Business tools custom-built for our industry

Say 'so long' to generic business software. Houzz Pro is designed for industry professionals like you.


MLV on inside of exterior walls, good or bad??

Joe Mon
January 9, 2020
last modified: January 9, 2020

Hello, I am trying to find an answer to a recent home “improvement” that I made. I own a brick veneer home near Baltimore MD that was built in the early 60’s

I recently gutted a bedroom that had backed fiberglass insulation and wood paneling. i discovered that I have black fiber board sheathing. Everything looked great when I replaced the insulation with rock wool. I noticed that someone put a hole in the sheathing when installing an outlet box and covered it with felt paper. I don’t know if the house is wrapped in felt paper or they just covered the hole.

Before installing rockwool, I caulked all the joints and sealed all gaps and openings around windows. I even wrapped the outlet boxes with fire retardant putty. I then covered the rockwool with sheets of MLV using roofing nails and taping all seams. I then applied one layer of 3/8” drywall and caulked all joints. I then used green glue and installed a second layer of 3/8” drywall, making sure to overlap joints and I caulked around all outlet boxes.

My concern is that I may develop mold or rot within the wall because of the MLV sheets. I am planning to update another room soon and don’t want to make the same mistake.

Comments (14)

Need help with an existing Houzz order? Call 1-800-368-4268