Understanding Long Span Flat Roof Systems and Benefits

Long span flat roof systems are a popular choice for modern buildings due to their sleek appearance and ability to provide a large, open space.

They can span up to 36 meters without intermediate supports, making them ideal for large warehouses, factories, and commercial buildings.

This is made possible by the use of advanced materials and designs that distribute the weight evenly across the roof.

A single layer of roofing material can be used, reducing the need for additional framing and labor costs.

Design and construction of long span flat roofs require careful consideration of truss design and bracing. A registered professional must be responsible for the design of both temporary and permanent bracing, as required by IBC 2015 Section 2303.4.1.3.

Temporary bracing, which is non-permanent and used to stabilize trusses during construction, is crucial for safety and preventing truss damage. Providing adequate temporary bracing enhances safety and prevents truss damage during installation.

Permanent bracing, such as plywood or OSB roof diaphragms, laterally braces the top chords of trusses and ensures the truss will support intended design loads. Other permanent bracing elements are used for conditions where the bottom chord is in compression, such as wind uplift or cantilever conditions.

In modular erection, trusses are assembled on the ground with most of the permanent plywood or OSB panels fastened in place to the truss top chords. This entire assembled unit is referred to as a "truss module" and is very stable relative to a single truss.

Diaphragm design must take into account the panel layup when designing the diaphragm, especially when using double-chord open-web trusses. Diaphragm nails should be long enough to penetrate through the plywood cap and into the truss chord.

When designing a long-span roof, the type of material used is crucial. Steel is often favored due to its tremendous durability.

The design of long-span steel and steel-concrete composite columns is generally carried out to comply with BS EN 1993, BS 5950, or BS EN 1994 standards. This ensures a safe and reliable structure.

A well-designed roof can also help prevent the spread of fire. Steel is preferred because it discourages the spread of fire.

For flat roofs, the design should take into account the lifespan of the materials used. A multi-layer built-up roof can last for 15 to 20 years.

The design should also consider the maintenance needs of the roof. Single-ply roofs are generally easy to maintain and can last for as long as 30 years.

The space deck is a modular architectural roofing system based on simplistic pyramidal units.

It's manufactured with tubular diagonals that are then attached by welding to a forming tray and apex boss.

Single span designs can produce large clear spans, up to 22 m, while two-way span designs can accommodate spans of up to 33 m.

The parts of a space deck can be quickly carried to the job site and constructed into beams at ground level before being winched into place on top of perimeter supports.

Any lightweight architectural decking is suitable as a roof coating, and roof lights can be optionally installed onto the square top space deck sections.

A space frame is a lightweight and rigid roofing system that's made up of a series of connectors tying together struts and bracing segments.

Space frames are manufactured out of structural steel or aluminum alloy pipes, making them durable due to the rigidity of the triangle.

The majority of space frames get manufactured out of structural steel or aluminum alloy pipes.

Buckminster Fuller invented the method of using space frames during the 1960s for his geodesic dome buildings.

Design considerations play a crucial role in ensuring the structural integrity of a building. A registered professional must be responsible for the design of both temporary and permanent bracing for trusses spanning 60 feet or greater.

Temporary bracing, which is non-permanent, is used to stabilize trusses during the construction process. Providing adequate temporary bracing is essential for safety and to prevent truss damage during installation.

Permanent bracing, typically consisting of a plywood or oriented strand board (OSB) roof diaphragm, laterally braces the top chords of the trusses. This helps ensure the truss will support the intended design loads.

Even without compressive forces, the bottom chord should be braced to hold the truss in proper alignment, which is usually perpendicular to the roof deck.

Modular diaphragm design is a game-changer for builders. Modular erection involves assembling trusses on the ground with most of the permanent plywood or OSB panels fastened in place to the truss top chords.

The engineer must take into account the panel layup when designing the diaphragm, especially with standard panel dimensions that result in an eight-foot-on-center continuous edge. This is crucial for a stable roof diaphragm.

Diaphragm nails should be long enough to penetrate through the plywood cap and into the truss chord. The American Wood Council's Special Design Provisions for Wind and Seismic (AWC SDPWS) provides guidance on this.

Using nailed diaphragms, the engineer can determine allowable diaphragm shear by referencing Tables 4.2A, 4.2B, and 4.2C in the AWC SDPWS. A nominal framing width of three inches should be employed when determining allowable shear.

The engineer should review the truss manufacturer's allowable nail spacing into the truss chord to verify the closest allowable on-center spacing is not exceeded.

Connections are a crucial part of open-web truss design, and it's essential to understand who's responsible for their design.

The truss manufacturer typically assumes design responsibility for connections if the engineer specifies the design loads, but only if the hardware is factory-installed on the truss.

It's not uncommon for truss hardware to be designed for gravity or uplift load conditions only, so additional hardware may be needed to resist lateral loads.

Engineers should work with the manufacturer to verify the capacities of the connections, including gravity, uplift, and lateral loads.

If you're using wall anchors and straps specifically designed for open-web trusses, make sure to choose a model that's compatible with the truss chords and bearing hardware.

Truss design length can be a challenge, especially when it exceeds what the manufacturer can build or ship to a given area.

Long-span trusses often require special considerations, and it's recommended that the engineer works closely with the manufacturer during the design process to avoid potential issues.

Trusses can sometimes be manufactured in two sections and assembled in the field using special connections where the sections meet.

Long-span trusses present additional considerations, such as the risk of buckling or rolling during installation.

For spans over 70 feet, modular erection is recommended to improve safety and speed up the installation process.

The structural engineer should include information in the contract drawings to let the contractor know modular erection is required.

Cable-stayed structures are a structural design obtained from bridge building. They're particularly effective for large spans, where the weight of the roof is evenly distributed among the cables.

The cables in cable-stayed structures hang downward from masts that tower above roof level, providing a sturdy support system. This design allows for a flat roof to be suspended from above, creating a load-resisting unit.

The cables in cable-stayed structures act as suspension elements, keeping the roofing system stable even in windy conditions. The weight of the roof itself helps to keep the cables in tension, preventing them from sagging or snapping.

Cable-stayed structures can be a great option for buildings with large roofs, as they provide a strong and stable support system.

Proper ventilation is crucial for a flat roof, as it helps maintain even temperatures throughout the year. Having the right ventilation and insulation will prevent temperature fluctuations.

A poorly ventilated roof can lead to a build-up of heat and moisture, which is trapped with nowhere to go. This can affect the roof's lifespan.

A flat roof with good ventilation will be able to breathe and release excess heat and moisture, preventing damage.

A long span flat roof is essentially a longer version of a traditional roof, typically exceeding 12 meters in span. They protect structures from weather elements and provide insulation when necessary.

These roofs are often made of steel, timber, and concrete. Steel is the preferred material due to its strength and fire resistance. They are cost-efficient and require less time to construct.

Long span flat roofs are ideal for structures that require lengthy roofing, such as manufacturing plants, aircraft hangars, and auditoriums.

When selecting a provider for your long span flat roof, consider their experience with similar projects.

A good provider should have a minimum of 10 years of experience in designing and installing long span flat roofs.

Look for providers with a strong track record of successful projects, including those with similar weather conditions to your location.

A reputable provider will have a team of skilled professionals, including architects, engineers, and contractors, who work together to deliver a high-quality roof.

UGC is the market leader in the manufacturing and distribution of prepainted and other galvanized roofing and galvanized steel building products in the Philippines.

They have the largest and most diversified distribution network in the industry, with warehouses and sales offices in strategic locations throughout the country.

UGC provides a wide range of services, including roofing estimates, onsite rollforming, delivery, and installation, making them a one-stop-shop for all your roofing needs.

Their onsite rollforming service preserves product quality and allows for faster workflow due to reduced material handling, which can help you save time and money.

You can contact UGC through their website or by calling their numbers: (02) 8520-8822-23; 8520-8831; (049) 545-0084 to 86 or 09175033965 (Globe) and 09190032303 (Smart).

Location plays a significant role in choosing a provider, as it can affect the quality of service you receive.

Humidity and ease of access can be a contributing factor to the overall health of the roof, depending on its location.

Properties in areas with high humidity may require more frequent maintenance to prevent damage to the roof.

The lifespan of a flat roof can differ depending on its location, which should be considered when selecting a provider.

Additionally, the location of your property can impact the availability and cost of labor and materials, making it an essential factor in your decision.

A well-maintained flat roof can last for 20-30 years or more.

The durability of a flat roof makes it a good option for homeowners who want their homes to last.

Heavy winds can affect the lifespan of a flat roof.

A flat concrete roof can hold up against heavy winds.

The materials used in construction can also determine the lifespan of a flat roof.

Traditional flat roofs tend to last only around 10-15 years before they need replacing.

Regular maintenance can extend the lifespan of a flat roof.

A well-maintained flat roof can last for 20-30 years or more.