The vast majority of the questions our building science experts receive from commercial building teams have to do with keeping moisture out of the building envelope. Many of these questions are around key transitions between materials and surfaces of the building, such between the roof and vertical wall.
In any part of the building, from the roof to the foundation, proper shingling of materials is essential. The goal is to craft a drainage system to pull water away from the building. Also, the order in which weather protection materials are installed is absolutely critical in keeping moisture out of the building.
It can all get fairly technical. So, we’ve created a series of new CAD details to help guide building pros through some of the most common problem areas in commercial and multifamily construction.
A CAD (Computer-Aided Design) detail is a precise, digital drawing that provides construction teams with intricate and exact representations of specific elements within a building project. These details are crucial because they ensure that all components, from structural elements to weather resistant barriers, are accurately designed, specified, and implemented. By using CAD details, builders, architects and contractors can avoid costly errors, maintain the integrity of the building envelope, and ensure that materials like TYPAR building wrap and accessories are installed to perform optimally. The new CAD details can be found on our website at typar.com/commercial-strength.
Another important consideration for critical building envelope transitions is the compatibility of the overlapping materials. This is why TYPAR is dedicated to developing and testing accessories that are proven to perform optimally as part of a complete weather protection system. Our new 18” Butyl Flashing and HD Heavy-Duty Sealant are prime examples.
Like all TYPAR Butyl Flashing, our newest 18” offering is designed to peel quickly, stick fast, and keep projects on budget. Compared to rubberized asphalt-based flashings, TYPAR Butyl Flashing simply brings more to the job. It’s pliable in cold weather. It’s stable at high temperatures. Plus it maintains a flexible, but tight seal for far greater durability and long-lasting performance.
The extra width of our 18” Butyl Flashing gives builders and contractors 9” of overlap on either side of a transition, which can help better secure adjacent materials and reduce the chance for water and air infiltration. And because our butyl flashings have been tested for optimal performance when installed alongside our building wraps, we can back up the complete system with the industry’s best lifetime limited warranty.
Similarly, our new HD Heavy-Duty Sealant was developed and tested to form a strong bond with our spun-bonded polypropylene building wraps for optimal system compatibility. It handles and spreads easily, with gunnability down to 40°F (4°C), so project timelines remain unaffected by cold weather conditions. Also, it fully cures within 48-72 hours, with a tack-free time of 60 minutes, further expediting construction timelines.
With that, here are four of the commercial building envelope transitions we get asked about the most:
1. Roof to vertical wall transitions
As stated above, the order in which materials are installed is critical when it comes to roof-to-wall transitions. Does the building wrap go underneath the flashing, or vice versa?
Our CAD detail advises contractors to flash before installing the building wrap. Protect your vertical wall first, then overlap the roof underlayment over the vertical wall. The key is to avoid reverse shingling that could lead to water intrusion.
Our new 18” Butyl Flashing could be particularly useful for these types of transitions. As stated above, the extra width of the product provides 9” of overlap on either side of the transition so there’s less worry about moisture or air intrusion.
2. Balcony beam penetrations
Balcony beam penetrations are pretty common in commercial and multifamily construction and are another type of transition we get a lot of questions about. Again, creating a seamless transition is all about installing your weather protection materials in the right order.
Start by installing your weather resistive barrier under the lower saddle of the beam. Next, the WRB should be installed against the sides of the beam, extending at least 6 in. above and below it.
Now you’re ready to flash around the beam itself. For this, we recommend TYPAR® Flexible Flashing, a high-performance, highly conformable peel-and-stick product that blocks air and moisture intrusion in tricky places. You’ll want to install the flashing first around the bottom half of the beam, then around the top, overlapping the layers by at least 2 in.
The final step is to shingle a top course of the WRB over all, leaving a 1 in. gap above the beam, then tape horizontally with TYPAR® Construction Tape.
3. Window openings
Window openings present one of the biggest opportunities for potential moisture intrusion into the building envelope—and there are often a lot of them in commercial or multifamily buildings! In fact, one of the leading sources of callbacks for national homebuilders is improperly sealed windows.
You can imagine we get a lot of questions about the right way to seal windows, and a lot of them come down to the order in which the flashing should be installed relative to the windows themselves.
The American Architectural Manufacturers Association (AAMA) outlines two possible methods: the “A” method in which flashing is installed after the window is in place; and the “B” method in which the flashing is applied to the rough opening before the window is installed.
While there isn’t a right or wrong approach, it’s important to make sure materials are installed in the proper order for whichever method is being followed. Our Installation Guide includes detailed instructions for sealing and flashing rough openings when following AAMA’s “B” method.
For these applications, cut a piece of TYPAR Flexible Flashing that is 12 in. longer than the length of the rough opening window sill and install it working your way from the center out toward the corners and then up the sides. The flashing should overlap the wall by 2-3 in. If needed, secure the fanned edges of the Flexible Flashing with a plastic-capped nail or staple.
Next, apply at least a 3/8 in. continuous bead of TYPAR® HD Heavy-Duty Sealant to the back of the window or on the wall. It’s important to not apply the sealant across the bottom of the sill or on the bottom of the window, as this area should be left open to allow for proper drainage. Install the window according to the manufacturer’s installation instructions.
After installing the window, apply flashing along both sides of the window, extending 1 in. above the head flange and 1 in. below the sill flange on each side. Make sure to cover the entire window flange and press firmly either by hand or using a J-roller, ensuring there are no wrinkles or bubbles. Finish by applying flashing across the top of the window, extending 1 in. to either side of the jamb flashing.
4. Bottom of wall
The last building envelope transition we get asked about often is where the building wrap terminates at the bottom of the wall. For these transitions between the WRB and the concrete foundation, a metal flashing should first be installed at the base of the wall. Then you can either apply TYPAR 4” Butyl Flashing, which as outlined above maintains strong performance over a broad temperature range; or you can use TYPAR HD Heavy-Duty Sealant to adhere the WRB directly to the concrete.
As you can see from each of these common transitions, proper shingling of each weather protection layer and following the right order of installation are critical for establishing a high-performance building envelope that will keep your building dry for years to come. Failure to follow the proper details creates risk of moisture infiltration, which can lead to major issues later on. But don’t worry—TYPAR has you covered when it comes to detailing the right way to create seamless transitions anywhere on your project. Check out our latest CAD Details here.
