Owens Corning web site says to use duct tape to repair torn insulation
facing. FWIW, after discussion here on NG, I wrote to them and received this
reply:

"Thank you for your interest in Owens Corning. We recommend a waterproof
builder tape. We manufacture the following product available at your
local building supply.

BILD-R-TAPE (Construction Tape) is a multi-purpose construction tape
assembled using an acrylic based, pressure-sensitive adhesive combined
with polypropylene film. Bild-R-Tape provides superior sealing, and
ease of handling which are the characteristics of a high quality
construction tape. Bild-R-Tape exhibits superior bonding to a range
building products over a broad temperature ranges. Bild-R-Tape is
formulated to resist mildew and mold growth. It is also designed to
maintain its adhesive properties under high humidity conditions to
provide a long lasting seal or closure.



PRODUCT USES:

Owens Corning's Bild-R-Tape is designed and engineered primarily for
seaming and sealing of joints in foam insulation and other sheathing
materials, to secure lap edges in house wraps and vapor barriers, and to
repair rips and tears in faced insulation, construction films and
membranes."

Bob