Combining wood and metal in a railing often creates a good balance between style, function, and maintenance: the metal provides a structurally stable framework, while the wood adds warmth and a more comfortable grip where the hand touches the railing.
However, these materials must be treated as two different materials. Wood swells and shrinks as its moisture content changes, while metal is significantly more dimensionally stable under the same conditions. If the wood is fastened too tightly against the metal frame, the fixings can be put under stress, causing the wood to crack and moisture to become trapped in the contact surfaces.
A durable result therefore depends on both the choice of materials and how the structure is built. The wood needs to be able to move and dry; the materials need to be joined properly; and the amount of wood should be adjusted based on how much of a “wooden feel” and how much ongoing maintenance you actually want.
Why do wood and metal expand and contract differently in a balustrade?
Wood moves primarily when its moisture content changes, while metal mainly changes in length when the temperature fluctuates. The fixings therefore need to allow the wood to move without it being tightly locked against the metal frame.
Moves when the moisture content changes
When wood absorbs or releases moisture, it swells and shrinks. This movement is greater across the grain than along the grain and must therefore be taken into account when fastening the wood component.
Moves mainly when the temperature changes
Metal expands and contracts as the temperature changes. This movement occurs differently than the movement of wood caused by moisture, which means that the materials should not be joined together as if they were one and the same material.
Allow the wood to move at the fixings
If a wooden component is securely fastened to metal at several fixed points, the wood’s natural movement can begin to put stress on the screw holes and fixings. Over time, this can lead to cracks or cause the fixings to deform.
How do you fix timber and metal together in a balustrade?
Install the components so that the wood can move, the contact surfaces can dry, and water can drain away. When wood is combined with metal in a railing, fixings, contact surfaces, screw holes, end grain, and drainage must therefore be addressed together.
Choose suitable fixings
Fixings must be suited to the type of wood, the metal, and the environment where the railing will be installed. Avoid material combinations where damp wood could affect the hardware or screws over time.
Avoid prolonged direct contact
A washer or spacer between the wood and metal can reduce direct contact while creating a small air gap that allows the surfaces to dry more effectively.
Give the wood room to move
The wood should not be clamped too tightly at each attachment point. An elongated screw hole can allow for movement as the wood swells and shrinks in response to changes in moisture content.
Protect the end grain before installation
End grain absorbs moisture more easily than other surfaces of the wood and can also be difficult to access once the component is installed. Therefore, the end grain should be treated before installation is completed.
Plan for drainage
Design the wood detail and the junction with the metal so that rainwater can run off. Avoid pockets and flat contact surfaces where water is likely to pool.
Which type of wood is best suited for an outdoor balustrade?
According to this comparison, jatoba is best suited for locations more exposed to the elements, while oak works well both indoors and outdoors, and ash is better suited for indoor use or more sheltered locations. Teak is naturally moisture-resistant but is used here only as a point of comparison.
Different types of wood also vary in appearance and maintenance requirements. An oiled surface retains its original colour longer than untreated wood, while untreated wood gradually takes on a more grayish, weathered appearance.
| Wood species | Character | Best for | Important to know |
|---|---|---|---|
| Oak | Hard and Classic | Indoor and outdoor use | Contains tannic acid, so choosing the right fixings is especially important. Outdoors, oak turns grey over time, taking on a silvery hue. |
| Ash | Light-coloured and soft | Indoor or sheltered use | It has a lighter appearance than oak but is better suited for sheltered locations than those where the wood is heavily exposed to the elements. |
| Jatoba | Dense and durable | More exposed locations outdoors | This dense wood withstands moisture better than many Nordic wood species and is therefore better suited for more exposed locations. |
| Teak * | Naturally moisture-resistant | Environments exposed to moisture | It has traditionally been used outdoors because of its resistance to moisture. Untreated teak also changes colour over time. |
How much maintenance does a wooden and metal balustrade require?
Maintenance depends primarily on what proportion of the railing is made of wood. A metal frame with wood only at the top requires significantly less ongoing maintenance than a railing where the posts or infill is also made of wood.
If the wood is used primarily in a handrail or top rail, you’ll feel the wood where your hand touches the railing, while the surface area that needs to be cleaned and treated remains relatively small.
Wood only in the top rail
When the wood is limited to top rail, the total wood surface area is small. This means fewer surfaces to clean, inspect, and treat when the wood begins to show signs of wear and tear from the weather and use.
Suitable when you want a warm grip but prefer metal to form most of the balustrade.
Wood in posts or as a filler
When a larger portion of the railing is made of wood, the surface area exposed to sun, rain, and dirt also increases. This means more parts need to be checked and maintained so that the wood retains the look you want.
Suitable when the visual appeal of the wood is more important than minimising ongoing maintenance.
The less wood the railing has, the less surface area normally needs to be maintained. Therefore, a metal frame with wood only where it serves a functional or aesthetic purpose is often the easiest combination to maintain over time.
Which combinations of wood and metal work best for balustrades?
A timber top rail on a metal frame is a good starting point when you want to bring in the warmth of wood without increasing maintenance more than necessary. Other combinations are better suited when you want a more stainless steel, open, or wood-dominated look.
The key is to let the materials serve different purposes. Wood can provide texture, warmth, and colour contrast, while metal, glass, or wire can account for most of the railing’s visual and structural character.
Timber top rail on an aluminium frame
The wood provides warmth and a more comfortable grip where the hand meets the railing, while aluminium makes up the majority of the structure. This creates a modern look with a distinct contrast in materials and a relatively small wooden surface area that requires maintenance.
Timber handrail on stainless steel
The stainless metal creates a cool, sleek look, while the timber handrail softens the overall appearance where the hand rests. This combination works particularly well on staircases and other interior railings.
Timber top rail on a glass balustrade
The glass preserves the sense of space and the view, while the wood provides a warmer finish at the top. This combination works especially well when you want to tie the railing together with a wood-clad façade, a wood floor, or other prominent wooden elements in the space.
Timber posts with metal fasteners
Here, the wood plays a much more prominent visual role, and the railing takes on a more wood-dominated appearance. At the same time, the amount of wood exposed to weather and moisture increases, which means more ongoing maintenance than when the wood is limited to the top rail.
If you want to combine a warm, natural look with minimal maintenance, using wood only in the top rail is often the simplest solution. If you want the wood to be the dominant feature of the railing’s design, you’ll also need to expect that a larger portion of the structure will require ongoing maintenance.
What should you keep in mind when combining wood and metal in a balustrade?
Above all, check where the wood will be used, how exposed the location is, and whether the materials can be joined without moisture or the wood’s movement causing problems. This will make it easier to choose a solution that works both practically and over time.
Review these six points
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Is the wood being used where it actually makes a difference?
If the primary purpose of the wood is to provide a warm grip, it may be sufficient to use it on the top rail or the handrail. This also reduces the amount of wood surface that needs to be maintained.
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Is this type of wood suitable for this location?
Estimate how much rain, sun, and moisture the wood will be exposed to. A type of wood that works well indoors or under a roof may not be the right choice for an unprotected outdoor area.
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Are wood, metal, and fixings compatible?
Fixings and fittings should be selected with consideration for the type of wood, the metal, and the environment. Also check whether the materials should be separated with a washer or spacer.
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Can the wood move without being constrained?
Wood swells and shrinks as its moisture content changes. The fixings must therefore be designed so that this natural movement is not concentrated at screw holes and fixed points.
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Can contact surfaces and end grain dry out?
Avoid designs where moisture becomes trapped between the materials. End grain and other exposed wood surfaces must also be accessible for proper treatment and future maintenance.
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Is there a plan for future maintenance?
Before installation, consider which wood surfaces need to be cleaned, treated, and inspected. The harder it is to access the wood, the more difficult maintenance will be later on.
A good combination allows the wood to provide warmth and functionality where needed, while the construction takes into account moisture, material contact, and the wood’s natural movement. At the same time, a smaller wood surface area means less ongoing maintenance.
Would you prefer timber where you hold the rail?
A wooden " handrail " or top rail provides a warmer grip without the entire railing having to be made of wood. Our " handrails " and top rail are available in wood and metal and are custom-made to fit your project at our production facility in Ängelholm.
What do you need to know before combining wood and metal in a balustrade?
The most common questions concern how the materials should be joined, how the wood is allowed to move, and how much maintenance the combination requires. Here are brief answers to a few practical questions.
Can you combine wood and metal in the same balustrade?
Yes. This combination works well when the fixings allow for that wood moves as its moisture content changes and that the contact surfaces need to be able to dry out.
Why does wood crack when it comes into contact with metal fixing?
If the wood is tightly secured at several fixed points, its natural swelling and shrinkage can put stress on the screw holes. This can cause cracks to form around the fixing.
Do wood and metal need to be separated from each other?
A washer or spacer between the materials can reduce direct contact and create a small air gap. This gives the contact surfaces a better opportunity to dry.
Why is it especially important to protect the end grain?
End grain absorbs moisture more easily than other surfaces of the wood and can be difficult to access after installation. Therefore, it should be treated before the wood component is fully installed.
Which type of wood is best suited for an exposed outdoor balustrade?
According to the article's comparison, jatoba is better suited for locations that are more exposed to the elements. Oak works well both indoors and outdoors, while ash is better suited for indoor use or more sheltered locations.
How can you reduce the maintenance required for a timber and metal balustrade?
Limit the use of wood to those areas where it provides the most functionality or aesthetics, such as the top rail. The less wood the railing has, the less surface area normally needs to be cleaned and treated.
Where in the balustrade does wood make the biggest difference?
Wood makes the biggest functional difference at the top rail or handrail where the hand meets the railing. There, you get the warmer feel of wood without the entire structure having to be made of wood.
