"And how long will it last?" — that is one of the first questions we hear about a CLT house. It is understandable: many people associate timber with fence boards turning grey over time or a rotting pergola. An engineered timber structure, however, is in a completely different position: covered, protected and dry — and that is precisely the key to its durability.
Timber's enemy is not time, but persistent moisture
Timber kept in a dry, well-ventilated place survives for centuries — as countless old church roof structures and log houses prove. The problem is a persistently high moisture content, because that is what creates favourable conditions for fungi. Durability therefore does not depend on how "strong" the wood is, but on keeping the structure dry.
1. Protection starts during construction
CLT panels arrive from the factory made of kiln-dried timber with a controlled moisture content. During construction, care must be taken that they do not stand in the rain for long and that the structure becomes weathertight as soon as possible. This is where prefabrication really pays off: since assembly takes days, the panels are exposed to the weather only briefly.
- Temporary membrane covering on floors and the roof.
- Protection of panel ends and joints during assembly.
- Moisture measurement before finishes and closing up.
2. Constructive timber protection — by design, not by chemicals
Modern timber construction protects wood primarily through design measures: the plinth raises the walls sufficiently above ground level, waterproofing separates the timber from the concrete, the roof and eaves keep rain away, and the ventilated cavity behind the façade makes sure that any moisture that does get in can escape.
That is why we always stress that the durability of a CLT house is decided at the junctions: in the details of the plinth, window installation, roof connection and wet rooms. These should not be improvised on site but defined precisely in the construction drawings.
3. Wet rooms and building services
In bathrooms and kitchens, CLT walls and floors receive a proper waterproofing system beneath the finishes, and service pipes preferably run in accessible installation walls. A leak can thus be spotted and repaired quickly, before it causes damage.
4. What about insects?
Kiln-dried timber produced under industrial conditions is far less attractive to insects than wet, untreated wood. Correct detailing — dry timber, closed and lined surfaces, protected junctions — is the best defence here too.
Maintenance while you live in it
A CLT house needs about as much maintenance as a conventional one — the only difference is that the path of water deserves particular attention:
- Clean gutters and downpipes once a year.
- Inspect the roof and flashings after major storms.
- Renew the finish of a timber façade according to the manufacturer's recommendation.
- Check the silicone joints in wet rooms.
So, the answer
A well-designed and carefully built CLT building has a lifespan comparable to that of conventional structures. The condition is the same as for any good building: careful design, disciplined execution and regular, simple maintenance. That is why we keep design and construction in one hand — under general contracting we are also accountable for the details that determine durability.
If you are curious about the basics of the technology, read our introductory article on CLT.
