter should the core drill hole ideally have to leave enough space for decoupling?
Thanks a lot in advance!
Ralf
I would appreciate some practical tips.
We want to install a simple gas boiler in our weekend house. Until now, heating has only been done with a fireplace. A heat pump doesn’t really make sense for this house, either financially or functionally.
My question concerns the LAS pipe. It should pass through the wall and be attached to the exterior facade. Since I am quite sensitive to structure-borne noise and buzzing sounds, I want to avoid vibrations being transmitted into the masonry through the LAS pipe as much as possible.
Of course, I will pay attention to rubber-coated pipe clamps. However, I’m uncertain about the wall penetration itself: What is the best way to route the pipe there to prevent the formation of a sound bridge?
As far as I understand, the pipe should not be rigidly set in mortar. Instead, I often read about using a sleeve pipe or an elastically sealed annular gap. I would be interested to know how this is implemented in practice and which materials are commonly used for this, such as mineral wool, Sylomer, or fireproof silicone.
One more question: If the LAS pipe has an outer diameter of 10cm (5 inches), what diameter should the core drill hole ideally have to leave enough space for decoupling?
Thanks a lot in advance!
Ralf