Wood and Metal Fabrication

Steel frames with timber infill — the warm-and-hard combination that suits West Coast homes.

Timber Species and Sourcing

The species decides the colour, the hardness and how the piece behaves once it is in a room or on a deck. What we specify depends entirely on where it is going.

White oak — the safe default for interior tops, treads and shelving. Hard, stable, takes a finish predictably and does not go orange.
Walnut — the one clients ask for by name. Beautiful, softer than oak, and it lightens in strong sun.
Douglas fir — local, warm, and honest on West Coast projects. Softer, so it dents. On a stair tread that is character; on a desk it may not be.
Western red cedar — the exterior choice. Naturally rot-resistant, light, and it silvers gracefully if left unfinished.
Live-edge slabs — for feature tables and counters. Availability drives the design rather than the other way round, so we shortlist slabs with you before the steel is drawn.

We source through local suppliers and mills. For anything where the grain is the feature, we would rather have you see the actual board than approve a species name on a drawing.

Fixing Methods

Wood moves and steel does not. Every fixing decision follows from that one fact.

A slab fastened rigidly to a steel frame at both ends will crack, reliably, usually in the first winter when the heating comes on. The frame has to allow the timber to expand and contract across its width while holding it firmly in place.

We do that with slotted holes and shouldered fasteners, with figure-eight or Z-clips on table tops, and by fixing tight at one point and letting the rest float. The visible hardware is chosen to suit the piece — countersunk and hidden where the design is quiet, exposed and deliberate where it is not.

For treads and cladding, concealed cleats and blind fixings keep the face clean. It is more work in the shop and worth it every time.

Interior vs Exterior

Interior and exterior are different projects even when they look the same.

Indoors, the enemy is humidity swing. Timber should be acclimatised in the space before final fitting, and the finish — hardwax oil, lacquer or a penetrating oil — should be applied to all faces including the underside, so both sides take on moisture at the same rate. Finishing only the top face is the fastest way to make a slab cup.

Outdoors, the enemies are water and UV. Detailing has to shed water rather than trap it: no flat surfaces that pond, no steel channel that holds a puddle against end grain, and clearance wherever timber meets metal. We isolate the two where we can, because damp wood in contact with steel accelerates corrosion in the steel and staining in the wood.

Fasteners outside are stainless. Plain steel screws in cedar will bleed black streaks within a season.

Movement and Maintenance

Timber in this climate moves through the year — swelling through a wet winter, shrinking through a dry heated spring — and a well-built piece accommodates that invisibly. Small seasonal gaps at a joint are the wood working as intended, not a fault.

Interior finishes want attention every few years rather than never. Oiled surfaces get a refresh coat; lacquered surfaces last longer but need proper refinishing when they eventually wear through. We will tell you which you are getting and what it asks of you.

Exterior timber is the higher-maintenance half of any wood-and-metal piece. Left unfinished, cedar silvers and is fine. Kept its original colour, it needs recoating on a cycle. Neither is wrong — but choose knowing which one you are signing up for.

The steel, meanwhile, will need nothing. That asymmetry is worth planning around: we detail so that timber elements can be refinished, or replaced outright, without cutting the metalwork apart.

Who Supplies the Timber

On most wood-and-metal jobs the timber comes from somewhere other than the metal shop — a millwork supplier, a slab yard, the client’s own material, or a piece already in the house. Deciding that early changes everything downstream: who is responsible for the moisture content, who machines it, who finishes it, and who takes the risk if it moves after installation.

The cleanest arrangement is usually that the timber is supplied and finished by whoever specialises in it, and the metal is fabricated to receive it. That keeps each responsibility where the expertise is, and it avoids the situation where a steel frame is built to a drawing and a slab arrives 4 mm out of it.

How the Two Materials Are Actually Joined

Through-bolting or countersunk machine screws from below into threaded inserts — the most reliable and the easiest to take apart later
Concealed cleats or a steel sub-frame the timber sits on and is screwed down to from underneath, so no fixings show on the visible face
Slotted holes rather than round holes wherever a run is longer than about a metre, so the timber can move across its width without splitting or bowing the frame
Adhesive alone — occasionally used on small interior pieces, but it removes any possibility of taking the piece apart and gives the wood nowhere to go
Captured details, where the timber sits in a metal channel — visually clean, but the least tolerant of movement and the hardest to service

Designing for Movement

This is the whole discipline of wood and metal. Steel is dimensionally stable through the seasons; timber is not. Wood moves mostly across the grain, very little along it, and the amount depends on the species, the width and the humidity swing in the room. A 900 mm wide slab in a house that runs dry in winter and humid in summer will move a noticeable amount across that width every year.

If the steel holds the wood rigidly at both edges, the wood does not stop moving — it cups, splits, or pulls the fixings. The fix is not stronger fixings; it is fixings that allow the movement. One fixed point, everything else slotted, and the movement runs to a free edge where nobody notices it.

Exterior Timber and Metal on the North Shore

The junction is the weak point: water sits in the gap between the two materials and stays there
Detail the metal so water drains away from the timber, not into an end grain that will wick it up
End grain is where exterior timber fails first — it needs to be sealed and it needs to be able to dry
Fasteners should be stainless outdoors; plain steel fasteners in wet timber will stain the wood black around every fixing
Exterior timber is a maintenance item on a cycle of years, so the detail should let the timber be replaced without cutting the metal apart

Finishes That Have to Live Together

The two finishes are applied at different times and by different processes, and they cannot overlap. Powder coating happens at temperatures that would destroy timber, so metal is always finished before the wood goes anywhere near it. That means any welding, drilling or modification has to be finished before coating — drilling a coated frame on site leaves a bare edge that will corrode.

It also means the sequence is fixed: fabricate, fit up dry, disassemble, coat, finish the timber separately, then assemble. Anyone compressing that sequence to save a week normally pays for it in touch-up.

Where Wood and Metal Is the Wrong Combination

Wet rooms, pool surrounds and anywhere with standing humidity
Fully exposed exterior handrails where the timber is the hand contact surface — it will need refinishing more often than anyone expects
Commercial and strata common areas where nobody owns the maintenance cycle
Any application where the piece must stay dimensionally exact, such as a close-tolerance opening or a mechanism
Rental and high-turnover interiors, where a solid timber surface will be marked long before the metal shows anything

Wood and Metal Questions We Get Asked

Can the wood be supplied to match existing floors or cabinetry?

Usually, but colour matching between a floor finish and a separate timber component is difficult and should always be approved on a physical sample in the actual room light rather than from a photograph.

Will the wood split where it is bolted to the steel?

Only if the fixings prevent it from moving. Splitting is nearly always a detailing problem rather than a timber problem — slotted holes and a single fixed point solve it.

Can timber treads be added to an existing steel stair?

Frequently, yes, and it is one of the more common requests. Whether it works depends on the existing stringer, the tread support and the finished floor level. See steel stairs.

Is a live-edge slab on a steel base a good idea outdoors?

Rarely. Live-edge slabs are interior pieces in this climate. Outdoors the slab will check, cup and grey unless it is under permanent cover and maintained on a schedule.

Free in-house consultation

We come to you, measure the site, and talk through options and budget before you commit to anything. No charge, no obligation.

Call (778) 805-5333 or email sales@trussmetal.com

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