Connect timber to timber, metal, concrete & bricks

Getting a secure fixing when working with wood and other materials like metal, concrete and bricks is vital for any construction project and using the correct type of fixing is key. In this guide we take a look at the different types of fixings, which can be used for different materials and the key factors to keep in mind when connecting timber.

What are the different types of timber fixings?

There are two groups of mechanical fasteners, defined by how they transfer the forces between the connected members:

  • Dowel-type fasteners, such as nails, screws, bolts and dowels, which transfer the load along the shank or length of the dowel
  • Connectors, such as metal plate fasteners, which carry the load at the surface of each member.

Joints can be fixed by other methods, such as adhesives or carpentry and joinery techniques or by a combination of methods. Generally, bolts and dowels are heavier duty fasteners than screws or nails, and have the greatest individual load-bearing capacity. Screws are normally chosen instead of nails for their demountability and better pull-out resistance. If the joint has to carry a structural load, the design must be checked by a structural engineer.

Types of timber fixings

  • Screws

    Although wood screws can be used for plain timber-to-timber joints, they are especially suitable for steel-to-timber and panel-to-timber joints. The diameter of a screw is measured on the smooth part of the shank, or the outer edge of the thread, and ranges from 6mm to 20mm for coach screws, and from 4mm to 8mm for countersunk screws. The root diameter of most screws in the threaded portion is about 70% of the outer diameter. The depth of the thread varies from 0.125d to 0.140d and the thread pitch from 0.4d to 0.5d (d being the diameter of the screw). The length of the threaded portion is normally about 60% of the total length of the shank. Pre-drill for screws with a diameter greater than 5mm to prevent splitting the wood. Pre-drill and use washers for coach screws, which are available in lengths of 25mm to 300mm. In large connections, they hold timber connectors conveniently in place or replace bolts when only single-sided access is available.

  • Bolts

    Bolts and dowels are used to hold two or more members together to form a joint, generally loaded in shear (across the fastener). Bolts are usually made from mild steel with a minimum tensile strength of 400N/mm2. The most common diameters for use with wood range from 8mm to 30mm. A typical bolt size is M8, meaning metric 8mm diameter. When installing a bolt, pre-drill the hole up to 1mm larger than the bolt to allow for easy insertion and to reduce the risk that the wood will split on assembly or after drying out. Bolts should be tightened so that the members fit closely. If the wood shrinks in service, the bolts should be retightened. Always use a washer under any head or nut in contact with the timber or steel. The diameter of the washer should be at least three times the bolt’s. Its thickness should be at least 0.3 times the bolt’s diameter.

  • Connectors

    Connectors are widely used in place of traditional carpentry joints to connect timber members together, usually in conjunction with a dowel-type fastener. Easy to use, they are readily available and do no require complex timber machining. Common types include joist hangers, framing anchors, truss clips and wall ties made of steel plate, sheet or strip. Mass-produced connectors are usually made form pre-galvanised mild steel, 1mm to 3mm thick. Heavier components, up to 12mm thick, are available for larger structures. Some manufacturers also supply stainless steel components to order.

  • Two-dimensional plates

    Punched metal plate fasteners are suited to factory prefabrication and transfer member forces with smaller connection areas than hand-nailed plates. They are widely used with trussed rafters, but also for in-plane joints in other components. Take care in handling, as the joints are flexible out of plane and can be damaged during erection.

  • Three-dimensional plates

    These are widely available for many applications, such as joist hangers, as brackets, or as multi-angled connectors. They can be face-mounted or fitted over a girder as ‘stirrup-type’ hangers. Follow the manufacturer’s instructions and loading guidelines when fixing them. Using the correct number of nails, screws or bolts, and fixing them in the right way, is essential to avoid potential failure.

Which products can be used with timber, metal, concrete & bricks?

Choosing the right product for the job is vital in getting the fixing you need, and when it comes to carrying structural loads, you need ensure you get it right. 

Here we break down the fixings we sell into what materials they can be used to secure timber with. 

  • Timber to timber:

    • Joyner Bolts
    • VGZ Full Threaded Screw with Cylindrical Head
    • TBS Evo Flange Head Screw
    • SBD HT Self-perforating Dowel
    • UV-T Connectors
    • Clik/Lock T Concealed Hook Connector
    • Titan Silent Angle Bracket

  • Timber to metal:

    • Joyner Bolts
    • MET Threaded Rods, Nuts and Washers

  • Timber to concrete & Bricks:

    • Joyner Bolts
    • MET Threaded Rods, Nuts and Washers
    • SKS CE Screw Anchor for Concrete CE1

Key factors to keep in mind:

  • Some wood species, such as black walnut, Douglas fir, oak, teak and western red cedar, react with iron to form a black compound that stains the wood. You will need to use fixings with a low iron content, such as stainless steel.
  • Hidden fasteners are often used for projects such as decking and cladding, where appearance is key.
  • Not all are suitable for every type of wood, so it is essential to follow the manufacturer’s guidelines.
  • Because they allow for closer fitting of boards, concealed clips should only be used with timber with a moisture content of 16% or less to avoid problems caused by the natural movement of the wood.
  • Keep in mind that individual boards are difficult to remove once fastened and installing hidden clips may be more time-consuming than fixing with screws.

Find the right products

Need advice on your soundproofing project?

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