Can You Install Tyvek Over DensGlass? (Helpful Guide)

DensGlass has had a track record of being the best sheathing product for over three decades. This fiberglass mat gypsum sheathing is structurally stable, durable, and fire-resistant.

DensGlass sheathing performs exceptionally well as the foundation for other building materials and promotes insulation.

However, some property owners crave better protection against air and moisture. That’s why they may consider installing house wraps such as Tyvek over DensGlass.

If you happen to be one of these people, the guide below will address whether Tyvek should be used over DensGlass and whether there are any benefits one may get from using these two products together.

Most people use Tyvek over wood frame sheathing because this material quickly absorbs water. However, that’s not the only substrate Tyvek can be installed over. Tyvek can also be installed over DensGlass and act as an air and moisture barrier.

With Tyvek over DensGlass, you will be guaranteed that no moisture will pass through the seams and penetrate the interior of the building.

Before I share with you a quick guide on installing Tyvek over DensGlass, let’s look at more benefits of using these products together.

Tyvek
“Tyvek” by Paul, Flickr is licensed under CC BY-SA 2.0

What are the Benefits of Using Tyvek Over DensGlass?

When you install DuPont’s house wrap, Tyvek, over DensGlass, you get the following benefits;

• Tyvek Stops Air Movement through DensGlass

When you install Tyvek over DensGlass, it acts as an additional air barrier. By limiting air movement through your walls, Tyvek allows DensGlass to perform closer to its R-value, thus improving insulation and energy efficiency.

• Tyvek Adds More Moisture-Resistance Capabilities to DensGlass

On its own, DensGlass is water resistant. However, it can only withstand moisture exposure for only 12 months.

When you add Tyvek home wrap over DensGlass, you significantly improve its moisture resistance capabilities. This benefit, however, appeals more to people who live in areas where it rains frequently and excessively.

• Tyvek Allows DensGlass to Breathe

Sheathing needs to breathe, whether made from fiberglass gypsum or wood. Most people assume that just because DensGlass doesn’t let water pass through, it doesn’t need to breathe.

When this happens, moisture will accumulate over the gypsum sheathing and weaken. To avoid that, you can cover it with some breathable Tyvek.

• Tyvek Protects Workers from the Fiberglass in DensGlass

From the description provided by the manufacturer, DensGlass sheathing is a fiberglass gypsum mat. Fiberglass, even though it’s a useful building material, it does have some side effects when it’s touched or inhaled.

To ensure the fiberglass in the DensGlass doesn’t escape into the air, you can wrap it with some Tyvek.

How to Install Tyvek Over DensGlass?

Step 1 – Gather Essential Tools

To install Tyvek over DensGlass, you only need a few things: some Tyvek, a stapler, contractor’s tape, and a pair of scissors. You may also recruit the help of another person. That should speed up the installation process.

Step 2 – Unfold the Tyvek on a Piece of DensGlass Sheathing

Tyvek often comes rolled in bundles. Unroll one piece of the Tyvek and ensure it stretches to the bottom. You may even want to use excess Tyvek on the bottom.

Step 3 – Start Stapling the Tyvek on to the DensGlass

This should be pretty easy. Using your staple gun of choice, staple the Tyvek in place. Start with the edges and work your way all through to the end.

Step 4 – Overlap Joining Pieces of Tyvek

Because you will need to join several pieces of Tyvek, it’s a good idea to overlap them for maximum efficiency. You must tape the seams if you decide to merge them without an overlap. That’s the only way you are assured of keeping moisture away from the DensGlass sheathing.

The most recommended method of installation is overlapping the pieces of Tyvek. The overlap should be ideally six to ten inches.

Step 5 – Tape the Seams

Even when you overlap the Tyvek, there will be some seams. These seams should be taped to ensure the project is 100% covered.

DuPont also sells a special Tyvek tape. This should be bought when you are purchasing the Tyvek. Tape all seams and proceed to the last step.

Step 6 – Cut Out the Doors and Windows

A mistake most people usually make is to cut the window and door openings amidst installation. This should be the last thing to do after installing the Tyvek over DensGlass.

Once the entire DensGlass sheathing is covered in house wrap, cut a big X on the windows. Fold each part on the inside, attaching the edges with staples and tape.

For the door, cut a capital ‘i’. Go on with some tape and staples to ensure it fits firmly. Then you will be done with your installation of Tyvek over DensGlass.

Now that you know Tyvek can be used over DensGlass and the benefits you may get let’s dig a little deeper into these two products.

DensGlass

Should Tyvek Be Placed Under or Over DensGlass Sheathing?

Tyvek house wrap is mainly used over DensGlass sheathing. That’s the only way you can enjoy all the benefits I shared with you earlier. However, not all scenarios are the same. You may also be interested in using it under DensGlass.

When Tyvek is installed on the interior side or under DensGlass sheathing, some of the benefits you may get is that Tyvek will be an air barrier. It will allow the DensGlass to breathe, thus expelling moisture.

It will also keep the workers away from fiberglass contamination. You can forget about water protection which is usually the main reason people install house wraps.

Do You Need to Tape DensGlass If You are Going to Use Tyvek?

Let’s assume that you are installing DensGlass and then Tyvek immediately after. In such a scenario, there is no need for you to tape the DensGlass. Most people tape DensGlass if it’s the only air barrier they use.

However, in this case, you have Tyvek, an excellent air barrier. When installed, it will prevent air from passing through the sheathing, and your property will be adequately protected.

Another thing, most tapes don’t often last very long when used over DensGlass. It’s best to delegate the air barrier duties to Tyvek because its tape adheres firmly and for longer.

What Other Air and Water Barriers Can Be Used Over DensGlass?

From the above guide, it’s clear that DensGlass is an ideal substrate for Tyvek. But aren’t there any other air or water barriers you can use over this sheathing? There are a couple, which include;

DensGlass also adheres well to liquid vapor barriers such as Grace Perm-A-Barrier and TremCo ExoAir.

Synthetic wraps like MetroWrap.

Asphalt coatings or Asphalt felt.

Water drainage membranes like DELTA-DRY.

Self-adhering membranes.

If you want to explore these alternatives, you should know they are compatible with DensGlass.

Does DensGlass Need a Vapor Barrier Like Tyvek?

Considering DensGlass is also water-resistant, you may wonder why it needs another vapor barrier like Tyvek. The answer is pretty simple.

When you use Tyvek and DensGlass, you create a double vapor barrier. If you live in an area that experiences high humidity or rain, two vapor barriers are more effective in protecting your building from water damage and mold.

Even though DensGlass sheathing can be used independently, adding another vapor barrier gives you peace of mind knowing that you are 100% protected from moisture damage.

Don’t forget that DensGlass can also withstand moisture exposure for only 12 months. From there, it will be defenseless.

Will Tyvek Cause Mold When Installed Over DensGlass?

On the contrary, Tyvek will keep mold completely at bay when used over DensGlass. By preventing moisture from passing through and allowing the sheathing to breathe, no water will be trapped in between. So no mold will grow over it.

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