A common question that we receive daily is whether customers can install mass loaded vinyl over existing drywall or CMU partitions. While it is well-publicized that Mass Loaded Vinyl (also called MLV) is best utilized when installed directly on studs, during the initial construction process, this is not possible if a tenant has already moved into the space. When this happens, then you may install MLV directly to the existing wall, but it may be less effective. Read more below to determine if it’s the right option for you.
Why Does MLV perform differently under and over drywall?
This answer is simple. Mass Loaded Vinyl works in 2 ways.
- It adds mass to the wall (hence the name). It generally weighs 1 lb/square foot, and can add a significant amount of overall weight to the wall if installed consistently across the entire space.
- It adds flexibility to the wall. That’s why Mass Loaded Vinyl is so much more effective at blocking sound than simply adding a piece of drywall (which is often-times 2 lbs/sf). The MLV separates the rigid drywall from the rigid studs, and stops sound from transferring directly through the system.
When installed under the drywall, the MLV separates the drywall and stud, which takes full effect of both of its soundproofing properties. However, when installed on top of drywall, the only benefit is the added mass, which can sometimes result in more than a 50% reduction in effectinvess!
What are your options if the wall is already constructed? It is highly recommended that you install a sheet of 1/2″ drywall on top of a layer of 1/8″ thick mass loaded vinyl, so that the top layer may then be decoupled (separated) from the underlying layers. If you do this, it’s also important to remember to add acoustic caulk around the sides of the wall (top, bottom, and sides) so that the finish layer of drywall is not directly touching the adjacent walls.
While still not as ideal as directly installing to the studs, this drywall-MLV-drywall sandwich does make a significant improvement from the initial design.
Do’s & Don’ts of Installing Mass Loaded Vinyl over Drywall
- Consider taking off existing drywall, and installing directly to the studs beneath
- If that’s not possible, you may install Mass Loaded Vinyl on top of existing drywall, and cover with another layer of drywall.
- When installing new drywall layers, ensure that acoustic caulk is used around all sides so that new drywall layers do not contact existing rigid construction elements around the exterior/periphery
- If extremely high STC ratings are needed (60+), consider building a new wall in front of the existing wall, with a 1-2″ air gap between the two.
