Comparing Western Redcedar and Old-Growth Redwood
Western redcedar and Old-growth redwood are two premier Pacific Northwest conifers prized for their warm coloration, natural rot resistance, and classic grain patterns. When building custom wood and epoxy river tables, choosing between them involves balancing weight, mechanical strength, and dimensional stability. Data published by the USDA Forest Products Laboratory in the Wood Handbook (FPL-GTR-282) highlights key engineering differences between these two species.
Weight and Density
Overall table weight is governed by wood density, expressed as specific gravity. At 12% moisture content, Western redcedar has a specific gravity of 0.32, while Old-growth redwood measures 0.40. Slabs of Old-growth redwood are noticeably heavier and denser than Western redcedar slabs of identical volume. For extra-large conference tables or wide river tables where frame load and transport weight are primary concerns, Western redcedar offers a significantly lighter assembly.
Dent Resistance and Surface Hardness
Softwood slabs demand careful consideration regarding surface protection. Dent resistance is reflected in side hardness and compression perpendicular to the grain.
- Side Hardness: At 12% moisture content, Western redcedar tests at 350 lbf, whereas Old-growth redwood reaches 480 lbf.
- Compression Perpendicular to Grain: Western redcedar yields 460 lbf/in² compared to 700 lbf/in² for Old-growth redwood at 12% moisture content.
Both woods are relatively soft compared to dense hardwoods, meaning both benefit from a durable surface finish or flood coat. However, Old-growth redwood provides substantially greater resistance to crushing from tabletop hardware, heavy decorative objects, or point loads along the wood surface.
Stiffness, Strength, and Overhangs
Tabletops spanning long distances between leg bases require sufficient bending strength and stiffness to avoid noticeable deflection. In the USDA data at 12% moisture content, modulus of rupture (bending strength) is 7,500 lbf/in² for Western redcedar and 10,000 lbf/in² for Old-growth redwood. Modulus of elasticity (stiffness) is 1.11 million lbf/in² for Western redcedar versus 1.34 million lbf/in² for Old-growth redwood.
Because Old-growth redwood offers higher bending strength and modulus of elasticity, it handles wider unsupported spans and edge overhangs with less flex. In shear parallel to grain at 12% moisture content, Western redcedar tests at 990 lbf/in² while Old-growth redwood tests at 940 lbf/in², showing comparable resistance along the bond line.
Seasonal Movement and Moisture
Wood movement against cured epoxy creates stress along the interface. Both species are famous for dimensional stability, but their movement patterns differ slightly.
- Shrinkage from Green to Ovendry: Western redcedar experiences 2.4% radial shrinkage, 5.0% tangential shrinkage, and 6.8% volumetric shrinkage. Old-growth redwood exhibits 2.6% radial, 4.4% tangential, and an identical 6.8% volumetric shrinkage.
- Tangential/Radial (T/R) Ratio: The calculated T/R ratio is 2.1 for Western redcedar and 1.7 for Old-growth redwood. Redwood’s lower ratio indicates more uniform movement across radial and tangential planes, which helps reduce warping stresses.
- Dimensional Change Coefficients: Per 1% change in moisture content, the tangential coefficient is 0.00234 for Western redcedar and 0.00205 for Old-growth redwood; the radial coefficient is 0.00111 for Western redcedar and 0.00120 for Old-growth redwood.
- Green Heartwood Moisture: Freshly cut Western redcedar heartwood averages 58% moisture content, whereas Old-growth redwood heartwood averages 86%.
Decay Resistance
According to Table 14-1 of the Wood Handbook, the heartwood of both Western redcedar and Old-growth redwood is classified as Resistant to decay. This natural durability makes both species suitable for protected outdoor tables or humid environments, provided the wood is properly dried and sealed per the resin maker’s data sheet.
Figures from the USDA Wood Handbook (FPL-GTR-282), Tables 4-1, 4-3, 5-3b, 13-5 and 14-1. Clear, straight-grained specimens; real slabs vary.
| Property | Western redcedar | Old-growth redwood |
|---|---|---|
| Specific gravity (12% MC) | 0.32 | 0.40 |
| Side hardness, lbf (12% MC) | 350 | 480 |
| Modulus of rupture, lbf/in² (12% MC) | 7,500 | 10,000 |
| Modulus of elasticity, million lbf/in² (12% MC) | 1.11 | 1.34 |
| Compression perpendicular to grain, lbf/in² (12% MC) | 460 | 700 |
| Radial shrinkage, green to ovendry (%) | 2.4 | 2.6 |
| Tangential shrinkage, green to ovendry (%) | 5.0 | 4.4 |
| Volumetric shrinkage, green to ovendry (%) | 6.8 | 6.8 |
| Dimensional change coefficient, tangential (per 1% MC) | 0.00234 | 0.00205 |
| Dimensional change coefficient, radial (per 1% MC) | 0.00111 | 0.00120 |
| Green MC of heartwood (%) | 58 | 86 |
| Tangential/radial shrinkage ratio (calculated) | 2.1 | 1.7 |
| Heartwood decay resistance (Table 14-1) | Resistant | Resistant |
Which to Pick When
Neither species is universally superior; each excels in distinct design situations:
- Pick Western redcedar when keeping overall table weight low is critical, when working with slabs that require lower initial heartwood moisture content for drying, or when you prefer a lower radial dimensional change coefficient (0.00111).
- Pick Old-growth redwood when the tabletop requires higher dent resistance (480 lbf hardness), greater resistance to crushing loads (700 lbf/in²), superior stiffness across wide spans (1.34 million lbf/in² MOE), or a more balanced shrinkage ratio (1.7 T/R).
Sources
Published October 28, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: If your slabs contain live edges with sapwood, note that green moisture content in the sapwood reaches 249% for Western redcedar and 210% for Old-growth redwood, demanding extensive drying time before resin casting compared to heartwood portions. (Source: USDA Forest Products Laboratory, Wood Handbook (FPL-GTR-282, 2021).)