C16 vs. C24 Treated Softwood – Which Should You Choose? (The Ultimate Guide for Builders & DIYers)

 

🔍 Quick Answer: C16 or C24 – Which is Best for Your Project?

If you need cost-effective timber for general construction, go with C16 treated softwood.
If you need stronger, more durable timber for heavy loads, choose C24 treated joists.

But there’s much more to consider! This guide will break down:
✅ Key differences between C16 & C24 treated timber
✅ Best uses for each grade (with real-world examples)
✅ Where to buy high-quality C16 & C24 timber in the UK
✅ Pro tips to avoid costly mistakes

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🏗️ What’s the Difference Between C16 & C24 Treated Softwood?

1. Strength & Load-Bearing Capacity

Grade	Bending Strength	Use Case
C16	Moderate	Floor joists (light loads), stud walls, roofing
C24	High	Heavy-duty flooring, beams, structural projects

🔹 C16 – Good for most residential projects (e.g., garden sheds, partition walls).
🔹 C24 – Best for commercial builds, long spans, and heavy loads.

2. Knots & Appearance

• C16 has more knots and imperfections (still structurally sound).

• C24 has fewer defects, making it cleaner & stronger.

3. Price Comparison

💰 C16 is cheaper (ideal for budget projects).
💎 C24 costs ~15-20% more but lasts longer under stress.

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🔥 Current Trends in Timber Selection (2024 Insights)

✔ More DIYers are choosing C24 for future-proofing their builds.
✔ Sustainable sourcing matters – W. Hanson’s home-grown KD (kiln-dried) timber is trending.
✔ Treated softwood demand is rising due to rot resistance & affordability.

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🏆 Best Uses for C16 & C24 Treated Timber

✅ When to Use C16 Treated Softwood

✔ Garden sheds & outbuildings
✔ Internal stud walls (non-load-bearing)
✔ Roof rafters (for smaller spans)
✔ Fencing & decking frames

✅ When to Use C24 Treated Joists

✔ Floor joists (especially for upstairs floors)
✔ Heavy-duty beams & lintels
✔ Long-span structures (e.g., garage roofs)
✔ Commercial projects (higher safety requirements)

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⚠️ Common Mistakes to Avoid

❌ Using C16 for heavy loads → Risk of sagging over time.
❌ Skipping treatment → Untreated timber rots quickly outdoors.
❌ Buying from unreliable suppliers → Poor-quality timber fails faster.

Pro Tip: Always check for BSI certification when buying C16/C24 timber.

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🛒 Where to Buy C16 & C24 Treated Timber in the UK

1. W. Hanson – Top Recommended Supplier

🔹 Why Choose Them?

• Premium C16 & C24 treated softwood (kiln-dried for stability).

• Home-grown timber (sustainable & high-quality).

• Competitive trade prices & fast UK delivery.
  📍 Shop Now:

• C16 Treated Softwood

• C24 Treated Joists

2. Other Reliable Suppliers

✔ Travis Perkins (good for bulk orders)
✔ Jewson (wide range of treated timber)
✔ Selco Builders Warehouse (budget-friendly)

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🔧 Actionable Tips for Builders & DIYers

1️⃣ For garden projects → C16 is sufficient (saves money).
2️⃣ For house extensions → Invest in C24 for safety.
3️⃣ Always use treated timber outdoors → Prevents rot.
4️⃣ Check moisture content → Kiln-dried (<20%) is best.

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❓ FAQs – C16 vs. C24 Treated Timber

Q: Can I mix C16 and C24 in the same project?

A: Yes! Use C24 for load-bearing parts and C16 for non-structural areas.

Q: How long does treated softwood last outdoors?

A: 15-25 years if properly maintained.

Q: Is C24 worth the extra cost?

A: For heavy loads, YES – it prevents future repairs.

Q: Where’s the cheapest place to buy C16 timber?

A: W. Hanson offers great prices for quality-treated softwood.

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🎯 Final Verdict: Which Should You Choose?

• Pick C16 if you need affordable, general-purpose timber.

• Choose C24 if you need stronger, longer-lasting joists.

👉 Ready to buy? Check out W. Hanson’s treated timber range today!