Detailing Continuity in Building Enclosure Systems

Integrated products and proper detailing help maintain air, water, and thermal barrier integrity

Sponsored by Huber Engineered Woods and ZIP System® sheathing and tape | By Peter J. Arsenault, FAIA, NCARB, LEED AP

This CE Center article is no longer eligible for receiving credits.

Detailing Solutions

By now, it is clear how important the details of construction are to assure that all barriers are appropriately selected and are indeed continuous throughout a building enclosure. This means that each area identified in an envelope review must be thought through and shown on the final construction drawings. Those details need to be straightforward to construct in the field to allow for proper installation that can produce the intended continuity and high performance to meet code or green building standards.

With all of the above in mind, then, we will look at some of the more common conditions in a wood-framed building envelope. The following details, shown roughly in the general order of construction, are meant to literally illustrate the points discussed throughout this course and include a discussion of the thought process and rationale for each. All are based on the use of integrated sheathing and compatible components to achieve full continuity for high-performance buildings. In all cases, the manufacturer’s literature and tested assembly results should be consulted to assure proper performance and use of their products.

DETAIL 1: FOUNDATION TO FRAMED WALL

Foundation walls and wood framing are typically aligned with each other in the same plane. The seam between the wood and foundation construction is a weak point in air and water barrier continuity that needs to be addressed. While sill sealers are common, their effectiveness can vary. Further, flashing is often needed at this joint to assure that water, which finds its way down the face of the sheathing, has a place to safely exit out and away from the wall assembly. A typical detail showing a flashed wood-framed wall on a concrete slab foundation is shown in the above diagram. The image on the bottom left shows a wood-framed floor resting on a CMU foundation wall with the wall sheathing extending past the floor structure down to the top of the CMU in typical fashion. At the wall/foundation joint, metal flashing is installed to direct water away. Using integrated sheathing in this case means that the sheathing surface provides a continuous air and water barrier to the end of the sheathing. By also providing self-adhering tape over the metal flashing (effectively acting as counter flashing), the joint is sealed along the top of the flashing, assuring that water and air do not penetrate along this top flashing edge. Placing sealant under the flashing will further strengthen the seal along this joint. The foundation should then be treated with separate coatings to assure that it meets the criteria for water and air resistance. In this way, all water and air barriers are run up to each other and are indeed continuous.

An alternative is shown in the image on the bottom right using liquid flashing. In this case, the framing is adjusted so that the outer face of the sheathing is aligned with the outer face of the foundation wall. This would allow for continuous insulation to run up from the foundation, continue past the floor framing, and up along the wall, thus creating a truly continuous insulation condition. However, the joint where the wood framing meets the foundation wall still needs attention to be sure that any wayward air or water does not penetrate. In this case, liquid flashing can be applied as a coating across the joint and assure the continuity.

DETAIL 2: FRAMED WALL INTERSECTION WITH CONCRETE/MASONRY

This is an example of a change in materials occurring not in a continuous plane but at intersecting planes. This could occur in any number of circumstances, but the point is that if a framed exterior wall abuts a concrete or masonry exterior wall, then all barriers need to be assured of continuity. The weak point is clearly the point of intersection shown in plan view in the diagram at the left and the image on the top right. The image on the bottom right shows a perspective view of the same condition. If this were two intersecting walls using integrated sheathing, then self-adhering tape along the joint would be a logical and effective solution to assure continuity of the air and water barriers. However, such tape is not designed to work with concrete or CMU, but liquid flashing is. Therefore, once an appropriate control joint and backing rod are determined for this detail, then a continuous layer of liquid flashing can be applied in the corner to completely fill and seal the two adjacent surfaces to each other.

DETAIL 3: MASONRY VENEER

Using masonry veneer over a wood-framed structure is common and offers many appealing benefits. However, it does require attention to the way the masonry and the wood framing and sheathing all work together. A gap or air space is a well-known best practice to use between the back of the masonry and exterior side of the sheathing. This allows any water, moisture, or bulk water that does enter the wall to be stopped and dispersed along the face of the sheathing. That means the sheathing still needs to be specified and shown as fully air and water resistant since the expectation is that it will indeed need to resist both. As the water collects and drains down the face of the sheathing, it needs to collect and have a place to exit the wall. Hence, flashing and weep holes are needed to collect, direct, and expel that water safely. In so doing, the flashing must be installed so it does not compromise the integrity of the barriers either because of fasteners being used or because a joint or seam is caused to remain exposed. Using self-adhering tape along all sheathing joints and seams as discussed for other walls is the first step. Then, locating metal or other flashing as appropriate for the design of the masonry veneer wall needs to be done with an eye toward protecting the integrity of the barriers. Finally, self-adhering tape should be applied across the top of the flashing to assure that no water makes its way behind it and into the wall.

DETAIL 4: WINDOW OPENINGS

Windows, particularly if they are recessed back into the wall assembly, can be considered an anticipated barrier detail in virtually every wood-framed building. Not only are openings like this a breach in the barriers simply by virtue of their presence, they also constitute one of the most likely places for water and air leaks to happen. Part of the issue here is the common practice of defining a rough opening size that is, by definition, slightly larger than the size of the window unit being installed. That means there is a gap around the window that needs to be addressed. Many windows have mounting flanges that surround the windows and are used as the basis to center, level, and hold the window in place. The surrounding flanges then become the exterior point that need to be sealed to assure the continuity of the air and water barriers. Using integrated sheathing and self-adhering tape is one method. The tape can cover the window opening first and be used as pan flashing. Once the window unit is installed with sealant appropriately applied under the sill, then the tape can be applied vertically along the jambs to seal those edges. Finally, the head can be sealed with tape covering the flange and the jamb tape to assure a complete seal.

For windows recessed into a framed wall, a mounting flange is not typically used. In this case, the entire perimeter of the recess needs to be addressed to extend the barriers from the face of the sheathing, into the framing recess, and to the window. Using liquid flashing along all of these areas as shown in the images above helps assure full and continuous sealing. Along the sill and for at least 6 inches up the sides of the jambs, the flashing should extend all the way from the exterior to the interior face of the wall. When ready, then the window should be installed and secured using sealant and appropriate fasteners.

Regardless of the condition on the outside, the interior of the windows needs the final piece of attention. The visible gap between the rough opening and the window unit needs to be filled with a sealant or spray-foam insulation that will complete the continuity between the exterior barriers and the window unit. Otherwise the gap remains and can allow air, water, or moisture to penetrate from either the exterior or interior.

DETAIL 5: WALL TO ROOF INTERSECTION

It is common to have a sloped roof over a lower portion of a building abut a vertical wall of a higher portion of the building. In this case, continuous metal flashing or step flashing is typically used to assure that water draining down the face of the wall does not penetrate the joint between it and the roof but instead flows harmlessly away. That should still be done when integrated sheathing is used, but in addition, the top of the flashing should be covered with a continuous run of self-adhering tape. That will seal the edge along the top of the flashing, as done elsewhere, and can help cover any irregularities in the line of the flashing.

DETAIL 6: PARAPET WALLS

Wood-framed buildings with low-slope roofing systems often use a parapet wall that continues up past the level of the roof and provides the appearance of a “flat roof” on a building. Technically, the parapet portion extends up above the line of the thermal envelope so insulation is often not installed in them. However, if continuous insulation is used, then it should continue to wrap up and around the parapet, extending down to meet the roofing insulation. Further, with or without insulation, the water and air barrier aspects of these walls are still critically needed since they can still be sources of failures and potential damage. The reality is that it is fairly straightforward to assure that these barriers are indeed continuous by simply treating both sides and the top of the parapet wall in a continuous manner. First, the air and water barrier needs to cover the full outside face of the parapet wall, not stop anywhere. At the top, it should extend across the top of the wall (which may only be the thickness of the framing) and back down the interior side to the roof deck. All joints and seams of integrated sheathing used for this purpose over the framing should be taped, just as elsewhere. Then, a sloped top cap can be placed on top of the parapet and the roofing membrane, and/or flashing should also extend up the full face of the interior side of the parapet wall, continue across the top, and lap down over the outside face for at least 12 inches. The exterior cladding or finish material will cover all of this and create the final look, but underneath, all of the barriers remain connected and continuous in this manner.

DETAIL 7: DECKS AND BALCONIES

Once the building is enclosed, then exterior decks or balconies should be looked at as if they are part of the envelope design. The key point of connection here is the ledger board that is typically installed across the face of the exterior wall to support the framing for the deck or balcony. This should only be done after the integrated sheathing is fully installed, taped, and sealed. Then, the ledger board with any joist hangers can be installed using appropriate fasteners. In some cases, those fasteners can be large and can cause significant damage to the water and air barrier, hence they should be treated like a penetration that is predrilled and sealed first. Then, the appropriate connection can be made and sealed again if needed. Once the ledger board is in place, then the joint between it and the wall needs to be addressed to be sure that the barriers remain protected. This is accomplished with metal flashing that extends from the wall and under the decking or above balcony flooring to channel water appropriately away. The top of the flashing should then be covered with a continuous line of tape.

Conclusion

The key to continuity in building enclosure systems is a careful and coordinated approach to consistent detailing. All conditions where the building form changes, where construction materials change, where joints and seams come together, or where penetrations and openings occur need to be thought through and addressed. Integrated sheathing products for wood-framed walls that provide an all-in-one, high-performance, cost-effective wall assembly solution can be a very effective way to help assure continuity of all critical building enclosure barriers. Coordinated tape, sealant, and flashing systems that integrate with other exterior wall products can prove to simplify installation, reduce the chance for construction defects, and mitigate the professional risk to everyone involved. While there are different material and product choices, the goal is the same for all: to create a highly effective and long-lasting solution for truly continuous barriers in a building enclosure.

Peter J. Arsenault, FAIA, NCARB, LEED AP, is a practicing architect, green building consultant, continuing education presenter, and prolific author engaged nationwide in advancing building performance through better design. www.linkedin.com/in/pjaarch

ZIP System^® products are next-generation exterior wall, roof, and sealing solutions. Innovated to meet today’s design and construction challenges, products including ZIP System sheathing tape, ZIP System^™ stretch tape, and ZIP System R-sheathing reduce installation steps and room for error on the job site, while helping to create tight, water-resistant building envelopes. Learn more at InsulateYourBuild.com.

The role of the building enclosure is to provide proper separation between the building interior and the exterior. Beyond the structural enclosure, separation is accomplished through the use of four primary types of barriers: water-resistant barriers (WRBs), air barriers, thermal barriers, and vapor retarders. All of them are intended to restrict or control the passage of a targeted item (water, air, heat, or moisture) through a roof, wall, or foundation system. While this can seem fairly straightforward along flat, continuous surfaces, it is the noncontinuous conditions that present design and construction issues. These can include transitions from one material to another, penetrations, or interruptions caused by planned openings such as windows and doors, or changes in surfaces such as roof/wall junctions or parapets. Proper design and specification details of all of these areas is critical, particularly in wood-framed exterior wall assemblies to reduce the risk of compromising any of the four primary barriers. Understanding the choices and developing complete details as part of construction drawings is the best way to achieve integrity and continuity of the building enclosure barriers to create air-tight, weather-resistant enclosures that promote energy efficiency and long-term durability. This course will look at the continuity issues of the four primary barriers and present a series of drawings and details that can help accomplish these goals.

Green building with construction workers for building enclosures

In order to assure the continuity of the water, air, thermal, and moisture barriers in building enclosures, detailed attention is required at changes in wall and roof surfaces, transitions, and openings.

The Primary Issue: Continuity of Barriers

It’s easy to write the word “continuous” on a construction drawing to describe any barrier in a building envelope, but that is hardly enough to assure that it will be achieved. The reality is that the building envelope and all of its details need to be designed and constructed to assure that all of the barriers are in fact continuous.

A common technique used in the process of commissioning building envelopes (yes, just like commissioning HVAC and other systems) is to look at a building cross section. Then, starting at the foundation level on one side, draw a line upward. At the first change in construction (i.e., an opening, a different construction assembly or material, etc.), draw a circle around it. Then continue on up the wall until the next change and do the same, and so on. When you reach the point where the wall meets the roof, draw a circle around that point too. Then continue along the line of the barriers at the roof level, at whatever pitch, and circle any changes in conditions there too. At the next roof/wall junction, draw a circle there and proceed down the wall in like manner as the other side until you reach the base of the foundation again. Every circle now represents an architectural detail that is needed to show how all of the barriers in the building envelope need to be treated to be fully continuous across each of the conditions encountered. If the building section is not representative of all possible cross sections of the building, (i.e., different sections are different heights, different massing, etc.), then building sections need to be looked at in the same way for those other areas, and the process of circling the details is needed there as well. Cases where there are offsets in walls or roofs or a change in materials used between sections will need attention. It is also important to address all typical and nontypical openings around windows and doors or penetrations for electrical and mechanical systems.

This process of identifying all of these areas for detailing is important to assure that air, water, heat, and moisture don’t end up in places where they aren’t intended. The integrity of each of the barriers is the only way to assure that doesn’t happen. If any one of them become compromised, then the performance of the building enclosure is lessened below what was intended or predicted. In some cases, that may be a minor inconvenience to occupants who experience a slightly uncomfortable draft or cool surface. In other cases, it can lead to a slow deterioration that may go unnoticed from the outside but cause damage within the construction assemblies that shortens the overall service life of the enclosure. Such damage can also compromise the ability of the envelope to remain energy efficient (i.e., wet insulation with reduced R-values or unintended gaps that increase air infiltration), causing an increase in the need for energy to heat or cool the building. In the worst case, it can lead to functional failure of the barrier and/or the construction assembly. That can subsequently domino to damage other areas of the building, including deterioration of the structural system. If water and moisture get trapped around organic material, it can lead to mold and mildew that can have health impacts on the occupants. These outcomes are undesirable on multiple levels: they aren’t good for the building, they aren’t good for the occupants, and they aren’t good for the professional liability of architects.

Hence, with all of the above in mind, let’s first take a closer look at defining each of these barriers and then look at some details to address their continuity.

The Four Barriers of a Building Enclosure

The barriers of a building enclosure are based on good building science and the collective body of knowledge regarding current common construction techniques. This is particularly true in wood-framed construction, which continues to dominate most residential construction and a lot of commercial construction as well. In either case, the requirements for all of them are codified in the family of International Construction Codes adopted in most of the jurisdictions throughout the United States. The science behind the barriers are also each sophisticated enough to warrant specialty organizations that address them in multiple ways. We will look at each one briefly below, but keep in mind that there are many different products and solutions to achieve the performance and requirements cited. Further, as we will discuss, it is entirely possible to select a single product that provides more than one of the barriers, thus streamlining the specification and construction process with the possibility of achieving higher performance overall.

Water-resistive barrier in the green building envelope

The IBC and IRC codes require a water-resistive barrier behind the exterior cladding plus a means for draining water along that barrier back out to the exterior.

Water-Resistant Barriers (WRBs)

The 2015 International Building Code (IBC) is very clear about the need for a WRB to protect the integrity of construction from bulk water (i.e., rain or other precipitation). Chapter 14: Exterior Walls, Section 1403.2 reads: “Weather Protection: Exterior walls shall provide the building with a weather-resistant exterior wall envelope.” Further, it goes on to state here and in Section 1405.4, “The exterior wall envelope shall include flashing…[which] shall be installed in such a manner so as to prevent moisture from entering the wall or to redirect that moisture to the exterior. Flashing shall be installed at the perimeters of exterior door and window assemblies, penetrations and terminations of exterior wall assemblies, exterior wall intersections with roofs, chimneys, porches, decks, balconies, and similar projections, and at built-in gutters and similar locations where moisture could enter the wall.” Clearly, the codes look at all of the same places that envelope commissioning agents do and that architects need to address.

The code doesn’t dictate how the required weather resistance and flashing is designed (that is the role of the architect), but it does require the weather-resistant performance of that wall, specifically with the ability to be water resistant. Given that there are a multitude of choices on the market, it behooves an architect to have a source of information on the performance of the products and the relevant data on how to use them. One such source is the Sealant, Waterproofing and Restoration Institute (SWRI) which is a nonprofit corporation that defines it membership as “the leading commercial contractors, manufacturers, and design professionals of our industry. [The] Institute provides a forum for those engaged in the application, design, and manufacture of sealant, waterproofing, and restoration products that is beneficial to the membership and the industry,” (www.swrionline.org).

One of the programs of SWRI is a product validation program that is designed to give an independent review and validation of the published test results of the various sealant, repellant, and coating products on the market. The stated intent of the program is “to provide specifiers and end users of [these] products an unbiased method to judge whether [these] products will perform at the levels of the manufacturer’s published data sheet for that particular product.” This can be very useful information when choosing a WRB and seeking to know if a particular product will perform as intended when applied to particular substrate surfaces as part of a specific construction condition.

Recognizing that there is more to continuity than just products (i.e., how they are used counts too), there are specialty consultants who focus on building enclosures. A nonprofit association known as RCI describe themselves as “an international association of building envelope consultants. Members specialize in design, investigation, repair, and management of roofing, exterior wall, and waterproofing systems.” These are the professionals who would likely be looking at the building sections and doing envelope commissioning in many cases. Their focus is on the best means to provide WRBs, roofing, and other protective surfaces for the building enclosure.

Working collaboratively to understand products and the way they are used by engaging organizations like those described above will help architects achieve the best set of WRB options for a particular building design. The goal should be to assure that the water resistance of a construction assembly performs as intended (i.e., shedding water or being fully water proof depending on the situation) without compromising or inhibiting the performance of other barriers in the assembly.

Air Barriers

An air infiltration barrier is required, not as part of the International Building or Residential Codes (IBC or IRC), but as part of the International Energy Conservation Code (IECC). It is typically placed along the plane of the exterior sheathing; however, it is worth noting that in a wood-framed wall with a multitude of individual materials and components, air infiltration can be difficult to control. The key to success lies first in the ability of a particular material to be considered a true air barrier. The codes rely on ASTM E2178: Standard Test Method for Air Permeance of Building Materials as the basis for determination. Hence, any individual material (or combination of materials) that can demonstrate compliance with this test showing a very limited air permeance can qualify as an air barrier material (maximum air penetration through a material at four-thousandths of a cubic foot per minute). The second key to the effectiveness of an air barrier is to look beyond the specific material and to its ability to be truly continuous as an entire system. That means any joints, seams, penetrations, or other breaches of the barrier need to be addressed in some manner as part of a total system. The codes then look to other specific tests; in this case, namely ASTM E2357: Standard Test Method for Determining Air Leakage of Air Barrier Assemblies and ASTM E1677: Standard Specification for Air Barrier (AB) Material or System for Low-Rise Framed Building Walls. Compliance is based on testing the entire assembled system, not just the individual materials in this case (maximum air penetration through an assembly at four-hundredths of a cubic foot per minute).

One of the leading sources for researching and testing materials and assemblies for air permeance is the Air Barrier Association of America (ABAA). It is a “national, not-for-profit trade association that consists of a wide cross section of stakeholders in the building enclosure industry. Its membership includes manufacturers, architects, engineers, trade contractors, researchers, testing and audit agencies, consultants, and building owners,” (www.airbarrier.org). Using data and information from this organization can help identify both individual materials and assembled systems that will qualify to properly restrict air flow through a roof or wall. It can also provide information on critical areas to address in those assemblies through its education and certification programs for professionals.

Corner of a building using single-panel sheathing systems with a layer of continuous foam insulation

One way to add R-value to wall assemblies is to use single-panel sheathing systems with a built-in layer of continuous foam insulation integral to the back of the panel.

Thermal Barriers

Code compliance for thermal performance is predictably based on the IECC and begins with identifying the climate zone for a particular building project. The building type (commercial or residential) then comes into play, and the IECC uses charts and tables to identify the minimum performance requirements for the entire building thermal envelope. Following this process, the prescriptive requirements of the IECC point out that, in many climate zones, it is no longer enough to simply provide insulation materials between wood-framing members. This is because the wood framing itself is known to compromise the effectiveness of the insulation. Rather, the code requires many wall and roof assemblies to use continuous insulation (ci) to reduce the effects of “thermal bridges” and help mitigate heat conduction through the wood framing (IECC C402 and R402).

Traditionally, the continuous insulation has been applied to the exterior side of the wall on one side or the other of the sheathing. The intent is to cover all wall framing, floor framing, etc. with a layer of insulation that is continuous around the entire building envelope. In most climate zones where this applies, 1 or 2 inches of rigid insulation (R-5 or R-10) is typically used. It is important to note that making ci truly continuous around the full envelope requires some attention to detail such that the interface of the continuous insulation on the wall meets and seals with the continuous insulation in the roof, floor, or basement.

The amount of ci to use will be based on meeting overall building energy performance targets, either to meet code minimum levels or higher levels called for in voluntary standards, such as LEED or Passive House. Hence, computer-based energy models or similar methods will come into play to determine the predicted performance values needed (R-values or U-factors). How to achieve those levels is based on the type of insulation used and the way it is detailed into a construction assembly. Most commonly, rigid foam insulation of different types is used and needs to be adhered or attached to the sheathing. Combination products that include engineered wood sheathing and rigid sheathing in one product are also available, again simplifying the design, specification, and installation.

Vapor Retarder

The IBC and IRC recognize that water vapor or air-borne moisture is different from bulk water. They also recognize the potential for damage to a wood structure from vapor condensing in an exterior wall and deteriorating construction materials through rot, rust, or mold. Therefore, the IBC and IRC require protection against condensation in the exterior wall assembly and go on to clearly require specific solutions to provide that protection. Although the determination for applicability and type (identified as Class I, II, or III) of the vapor retarder is determined by the IECC climate zones, the requirement for its inclusion remains in the IBC/IRC. In the climate zones where the vapor retarder is required, it is called for on the “interior side of frame walls,” typically meaning on or behind the finished interior surface of the wall.

There is one caveat regarding vapor retarders in that a significant code exception exists in regard to the use of lower permeance Class I and II vapor retarders in the colder climate zones 5, 6, 7, 8, and Marine 4. Specifically, the exception applies if plastic foam continuous insulation is used outside of the studs in these zones since the ci will warm the stud cavity above the typical dew point. That means there is less chance of condensation in the wall cavity so less interior vapor control is required. The amount of ci used that triggers this exception varies based on the climate zone and whether 2-by-4 or 2-by-6 insulated framing is used. If the wall design meets the stated criteria, then a Class III or more permeable vapor retarder is all that is called for.

Choices in Barrier Systems

As with most design and construction systems, there are choices available in how to achieve each of the four building enclosure barriers and assure their continuity on and around a structural framing system. The conventional approach is to use a multi-product, multilayer solution where each of the four barriers is specified and installed as a separate layer in an assembly. This requires specifying multiple products that need to be compatible and performing multiple labor tasks, perhaps by different trades, during construction, all of which need to be coordinated. Further, to be assured that their installed performance will be met, the particular combination of products needs to have been tested to assure they meet all of the water, air, and thermal thresholds required for the assembly. There also needs to be proper detailing between the materials to assure the total system will work as intended.

As an alternative, there are integrated product solutions that have become available, most notably in the form of integrated sheathing. These products typically come in the form of engineered structural wood sheathing that can also provide at least two of the needed barriers with preapplied coatings that qualify as both a WRB and an air barrier. This means that a single, high-performing wood sheathing product can be specified, used as the basis of design, and installed by a single trade in the building. Such integrated sheathing systems rely on factory-created surfaces on the sheathing that can meet both air and water barrier requirements with a higher assurance of performance since they are installed under controlled conditions. In some cases, they can also include a thermal barrier of continuous insulation of differing thickness preapplied to the sheathing and ready to install. Overall, the installation can be simpler and quicker, reducing the amount of labor and skill needed to create an effective end result.

Of course, such integrated sheathing products need to address the joints, penetrations, and openings, just like any other system, to assure continuity and effectiveness. In this case, that is achieved with compatible self-adhering tape, sealants, and even liquid flashing where appropriate.

construction worker using a roll tape system

A complete roll tape system includes everything needed to seal any gaps or seams for both water and air barriers, including along flashing locations.

The beauty of these components is that they allow for a lot of versatility to accommodate the differing site conditions and design variations that may occur. The flexible nature of the sealing tape and liquid flashing is such that they can conform completely to the shape of the substrate surface to seal and protect the surrounding construction in a truly continuous manner by covering the joints and seams between the pieces of sheathing. This allows for the needed structural gapping in the sheathing but assures that the air and water barrier is fully continuous even with minor expansion and contraction of the sheathing panels.

Other conditions of construction need a little more attention. Small bump-outs or recesses in a wall system should be sheathed with the same integrated sheathing as the flat, continuous sections. Then, the tape can be used to cover all of the irregular shapes and edges of the condition to assure full continuity of the barriers. Penetrations should be treated in the same, with the self-adhering tape covering the entire perimeter of the hole or opening and wrapping the edge of the sheathing. Once the reason for the penetration is installed (i.e., pipe, duct, wire, etc.), then a compatible sealant should be used to fill in completely any remaining gaps.

Window and door openings also require attention. It is important that the barriers continue tightly and seal completely against the window and door frames to avoid gaps and breaches in the air and water barriers. It is also critically important that those windows and doors are properly flashed to avoid any water or air seeping in behind the frames and causing damage. Metal head flashing can be used in these cases, or “self-flashing” clad windows may have the flashing already incorporated. Either way, the place where the flashing meets the integrated sheathing should be covered with self-adhering tape too in order to assure full continuity.

Recessed conditions or areas prone to more severe weather may warrant that the full perimeter of the opening is covered and treated with a continuous, flexible, liquid flashing that will cure to protect the opening and assure continuity of the barriers. Then, a compatible sealant can be used to fill any remaining gaps between the sealed rough opening and the window or door frame.

Construction workers filling in liquid-applied flashing

Liquid-applied flashing can be used to seal surfaces completely even in wet or cold conditions.