For my house, do I need a vapor barrier with Havelock Wool?Updated 2 months ago

Vapor Barrier? No.

Vapor Open Air Barrier? Yes!

Short Answer: We recommend a vapor variable barrier with Havelock Wool. ou should not use a traditional vapor barrier, defined as impermeable. (Always check local building code too.) 

Some details : 

A vapor barrier limits the movement of water vapor through walls. Different materials allow varying amounts of moisture to pass. For example, about a third of a quart of water can diffuse through an 8’ x 4’ section of drywall in a heating season, vapor barriers help prevent this.

What is a vapor variable barrier?

Moisture will inevitably enter walls, and trapping it can lead to mold and mildew. Traditional vapor barriers prevent moisture from passing through, but if moisture gets trapped, it can cause damage. Modern building science favors a vapor-open approach, which allows walls to dry inward, outward, or both.

 Here is one we recommend.

Where do I put a Vapor Variable Barrier?

A vapor variable barrier is typically installed on the interior side of your wall assembly—between the drywall and the insulation. This type of barrier adapts to changing humidity conditions: it slows vapor movement in winter to keep walls dry, and allows drying in summer when humidity levels rise.

In most climates, placing the vapor variable barrier on the warm-in-winter side of the insulation is ideal. This allows your wool insulation to naturally regulate moisture while the barrier provides seasonal control—helping your wall system stay both dry and breathable throughout the year.