Timber cladding brings a natural warmth, texture, and enduring elegance to the outside of a home. It helps create an appealing, natural, organic connection with its surroundings, while also providing durability, versatility, and sustainability.
However, over time, poor installation and lack of maintenance can cause timber cladding to fade, and ugly, unwanted streaks appear around fixings. Here we look at the reasons why timber cladding spoils, suggestions for fixing them, and expert tips to help protect and maintain it for a longer life.
Tom Barnes heads up Vastern Timber, a family owned company that manufactures oak beams, timber cladding and hardwood flooring.
Reasons why timber cladding gets ruined
There are several reasons timber cladding gets spoiled. Some are mistakes in the fitting, whilst others are nature taking its course. The type of problem is a good indicator of the issue.
Article continues belowTom Barnes, managing director of Vastern Timber, shares one of the most common problems: ”The most common culprit is the fixings. Galvanised or zinc-plated nails and screws are not designed for external timber.”
He adds, “Once moisture gets through the protective coating, corrosion begins. That corrosion reacts with the natural tannins in the wood, leaving dark streaks running down from every fixing point.”
Another common reason is a lack of maintenance and nature taking its course. Barnes says, “Greying is a different matter entirely. Left untreated, timber weathers naturally to silver-grey.” He adds, “In polluted areas or on north-facing elevations, the boards may darken to black rather than grey. That is not a failure. It is timber doing what timber does outdoors.”
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The best fixings for timber cladding
Choosing the wrong fixing is a common cause of ugly, unwanted streaks, so it's essential to use the right one. Martin Dooley, carpentry specialist and the founder of MD Carpentry Workshop, says, “There’s no shortcut here. People try to save money with galvanised nails, but you risk cracking the protective zinc coating. Once that's breached, the nail rusts and the wood gets stained.”
To make sure this doesn’t happen, Barnes says, “Always use stainless steel. A2 grade for most exterior environments, A4 for coastal or high-exposure locations.” He explains why, “Stainless steel does not corrode and does not react with tannins. It costs a little more than galvanised, but compared to the cost of the timber and installation, it is a small price to pay.”
Martin Dooley is a carpentry expert and the director of MD Carpentry Workshop. With decades of experience, he specialises in all aspects of carpentry, from bespoke staircases to complete home renovations.
Does it make sense to replace fixings?
Replacing fixings is an option to help ensure they don't cause any further damage. However, it's not always a viable or sensible option, explains Barnes, “Removing fixings from installed cladding is risky.”
He adds, “If the boards have been nailed rather than screwed, recovery is unlikely. The boards will split during extraction and will need to be replaced entirely.”
However, the real issue isn’t replacing the fixings, but the timber itself continues, Barnes, “The bigger problem is that by the time staining appears, the damage runs through the full depth of the board. The tannin reaction is not surface-level.”
How to replace fixings on timber cladding
If you decide that replacing fixings is the way forward for your timber cladding, there are a few options available. But it is worth noting that this isn’t a quick or easy job and can be risky.
However, if you do want to go ahead, Dooley suggests one approach: “Don't try to yank out with a claw hammer, you'll crush the wood fibres and leave a scar.” He adds, “I use a 'punch-and-fill' method. Drive the old nail about 5mm deeper into the batten using a pin punch and fill the hole.”
Once this has been done, Dooley says, “Place your new stainless steel screw (or nail) slightly above or below the original hole.” However, he warns, “It’s a tedious job, but it can save the face of the timber.”
Restoring timber cladding
How you restore timber cladding will depend on the state of the wood, Barnes says, "For heavy staining, oxalic acid is the most effective treatment for drawing out discolouration from the surface of the wood."
He adds, "For deep staining, expect improvement rather than full restoration. Once timber has been in contact with the wrong fixings, it has been permanently altered. Your best outcome is cosmetic improvement, not a return to new."
However, for lighter marks, Dooley says, "I always recommend a wood reviver power gel. You apply it to the damp wood, scrub it with a stiff nylon brush, and it chemically lifts the greyed cells and neutralises the black iron stains."
He adds, "After a gentle rinse, the wood looks raw and fresh again. That’s your window to apply a high-quality UV oil to stop the cycle from starting over.”
Barnes adds, "For lighter marks, Osmo Wood Reviver Power Gel is worth trying. Allow whatever product you use to dry fully before assessing what remains. "
Ideally, you want to avoid sanding if at all possible. However, if needed Buckley says, "Only use light sanding if the surface is rough or uneven, not as a first step." A fine sandpaper grade (120 grit) is typically a good choice. Remember to feather the edges for a smooth finish.
5 tips to maintain timber cladding
Prevention is better than repair, so maintenance is critical to keep your timber cladding looking good. Here, the experts offer some smart tips.
1. Deal with issues early
Joe Buckley, Director of Heritage Joinery Solutions, says, “Keeping airflow behind the cladding and dealing with small issues early is what really extends its lifespan, rather than waiting until the damage is obvious."
Joe is the founder and driving force behind Heritage Joinery. He is passionate about preserving the timeless beauty of traditional timber architecture while delivering quality and craftsmanship that stands the test of time.
2. Keep it clean
Barnes recommends regular cleaning: “The single best thing you can do is clean your cladding with a wood reviver every one to two years. It keeps the surface in good condition and deals with any discolouration before it takes hold."
3. Avoid pressure washers
While using a pressure washer may seem like a good idea its not recommended. Barnes says, “They can damage the surface of the wood and leave unsightly patterns that are difficult to reverse.” Dooley suggests what you should do instead: “A garden hose and a soft brush are all you need for a yearly clean.”
4. Protect bottom of cladding
The base of the boards, nearer the ground, needs more attention. Dooley says, "It takes the most abuse from rain bouncing off the ground. Give this area an extra coat of protection every couple of years.”
Barnes adds another smart move, “Keep plants clear of the base of the boards. Ivy and overgrown borders hold moisture against the lower courses, and the timber never dries out properly between wet periods.”
5. Protect the end grain
The end grain of timber cladding is more vulnerable and therefore needs extra protection. Dooley says, “Make sure the end grains are heavily sealed with a wax or end-grain protector to prevent splitting and rot.”
FAQ
How long should timber cladding last?
Several factors affect the longevity of timber cladding. However, if installed and maintained correctly, it should last for decades, as Joe Buckley shares, “Well-installed timber cladding should last 40 to 60 years, but the type of wood makes a big difference."
Buckley continues, “Hardwoods like oak or larch tend to be more durable and weather-resistant, lasting up to 60 years. Softwoods such as pine or spruce require proper treatment to achieve a similar lifespan.”
Without treatment, the lifespan can be severely reduced. “Typically, they'd last only 15 to 25 years unless they’re pressure-treated and maintained regularly, which can extend them closer to 30 to 40 years.”
Tom Barnes reinforces the point, “Installed correctly with stainless steel fixings and proper ventilation, timber cladding is a long-term investment.” He adds, “Larch, British cedar and sweet chestnut will last at least 30 years. More durable options, such as Canadian cedar and Brimstone, will last as long as 60 years.”
And it's not always the timber that is the weak point, “Where cladding fails sooner, it is almost never the timber itself. In our experience, it comes down to the battening system or the wrong fixings”, shares Barnes.
He also suggests an alternative, “If you want maximum longevity with minimum maintenance, Brimstone cladding is worth a serious look. It is the specification choice for people who want to fit it and forget it.”
If you are looking to add new timber cladding or replace your old timber cladding, check out our timber cladding ideas for inspiration. An alternative to standard timber cladding is shou sugi ban, a traditional Japanese wood-burning technique that creates a dramatic black finish. To find out how much you can expect to pay for timber cladding (and other cladding options) in our house cladding costs guide.
