Not many materials can compare to glulam when it comes to creating different types of architectural and constructive expressions. Below are some examples of different standard solutions for junction connections and fittings.
Corrosion protection, etc.
The material for brackets and fixings should have corrosion protection adapted to the actual corrosive class - typically at least the equivalent of galvanized steel with zinc coating ≥ 55 µm (micrometer).
Hinged fixings transmit horizontal and vertical forces but not momentum. Any fixings that can transmit torque must be clamped.
In addition to standard solutions, new fittings and fixtures for glulam structures are constantly evolving. Different requirements are demanding new solutions. Recessed fittings have many advantages compared to externally lying fittings, such as improved fire resistance.
Connection Point of a Truss Structure
The connection point of a truss structure with slotted steel plates, steel dowels and bindings.
Dowel Joints with Slotted Plate
Nailing plates can be used as splice plates on glulam beams and roofs or on of column foot fixings. To avoid eccentric loading, two plates per dressing should be used (so-called double brackets). The plates are made of galvanized sheet steel or acid proof stainless sheet steel with a thicknesses of 1.5, 2.0 and 2.5 mm and a hole diameter of 5 mm.
Roof Ridge Bracket
Used for roof structures and intersecting beams, mainly the anchoring rooftops for the primary beam. They are especially useful in designs that will be equipped with cladding on the outside of the bearing frame or where it’s not important if the fitting is visible. Manufactured in various models, the left and right brackets are galvanized sheet steel with a hole diameter of 5 mm.
Fork anchors are mainly used as connections between the trusses and the underlying construction but can be used when angle bracketing the wood. Fork anchors are manufactured in various models of galvanized sheet steel with a thickness of 1.5 mm and a hole diameter of 5 mm.
A strap of steel which is used for the stabilization of a roof construction. They are also used for wind bracing in floors and walls. Made of galvanized sheet steel with a hole diameter of 5 mm for mounting with anchor nails or anchor screws.
Post Anchors are used for potting or fitting in concrete to attach laminated timber columns, for example, fences and patios. Manufactured in various models, with or without adjustable versions, in galvanized steel.
Angle brackets are used on wood and glulam. They can also be used for fixings for wood to concrete. Available in a variety of dimensions for adaptation to the current load. Made from galvanized or stainless steel sheet with a thickness of 2 or 3 mm. A hole diameter of 5 mm for anchor nails or anchor screws, as well as larger holes for expansion bolts.
Nail Plate Angle Bracket
Nail plate angle brackets can be used at the joints between the pillar and joist or at angles with a moderate load. Made of galvanized or stainless steel sheet with a thickness of 2 mm or 4 mm and a hole diameter of 5 mm.
Joist Hanger with Outward Folding Tabs
Joist hangers are used when connecting beams on the same plane and at the connection point between the columns and beams of glulam. There are many different types of hangers with tabs having different widths. Within each type there are several heights. Hangers can have inward or outward folded tabs. Made of galvanized sheet steel with a thickness of 2 mm and a hole diameter of 5 mm.
Gerber fittings are used in non-torque transmitting splicing beams on the same plane. To avoid eccentric loading, two fittings per binding are used (so-called double brackets). Made of galvanized sheet steel with a thickness of 2 mm and a hole diameter of 5 mm.
Nailing Plate for Column Foot
Hinged or clamped fixing of the column foot by nailing plates on both sides. This is a simple solution, suitable for small as well as high horizontal and vertical forces (lift).
With pin-jointed attachments the nailing plates are usually placed with on the broader sides, with clamped fixing it is usually placed on the narrower sides. The fitting can either be cast into the concrete structure or welded to a molded support plate. Load is transferred through the anchor nail or screw. The wood ends need to be protected against moisture from concrete and other moisture absorbent materials and should be accessible for moisture protection maintenance. Special measures for fire protection may be required, for example, fire protection painting or cladding.
Steel Plate for Column Foot
Hinged or clamped fixing of the column foot with flat steel is an equivalent alternative to using nailing plates. With pin-jointed attachments the flat steel is usually the on broader sides and with clamped fixing it is usually on the narrower sides. Flat steel is cast into the concrete structure or welded to a cast mounting plate. The load transfer takes place with through bolts or any type of wood screw. The wood ends need to be protected against moisture from concrete and other moisture absorbent materials and must be accessible for moisture protection maintenance. Special measures for fire protection may be required, for example, fire protection painting or cladding.
Steel Angle for Column Foot
The column foot is joined to the steel angle with screws for a simple solution suitable for small horizontal forces and vertical forces (lift). The steel angle is bolted to the concrete structure with anchor screws or so-called chemical anchors, allowing for accurate measurement and reduces the risk of misplacement. Usually symmetrical steel angles are used on each side of the column. The wood ends need to be moisture-protected and must be accessible for moisture protection maintenance.
Post Shoe with L or U profile on the Column Foot
For hinged attachments outside or in places where there is free running water and if the forces are small, post shoes are a suitable solution because the absorption of water through the column end face is prevented. The fitting often consists of a U-profile and a welded-on tie bar. Usually the lower part of the anchoring rod is molded into the concrete structure, but the rod may also be welded to a molded support plate. Load transfer is usually done with the help of a screw. Adjustable standard fittings are also available.
Nailing Plates at the Top Panel
Hinged connection with nailing plates on both sides of the glulam structure is simple and suitable for both small and large loads. The plates that are available in standard catalogues have a thickness which restricts the use to moderate loads. The sheet metal manufacturer's instructions must be followed carefully. Load transfer takes place using the anchor nail or screw. The plates should be placed as close to the pillar inner edge as possible so that they do not prevent the beams angle.
Special measures for fire protection may be required, for example a protective coating.
Flat Bars at the Top Panel
Inserted Plates at the Top Panel
At the hinged connection with inserted steel and steel dowels, the attachment is completely hidden. Steel dowels can be recessed in the glulam beam and covered with wooden pegs. This solution provides completely concealed fittings, which is an acceptable fire protection.
Recessed Beam and Angled Plates at the Top Panel
Recessed glulam beams are often used at the upright ends to transfer the pillars’ horizontal forces to the glulam beam. The recess in the glulam column is often as large as the beam width. The load transmission between the laminated beams and pillars usually takes place by means of screws, washers and nuts. Attachments with sheet metal angles, universal screws or wood construction screws can also help with small horizontal forces and lift forces.
Recessed Beam and Angled Plates at the Top Panel
Articulated Ridge Seam Nailing Plate
Articulated ridge seam nailing plates on both sides is simple and effective. The nailing plate is suitable for both small and large forces. Sheet metal manufacturer's instructions must be followed carefully. The load force transmission between the nailing plate and glulam wood beams is done by means of anchor nail or screw. The plates should be placed as close to the glulam beams bottom edge as possible so that they do not prevent the beams slope deflection. A suitable distance between the bottom edge of the glulam beam and the bottom row of nails is 10 × nail / screw diameter. There are pre-drilled nailing plates of galvanized sheet steel stock in various sizes and thicknesses between 1.5 and 5 mm.
Articulated Beam Jointed with Nailing Plates
An articulated beam jointed with nailing plates is simple and effective. It is suitable for small or moderate forces. The sheet metal manufacturer's instructions must be followed carefully. The plates should be placed centrally with respect to the center line the glulam beams middle line = system line. The load force transmission between the sheets and glulam beams is done with the help of an anchor nail or screw.
Welded Gerber Fittings
Hinged beam joints with Gerber fittings are recommended if large forces are being transferred and the load force always has the same direction. Small forces in the opposite direction are transmitted through screw joints on the side plates. The forces are transmitted primarily by contact. If the Gerber fittings are going to transfer tensile forces, they should be supplemented with welded flat bars. In order not to counteract the glulam beams slope deflection, side screws should be positioned as close to the top and bottom plate as possible. A suitable edge distance is 2 × the screw diameter if the only the screw is transferring horizontal forces and 4 × the screw diameter if the screw also transmits vertical forces.
Standard Gerber Fittings
Gerber Fittings are manufactured to always be in stock. They are made of galvanized sheet steel and are suitable for small and moderate load force bearing. The sheet metal manufacturer's instructions must be followed carefully. The fittings can be whole or split. Whole fittings are ideal for certain cross-section dimensions of glulam beams, while the split fittings as a rule, are used independently of the glulam beams cross-section dimensions. The load forces are transmitted primarily by anchor nails or screws. If you use the type of double brackets shown here, give special consideration to the risk of tearing, see the Glulam Handbook Part 2. A rule of thumb is that the height to the top nail or screw is divided by the beam height which should be ≥ 0.7.
The fastening of ridges in the primary beams top side usually takes place by means of factory-made structures of cold-formed, galvanized sheet steel, such as angle brackets. The fittings can be designed with stiffening grooves. Load forces are transmitted mainly by contact pressure and with the help of an anchoring nail or screw. The fittings Manufacturer's instructions should be carefully followed.
Standard Joist Hangers and Welded Joist Hangers
Connection of the secondary beam with a standard joist hanger is a simple and effective solution, especially when the glulam timber beams upper side should be on the same plane. Load forces are transmitted mainly by contact pressure and with the help of an anchor nail or screw. The hanger instructions should be followed carefully. When large support reactions (transverse forces) are to be transferred from the secondary beam, welded hangers of hot rolled steel (flat bar or universal rod) are usually needed. The load transmission between the secondary beams and welded joist hanger is mainly through contact pressure while the load force transmission between the joist hanger and the primary beam is carried via nails, through screws or any type of wood screw. Hangers can be designed in various ways.
A strap attachment transmits only horizontal tensile forces on the glulam beam. The strap consists usually of two or more steel bars. For small tensile forces the band can be made from glulam. The attachment is normally designed so that the pulling forces draw so close to the intersection of the glulam beams and pillar lines as possible.
A strap made from high-grade steel is suitable for both small and large tensile forces. The simplest attachment is with a strap on each side of the glulam beam. At moderate tensile forces, the two pull bands are replaced by a single strap that is pulled through a centric hole in the glulam beam. This should be avoided on very high laminated beams for manufacturing reasons. With large tensile forces the two anchoring straps on the sides should be supplemented by a third, centrally placed strap. The steel plate against the glulam beams wooden ends is provided with nail holes to facilitate assembly. Load bearing forces are transmitted primarily through contact pressure along the fiber grain angle.
A strap made from glulam is suitable for use with small tensile forces. The attachment of the strap onto the glulam beam can be done with flat bars that either go around the glulam beam end or that stop a few notches in on the strap. The flat Steel or nailing plates length, should be the same as is shown in Figure 90. For small traction forces, flat steel can replace nailing plates. The transfer of horizontal forces takes place via adhesion by means of a welded steel plate using an anchor nail or screw.