Checking — the small surface cracks that develop in log furniture — is a physics problem, not a quality problem. But how bad it gets depends almost entirely on where you live and how you heat your home. This tool gives you a straight answer, by province.
Most people assume cold winters cause checking. They don't — not directly. The real culprit is relative humidity (RH), and in Canada, heated homes destroy it.
When you fire up a forced-air furnace in Alberta in January, you're heating frigid outdoor air (which holds almost no moisture) and pumping it through your house. Without aggressive humidification, your indoor RH can drop to 15–20%. That's drier than most deserts. Wood that was manufactured at 30–35% RH is suddenly equilibrating to an environment 15 percentage points drier.
Wood shrinks as it loses moisture — and it doesn't shrink evenly. The outer surface of a log dries and shrinks faster than the core. That differential shrinkage creates tension. When the tension exceeds the wood's tensile strength along the grain, it releases as a crack. That's checking.
Kiln-drying brings wood down to a target moisture content (MC%) before it's used in furniture. For furniture destined for heated Canadian homes, that target should be 7–10% MC — matching the equilibrium moisture content of a heated interior.
A kiln-dried piece starts at MC close to its final equilibrium. There's less drying left to do, so less checking occurs. But kiln-drying is not a guarantee: if the wood was dried to 15% MC for "shop dry" and then sits in your prairie home, it still needs to shed another 5–8% — and it'll crack doing it.
The question to ask your maker: "What MC% did you dry to, and what's your target for a heated Alberta home?" A good maker will know the answer. If they say "it's fully dry," ask for a number.
| Climate Zone | Typical Winter Indoor RH | Target MC% for furniture | Kiln-dried essential? |
|---|---|---|---|
| Prairie (AB/SK/MB) | 15–25% (without humidifier) | 7–9% | Yes — insist |
| Southern ON (Great Lakes) | 25–35% | 9–11% | Strongly recommended |
| Quebec (heated) | 25–35% | 9–11% | Strongly recommended |
| BC Interior | 25–35% | 9–11% | Strongly recommended |
| BC Coast | 40–55% | 12–15% | Helpful, not critical |
| Atlantic Canada | 35–50% | 11–13% | Helpful |
| Unheated cottage | Tracks outdoor (15–80% annually) | — | Less relevant; oil finish matters more |
Species matters as much as drying. Some woods are naturally more stable; others crack reliably even when well-dried.
A typical log furniture piece in a heated Canadian home will develop 2–6 surface checks in the first two winters. They run along the grain, look like the wood split slightly, and are usually less than 2mm wide and a few inches to a foot long. They may partially close in summer when humidity rises. This is normal.
What's not normal: checks that go through the log (visible on both sides), checks at joints that cause structural looseness, or checks wider than a finger. Those indicate either green wood, structural failure, or a manufacturing defect. See our full checking guide for what to flag and what to ignore.