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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 (mm) | Fixing | Notes |
|---|---|---|---|
| Standard face fix | 38–50 | Joist hanger nails | Most common for trimmed openings |
| Heavy duty face fix | 47–75 | Joist hanger nails + bolts | Higher loads, wider joists |
| Concealed flange | 47–75 | 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 Timber Span Calculator to determine joist sizes, or the UK Timber Sizes reference for standard joist dimensions.
Next up: related pages
Frequently Asked Questions
The hanger must match both the width and depth of your joist. For standard 47 mm wide joists, common depths are 100, 125, 150, 175, 200 and 225 mm. For 75 mm wide joists (purlins and heavy beams), the same depth range applies. The joist should fit snugly in the hanger with no more than 5 mm gap — too loose and the load will not transfer correctly.
Masonry joist hangers have a flat back plate designed to be built into blockwork or brickwork mortar joints. Timber-to-timber hangers (also called face-fix hangers) bolt or nail to a supporting timber beam or header. Some hangers are designed for both applications. Always check the manufacturer specification matches your support type.
Joist hangers used in structural applications must comply with BS EN 14545 and carry CE/UKCA marking. Building Control will check that the correct hanger type, size and fixing specification has been used. For domestic floor joists, hangers are typically a Building Regulation requirement at masonry support points.
Masonry hangers should be bedded in at least 100 mm of mortar joint and the leg folded over the top course. Timber-to-timber hangers are fixed with the nails specified by the manufacturer — typically 3.75 x 30 mm or 4.0 x 30 mm joist hanger nails. Every nail hole must be filled for rated load capacity. Never use ordinary wire nails.
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Last updated: April 2026
Verified against UK standards · estimates only, confirm with your supplier.