RSJ Load Span Tables UK/EU 2026 – Maximum Spans for 152x127x37, 203x203x46, Universal Beams vs RSJ

Quick reference load span tables are essential for preliminary beam sizing. This comprehensive guide provides maximum safe spans for common RSJ and Universal Beam sections under various loading conditions, all updated for 2026 Building Regulations compliance.

Understanding the Tables

These tables show maximum recommended spans for various beam sizes under different uniform distributed loads (UDL). All values assume:

• Simply supported beams (resting on supports at each end)
• S275 grade steel
• Deflection limit: span/360 for floors, span/200 for roofs
• Safety factors included
• Residential/light commercial use

Important: These are guidance values only. Always obtain structural engineer verification for actual projects.

Load Categories Explained

Light Load (5 kN/m UDL):

• Typical application: Single story residential floor
• Dead load ~2.0 kN/m² + Live load ~1.5 kN/m²
• Load width: ~1.5-2m
• Examples: Small bedroom extension, single door opening

Medium Load (10 kN/m UDL):

• Typical application: Standard residential floor with moderate load width
• Dead load ~2.0 kN/m² + Live load ~1.5 kN/m²
• Load width:~3-4m
• Examples: Typical knockthrough, living room opening

Heavy Load (15 kN/m UDL):

• Typical application: Two-story loads or concrete floors
• Multiple floors above or heavy finishes
• Load width: ~3-5m
• Examples: Extension supporting floor + roof, garage with room above

Very Heavy Load (20+ kN/m UDL):

• Commercial applications, vehicle loads, multiple stories
• Concrete floors with tile finishes
• Examples: Garage with concrete floor above, commercial premises

Maximum Span Tables by Beam Size

Small RSJ Sections (152-178mm depth)

152×127×37 RSJ

Load (kN/m)	Max Span	Governing Factor	Typical Use
5	3.2m	Deflection	Light partition
7.5	2.6m	Deflection	Single door
10	2.3m	Deflection	Small window opening
15	1.8m	Strength	Very short spans only

Properties: I = 1,358 cm⁴, Z = 159 cm³

178×102×19 RSJ

Load (kN/m)	Max Span	Governing Factor	Typical Use
5	3.0m	Deflection	Lightweight internal
7.5	2.4m	Deflection	Non-structural partition
10	2.0m	Strength	Short spans

Properties: I = 1,357 cm⁴, Z = 146 cm³

Note: These smaller sections suitable only for short spans or light loads. Not recommended for primary structural work.

Medium RSJ Sections (203mm depth)

203×133×25 RSJ (Most Popular!)

Load (kN/m)	Max Span	Governing Factor	Typical Use
5	4.5m	Deflection	Light floor load
7.5	3.7m	Deflection	Typical door opening
10	3.2m	Deflection	Standard knockthrough
12.5	2.9m	Deflection	Medium opening
15	2.6m	Deflection	Heavier loads
20	2.2m	Strength	Short heavy spans

Properties: I = 2,896 cm⁴, Z = 208 cm³

Typical application: 3-4m knockthrough openings supporting single floor above

203×133×30 RSJ

Load (kN/m)	Max Span	Governing Factor	Typical Use
5	5.0m	Deflection	Long light span
7.5	4.1m	Deflection	Medium opening
10	3.5m	Deflection	Standard knockthrough
12.5	3.2m	Deflection	Heavier loads
15	2.9m	Deflection	Two-story loads
20	2.5m	Strength	Heavy loads
25	2.2m	Strength	Very heavy

Properties: I = 3,438 cm⁴, Z = 245 cm³

Typical application: Better choice than 203×133×25 for spans >3.5m or when deflection is critical

203×203×46 Universal Beam

Load (kN/m)	Max Span	Governing Factor	Typical Use
10	4.5m	Deflection	Wide flange stability
15	3.7m	Deflection	Medium-heavy loads
20	3.2m	Deflection	Heavy residential
25	2.8m	Strength	Commercial use

Properties: I = 4,568 cm⁴, Z = 410 cm³

Note: Wider flange provides better lateral stability, useful where top flange restraint limited.

Large RSJ Sections (254mm depth)

254×146×31 RSJ

Load (kN/m)	Max Span	Governing Factor	Typical Use
5	6.0m	Deflection	Long light span
7.5	4.9m	Deflection	Medium span
10	4.3m	Deflection	Typical loft conversion
12.5	3.8m	Deflection	Extension beam
15	3.5m	Deflection	Heavier loads
20	3.0m	Deflection	Heavy loads
25	2.7m	Strength	Very heavy

Properties: I = 6,572 cm⁴, Z = 354 cm³

Typical application: Loft conversions, extensions, 4-6m knockthroughs with significant load

254×146×37 RSJ

Load (kN/m)	Max Span	Governing Factor	Typical Use
5	6.5m	Deflection	Very long light span
7.5	5.3m	Deflection	Long span
10	4.6m	Deflection	Wide opening
12.5	4.2m	Deflection	Loft conversion
15	3.8m	Deflection	Two-story loads
20	3.3m	Deflection	Heavy loads
25	2.9m	Strength	Very heavy
30	2.7m	Strength	Extreme loads

Properties: I = 7,628 cm⁴, Z = 411 cm³

Typical application: Similar to 254×146×31 but better where deflection is critical or loads heavier

254×146×43 RSJ

Load (kN/m)	Max Span	Governing Factor	Typical Use
10	5.0m	Deflection	Wide opening
15	4.1m	Deflection	Heavy residential
20	3.5m	Deflection	Very heavy
25	3.2m	Deflection	Commercial
30	2.9m	Strength	Industrial

Properties: I = 8,503 cm⁴, Z = 464 cm³

Extra Large Sections (305mm+ depth)

305×165×40 Universal Beam

Load (kN/m)	Max Span	Governing Factor	Typical Use
5	8.0m	Deflection	Very long span
7.5	6.5m	Deflection	Long span
10	5.7m	Deflection	Wide opening
15	4.6m	Deflection	Heavy loads
20	4.0m	Deflection	Very heavy
25	3.6m	Deflection	Commercial
30	3.2m	Strength	Industrial
35	3.0m	Strength	Heavy commercial

Properties: I = 12,350 cm⁴, Z = 568 cm³

Typical application: Commercial premises, very long residential spans (6-8m), multiple story loads

305×165×46 Universal Beam

Load (kN/m)	Max Span	Governing Factor	Typical Use
10	6.2m	Deflection	Long span
15	5.0m	Deflection	Wide opening
20	4.4m	Deflection	Heavy loads
25	3.9m	Deflection	Very heavy
30	3.5m	Deflection	Commercial
40	3.0m	Strength	Industrial

Properties: I = 14,100 cm⁴, Z = 652 cm³

305×165×54 Universal Beam

Load (kN/m)	Max Span	Governing Factor	Typical Use
15	5.5m	Deflection	Heavy residential
20	4.7m	Deflection	Commercial
25	4.3m	Deflection	Heavy commercial
30	3.9m	Deflection	Industrial
40	3.3m	Strength	Very heavy
50	3.0m	Strength	Extreme loads

Properties: I = 16,100 cm⁴, Z = 749 cm³

How to Use These Tables

Step-by-Step Selection Process

1. Calculate Your Load:

• Determine dead + live loads (kN/m²)
• Calculate load width (m)
• UDL = (dead + live) × width

Example:

• Loads: 2.0 kN/m² (dead) + 1.5 kN/m² (live) = 3.5 kN/m²
• Width: 3.0m
• UDL = 3.5 × 3.0 = 10.5 kN/m

2. Measure Your Span:

• Clear opening width
• Add 150mm each end for bearing (= total beam length needed)

Example:

• Opening: 4.0m
• Beam length: 4.0m + 0.3m = 4.3m

3. Find Suitable Beams:

• Look in tables for load ≥ 10.5 kN/m
• Find beams with max span ≥ 4.0m

From tables:

• 203×133×25 at 10 kN/m: Max span 3.2m ✗ (too small)
• 203×133×30 at 10 kN/m: Max span 3.5m ✗ (still too small)
• 254×146×31 at 10 kN/m: Max span 4.3m ✓ This works
• 254×146×37 at 10 kN/m: Max span 4.6m ✓ Also works, more expensive

Selection: 254×146×31 is most economical option.

4. Add Safety Margin: For critical applications, choose beam with 10-15% extra capacity.

5. Verify with Engineer: Use table selection as starting point, but always get professional verification.

Special Considerations

Point Loads

If you have significant point loads (columns, concentrated fixtures), these tables may underestimate requirements. Point loads increase maximum bending moment beyond uniform load assumptions.

Rough adjustment: A point load P (kN) at mid-span creates similar effect to UDL of (1.6P/L) kN/m

Example:

• 12 kN point load at center of 5m span
• Equivalent UDL ≈ (1.6 × 12) / 5 = 3.8 kN/m
• Add this to actual UDL when using tables

Lateral Restraint

Tables assume adequate lateral restraint (top flange held by floor joists at ≤1.2m centers). Without restraint, capacity may reduce 20-50%.

Continuous Beams

If beam continues over intermediate supports rather than simply supported, capacity increases ~20-30%. These tables are conservative for continuous beams.

Cantilevers

DO NOT use these tables for cantilever beams – cantilevers require much stronger sections (approxrequire 4× the capacity).

Roof vs. Floor

Tables use span/360 deflection limit (floor standard). Roofs allow span/200, so table values conservative for roofs – you might use smaller beam.

RSJ vs. Universal Beam Comparison

RSJ (Rolled Steel Joist):

• Narrower flanges
• Lighter weight for given depth
• Better for concealed installations (easier to box in)
• Simpler designation system

Universal Beam (UB):

• Wider flanges
• Better lateral stability
• More efficient for heavy loads
• Sometimes cheaper per unit capacity

When to choose UB over RSJ:

• Long spans with limited depth
• Heavy point loads
• Limited lateral restraint
• Commercial applications

When RSJ is better:

• Standard residential work
• Easier to conceal (narrower)
• Matching existing steel sizes
• Simpler fabrication/connections

Regional Variations (UK vs. EU)

UK Standard Sections: Most tables in this article use UK designations (e.g., 203×133×25)

European IPE Sections: Common in Poland and EU, slightly different profiles

Approximate Equivalents:

• IPE 200 ≈ 203×133×25
• IPE 270 ≈ 254×146×31
• IPE 300 ≈ 305×165×40

Note: Not direct substitutes – always verify section properties if substituting.

Worked Examples

Example 1: Kitchen Knockthrough

Requirements:

• Opening: 3.5m
• Floor joists spanning 2.5m rest on beam
• Bedroom above
• Dead load: 0.50 kN/m², Live load: 1.5 kN/m²

Calculation:

• Total load: 0.50 + 1.5 = 2.0 kN/m²
• UDL: 2.0 × 2.5 = 5 kN/m
• Span: 3.5m

From tables (5 kN/m column):

• 203×133×25: Max 4.5m ✓ Works, good safety margin
• 178×102×19: Max 3.0m ✗ Too small

Selection: 203×133×25 RSJ, total length 3.8m

Example 2: Garage Header

Requirements:

• Opening: 5.0m
• Concrete floor above (potential vehicle storage)
• Dead load: 2.5 kN/m², Live load: 5.0 kN/m²
• Load width: 4.0m

Calculation:

• Total load: 2.5 + 5.0 = 7.5 kN/m²
• UDL: 7.5 × 4.0 = 30 kN/m
• Span: 5.0m

From tables: None of standard sections adequate for 30 kN/m at 5m!

Solution: Need very large section not in residential tables, or reduce span with intermediate support.

Try 305×165×54 UB:

• At 30 kN/m: Max span 3.9m ✗ Still inadequate

Final solution: Add central column to create two 2.5m spans, using 254×146×37 (30 kN/m max span 2.7m ✓)

Example 3: Loft Conversion

Requirements:

• Opening: 4.5m
• New floor joists 3.0m span
• Loft bedroom use
• Dead load: 1.0 kN/m², Live load: 1.5 kN/m²

Calculation:

• Total: 1.0 + 1.5 = 2.5 kN/m²
• UDL: 2.5 × 3.0 = 7.5 kN/m
• Span: 4.5m

From tables (7.5 kN/m column):

• 203×133×30: Max span 4.1m ✗ Just short
• 254×146×31: Max span 4.9m ✓ Good
• 254×146×37: Max span 5.3m ✓ Even better deflection

Selection: 254×146×31 RSJ (most economical) or 254×146×37 if deflection/floor feel important

Conclusion

These comprehensive span tables provide quick-reference maximum spans for common RSJ and Universal Beam sections under various loading conditions. Use them for preliminary sizing and feasibility assessment, but always engage a chartered structural engineer for final verification and Building Regulations compliance.

Key Takeaways:

• Match your calculated UDL to table columns
• Find beams with max span ≥ your required span
• Choose most economical section with adequate capacity
• Add safety margin for uncertainty
• Always get professional verification

Remember: Deflection often governs beam size for longer spans, while strength governs for heavily loaded short spans. These tables account for both criteria.

Disclaimer: Tables provided for guidance only. All beam selections must be verified by a chartered structural engineer before purchase and installation. Building Regulations compliance mandatory for all structural alterations.