Repair or replace? How to decide what your weatherboards need

Most people call us because a few boards have started to look tired, or a decorator has taken one look and said the lot needs coming off. The honest answer usually sits somewhere in between. Working out where a property falls on that scale is the difference between a sensible repair and an expensive job that was never really needed.

The instinct to strip it all off

There is a reflex, particularly among general builders, to take an elevation back to the frame and start again. It feels decisive. On a period property it is usually the wrong place to begin.

Original boarding is part of what the building is. Once it has gone, the slightly uneven character that comes from decades of settling goes with it, and a brand new elevation rarely sits comfortably against old brick and tile. On a listed building, removing or replacing historic fabric may require Listed Building Consent, particularly where the work could affect the building’s character. It is always sensible to check with the local authority conservation officer before work begins. None of that means keeping timber that has genuinely failed. It means looking properly before you decide.

What actually goes wrong

Timber cladding fails for one reason above all others: water getting in and not being able to get back out. Softwood weatherboarding is meant to shed rain and dry between showers. Problems start when that drying stops happening.

Paint that has hardened and cracked traps moisture against the timber. Boards sitting tight against a raised bed or a path that has been built up over the years wick water from below. A split opens at a fixing, water sits in the joint, and decay works outwards from there. You will often find the worst of it along the bottom edge of a board, at the ends where the grain is exposed, and wherever two boards meet. Those are the vulnerable points. The middle of a board can look poor and still be perfectly sound underneath, which is exactly why a blanket verdict from the ground is worth so little.

Signs worth a closer look

A few things are worth checking before you assume the worst:

• Paint lifting or flaking in sheets rather than simply dulling. That often means moisture is moving behind the finish.
• Timber that feels soft or spongy when you press it, or gives under a firm push. Sound timber feels solid.
• Dark grey or black staining that will not wash off, especially low down.
• Boards that have worked loose, sprung away from the frame or begun to cup.
• Gaps opening at the joints and at the board ends.
• Edges that crumble or feel powdery. That is advanced decay.
• A green film of algae. Worth listing on its own, because it usually means the surface is damp and shaded rather than rotten, and often a clean and repaint is all it needs.

Some of these point to a quick repair, others to something that needs opening up to understand. On their own, none of them mean the whole elevation is finished.

When repair is the right call

If most of the boarding is sound and the trouble is confined to a few clear areas, a targeted repair is often the most sensible answer and usually the less expensive one. A good deal of our work is exactly this. Loose boards are fixed back securely. Individual boards that have rotted through are taken out and renewed while their neighbours stay put. Where only the lower part of a long board has gone, we can cut out the failed section and splice in new timber matched to the profile, rather than replacing the whole length. Prepared and painted properly, those repairs disappear.

On a listed property on Bridewell Lane in Tenterden the paintwork was flaking badly and, from the pavement, it looked a big job. In the event only two boards had actually rotted through. Everything else was rubbed down, prepared and repainted, and the front door restored by hand. Caught a season or two later, that same elevation could easily have needed far more. The same thinking applied to a Grade II listed oast house near Northiam, where a number of boards on the rear elevation had rotted through. Those were renewed on a matching profile, while plenty of loose boarding was carefully fixed back and saved rather than torn off for the sake of it. This is what our weatherboard repair work is built around.

When replacement is genuinely necessary

Sometimes the timber has simply had enough, and no amount of patching will bring it back. If rot is widespread rather than local, if boards crumble along their length, if the fixings have nothing solid left to bite into, or if an elevation has reached the end of its life all at once, then replacement is the sensible course. It is also the right call where earlier repairs were done badly, with the wrong materials or over decayed timber, and the problems have carried on underneath.

Replacement need not mean the whole building. Often it is one elevation that has taken the weather while the others are fine, or an upper storey above a brick ground floor. On a house in Ticehurst the weatherboarded upper elevation had failed and was stripped, renewed where needed and repainted, while the brickwork below was left untouched. The aim is to renew what has gone and keep what has not.

Matching what is already there

When boards are replaced, matching the existing profile matters more than people expect. Get it wrong and the eye picks it up straight away, even under fresh paint. Most older Kent and Sussex properties are clad in traditional featheredge, the tapered board that sits thicker at the bottom than the top. Others use shiplap, with its rebated, slotted joint, or plain square edge boards on barns and outbuildings.

Beyond the profile there is the width, the thickness and the timber itself to think about. A replacement board a few millimetres out, or a different species that weathers at another rate, will always announce itself. When we renewed a failed fascia and several rotten boards on a listed property on The Moor in Hawkhurst, the whole point was that you should not be able to tell afterwards which parts were new.

Listed buildings and conservation areas

Listed buildings and properties in conservation areas carry an extra layer to think about, and it is one that catches owners out. On a listed building the boarding is part of the protected fabric. Repair on a like for like basis is generally the expectation, and significant replacement may need listed building consent before anyone lifts a tool. It is always worth an early conversation with the local conservation officer. They tend to be far more helpful than people fear, and it is a great deal easier than putting something right after the event.

There is a practical side too. Traditional timber boarding needs to be able to shed moisture and dry effectively. A coating system that traps moisture can contribute to decay, so the existing paint, timber condition and exposure all need to be considered before choosing a finish. It is also why stripping an old building back to the frame is so often the wrong answer. It is rarely needed, it removes historic material that cannot be got back, and a sympathetic repair usually lasts perfectly well while keeping the character intact.

How we work out what a property needs

Working out whether a property needs repair, selective replacement or more extensive renewal requires a proper inspection. Photographs can be useful for an initial conversation, but they rarely show enough to make a reliable final decision. That normally requires getting close to the timber and inspecting the vulnerable areas properly. On a site visit that is exactly what we do, rather than judging the boards from the drive. We press and probe the places most likely to have gone: bottom edges, board ends, joints and around the fixings. We look at what the paint is doing and, where we can, at what is happening behind it. We take in the setting too, whether ground levels or a blocked gutter are feeding the problem, and whether the boards can be reached safely or need scaffold.

Only then is it possible to say, with any honesty, how much genuinely needs renewing and how much can be saved. As often as not, that conversation ends with less work than the owner was bracing for.