UK Joist Hanger Sizes & Load Ratings
Standard joist hanger sizes for 47 mm and 75 mm timber, masonry and timber-to-timber types with safe working loads.
Standard Masonry Joist Hangers (47 mm wide)
For building into blockwork or brickwork mortar courses. Minimum 100 mm bearing into masonry.
| Hanger Size (mm) | Joist Size | Safe Working Load (kN) | Typical Use |
|---|---|---|---|
| 47 x 100 | 47 x 100 | ~4.5 | Ceiling joists, light rafters |
| 47 x 125 | 47 x 125 | ~5.0 | Ceiling joists, flat roof joists |
| 47 x 150 | 47 x 150 | ~5.5 | Floor joists (short spans) |
| 47 x 175 | 47 x 175 | ~6.0 | Floor joists |
| 47 x 200 | 47 x 200 | ~7.0 | Floor joists (standard domestic) |
| 47 x 225 | 47 x 225 | ~8.0 | Floor joists (longer spans) |
Safe working loads are indicative — always check manufacturer rated capacity (e.g. Simpson Strong-Tie, BAT, Expamet).
Standard Masonry Joist Hangers (75 mm wide)
| Hanger Size (mm) | Joist Size | Safe Working Load (kN) | Typical Use |
|---|---|---|---|
| 75 x 150 | 75 x 150 | ~8.0 | Purlins, heavy rafters |
| 75 x 200 | 75 x 200 | ~10.0 | Ridge boards, trimmer beams |
| 75 x 225 | 75 x 225 | ~12.0 | Large purlins, structural beams |
Timber-to-Timber (Face Fix) Hangers
Nail or screw-fixed to a supporting timber beam or header. All nail holes must be filled for rated capacity.
| Type | Joist Widths | Fixing | Notes |
|---|---|---|---|
| Standard face fix | 38–50 mm | Joist hanger nails | Most common for trimmed openings |
| Heavy duty face fix | 47–75 mm | Joist hanger nails + bolts | Higher loads, wider joists |
| Concealed flange | 47–75 mm | Nails into concealed flanges | Hidden fixing for exposed beams |
Fixing Nails
Joist hanger nails are shorter and thicker than standard nails to maximise shear strength in the thin metal flanges. Typical sizes are 3.75 x 30 mm or 4.0 x 30 mm. Never substitute ordinary round wire nails — they do not develop the rated shear capacity.
Related Calculators
Use the Joist Span Calculator to determine joist sizes, or the UK Timber Sizes reference for standard joist dimensions.
How We Calculate This
Frequently Asked Questions
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Last updated: April 2026
All calculations are estimates. Verify with your supplier.