Builders metalwork should be chosen around the joint it needs to form, support or restrain. Start with the actual timber dimensions, the job the connector needs to perform, the supporting material, the required fasteners and the exposure conditions. A connector that happens to fit is not automatically suitable for the job.
For straightforward non-structural work, selection often comes down to identifying the correct connector type and checking its dimensions, fixing requirements and finish. Where metalwork forms part of a floor, roof, loadbearing wall, structural restraint system or another safety-critical assembly, the connector and its fasteners need to follow the project design and current manufacturer documentation.
Start with the joint, not the connector catalogue
Before choosing a bracket or hanger, establish what the connection needs to do.
Consider:
- which timber members or materials are being connected;
- whether the connector is supporting a vertical load, providing restraint, reinforcing a joint or simply holding components in position;
- the actual width and depth of the timber;
- whether the supporting member is timber, masonry, concrete or another material;
- whether there is enough access to install the specified fasteners correctly;
- whether the connection is internal, external, damp, coastal or in contact with treated timber.
Measure the timber itself rather than relying only on a nominal trade size. Planed, regularised and finished timber can differ from the nominal dimensions used to describe it, and connector fit can depend on relatively small dimensional differences.
The connector profile matters as well. An angle bracket, joist hanger and restraint strap may all be formed from galvanised steel, but they perform different jobs and should not be treated as interchangeable.
Angle brackets for general timber joints
Angle brackets are commonly used to form or reinforce 90-degree timber connections. Dimensions, steel thickness, hole pattern and corrosion protection vary between products, so choose the bracket around the joint rather than selecting one solely by its overall size.
For example, Bucko's 90 x 90 mm galvanised angle bracket is a general-purpose carbon-steel bracket intended to strengthen timber joints. It is 62 mm wide and 2 mm thick.
Those dimensions alone do not establish that the bracket is suitable for a particular structural load. An angle bracket should not be used as an improvised substitute for a connector designed for a different purpose.
Metalwork also cannot make unsound timber structurally sound by itself. Rot, significant splitting, decay or other deterioration in the timber should be assessed and dealt with before a new connector is fitted.
Choose joist hangers for the supporting arrangement
Joist hangers support timber members at their ends, but the correct hanger depends on both the supported timber and the supporting construction.
Match the hanger to:
- the actual joist width;
- the permitted joist depth range;
- the supporting member;
- the required bearing arrangement;
- the manufacturer's specified fasteners and fixing pattern.
Timber-to-timber and masonry-support applications require connector types designed for their particular arrangement rather than being treated as interchangeable.
The 125 mm TIMCO standard timber hanger is designed for timber-to-timber connections such as joists and stairwell trimming. It is listed for a 125 mm joist width and joist depths from 100 to 225 mm, with a 50 mm bearing, 300 mm legs and 1 mm carbon-steel construction.
TIMCO currently states that this hanger conforms to Eurocode 5 and is suitable for service class 2. That information applies to the identified hanger and should not be assumed to apply to other sizes or connector types without checking their own technical data.
Structural connector performance is not determined by the steel component alone. The hanger, timber and specified fasteners work together as a connection system.
Do not cut, flatten, bend or otherwise modify a hanger unless the manufacturer's current instructions specifically permit it.
Use restraint straps for the intended restraint detail
Restraint straps are used where building elements need to be tied together to resist movement. In structural work, their location, dimensions, fixing arrangement and supporting construction form part of the designed detail.
The TIMCO 900/100 heavy-duty bent restraint strap is intended for horizontal restraint applications such as tying roof trusses, rafters or joists to masonry. The identified product has a 900 mm length before the bend, a 100 mm bend, a 1000 mm total length, a 27.5 mm width and 4 mm thickness.
That does not mean the strap can simply be added wherever extra restraint appears desirable. Structural restraint depends on the complete detail, including the masonry, timber, fixing positions and specified fasteners.
For work subject to Building Regulations in England, Approved Document A provides guidance relating to structural elements. Requirements and supporting guidance differ across the UK, so structural metalwork should be checked against the requirements applying to the project location, the project drawings and current manufacturer documentation.
Post supports and fencing connectors
Post bases, bolt-down supports, ground spikes and other fencing connectors perform different functions, so their suitability depends on more than the post size.
Check:
- the post dimensions;
- the supporting ground, concrete or structural base;
- the height and exposed area of the fence or structure;
- the connector's stated application;
- the required anchors or fasteners;
- the environmental exposure.
A post support cannot compensate for an unsuitable foundation or an inadequately designed fence. Solid fencing in an exposed position can place substantial loads on posts and their bases, so do not assume that a connector used for a small decorative structure will suit a taller or more exposed installation.
Where loads are significant or failure could create a safety risk, use a properly specified system rather than selecting the support by appearance alone.
Match the metalwork to the environment
Builders metalwork is available in different materials and protective finishes. The right choice depends on where the connector will be installed and what it will be in contact with.
A dry internal connection presents a different corrosion risk from an exposed fence, a damp location, treated external timber or a coastal environment. Galvanised steel provides corrosion protection, but the word "galvanised" should not be treated as meaning suitable for every exterior or aggressive environment.
The TIMCO products linked above, for example, carry a corrosion rating intended for occasionally damp or wet, rural and sheltered conditions. More aggressive exposure may require a different connector or finish.
Treated timber, persistent moisture, salts and other corrosive conditions can affect both connectors and fasteners. Where these conditions apply, check the connector manufacturer's environmental and material-compatibility guidance.
Fastener material matters as well. Dissimilar metals can create additional corrosion risk when moisture is present, so follow the manufacturer's specified connector and fastener combination rather than mixing materials without checking compatibility.
The fasteners are part of the connection
One of the most important selection checks is also one of the easiest to miss: the holes in a connector do not automatically mean that any convenient screw or nail can be used.
For structural metalwork, published performance can depend on a defined fixing arrangement. Depending on the product, this may specify:
- fastener type;
- diameter and length;
- material or coating;
- quantity;
- which holes are to be used;
- the supporting timber or substrate.
Ordinary general-purpose screws should not be substituted for specified connector nails or approved structural connector screws unless the manufacturer permits the substitution.
Equally, do not assume that every visible hole should automatically be filled. Follow the fixing pattern stated for the exact connector. Different products can use different schedules, and changing the specified arrangement can alter the behaviour of the connection.
When a connector is fixed to masonry or concrete, the substrate becomes part of the selection process. Dense concrete, solid brick, lightweight blockwork and hollow masonry do not provide identical anchoring conditions. Select the fixing from verified information for the actual substrate and required application rather than choosing one simply because it fits through the connector hole.
Check the complete assembly before ordering
A short pre-purchase check can prevent many compatibility problems.
Before ordering builders metalwork:
- measure the actual timber width and depth;
- identify whether the connector supports load, provides restraint, reinforces a joint or simply positions a component;
- confirm the supporting material;
- check the connector dimensions and orientation;
- confirm that the stated application matches the joint;
- verify the manufacturer's required fasteners and fixing pattern;
- make sure there will be enough access to install those fasteners correctly;
- choose a material and finish suitable for the exposure conditions;
- check compatibility with treated timber where relevant;
- inspect the existing timber, masonry or other substrate for deterioration;
- check whether the product is handed or has another orientation-specific requirement.
These checks matter more than selecting a connector because it resembles one already used elsewhere on the project.
Know when general selection advice is not enough
General connector guidance is useful for routine joinery, maintenance, fencing and other straightforward work, but it has clear limits.
Do not use a general article to design or approve connections involving:
- loadbearing floors or roofs;
- structural timber framing;
- retaining structures;
- structural restraint;
- safety-critical fencing or external structures;
- fire-resisting construction;
- engineered timber systems;
- any connection specified by structural drawings or calculations.
In these situations, follow the project drawings, current manufacturer technical documentation and the appropriate competent designer or engineer.
The practical rule is simple: choose builders metalwork by the job the connection must perform, then verify the timber dimensions, substrate, fasteners and exposure before ordering. The connector itself is only one part of the assembly, and the strongest-looking bracket is not a substitute for the correct specified system.
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