ᐅ How to Properly Seal a Vapor Retarder?

Hello!

I have to admit I'm a bit confused after reading various blogs and brochures about insulation. Maybe someone here can help me!

We are currently insulating our semi-detached house. The insulation between the rafters is already installed, and now I am waiting for the vapor barrier to be delivered.

From different sources, I’ve heard that the vapor barrier should always be overlapped and taped from top to bottom, but other sources say exactly the opposite… Does this actually make a difference? Based on the information I have so far, I would start at the gable and then overlap and tape each upper sheet over the lower one.

Also, I’m not completely sure whether to install the insulation below the rafters before or after applying the vapor barrier?!

I would really appreciate an answer!

Thanks in advance!

Hello,

Doppelhaus0815 schrieb:
.. Based on the information I currently have, I would start from the gable and then always overlap and seal the upper membrane over the lower one.

That is correct.

Doppelhaus0815 schrieb:
... Furthermore, I am not quite sure whether to install the insulation below the rafters before or after the vapor barrier?!?

The better solution is always to install the vapor barrier on the inside, after the insulation below the rafters. This means the vapor barrier protects the entire insulation layer.

Best regards.