Serious Chemistry: Kiln Dried Before Treatment (KDBT) Lumber
Understanding Kiln Dried Before Treatment (KDBT) Lumber
TL;DR:
BarrierBoss is excited to announce we have made the switch to KDBT lumber. Customers can still expect the same beautiful honey-brown colour our treated lumber has always had, as well as celebrate a wood whose processing allows it to withstand weather even better.
The Process Behind the Product
Traditional pressure-treated lumber follows a straightforward path: wood gets immersed in liquid preservatives within a pressure chamber, forcing chemicals deep into the wood fibers. But KDBT lumber takes this process one crucial step further.
Before pressure treatment with chemicals, KDBT lumber enters a controlled kiln environment. Here, carefully managed temperatures and strategic stacking create optimal airflow between boards, ensuring uniform drying throughout. This additional step removes up to 80% of the moisture content—a dramatic reduction that transforms the lumber's performance characteristics.
It's Science!
While KDAT (kiln-dried after treatment) boasts proven advantages for lumber, KDBT (kiln-dried before treatment) relies on proven chemistry principles to achieve optimal results. When lumber is kiln-dried first, treatment will actually permeate deeper into the wood fibres in the pressure chamber; the dried wood fibres pull the treatment in.
Green wood still “remembers” how it behaved as a tree. Its fibres were trained to move water from the roots to the outer layers. When cut into lumber, even though the wood has stopped growing, the fibres continue to act in the same way—pushing moisture outward rather than storing it.
To put it technically, if you treat material first then put it through the kiln, you negate absorption efficacy. There may be substantial pieces of board that do not make the grade. In some cases, longer kiln cycles are required to deal with higher moisture impregnation. The process causes distress on the fibre as it dries, resulting in cell collapse, and this is why wood boards shrink or swell, adjusting to the humidity of a new environment.
Instead, because of kiln-drying before treatment, our workshop, and, hence, our customer, gets the most suitable fibre for their BarrierBoss panels.
Why KD Treated Lumber Outperforms Traditional Treated Lumber
The benefits of this enhanced drying process extend far beyond simple moisture reduction:
Dimensional Stability: The controlled drying process dramatically reduces cupping, warping, checking, and shrinking that plague traditional treated lumber.
Superior Workability: Handling, cutting, and planing become significantly easier.
Tool-Friendly Properties: Drilling and sawing operations proceed smoothly without the resistance common in green lumber.
Critical Applications Where KDBT Excels
Decking Solutions
Perhaps nowhere is KD lumber more valuable than in composite decking applications. Traditional pressure-treated substructure creates ongoing problems as joists shrink, cup, and warp during their natural 8-month drying period. This movement causes deck boards to twist and warp, leading to customer complaints and expensive callbacks.
KD lumber eliminates these issues by arriving already stabilized, with minimal tendency toward shrinking, warping, or cupping.
Versatile Project Applications
KD Lumber can be used comprehensively in a wide variety of cases:
- Deck construction (boards, rails, joists, posts)
- Pergola frames
- Fencing systems
- Marine construction and boardwalks
- Flatbed trailer construction
- Storage shed framing
Chemical Treatment Overview
Micronized Copper Azole (MCA): The current preferred treatment, offering versatility across above-ground, ground contact, and freshwater applications while providing a more environmentally conscious copper-based preservation system.
Maintenance Considerations
Both KDBT and traditional treated lumber require periodic maintenance—typically sanding, cleaning, and re-staining every two to five years, depending on climate exposure and stain quality. However, KDBT's superior dimensional stability means fewer structural issues and repairs over time.
Economic Analysis
KD lumber can go for 15-25% over traditional wet treated lumber, reflecting its specialty processing requirements. This pricing is extremely favourable due to its delivery of significantly better performance than commodity green lumber.
The investment pays dividends through reduced callbacks, fewer structural problems, and immediate project completion capabilities—factors that often justify the initial cost difference for both contractors and property owners.
