wooden-roof-solutions

Why Bowstring Roof Trusses Are Ideal for Wide Interior Spaces

Wed, 12 Aug 2026 18:16:00 GMT

The Advantages of Bowstring Roof Trusses

Bowstring roof trusses combine wide, clear spans with efficient structural behavior, and Wooden Roof Solutions uses them to support large interior spaces for our clients. The curved top chord and straight bottom chord work together to move loads into supports without heavy interior framing. This layout keeps floor areas open for equipment, staging, or flexible layouts. In addition, it allows older commercial buildings to use their full interior width with fewer structural changes.

What Are Bowstring Roof Trusses?

Bowstring roof trusses use an arched top chord and a straight bottom chord tied together with web members. This shape creates a strong, shallow curve that carries roof loads across long distances. The design offers a wide-span roof truss layout without requiring interior columns. They also provide a clear framework for reinforcement and inspection in historical buildings.

How These Trusses Create Open Interior Spaces

Bowstring trusses are unique, offering their own advantages and challenges. These trusses provide support for long spans, allowing the roof to extend across a building without stopping at interior supports. The curved top chord gives the roof its slope, while the straight bottom chord acts as a tension tie. This combination allows designers to remove many interior columns that would impede movement or storage. The result is a large span roof structure with open, flexible floor space for changing uses over time.

Benefits of Bowstring Trusses for Large Buildings

The geometry of bowstring trusses supports broad roof areas while keeping member sizes and connections practical. This makes them a good fit for many properties, with advantages such as:

Wide Span Capacity - Bowstring trusses carry loads across long distances. This makes them ideal for hangars, warehouses, and similar facilities that need column-free interior space.
Efficient Load Distribution - The arched top chord shapes how loads move into supports. Balanced forces reduce stress at individual joints and help maintain long-term roof performance.
Flexible Interior Layouts - Open spans allow new equipment, shelving, or tenant layouts without major structural changes. That flexibility makes building reuse and modernization much easier.
Clear Structural Visibility - Exposed trusses make inspection simpler. Visual inspections support planning for wooden truss repairs and early detection of issues in older structures.

Durability, Cost Efficiency, and Long‑Term Strength

Bowstring roof trusses offer durability by distributing loads across the chords and webs rather than concentrating stress at single points. Their shape supports good drainage and reduces excess water buildup, which helps protect wood members and connectors over time. Cost efficiency comes from using smaller, repeated pieces and straightforward connections. These elements can ease the fabrication and installation process compared to heavy framing. In addition, the long‑term strength of these systems enables wide spans for decades when paired with regular inspection and targeted wooden truss repair .

What Are the Best Applications for Bowstring Roof Trusses?

Bowstring roof trusses work best in buildings where wide, clear interiors support daily activity. Their ability to span large distances makes them useful across several common property types:

Warehouses and Distribution Centers - Open floor plans support racking, forklifts, and varied storage layouts. Wide span roof trusses reduce interior columns that could slow movement.
Manufacturing and Industrial Facilities - Equipment lines and overhead systems benefit from clear space. Bowstring trusses allow flexible placement of machinery and service routes.
Sports, Event, and Community Buildings - Arenas, rinks, and gathering halls need large open volumes. Curved roof profiles provide both span and distinctive interior character.
Adaptive Reuse Commercial Spaces - Former industrial buildings converted to offices, retail, or mixed use gain open layouts. Existing bowstring trusses support modern designs with fewer major structural changes.

Why Choose Us?

Bowstring truss projects benefit from partners who focus on structure rather than only surface roofing. Wooden Roof Solutions brings this targeted experience in wooden truss repair. This helps project teams move from inspection to reinforcement with clear, practical guidance. Here’s what sets us apart from the rest:

Dedicated Bowstring Truss Expertise - Truss repair is our primary focus. We can handle wooden truss inspections, design review, and reinforcement for wood bowstring systems in pre-WWII commercial and industrial buildings.
Preservation-Driven Approach - Our methods support structural safety while respecting historic architecture. Careful detailing helps maintain original roof profiles and interior space.
Safety and Compliance Commitment - We exceed OSHA standards and work as a fully licensed and bonded contractor. This protects crews, clients, and properties throughout every phase of the repair process.
Free Visual Inspections - We provide visual inspections at no cost. This early assessment supports clear decisions on wooden truss repair and design improvements.

Secure Wide Interior Spans With Confidence Today

Wooden Roof Solutions supports bowstring roof trusses and wooden truss repair in Oshkosh, Milwaukee , the Chicago area , and throughout the Midwest. Our team helps evaluate wide-span roof trusses, plan reinforcement, and maintain the structural integrity of large interior spaces in historical and active commercial buildings. Call us today for a free visual inspection!

How to Inspect Wood Trusses for Damage Over Time

Thu, 02 Jul 2026 11:36:21 GMT

Maintaining the structural integrity of your property requires a proactive approach to the components that support it. Wood trusses are engineered with precision to distribute weight efficiently across a building’s frame. Environmental factors and the passage of time can compromise these systems. Regular wood truss inspection is essential for identifying minor issues before they escalate into costly repairs or hazardous structural failures. By understanding what to look for, property owners and facility managers can ensure long-term safety and durability. Wooden Roof Solutions offers a guide on how to inspect wood trusses for damage over time. Reach out today.

Understanding How Wood Trusses Behave Over Time

Wood is a natural, hygroscopic material, meaning it absorbs and releases moisture based on its environment. Over several years, trusses undergo natural cycles of expansion and contraction. While modern engineering accounts for some movement, excessive moisture fluctuations can lead to "season checking" or minor splitting. Furthermore, wood trusses are subject to creep, a slow, permanent deformation occurring under a constant load. Monitoring these gradual changes is a critical part of determining how to inspect wood trusses for damage over time.

Common Signs of Wood Truss Damage

Identifying signs of wood truss damage early requires a keen eye for detail. Look for the following issues:

Localized darkening or staining on the timber, which often indicates water infiltration or fungal decay.
Frass, a sawdust-like substance, or small exit holes, as these are primary indicators of wood-boring insect infestations.
Any audible creaking or popping during mild weather conditions may also suggest that the truss members are struggling to manage their intended loads.

Identifying Structural Deformation in Trusses

Identifying structural deformation in trusses involves looking for deviations from the original geometric design. Using a plumb line or a laser level, check for "out-of-plumb" bowing or "lateral discharge," where the truss chords curve sideways. Significant sagging in the bottom chord, the horizontal beam visible from the attic or ceiling, is a clear red flag. Even a deflection of an inch can indicate that the internal stresses of the truss have exceeded their design limits, potentially leading to a roof collapse risk from truss damage.

Truss Joint and Connector Plate Inspection

The strength of a truss system is only as good as its connections. During a truss joint and connector plate inspection, focus on the galvanized steel gusset plates that hold the members together. Look for signs of corrosion, backing out, or teeth that have sheared off entirely. If there is a gap greater than 1/32 of an inch between the plate and the wood surface, the structural capacity of that joint is officially compromised and requires immediate reinforcement.

Step-by-Step Wood Truss Inspection Process

Our experts can help you inspect your wood truss. Follow these steps:

Safety First – Ensure the area is well-lit and you have a stable ladder or catwalk. Wear protective gear, including a mask and eye protection.
Visual Alignment – Stand at one end of the attic and sight along the peaks and bottom chords to check for straightness.
Check the Plates – Inspect every junction where wood members meet, looking for loose or rusted metal plates.
Moisture Assessment – Use a moisture meter to check for dampness in the wood, especially near roof penetrations like chimneys or vents.
Document Findings – Take clear photographs and notes of any splits, cracks, or "notching" that appear to have been done after the original installation.

When to Call a Professional for Truss Damage Inspection

While a preliminary walkthrough is helpful, a formal truss damage inspection should be performed by a licensed structural engineer if you find significant anomalies. If you observe broken webbing, severe crushing at the bearing points, or if the building has recently survived a major weather event like a hurricane or heavy snow load, professional intervention is non-negotiable. Wooden Roof Solutions can provide a sealed repair specification that restores the truss to its original design strength.

Preventive Maintenance and Long-Term Safety

The best way to prevent truss failure is to control the attic environment. Ensure adequate ventilation to prevent heat and moisture buildup, which can accelerate wood rot and plate corrosion. Avoid using truss members for storage unless they were specifically designed for attic loads. Hanging heavy equipment or stacking boxes on the bottom chords can cause unintended deflection and structural fatigue.

Contact Wooden Roof Solutions

Wooden Roof Solutions provides comprehensive truss roof repairs and reinforcement services throughout the Midwest, including Oshkosh and Milwaukee, WI and Geneva, Glenview , La Grange , Evanston , and Arlington Heights, IL . Wood trusses are the silent backbone of your structure, but they are not invincible. Regular monitoring and timely repairs are the only ways to guarantee the safety of the occupants beneath them. If you have concerns about the stability of your roof system or have identified any of the warning signs mentioned above, do not delay. Contact our team of structural experts today for a professional wood truss evaluation.

Frequently Asked Questions

Can I Repair a Broken Wood Truss Myself?

No. Trusses are engineered components. Any repair, such as scabbing or sistering a joint, must be designed by a professional engineer to ensure the load-path remains intact.

How Often Should I Perform a Wood Truss Inspection?

We recommend conducting a visual inspection at least once a year, preferably in the fall before heavy snow loads or in the spring after peak storm seasons.

Does a Small Crack in the Wood Mean the Truss Is Failing?

Not necessarily. Small surface cracks are often cosmetic. Any crack that travels through the thickness of the wood or occurs near a connector plate should be evaluated by a professional.

Why Cutting or Drilling Wood Trusses Is Dangerous

Tue, 30 Jun 2026 11:29:08 GMT

When managing a construction or renovation project, the temptation to make space for HVAC ducts, plumbing lines, or electrical wiring by notching or drilling into wooden components is common. These minor adjustments can lead to catastrophic results when dealing with engineered wood trusses. Unlike traditional rafter framing, trusses are precision-engineered components designed to support specific loads. Any unauthorized modification compromises the safety of the entire building, leading to expensive repairs or structural failure. Wooden Roof Solutions explains why cutting or drilling wood trusses is so dangerous.

How Wood Trusses Function as a Structural System

Wood trusses are designed as an integrated system of triangles, utilizing the inherent strength of triangles to distribute weight across a wide span. Each chord and web member is calculated to handle specific tension and compression forces. They are held together by metal connector plates positioned at exact locations. Because every piece of wood in a truss is interdependent, the system only functions correctly when every component remains fully intact and in its original configuration.

Loss of Structural Strength and Stability

The primary dangers of cutting wood trusses stem from the fact that they lack the "redundancy" found in heavy timber framing. In an engineered system, removing even a small section of a bottom chord or a diagonal web can reduce the truss's load-bearing capacity by more than 50%. This loss of stability means the truss can no longer effectively transfer the weight of the roof or floor to the bearing walls, leading to sagging or twisting.

Risk of Progressive Failure or Roof Collapse

One of the most significant structural risks of cutting trusses is the potential for progressive failure. Because trusses are often spaced 24 inches apart and tied together with bracing, the failure of one modified truss places an extreme, unanticipated load on the adjacent units. This domino effect can lead to a sudden, total roof collapse, especially during high-stress events like heavy snowfall or high winds, where the weakened member acts as the point of least resistance.

Structural Consequences of Drilling or Modifying Trusses

While a small hole for a wire might seem harmless, drilling through the center of a chord or near a joint plate can sever critical wood fibers. This creates a "stress riser," a point where the wood is likely to crack under pressure. Unlike solid 2x10 joists, which may have some allowance for holes, engineered trusses have almost zero tolerance for field-drilling unless specifically detailed by a licensed structural engineer.

Legal, Insurance, and Building Code Issues

Modifying a truss without an engineer's sealed repair plan is a direct violation of international and local building codes. If an inspection reveals cut trusses, you may be forced to halt work or face significant fines. Furthermore, building code violations for truss modification can void your property insurance. If a collapse occurs and it is determined that the trusses were altered on-site, insurance providers often deny claims, leaving the property owner or contractor liable for all damages. Let Wooden Roof Solutions make your repairs legal and safe.

Safety Hazards for Occupants and Property

The risks of modifying engineered wood trusses include a threat to human life. A compromised roof system may not show signs of distress immediately, creating a false sense of security. Over time, environmental stressors can cause the weakened wood to snap without warning. This endangers occupants and potentially leads to a total loss of the property.

Contact Wooden Roof Solutions

Wooden Roof Solutions specializes in truss roof repairs and reinforcement throughout the Midwest, including Oshkosh and Milwaukee, WI and Geneva, Glenview , La Grange , Evanston , and Arlington Heights, IL . The integrity of your roof or floor system is non-negotiable. If you discover that a truss has been cut, or if a project requires a truss modification, you must consult a professional structural engineer immediately to design a formal repair or reinforcement plan. Never attempt to "scab" or patch a truss with scrap lumber. Reach out to us today to schedule an appointment.

Understanding the Signals Your Bowstring Trusses Send

Mon, 20 Jan 2025 19:26:49 GMT

Probably ‘Please, please pretty please, keep the roof drains clean.’

One of the most common repairs we complete is a rotted end, often caused by clogged roof drains. What happens? Your roof drains fills with leaves, twigs, whatever, during a rain the water backs up to the point where you have a puddle on your roof. Your roof is not designed for standing water, so the water leaks inside your building. Often there are roof drains located near the end of bowstring truss. The water runs down to the end of the truss, soaking the end of the truss (the truss ends carry the weight of the truss and roof). Overtime this causes the truss end to rot and then fail. If you're lucky the rotted end is identified and repaired before the truss completely fails only costing you several thousand dollars, if you're not…….

Picture of a classic rotted end.

Avoid Truss Failure, Protect Your Roof Before Snow Hits

Wed, 15 Jan 2025 05:29:06 GMT

The most likely time for your trusses to fail is during a major snowstorm.

The snow can add significant weight to your roof. Snow and then rain are the worst combination possible. A foot of snow can weigh 10-20 lbs per square foot of roof area. One inch of rain absorbed by the snow can add an additional 5 lbs per square foot. (current design snow load is 25 lbs per square foot, your 100-year-old building was very likely designed for less). So, you can see this could be a problem.

But you say, ‘My building is 100 yrs old and has seen everything, I’m not worried. If it hasn’t failed in the last 100 years, why would it fail now?’

It has been a couple of years since we have had a major snowstorm in the Chicago area and things could have changed with your trusses since the last big snow.

What could have changed:

A roof leak could have rotted portions of your trusses.
Termites could have eaten portions of your trusses.
A truss could have been damaged by impact by something…a forklift a truck.
Maybe someone decided to attach a chain fall to your truss to do some heavy lifting.
A small crack or imperfection in the wood could have worsened or could worsen with additional weight.

Any number of things could have happened to place your roof at risk. So what do you do? Call Wooden Roof Solutions for a free visual inspection of your bow string trusses and give yourself some peace of mind when the snow finally flies.

Bowstring Truss, an Architect's Dream with Challenges

Mon, 08 Apr 2024 08:14:20 GMT

An architect's dream that presents special challenges

In the 1940s, the wood bowstring truss, with its curved top chord and straight bottom chord, gave architects the ability to design modern, attractive structures with open floor spaces and no columns. These trusses can be found in commercial and institutional buildings across the U.S., particularly in the Midwest. However, bowstring trusses in structures built before 1980 most likely will not meet current code requirements for load capacity.1

No matter their construction date, buildings with wood bowstring trusses present their owners with extra maintenance requirements to avoid failures. Regular inspection — and in some cases, rebuilding or replacement — will be needed. Also, firefighters are often reluctant to enter such buildings due to the risk of roof collapse.

Some practical advice to help avoid a truss failure.

Fortunately, there are steps you can take to help avoid wood bowstring truss failures leading to collapse:

Have trusses on your building inspected by a licensed or professional structural engineer (designations vary by state) with wood bowstring truss experience. Complete re-inspections by a licensed or professional structural engineer at 5-year intervals.

Instruct maintenance staff and contractors never to cut, modify or hang equipment from the trusses.

Clear debris from roof drains and gutters to prevent standing water. Perform this task at least quarterly, or more frequently as needed.

Institute your own inspection program. At quarterly intervals, look for these conditions:
Signs of water staining or efflorescence on trusses or masonry supporting walls
Deformities in the truss or change in the smooth curvature along the top chord
Cracking anywhere on the wood truss or masonry wall supporting the truss

If any of these conditions are identified, engage a licensed or professional structural engineer to complete a further evaluation.

Reasons why wood bowstring trusses fail.

There are many reasons why these trusses fail. Here’s a brief summary:

Safety factors for wood stress levels are better understood today than they were in the 1940-1960 time period, when most construction using wood bowstring trusses was completed. As a result, many of these old trusses have been found to be significantly overstressed — possibly by more than a factor of 2.

The curved top chord allows the buildup of snow and water weight on the roof to cause uneven loading, increasing the stress on the wood members. In turn, the uneven loading can reverse the stress on the wood members causing a “push-pull” situation that weakens the wood joints.

Wood truss members are compromised by water leaks, due to lack of maintenance, or by the construction methods used in erecting masonry supporting walls.

Some building owners make improper modifications, such as the addition of roof-mounted mechanical equipment, suspended ceilings or other items not included in the original design.

Trusses sometimes sustain damage from material-handling equipment (such as forklifts) or cutting/notching of the wood members.

Structural weakening may be caused by the subsequent addition of a loft with a load-bearing floor, perhaps to create additional storage space, along the bottom chord of the truss.

As indicated on the previous page, if any of these conditions are identified, engage a licensed or professional structural engineer to complete a further evaluation. Wood bowstring trusses can be repaired or rebuilt by experienced contractors. Types of repairs include adding reinforcing wood, lateral supports and/or post tensioning elements.

1 Bowstring Trusses ‘Fail’ to Meet Current Code Requirements, Western Wood Structures White Paper, Paul C. Gilham, Terry D. McKee (2015).

Article shared from Nationwide Insurance.

The information used to create this post was obtained from sources believed to be reliable to help users address their own risk management and insurance needs. It does not and is not intended to provide legal advice.