The critical role of wall upturns with parapet walls is sometimes underestimated when it comes to commercial roof durability, weather resistance and other performance factors. The risk of leaks and water damage can be reduced by properly designing and carefully installing the vertical barrier where the roof meets walls or parapets. Read on to find out why the construction of effective upturns is so important in preventing roof failures.
What are wall upturn details?
Wall upturn details are vital whenever there is a transition between a vertical wall and a horizontal roof surface. A wall upturn could be at a knee wall between two roof levels. They can also abut a stairwell, a mechanical penthouse or be part of the roof parapet. Wall upturns are a critical aspect of risk reduction in many roofs. There are, of course, different options when designing roof and wall terminations, including:
- a full upturn up and over the parapet wall,
- a partial upturn to a recommended minimum 8” (200mm) above the top of roof membrane, and
- a drip edge detail with no upturn
The method chosen will determine the type of drainage system to be utilized.
Correctly installed wall upturns reduce maintenance issues by preventing common causes of roof damage, including water intrusion. Wall upturns are also a major source of stress on the membrane due to the 90 degree transition in the membrane. The use of cant strip in built up and some SBS modified bitumen roof membrane assemblies reduces the transition from (1) at 90 degrees to (2) transitions at 45 degrees each.
10 elements in evaluating existing roofs for wall upturn solutions
The roofer must understand all the considerations to make the right recommendation to the landlord. Each roofing situation is different. The roofer will evaluate the existing roof, including:
- Roofing system types, such as BUR, SBS modified bitumen or single-ply (TPO, PVC, EPDM)
- Waterproofing and drainage needs
- Integration with the flashing system
- Materials compatibility to prevent bonding issues
- Building design and geometry, including wall height and angle, parapets and vertical walls, and roof slope (if not a flat roof)
- Environmental climate conditions, including rainfall, snow loads, wind resistance, expansion and contraction, and UV exposure
- Compliance with codes and regulations
- Installation complexity, especially for retrofits and repairs
- Aesthetic considerations including possible exterior signage, cornice mouldings, and ACM or EIFS wall systems
- Balancing performance and durability with budget restraints
The combination of such factors will lead to decisions including the best fastening techniques, caulking methods, the need to alter existing construction, adding a metal trim, or removing or cutting down siding.
Common concerns with wall upturns
No two roofing projects are the same. Roofers must find solutions that make the most sense for each situation. Below are some common concerns regarding wall upturns.
Parapet wall height: Different parapet wall heights call for different solutions. For example, a wall higher than four feet may have a section of exposed concrete, masonry or other material. This may call for termination into a reglet joint or the need for overflow scuppers.
Variations in material: Structures may use multiple different surfaces. Upturns may vary within the project if there is some combination of wood, metal, stucco, concrete, masonry, corrugated metal or other materials.
Coverage: The entire top of the parapet must be covered and turned down onto the outside face of the wall.
Regulations: The CRCA (Canadian Roofing Contractors Association) specifies that wall upturns be no less than 8-inches, or 200-millimeters above the top of roof membrane. When upturns are too low, snow drifts are more likely to pile up against the walls and seep into the membrane, causing leaks or other roof failures.
Obstructions: Roofers must identify obstructions within the first 8” (200mm) of a wall upturn to comply with regulations. This may include window and door frames, wall cladding, cellular mounted equipment, electrical cabling, sign boxes, skylights or HVAC equipment. Some equipment may need to be removed or disconnected for a proper upturn detail.
Scope: Roofers must alert landlords if any required or potential items are out of scope, such as replacing/repairing the metal cladding or masonry on a parapet wall.
Project: Wall upturn options for Burloak Marketplace, Oakville
Elite Roofing recently completed a new construction project for the Burloak Marketplace shopping mall in Oakville (3515-3545 Rebecca Street). The project consists of multiple buildings that share similar roof design elements and challenges. One challenge was how to install the vapour barrier membrane and vertical siding inside very high parapet walls. It was also a challenge to waterproof and install metal skirt flashing on the outside vertical surface of the parapet walls. Yet another issue was that different types of surfaces needed to be waterproofed.
We resolved the issues related to the parapets by using a rolling scaffold, allowing us safe access to complete work on these hard-to-reach areas. To deal with the different types of surfaces, we use a variety of products, carefully checking for compatibility and coverage of areas designated for waterproofing.
A reputable, high-quality roofer knows how to meet challenges as they arise, whether it’s extremely high parapet walls or inconsistent surfaces . Experience counts in developing options and determining the right solution to the issues at hand as in this case.
Beware of a roofer who is focused on just getting the job done or not rocking the boat by questioning plans and specifications. At Elite Roofing we look at the long term performance of the roof and will bring forward issues that we feel compromise these criteria. An experienced, reputable, highly skilled roofer should assess the plans and specifications and recommend changes that would reduce the likelihood of future leaks. Keep in mind that this value-add is hard to quantify when looking at contractors’ price comparisons alone.
Use a high-quality roofer for the best solutions
Proper wall upturns are critical to maximize your roof’s longevity while reducing maintenance costs. Hiring a contractor with a reputation for high-quality workmanship who understands your requirements and other factors will help ensure you get the most from your roof.
Trust Elite Roofing for all your commercial, industrial, and multi-residence property roofing needs, backed by our 24/7 emergency service. Contact us today and get The Elite Advantage.
