Creating/enclosing boiler room Q

Alan

This is somewhat related to my previous thread on combustion air.

I have most of the details worked out in enclosing our boiler and providing the proper combustion air source.
Well, while staring at the boiler piping I didnt' consider what to do with the existing runs of supply and return pipes that will need to protrude through the parition wall that is to be built.
In order for the outside combustion air venting to work properly, the passage for the pipes would need to be sealed fairly well.

In new construction this detail would be worked out in advance - I would like some feedback on how this is handled on retrofits.
I'm guessing build around the pipes and then do the final sealing with some sort of heat resistant foam or soft material that is fitted around the pipes ?

Thanks,

Alan