ᐅ Ventilation duct insulation for unheated attic

Hello everyone,

What is the best way to insulate the vent pipe system of the bathrooms in the uninsulated area of the roof to prevent condensation?

Do I only need to insulate the section of the soil pipe, or also the flexible duct that connects to the roof tile? In other words, should the insulation cover the entire area from the vapor barrier on the top floor ceiling up to the underlayment, or just from the vapor barrier to the start of the flexible duct?

Thank you very much.

Best regards,

Sky

Hello

I wouldn’t insulate the sewer vent pipe at all.
The warm, moist air inside the pipe will simply condense and drain away along with the wastewater.
There won’t be any condensation on the outside of the pipe.

Olli

According to the contractor, the pipes need to be insulated. My only question is: with what?