Moisture Management in Mass Timber Construction

Timber is a hygroscopic material. It absorbs and releases moisture to equilibrate with its environment. Uncontrolled moisture exposure can lead to a range of issues in mass timber elements, including cross-laminated timber (CLT), glued laminated timber (GLT or Glulam), nailed laminated timber (NLT), and others. Prolonged wetting may reduce structural performance and cause dimensional instability, while also creating conditions for biological growth and material degradation. Key moisture-related risks include:

Fungal Decay (Rot)

Wood-decay fungi thrive when wood moisture content exceeds the fibre saturation point (~28% Moisture Content, MC) for extended periods. In warm, damp conditions, rot can substantially erode the wood’s cellulose structure, weakening the member’s strength. Once wood has decayed, it cannot be restored; severely rotted timber typically requires replacement to ensure structural safety. Design practitioners should specify appropriate timber durability treatments or protective measures if any mass timber will face high levels of moisture (e.g. external use) to mitigate this risk.

Figure 1: Dark stains indicating the initial stages of fungal decay

Fastener Corrosion

Moisture can corrode metal connectors (screws, nails, plates) embedded in or attached to timber. Corroded fasteners lose strength and can stain the surrounding wood black (iron stain). Fastener corrosion is often irreversible on-site; severely rusted connectors must be replaced to restore capacity. To prevent this, specify durable metal finishes (galvanized or stainless steel) and avoid contact between wet timber and incompatible metals.

Figure 2: Fastener corrosion

Dimensional Changes and Cracking

Wood swells when wet and shrinks as it dries. In large timber panels and members, these moisture-driven movements can cause warping, “checking” cracks, and splits. Superficial checking is common as mass timber adjusts to ambient humidity levels, but uneven or cyclical wetting and drying can lead to excessive shrinkage/swelling that may split members or induce differential movement at connections. For example, repeated wet-dry cycles can exacerbate checking and put strain on fasteners and seals. Designers should detail connections and joint interfaces to tolerate some movement and avoid trapping moisture (which can cause differential swelling).

Mould and Surface Growth

Elevated moisture (generally wood with a Moisture Content (MC) around > ~19% for more than a week, with >80% relative humidity) can trigger mould growth on timber surfaces. Mould is typically a black or green fungal film (as distinct from algae) that feeds on sugars in the wood’s surface. While unsightly, most mould is superficial and does not structurally damage the wood. However, it poses health and safety concerns (spores can irritate occupants, and active mould on wet timber can be slippery). If wood stays damp, mould can colonise rapidly in warm conditions, so it’s critical to dry and clean affected areas. The threshold for mould is commonly taken as 20% MC. Keeping timber below this during construction is therefore a prudent target.

Figure 3: Mould on a timber ceiling

Algae and Mildew

In very wet conditions, green algae can grow on timber (often mistaken for mould). Like mould, algae growth is mostly a surface/aesthetic issue and can make surfaces slick. It indicates persistent wetness and should be cleaned off and the underlying moisture issue addressed.

Figure 4: Algae growth on a timber surface

Staining (Water, Tannin, Iron)

Staining occurs when rainwater or pooling moisture leach tannins and extractives from the wood, leaving dark discolorations on the surface. This commonly appears as dark blotches or drip marks (e.g. on undersides of CLT panels exposed to rain). Similarly, iron staining happens when steel particles (from tools, nails, etc.) react with wood tannins in the presence of water, producing blue-black stains. Tannin bleed from certain species can also stain adjacent materials. These stains are primarily aesthetic and do not affect structural capacity, but they can mar the appearance of exposed timber. Remediation often requires sanding or chemical cleaners (e.g. oxalic acid) to restore the intended finish. This is an avoidable cost with proper protection.

Figure 5: Tannin staining from timber installation

Trapped Moisture in Panels

Mass timber panels are thick and laminated, so if water does seep deep into a panel or between laminations/joints, drying can be very slow. Trapped moisture inside a CLT or glulam element can create a hidden pocket of high MC where decay can be initiated that inspectors are unable to see. Interfaces between panels (e.g. at column or wall penetrations, or under concrete toppings) are especially vulnerable to water ingress that gets “sealed in”. End grain surfaces (panel edges, cut outs, bolt holes) absorb moisture faster than flat grain, making those locations prone to deeper wetting. Without intervention, such trapped moisture can lead to mould or rot inside assemblies even after the exterior appears dry. This underscores the need for diligent sealing of joints and prompt drying of any wet areas.

Summary

Left unmitigated, these moisture issues can lead not only to structural deterioration or aesthetic damage, but also to construction delays and added costs. Wet timber may require work stoppages for drying, replacement of damaged sections, or refinishing of surfaces, all of which impact project schedule and budget. For example, extensive water staining or mould clean up can require sanding and recoating large areas of exposed wood, and severe swelling can necessitate planing or adjustment of assemblies. Proactively managing moisture avoids these costly remedies. In short, keeping mass timber dry (or promptly dried) is critical to maintain its structural integrity, appearance, and the overall construction program. 

Mass timber components are intended for use in dry service conditions, typically enclosed within the building envelope where the wood will equilibrate to around 8-14% moisture content. Structural standards limit the in-service moisture for CLT and glulam; for example, ANSI/APA PRG 320 requires that “CLT panels shall be used in dry conditions, such as covered structures where the wood’s equilibrium moisture content remains below ~16% (U.S.) or 15% (Canada), and does not exceed 19%”. In practice, this means mass timber elements are not meant to be left exposed to the weather long-term. Any exterior application must use appropriate protective finishes or treated wood, and during construction the exposure should be temporary. During construction, short-term weather exposure is often unavoidable, but it must be limited in duration and severity. Industry guidelines provide practical limits on how long mass timber can remain exposed before protection or enclosure, including:

Time Limits

A common rule of thumb is to avoid more than about 8 weeks (2 months) of full weather exposure for untreated CLT panels in any climate. Extended exposure beyond a couple of months greatly increases the risk of deep wetting, fungal growth, and surface degradation. Project sequencing should be planned to cover or enclose the timber structure as quickly as possible.

Weather Conditions

Repeated heavy rain events in short succession are especially risky. Ideally, scheduling major mass timber installation in a season with less rainfall is preferable. In wet climates or during a rainy season, additional temporary protection (tents, temporary roofs) should be used rather than allowing the wood to repeatedly soak and dry.

Adhesive and Material Ratings

Most certified CLT and glulam manufacturers use exterior-grade adhesives and bonding methods that can tolerate some wetting during construction (they are tested to resist moisture-related delamination under “wet use” conditions). This means short-term rain exposure typically will not compromise the structural glue bonds or cause delamination. However, “wet tolerant” does not mean “waterproof” - even though the adhesives won’t fail from a few wet/dry cycles, the surrounding wood can still swell, develop mould, or suffer surface damage if saturated. The products are rated for construction-phase exposure delays, but they must be protected for long-term performance.

Service Class Considerations

Design codes often categorise timber environments by Service Class or Exposure Class. Mass timber in enclosed building conditions is Service Class 1 or 2 (dry interior or occasionally damp) where CLT/GLT products are intended to perform. Service Class 3 (exterior/exposed conditions) is generally outside the scope for standard mass timber without additional measures. If a mass timber element will eventually be exposed to weather (e.g. an external canopy or soffit), it should be detailed with durable coatings, roof overhangs, or protective cladding to achieve an equivalent level of protection.

Moisture Content Limits

A critical aspect of “weather exposure limit” is how wet the wood gets (moisture content) rather than just days of exposure. During construction, it is good practice to prevent wood moisture content from rising above ~20%, even temporarily. The upper safe limit before enclosure is often set at ~18%-20% MC; above that, the timber should be dried back to an acceptable level. Many specifications require the wood to be below 15%-16% MC before enclosing it behind finishes or membranes. This ensures a margin of safety below the mould-risk threshold and allows for a degree of re-equilibration. For example, WoodSolutions Guide 53 recommends that “linings and membranes should not be installed until the timber’s moisture content can be maintained at 15% or lower”. Similarly, Canadian guidance suggests targeting ≤19% MC prior to enclosure, and ≤16% if the assembly will be covered with a low-permeance material (like a vapor-tight roofing or a concrete topping slab). In summary, never seal wet wood inside an assembly. Let it dry to the specified level to avoid trapping moisture.

Drying Window

Implicit in these limits is the need for a “drying window” if the wood does get wet. Mass timber, having substantial thickness, dries slowly. Construction schedules should allow time (or apply active drying methods) for timber to drop back to safe moisture levels following significant wetting. For example, if a panel’s moisture content has spiked to ~25% due to rain, it may be necessary to pause construction or use dehumidification until it falls to appropriate levels before closing it in. Rushing to cover up wet timber risks long-term issues.

Drying Upon Completion

When the building is complete in its weather enclosure and the HVAC systems are ready for use, take care not to dehumidify the interior quickly. Rapid dehumidifying from HVAC systems can create differential movement in timber systems, especially if the timber elements are large, and if they have moisture trapped inside. Slowly increase the use of HVAC systems keeping in mind the state of the timber elements. It is good practice to monitor moisture levels of timber elements during this process.

Ultimately, the intent is to minimise both the degree and duration of exposure. Design professionals should communicate these limits to contractors and include them in the moisture management plan. It is important to specify that timber elements be protected from rain as much as possible, and set quantitative criteria (e.g. “Max 18% MC prior to installing drywall” or a required check of moisture before sealing up). By adhering to exposure classifications and drying thresholds such as those above, it is possible to reap the benefits of mass timber construction without compromising performance through moisture damage. 

Figure 6: Rapid enclosure of a mass timber structure with exterior façade and roof installation (early in construction) to limit weather exposure - from TDG 53.

(Design tip: Consider contractual moisture limits - e.g. require the contractor to monitor and keep timber moisture below 18% MC. Many projects also designate an “allowable exposure period” in the specs, after which additional protection or drying must be implemented. Note that specific limits of moisture meters can obfuscate the data. It is best to create a broad moisture management plan.)
 

To manage moisture on site, a combination of preventative measures (often called the “3 Ds” - Deflection, Drainage, Drying) is used. The following discussion will focus on Deflection measures, i.e. keeping water off the timber using tapes, membranes, wraps, and other barriers as well as some drainage tactics. These measures form a toolkit that design and construction teams can deploy to protect CLT and other mass timber during construction:

Prefabrication Treatments

Protection can start before panels even arrive on site. Many manufacturers apply factory sealants or wraps to their products. For example, glulam beams and CLT panels are often supplied with a plastic shipping wrap. It is best to leave factory wraps in place until installation. The wrap shields the wood from incidental rain during transit and staging. If factory wrap is damaged or removed, replace it with a tarp or temporary covering immediately. Some manufacturers can also apply primer coatings or self-adhered membranes in the factory on request: for instance, a CLT floor panel might be delivered with a peel-and-stick waterproof membrane already on its top face and tape on the panel edges. This provides instant protection once the panel is installed. Where budget allows, such factory-applied membranes can significantly reduce on-site exposure (Figure 27 of TDG 53 shows an example of a vapour-permeable membrane pre-applied to CLT floor panels).

Weather-Resistive Barriers (WRBs) and Air Barriers

As soon as mass timber walls or roof panels are in place, cover exposed wood surfaces with a weather-resistant barrier. For vertical surfaces (walls, columns), a breathable building wrap (vapour-permeable membrane) is typically used. This acts as both a rain barrier and an air barrier behind the cladding. It’s important to use a vapour-permeable membrane on timber that might still have some drying to do, so that moisture isn’t trapped inside. For horizontal surfaces (floors, flat roofs), a more robust waterproof membrane (often peel-and-stick) may be used, but if it will be in place for a long duration, ensure it is vapour-open or remove it once the permanent dry-in is achieved. Do not install internal vapor barriers or impermeable finishes on wet timber - wait until the wood is at target MC (as noted earlier) so that once sealed, it stays dry.

Sealing Joints and Penetrations

Joints between timber panels are prime pathways for water ingress. As soon as panels are placed in position, cover all panel joints, gaps, and end-grain exposures with a durable tape or membrane. Use wide self-adhesive flashing tapes over floor panel seams, wall-to-floor connections, and around columns or beam penetrations. 

Figure 7: Taped seals on a timber floor

Installers often apply tape or specialty end-grain sealant to the ends of beams and the edges of floor panels. All tapes and membranes should be rated for outdoor exposure (some construction tapes degrade under UV if left for long periods, so choose tapes suitable for the required duration). Importantly, inspect taped joints regularly - construction activity can damage them. Wheeled equipment or foot traffic can peel up floor joint tape, so the site team should re-inspect and replace any compromised tapes to maintain a continuous seal.

Figure 8: End seals applied to site cut members

Temporary Roofs and Canopies

One of the most effective deflection measures is to keep rain off the structure entirely. Projects in rainy climates often use temporary roof structures or tents over the building during construction. This could be a scaffold-supported roof with tarpaulins or shrink-wrap, or a mobile roofing system that is moved up as each level is built. European projects have popularised movable big-top tent systems that can be craned into place and can be repositioned floor by floor. While a full temporary roof adds cost, it provides maximum protection essentially creating a controlled indoor environment for construction. Even on projects without a full temporary roof, small-scale canopies or rain shelters can be used over sensitive work areas (for example, tenting over a connection while applying sealant in wet weather).

Figure 9: The roof canopy of The Boot Factory - showing temporary works completely enclosing the timber structure during construction.

Figure 10: The same temporary structure housing the roof canopy at The Boot Factory, shown during construction from the outside, on Google Earth

Impermeable Covers and Tarpaulins

For short-term protection (overnight or during a rain spell), it is recommended that a tarpaulin be used to cover the the timber. Impermeable tarpaulins or plastic sheeting can be draped over floors or wrapped around beams to shed rain. It’s crucial to secure tarpaulins well (wind can blow them off, exposing the wood unexpectedly) and avoid trapping moisture underneath. Never wrap timber so tightly that condensation builds up; leave gaps for airflow under the cover. A good practice is to cover the top of horizontal surfaces but keep the sides open for ventilation, or use spacers so the tarpaulin isn’t in full contact with the wood. If water does sneak under a cover, ensure it can drain out and the wood can dry.

Drainage Provisions

No deflection measure is perfect. Some water will get through, so  it is important to design for drainage. Slope horizontal surfaces if possible or use cricket boards to avoid ponding. Where water could collect, for example on a CLT floor panel that has a ledge or in a connection pocket, drill temporary drain holes or routes for water to escape. Contractors occasionally drill small weep holes at the lowest point of a CLT floor during construction to drain rainwater that lands on it (these can be epoxy sealed later if needed). Use temporary downpipes to route water off the structure: if the permanent roof gutters aren’t already in place, attach flexible hoses or PVC pipes to edge drains so water is directed away safely. Here is an example of temporary downpipes installed to drain a mass timber building under construction.

Figure 11: Temporary downpipes installed to drain a mass timber building under construction

By combining these measures, it is possible to create layered protection. For example: a CLT floor might have a factory-applied membrane, with seams taped on-site, plus a slight slope and drain holes. If heavy rain does occur, it is possible to throw a tarpaulin over it and later use a squeegee to push water to the drains. Such a multi-faceted approach (materials + site practices) is the essence of moisture management.

Along with physical protection materials, proactive construction practices are vital to keep a mass timber project dry. Good planning and on-site habits can dramatically reduce the risk of moisture problems occurring. Key practices for design and construction teams include:

Plan for Moisture Management in the Construction Schedule

Treat moisture protection as a scheduled activity, not an afterthought. Minimise the time timber is exposed, for example by ensuring that once timber erection starts, the follow-on tasks like roofing and façade installation happen as quickly as possible. Aim to “dry-in” the structure (get it under a permanent roof and behind cladding) at the earliest opportunity. In practical terms, stage construction to limit open timber exposure to a few weeks. Also, try to time installation for favourable weather if possible (i.e, avoid erecting the timber during the wettest months of the year). If a long exposure is unavoidable, it is important to plan for temporary covering or breaks to dry the wood.

Just-in-Time Delivery and Storage

Avoid storing mass timber on site for long periods. Ideally, panels and beams arrive and get installed within days. Off-site prefabrication should be sequenced so that timber elements are delivered in the order of erection and can be lifted into place immediately. This prevents stockpiles of wood sitting through multiple rain events. When on-site storage is necessary, choose a protected location: keep timber bundles off the ground (at least 150 mm on dunnage) and on high, well-drained ground. Cover stored timber with waterproof sheeting or tarpaulins that are secured against wind. However, it is important to ensure there is air circulation under the covers to prevent trapping moisture (don’t wrap tightly in plastic in hot weather). Check underneath covers regularly for condensation or leaks. If factory packaging is intact, leave it on but monitor for any water ingress or high humidity under the wrap. (Pro tip: The site manager should monitor the relative humidity under tarps or in storage areas - if RH stays above ~80% or wood MC goes above 15% in storage, steps should be taken to improve ventilation.)

Dedicated Moisture Management Roles

Assign one of the project team (often the superintendent or a quality officer) to oversee on-site moisture protection. This person ensures that after every work day and every rain event, protective measures are in place - tarpaulins are deployed, drains are clear, water is swept off, etc. They also coordinate inspections of wood moisture. Clear communication protocols help; for example, mandate that if rain is forecast, the crew secures all coverings at day’s end. By making moisture management an ongoing responsibility, ideally as part of a daily checklist, the site team stays ahead of problems.

Rapid Response to Weather Events

When rain is imminent or starts, crews should act fast to protect the timber. Close up temporary coverings (sheet over floor openings, close windows or wrap wall sections) before a storm. After a rain event, remove standing water immediately – it is important not to let water sit on timber longer than necessary. Squeegee or vacuum up puddles on floors, empty any water that may have pooled in tarp low points or in cutouts. Pay special attention to “traps” like shaft openings or depressions (e.g. bathroom set-downs in floors) - provide temporary pumps or drilled drains in these areas so they don’t hold water. Debris management is also important: construction debris can block intended drainage paths or gutters, or can wick water against timber. Keep the site clean, and clear away any wet soggy materials leaning on timber surfaces, such as that shown in the case below where water is shown to bypass the end grain protection.

Figure 12: Water that has bypassed the end grain protection

Enclose the Structure in Stages

Rather than waiting to erect an entire superstructure before adding any cladding or roofing, consider phased enclosure. For example, after a few levels of CLT have been erected, start installing the permanent façade on the lower levels. This staged approach means portions of the timber get protected earlier. Similarly, if it’s not possible to install the roof immediately, getting a temporary membrane on the top floor deck is advisable. The mantra should be; “roof-on and walls-on ASAP.”

Use of Temporary Weather Protection

For projects where significant rainfall is expected, it is important to budget for temporary weather protection like scaffold tents, large tarpaulins, or even the rental of moveable roofs. These can be deployed when needed (e.g. the use of a large tarpaulin to cover a floor pour overnight, or tenting over an entire roof in progress). The cost of renting a scaffold cover can often be justified by the reduction in rework from water damage. If a full temporary roof isn’t feasible, try to protect critical components: for instance, wrap column tops with plastic so they don’t act like wicks, or cover half-constructed connections at day’s end.

Drainage and Ventilation During Construction

It’s important to ensure that any permanent drainage (e.g. roof drains, scuppers, balconies) remain functional as construction progresses. Even if a roof isn’t finished, connect downpipes to any installed gutters or use temporary leaders to lead water away from the structure. Keep wall cavities or floor voids ventilated if they’re open - this helps wet timber dry out between rains. If timber gets wet, taking advantage of sunny or windy days by opening up enclosures or using fans will accelerate drying.

Successful moisture management is as much about process as products. By planning ahead (scheduling and budgeting for protection), training the site team on these practices, and responding swiftly to changes in the weather, it is possible to significantly reduce moisture ingress. A well-run mass timber project should have daily routines for checking covers and moisture, much like routine safety checks. This diligence pays off in preserved wood quality and on-time project delivery.

Practical tool: Weekly Moisture Management Meeting - Some projects institute a short weekly meeting or report focused just on moisture. The team reviews upcoming weather, checks from the past week (any wet spots, any readings taken), and plans actions. This keeps everyone aware and accountable on the topic of moisture control.

Throughout the construction process, it is crucial to actively monitor the Moisture Content (MC) of mass timber elements and verify that they remain within acceptable limits. This ensures that any wetting is detected and remedied before it can cause significant damage, and that the structure is sufficiently dry before enclosure. 

For further reading check out the page Measuring Moisture in Timber: Choosing the Right Method

Key aspects of a moisture monitoring and verification plan include:

Moisture Meter Use: Handheld moisture meters are the primary tools for checking wood moisture on site. There are two main types: resistance (pin) meters and capacitance (pinless) meters. 

• Resistance meters use two pin probes that are inserted into the wood. By measuring the electrical resistance between the pins, the device is able to calculate moisture content because wet wood conducts electricity more efficiently than dry wood. These are quick and fairly accurate for spot-checks. However, standard pins only read the surface or near-surface moisture, which can be misleading if the outer layer is drier or wetter than the core. It’s recommended to use insulated deep-pin probes (“hammer probes”) for more accurate core readings on larger scale timber. With insulated pins, only the tip measures the MC, making it possible to gauge moisture at a specific depth (e.g. 1/3 into a CLT panel).
• Capacitance meters, on the other hand, have no pins but a flat plate sensor that is used to measure the wood’s dielectric properties to estimate MC. These can scan a larger area and don’t leave pinholes, but they are sensitive to density and only measure shallow depth. Calibration is important: many meters have settings for wood species or temperature to improve accuracy, and for engineered products like CLT (with adhesives) the readings might need correction. 

Monitoring Schedule

Moisture checks should be performed at key milestones and after weather events. At a minimum, readings are typically taken: upon delivery (to establish baseline MC, usually around 12% for kiln-dried mass timber), after any major rain event (to check if the wood has absorbed significant moisture), and before enclosure/closing up. Weekly moisture logs are conducted on many projects, where a set of locations on each floor are tested and recorded. It’s recommended to monitor the most vulnerable or indicative spots - for example, the underside of floor panels, interior of connections or beam pockets, and any areas that experienced wetting. In one case study, moisture sensors were installed in a 6-storey CLT building in Sydney during construction, the CLT wall panels (which were initially exposed) reached moisture contents well above 20%, whereas protected floor panels stayed closer to 12%-15%. This illustrates how monitoring can pinpoint where moisture is an issue. If manual checking is too time-consuming, consider using wireless moisture sensors embedded in some panels - these can provide continuous data remotely (useful for long-term tracking, although still emerging in use).

Thresholds for Action

As part of verification, it’s important to define clear criteria for acceptable moisture content. Common practice is to require MC < 18% (or 15% for interior/exposed finish surfaces) before applying finishes or membranes. If readings show moisture above a threshold (say, a panel at 22% MC), this should trigger action: typically to delay enclosure of that element and implement drying measures (described below) until it falls to safe levels. In general, sustained MC above ~20% warrants concern and intervention, since that’s approaching the range where mould can germinate and where wood is no longer considered “dry” by building standards. The contract documents can stipulate a “hold point” for moisture - for example: “Before closing any timber frame section, an inspection shall be done. If any member exceeds 16% MC, drying is required and approval from the consultant is needed to proceed.”. Non-structural coverings must not be installed on damp timber and that an inspection of moisture content should be conducted with sign-off prior to closing in the structure. This ensures all stakeholders agree the timber is in good condition before it is hidden.

Active Drying and Reconditioning

Monitoring is coupled with remediation - when the meter indicates that a timber is above the stipulated level of MC it is necessary to dry it. Natural drying will occur if weather improves (warm, low-humidity air will slowly dry the wood), but it can also be necessary to accelerate the process to stay on schedule. Common drying tactics on site include deploying fans to increase air circulation, using electric heaters or heat lamps to gently warm and dry the space (electric devices are preferred over fuel-burning heaters to avoid adding moisture or fire risk), and using dehumidifiers to lower ambient humidity and draw moisture out of the wood. For example, after a wet period, it can be beneficial to close the building, run dehumidifiers and fans for a week or so to bring the overall moisture down. Targeted hot-air blowers can be used on particularly wet patches or joints to speed up evaporation. It’s important to not over-dry or dry too rapidly: blasting very hot air on one spot can cause surface checking or cupping. A slow, steady drying is best, ideally dehumidifiers to control the climate. 

• When the HVAC system is operational, it should be used in a controlled way to avoid shocking the timber with sudden heating or cooling. Gradually commission the building heating over 2-3 weeks to let the wood acclimate. Throughout any active drying, it is necessary to measure MC daily to track progress and avoid overshooting (wood around 8%-10% MC is actually too dry for indoor conditions and could lead to excessive shrinkage). The end goal is to have all timber members at a stable, moderate moisture content before they are concealed and before the building is occupied.
• Documentation and Handover: All moisture readings and actions should be documented in a logbook. This provides quality assurance to the owner that the structure was properly dried. If any areas were persistently high in moisture, it should be noted and monitored post-occupancy. Occasionally owners choose to leave a few sensors in place to continue monitoring during the building’s early life (since timber might release construction moisture into the indoor air). While not always necessary, it can be part of a robust quality strategy for important projects.

“If you don’t measure it, you can’t manage it.” Regular moisture monitoring allows the project team awareness of an invisible threat and confidence that the timber structure remains in good condition. By establishing clear MC targets (often 12%-15% at handover for interior timber) and verifying with reliable measurements, design practitioners and contractors can ensure that the mass timber structure they’ve built is not hiding a moisture problem.