Introduction
Plywood comes in many forms — and choosing the wrong type can mean warped shelves, failed joints, or unnecessary cost overruns. Birch, poplar, okoumé, and CTBX are the four types you’ll encounter most often in woodworking, joinery, and DIY projects.
Each has a distinct density, surface quality, resistance to moisture, and price point. Birch plywood, for example, weighs around 680 kg/m³ — roughly 20% more than poplar plywood at 550 kg/m³. That difference matters when you’re building furniture, fitting out a van, or cutting a full sheet on your own.
This guide gives you a clear, data-driven comparison so you can match the right plywood to your specific project from the start.
Quick Comparison: Birch vs Poplar vs Okoumé vs CTBX
Before diving into each type, here is a side-by-side overview of the key characteristics.
| Property | Birch | Poplar | Okoumé | CTBX |
|---|---|---|---|---|
| Density (kg/m³) | 650–700 | 500–580 | 520–600 | 580–650 |
| 18mm sheet weight (kg/m²) | ~12.5 | ~9.5 | ~10.5 | ~11.5 |
| Surface quality | Excellent | Good | Excellent | Standard |
| Moisture resistance | Low–Medium | Low | Medium | High |
| Machinability | Very good | Good | Good | Good |
| Typical price (relative) | $$$ | $$ | $$ | $$ |
| Best for | Furniture, CNC, laser | Interior joinery | Marine, decorative | Outdoor, humid spaces |
Weight estimates are based on standard densities for 18mm panels at 1.0 × 1.0 m. Use the wood weight calculator to get precise figures for your sheet dimensions and thickness.
Birch and Poplar Plywood: Strength vs Weight
Birch plywood (also called Baltic birch) is one of the most used hardwood plywood grades worldwide. Its density — typically 680 kg/m³ — gives it outstanding rigidity and resistance to compression. It machines cleanly, holds screws well, and sands to a smooth finish. These properties make it the first choice for:
The downside is weight. A full 18mm birch sheet (2440 × 1220 mm) can weigh around 37 kg — a two-person lift in most cases.
Poplar plywood is significantly lighter at 500–580 kg/m³. It is produced with a softwood poplar core and offers a reasonable strength-to-weight ratio for interior applications. Van conversions and interior wall panelling are two areas where poplar is often preferred precisely because weight matters over long distances. It is less dense than birch, which means it is also easier to work by hand.
Key take-away: If your project demands rigidity and longevity — choose birch. If you need to reduce overall weight without sacrificing too much strength — choose poplar.
Okoumé Plywood: The Surface-Quality Choice
Okoumé (also spelled Okume or Gaboon) is a tropical hardwood species from Central Africa. Its plywood is prized for its reddish-pink face veneers, which are naturally smooth and require minimal sanding before finishing. This makes okoumé plywood particularly well-suited for:
Okoumé is classified as a marine-grade plywood in many countries when bonded with waterproof glue (WBP). The density ranges from 520 to 600 kg/m³ — similar to poplar but with a notably superior surface. This puts it between poplar and birch in terms of weight and cost.
One important distinction: the moisture resistance of okoumé plywood depends on the glue type, not the wood itself. Standard okoumé is not inherently waterproof. For outdoor or humid environments, you need either marine-certified okoumé (WBP bond) or CTBX (see below).
If you are planning a project that combines visible faces with a reasonable panel weight, okoumé often represents the best balance. It is also widely available in Europe in standard sheet sizes (2500 × 1220 mm, 2440 × 1220 mm) across thicknesses from 4 mm to 25 mm.
CTBX Plywood: When Moisture Resistance Is Non-Negotiable
CTBX (Contre-plaqué Traité Bois eXtérieur) is a French standard designation for exterior-grade plywood bonded with phenolic glue. The phenolic bond — also called class 3 glue in the EN 314 standard — is designed to withstand repeated cycles of wetting and drying without delaminating.
This makes CTBX the correct choice for:
CTBX is typically made with a poplar, spruce, or mixed core. Its density sits around 580–650 kg/m³. The surface finish is generally not as clean as birch or okoumé — CTBX is an engineering-grade product, not a decorative one.
One frequent mistake: using interior-grade plywood (birch or standard okoumé) in humid environments because it “looks better.” After one wet season, delamination is almost guaranteed. CTBX costs no more than mid-range birch, so there is no financial argument for the wrong choice when humidity is involved.
If you are building outdoor furniture or installing panels near a water source, CTBX is the baseline, not an upgrade.
How to Match Plywood Type to Your Project
The decision tree is straightforward once you know the key variables.
1. Is the panel exposed to moisture or outdoor conditions?
Yes → CTBX (or marine okoumé). No → continue.
2. Does the surface need to be visible and finished?
Yes → Okoumé or birch (depending on weight constraints). No → continue.
3. Is structural rigidity a priority?
Yes → Birch. For lighter builds where strength is secondary → Poplar.
4. Weight matters for transport or installation?
Birch is the heaviest. Poplar and okoumé are lighter. Use the wood weight calculator to compare specific panel weights for your sheet size and thickness before buying.
Once you have selected your plywood type and dimensions, the next step is planning your cuts efficiently to minimise waste. The Offcut panel cutting optimiser lets you enter your sheet dimensions and required pieces, then generates an optimised cutting layout — reducing off-cuts and saving material cost.
Conclusion
Birch, poplar, okoumé, and CTBX each serve a distinct purpose. There is no single “best” plywood — only the right plywood for a given project.
For interior furniture with high structural demands: birch. For lightweight interior builds: poplar. For visible, decorative applications: okoumé. For any environment involving moisture: CTBX.
The comparison table in this article gives you the core data. Before purchasing, calculate your panel weights with the wood weight calculator to avoid handling surprises on site. Then use Offcut to plan your cuts, reduce waste, and export a ready-to-use cutting plan — for free.
