Full technical guide: read our structural engineer’s guide to moisture management in mass timber and CLT — covering safe moisture-content thresholds, the Construction Stage Moisture Control Plan, monitoring methods and the standards.
Cross-laminated timber (CLT) is hygroscopic. Sustained elevated moisture content leads to fungal decay, loss of structural capacity and, in extreme cases, catastrophic failure. Moisture monitoring exists to detect this before it becomes structural.
Why CLT needs monitoring
During construction, panels are exposed to weather. Once enclosed, CLT should dry back to an equilibrium moisture content of 8–12%. Waterproofing defects, missing AVCLs, or incorrect vapour barriers cause moisture to accumulate — invisibly, behind finishes — and the damage can progress for years before it becomes obvious.
How moisture monitoring works
Embedded sensors at high-risk locations measure moisture content, temperature and (in some systems) relative humidity. Data is transmitted wirelessly to a cloud dashboard. Live and historical readings sit alongside threshold alerts that flag changes before they become defects.
The systems we specify can run unattended for the full warranted life of the building — typically 20+ years on a single battery.
Where sensors should be placed
- Beneath the roof waterproofing
- At panel-to-panel junctions
- At service penetrations
- At interfaces between CLT and concrete, steel or masonry
- At exposed end-grain
Vector designs the layout to match the waterproofing strategy and the construction programme, and documents sensor positions in the as-built record.
When to install
The right moment is during construction, before panels are covered. Retrofit installation is possible — and often valuable — but the cost is higher and the sensor positions are constrained by what is already concealed.
What monitoring tells you
- Whether construction moisture is drying down as expected
- Early warning of new moisture ingress before structural damage occurs
- A long-term, defensible dataset for insurers, funders and warranty providers
The Vector position
We are independent. We are not tied to any sensor manufacturer. We specify what works for the building — not what generates the highest margin for an installer.
If you’re delivering a CLT project, talk to Vector about a monitoring strategy.