Choosing Exterior Timber: Why Species Matters
Selecting the wrong timber for an outdoor project — decking, cladding, gates, garden furniture — can mean premature rot, costly replacement, and a finish that never looks right. Three species regularly stocked by Irish timber merchants cover a broad range of budgets and performance levels: White Deal (Scots Pine) and Iroko. Here is how they compare.
White Deal (Scots Pine)
White Deal is a European softwood and the most affordable option of the three. In its natural state, it sits in Durability Class 4–5 (slightly to not durable) — meaning it requires preservative treatment for any exterior use. Pressure-treated or tantalised White Deal is widely used for fencing, structural framing, and shed cladding where appearance is secondary to function.
- Durability (untreated): Class 4–5 — requires treatment
- Workability: Excellent — easy to saw, nail, and plane
- Finish: Accepts paint, stain, and preservative readily
- Best for: Treated fencing, roofing battens, structural exterior framing
- Typical cost: Lowest of the three
Tip: Always specify tantalised or pressure-treated White Deal for ground-contact or exposed applications.
Iroko
Iroko is a West African hardwood often used as a cost-effective alternative to Teak. It falls in Durability Class 2 (durable to very durable) and is suitable for exterior joinery without treatment in most climates. It is a popular choice for window boards, external cills, garden furniture, and boat decking.
- Durability (untreated): Class 2 — durable, suitable for exterior use
- Workability: Good, though interlocked grain can cause tearout; keep blades sharp
- Finish: Weathers to a silver-grey without oil; apply teak or decking oil to maintain a warm brown tone
- Best for: External window boards, garden furniture, gates and decking
- Typical cost: Mid-range — significantly less than Teak
Tip: Iroko can cause skin sensitisation in some individuals — wear gloves when machining.
Side-by-Side Comparison
| Property | White Deal | Iroko | |
|---|---|---|---|
| Durability Class (untreated) | 4–5 | 2 | |
| Treatment required? | Yes | No | |
| Workability | Excellent | Good | |
| Typical finish | Paint/stain / preservative | Oil or natural weathering | |
| Relative cost | Low | Mid |
Which Should You Choose?
For structural or utilitarian exterior work where budget matters, pressure-treated White Deal is the practical choice. For exterior joinery, decking, and garden furniture where you want natural hardwood performance at a reasonable price, Iroko delivers excellent durability and attractive grain.
If you are unsure which species is in stock or need a specific dimension, contact the Strahan Timber team — we can advise on current availability and cut-to-size options.