Safe equilibrium moisture content targets for furniture, flooring, exterior, and structural timber.
| Application | Target MC | Notes |
|---|---|---|
| Fine furniture (heated interior) | 6–8% | Critical — even small movement can rack joints or crack panels |
| Kitchen & bathroom cabinets | 7–9% | Slightly higher tolerance; face grain panels should be≤ 8% |
| Interior doors & frames | 6–8% | Must be stable before hanging — otherwise doors won't close properly in summer |
| Interior trim & moulding | 6–8% | Paint-grade can tolerate 9%; stain-grade must be fully dry |
| Hardwood flooring (solid) | 6–9% | Acclimate 3–7 days on-site before installation |
| Hardwood flooring (engineered) | 6–9% | Less sensitive to MC than solid; follow manufacturer guidance |
| Application | Target MC | Notes |
|---|---|---|
| Exterior doors & window frames | 9–14% | Pre-prime all surfaces including end grain before installation |
| Exterior decking | 12–15% | Leave expansion gaps — decking will swell and shrink seasonally |
| Exterior siding & cladding | 12–14% | Back-prime before nailing; leave 1/8″ gaps at end joints |
| Outdoor furniture | 12–16% | Use species with natural rot resistance or treat with preservative |
| Application | Target MC | Notes |
|---|---|---|
| Structural framing (studs, joists) | <19% | Building codes require ≤19%; kiln-dried (KD) framing is≤ 19% by definition |
| Timber frame & post-and-beam | <18% | Green timber is often used deliberately — joints are cut large and tighten as wood dries |
| Glulam & engineered lumber | 10–14% | Manufactured at controlled MC; store dry |
| Application | Target MC | Notes |
|---|---|---|
| Musical instruments | 6–8% | Extremely sensitive — a single humidity spike can crack a guitar top |
| Boat building (hull planking) | 12–15% | Traditional carvel planking swells to seal seams; cold-moulded uses epoxy at lower MC |
Wood naturally gains or loses moisture until it reaches equilibrium moisture content — the MC at which it neither absorbs nor releases water for a given temperature and relative humidity. In most of the US, indoor EMC ranges from 6–9%.
Rule of thumb: acclimate lumber in the room or environment where it will live for at least 48–72 hours (and up to 2 weeks for thick stock) before machining. Measure MC with a pin or pinless moisture meter before cutting joinery.
A 1% MC change causes roughly 1% dimensional change tangentially (across flat grain) and 0.5% radially. In a 12″ wide panel, that's ⅛–¼″ of movement — enough to split a glued-up panel or rack a face frame.