Heavy Timber Trusses
Structural Wood Components supplies heavy timber trusses for both Interior and Exterior installations. Interior trusses are utilized in Lobbies, Dining Areas, Retail Spaces, Church Sanctuaries, Building Facades, Family Rooms, Studies, Trophy Rooms, Kitchens, Entry Ways and numerous other spaces. Exterior Trusses are installed in Pavilions, Commercial Drive-thrus, Covered Walkways, Porte Cocheres, Patio Covers, Outdoor Kitchens, Garden Structures, and other outdoor areas.
Most customers asking for a Heavy Timber Truss are seeking a Decorative truss because of its hand crafted, exposed beam appearance. Hence all of our trusses are Decorative. The design of a particular building or structure in which the truss is located will determine whether or not the truss is also Structural.
A Structural timber truss requires engineering certification by the customer or SWC. We provide this service if required. The customer needs to provide building plans or sufficient detail regarding the roof configuration for our engineer to make roof load assumptions and check the truss for structural integrity. In many cases the customer’s timber truss plans are already detailed and certified by an engineer. In this instance, we may proceed with fabrication based on the customer’s certification.
Design & Appearance
Standard Truss Geometries - SWC can fabricate Heavy Timber Trusses in a variety of well known truss geometries using connected straight members. Typical designs include:
- Traditional King Truss
- Traditional Queen Truss
- Fink or W-Shape Truss
- Howe or M-Shape Truss
- Scissor Truss
- Mono Truss
- Parallel Chord Truss
There are unlimited variations of these designs when using different beam sizes, overhangs, repeated element patterns and other feature changes. Most designs above are configured to bear weight and are well-suited for Structural applications.
Click Here to see CAD drawings of standard truss geometries.
Trusses With Combined Straight & Arched Members - Another alternative is to utilize a combination of straight and arched solid timbers. Again, the number of possible configurations is almost unlimited and makes for very unique and beautiful trusses. While trusses utilizing curve members are attractive, the geometry of the members and connections frequently does not support loads effectively. This style of truss is typically used for Decorative applications.
SWC is capable of cutting and joining arched members of almost any thickness. However, arch radius, finished member width and length is limited by the width of standard material available. Because these trusses involve use of wider material stock and involve more labor for layout, cutting and assembly, they are priced accordingly.
Straight Glue-laminated and Arched Glue-laminated Trusses - The standard truss configurations listed above can be fabricated by using straight Glulam (glue laminated) beams. These beams, supplied by certified Glulam manufacturers, are fabricated by gluing multiple layers (laminations) of solid wood (typically 0.25” – 1.5” thick) into a large beam. SWC can fabricate trusses using straight Glulams of sizes similar to solid wood beams, or utilizing Glulams of much larger dimensions.
Exposed beam trusses fabricated with Glulam material have a refined appearance and are supplied for both commercial and residential installations. Load carrying capacity is generally higher for Glulam trusses when using members similar in dimension to solid beams. Because Glulam beams can be fabricated to much larger sizes than solid timbers, fabrication of significantly larger trusses for commercial or institutional buildings is possible, and SWC has supplied a number of oversized Glulam trusses.
Many of the Glulam manufacturers who make straight Glulam beams can also manufacture custom curved Glulam beams for use in the fabrication of small or large structural arches and trusses. Arches may be installed alone, or combined with other members as part of an overall truss assembly. These are frequently used in buildings such as church sanctuaries or athletic facilities and Structural Wood Components has experience engineering these components, sourcing the material, and fabricating the trusses.
Other Truss Configurations - There are many other exposed beam truss designs. Some of these are the following:
Multi-ply Trusses - The Multi-ply Truss is sometimes referred to as a “layered” or “sandwich” truss, and is fabricated by using multiple layers of thinner timbers (normally 2”, 3” or 4” thick) bolted together in some combination of overlapping members. Frequently the top and bottom chords are comprised of two members “sandwiched” around a single king post and webs.
Composite Wood and Steel Trusses - Some of SWC’s exposed trusses are configured with both wood and steel chord members. These are common in commercial applications and can involve various combinations of wood timbers, steel tube, and steel tie rods, with turnbuckles and custom fabricated attachment brackets. We have supplied this style of truss for restaurants, banks and golf clubs, to name a few installations.
Split Trusses – Many architects call for decorative trusses mounted flat against the end walls of a room to give the appearance of a half-embedded structural truss at each wall similar to those in the middle of the room. Our usual approach in this case is to fabricate a truss having half the thickness of a full truss located in the middle of the room. Plates are attached on only one side of the truss with lag screws; then the truss is attached similarly to the wall. Variations of this truss are also used for exterior building facades.
External Plate & Bolting - Except for the Multi-ply Trusses discussed above or Embedded Tension Hardware mentioned below, gusset plates and bolts are required for all Structural trusses and most Decorative trusses. External plating and bolting is the most economical way to join truss members. Most of our trusses are constructed with externally placed, 1/4-inch, A36 gusset plates. The plates are custom-shaped by our designer to coincide with the members of the truss using our in-house CAD system, then cut in our shop on a computer-controlled Plasma Cutter. Plates are normally painted black in our shop, but may be galvanized before painting, or powder coated based on customer preference and application.
Hidden Plate With Exposed or Hidden Bolting - For customers who prefer not to have as much hardware showing, but still require a Structural truss or Decorative truss with large heavy members, SWC can use a “Hidden” or “Knife” plate method of construction. This method involves cutting concealed slots (“plunge cuts”) in the center of timbers, into which a single gusset plate is inserted out of view. The plunge cuts are generally made from the top sides of the truss members so they are not visible from below. Bolting may be installed so that it is visible at the surface, or depending on the timber thickness, can be counter-sunk and plugged for total concealment.
Embedded Tension Hardware - Another connection method SWC uses for Structural trusses requiring concealed connections is internal tensioning hardware. These special embedded anchors utilize tension rods and expanding pins to preload timber joints in a variety of configurations. Wooden dowels are inserted where pins are installed, creating a more classic “dowelled” appearance. This connection method, while “classic” in appearance, is significantly more economical than true mortice and tenon or dowelled connections.
Use of Specialty Wood Screws & Dowels - In some instances, where a purely Decorative truss is called for and visibility of hardware is not desired, concealed wood screws or small dowels may be used to assemble the trusses. For this assembly technique to be used, certain conditions must apply such as limited truss span, smaller member size and lighter weight wood species. SWC assembles these trusses utilizing specially engineered and counter-sunk wood screws or dowels which can be sanded flush with beams or left protruding slightly for an antique appearance. This approach allows for an economically priced Decorative truss with no hardware showing.
A number of factors come into consideration when selecting materials for truss construction. Some of these are appearance, strength and resistance to the surrounding environment. It is simplest to look at materials from the standpoint of wood and hardware.
Species - Although other materials are sometimes used, our timbers most commonly consist of the following materials:
- Southern Yellow Pine
- Douglas Fir
- Western Red Cedar
- Glulam Beams
- Reclaimed Timbers
The color, grain, knot size and knot quantity vary between species. The grade specification chosen also affects some of these characteristics. The visual characteristics of different wood species are a matter of preference for the customer or architect, and many of the visual characteristics can also be influenced by stain or other finishing techniques.
Southern Yellow Pine, Douglas Fir, Cypress, Glulams and Reclaimed Timbers are good choices for Structural trusses.
Western Red Cedar and Cypress are known for their natural resistance to insect or moisture-related decay over time. Western Red Cedar is frequently the material of choice for pure Decorative trusses.
Surface Textures - The two most common surface textures used are Rough Sawn and S4S. The Rough Sawn material SWC supplies is also referred to as “Resawn” or Band Sawn”. This is because the timbers are cut on a large band saw and have a uniform “fuzzy” finish. Our Rough Sawn material does not have the prominent, circular mill marks associated with large circular saws of older saw mills. S4S material, or “smooth on four sides” is the planed or smooth finish most individuals are familiar with as used for dimensioned lumber.
Reclaimed Timbers - Reclaimed Timbers have a variety of textures depending on their original milled or hand-prepared surface and the effects of time and wear over the life of the material.
Faux Surface Texture - If a customer finds the surface irregularities, size constraints or price premium of true antique material undesirable, SWC offers several faux finishes that can be applied to new timber to achieve a Hand Hewn or Time Worn appearance associated with age.
Material Grades - Most wood species are sorted into a number of grades by standards organizations. Grading is used to evaluate the physical characteristics of a piece of wood and rate it with regard to strength and appearance. Click Here to see the SWC Grades Table commonly used for truss fabrication.
Gusset Plates, Brackets and Saddles - SWC fabricates most all gusset plates from A36 plate. These are typically flat, 2-dimensional shapes, cut to conform with truss members. Plates are cut on a computer-controlled plasma cutter operating from CAD files of the components. Plate is most frequently painted with a general purpose alkyd-based, black paint. Galvanized gusset plates and fabrications can be supplied for exterior applications at the customer’s request. The galvanized finish can be left as-is or over-coated with the standard black paint described above. Powder coating in a variety of colors and finishes is also available. If special circumstances require it, higher strength or stainless steel plate can be supplied.
Fasteners - Unless requested otherwise, our standard fasteners for every job are hot-dip galvanized A307 bolting painted with black alkyd-based paint. Galvanized bolts may be supplied unpainted. Fasteners are sized base on timber size and loading considerations. Bolt diameter can vary, but 3/4” is the most common size used for truss fabrication.
Clevises & Tie Rods - As mentioned above, trusses having a more contemporary appearance may utilize steel tie rods for some members. SWC can source these rods in a variety of diameters, lengths and materials, along with appropriately sized clevises to create a clean, pinned connection to attachment points. Tie rods are supplied with left-hand and right-hand threads so that they may be rotated and tensioned after truss fabrication.
Cross Section - Truss beam size is dependent upon the appearance desired and structural considerations. Either factor may override the other. Every truss must be of adequate size to support itself. Additional beam cross section may be required to support roof loads. We commonly fabricate trusses with members from 2” to 12” thick and 4” to 24” wide. Members of 2-inch thickness are typically used in Multi-ply trusses. Most single-ply trusses start with a minimum size of 4” x 6” section and increase in size from there. Strength may be increased by adding either thickness or width, but adjustments to the latter dimension add more strength per unit increase.
Length - Continuous length solid timbers are limited by sizes stocked at timber mills, which is determined by available tree size. Larger section timbers are more difficult to obtain in longer lengths. Timbers in most species can be obtained up to 40 feet in length. If solid timbers are desired for spans greater than 40’, splices can be engineered in most trusses. Much larger beam lengths can be achieved using Glulam material.
Engineering - If a heavy timber truss is Structural, SWC requires either: (a) the customer certify in writing (signed SWC proposal or customer purchase order) that the truss has been designed appropriately for building loads by the customer’s engineer, or (b) we have an engineering check performed by a certified Professional Engineer who will deliver stamped drawings that will be supplied with the trusses. If the trusses are purely decorative and the customer will certify the trusses as such, no engineering is usually required.
Lead Times & Schedule - Lead times for a typical truss job is 2-4 weeks. However, this can be influenced by a number of factors such as:
- Truss design
- Engineering and shop drawing requirements
- Customer approval process and timeframe
- Material species, size and procurement time
- Overall project scope of work
- Shop load and schedule at the time of order placement
Jobs requiring stamped engineering drawings typically require at least one week of lead time after order placement before any material can be ordered. Lead times for larger projects, or jobs having unusual design and/or material requirements can extend up to 6-8 weeks.
Delivery - Shipping is available for any job produced by SWC. Some smaller jobs local to the Houston area will be handled using a company truck or trailer. Jobs elsewhere in the state of Texas and out of state, or requiring oversize provisions are handled by a third party trucking company we utilize for all of our work. Most trusses are delivered stacked horizontally on a trailer, fully assembled and ready for installation. Customers are required to have personnel or equipment adequate for handling the trusses ready at the job site for off-loading.
Installation - Structural Wood Components does not provide installation services but can recommend contractors experienced in heavy timber truss installation or advise the customer regarding many aspects of installation.CLICK HERE TO LEARN MORE ABOUT OTHER CONSIDERATIONS