Warning: that "energy efficient" attic insulation might be hiding a mold problem

I found out last week that R-49 blown fiberglass can trap moisture against your roof deck if you don't have proper ridge venting. Read a study from Building Science Corp that said 60% of attics with thick insulation and poor airflow develop hidden mold within 2 years. Anyone else had their roofer mention this when adding insulation?

2 comments

2 Comments

abbychen28d ago

60% in just two years? thats wild.

james_butler28d ago

Had the same problem with blown in cellulose after a reno. Ended up having to tear out the new insulation and install proper baffles at the eaves before putting anything back. Also switched to rigid foam board against the roof deck with a closed cell spray foam seal around the edges. Its been 3 years now and no mold issues even with heavy snow loads up here. That ridge vent plus soffit vents combo is critical though, learned that the hard way.