Structural Requirements for Internal Alterations

What This Requirement Covers

Internal alterations that affect the structural stability of a building require Building Regulations approval and structural engineering design. Common alterations include removing load-bearing walls, creating new openings, installing mezzanine floors, and modifying roof structures.

Key Requirements

Identifying Load-Bearing Elements

1. Load-bearing walls support the weight of floors, roofs, or other walls above; they typically run perpendicular to floor joists
2. Non-load-bearing walls (partitions) carry only their own weight and can usually be removed without structural implications
3. If in doubt, always assume a wall is load-bearing until a structural engineer confirms otherwise

Removing Load-Bearing Walls

1. A steel beam (RSJ, UB, or UC section) or engineered timber beam must be designed to carry the loads
2. The beam must have adequate bearing on each side (minimum 150 mm on masonry, or padstones for concentrated loads)
3. Temporary propping must be installed before any demolition to support the structure above
4. The beam size depends on the span, the loads supported, and the deflection limits

Creating Openings in Floors

1. New openings in floors (for staircases, lifts, or services) require trimming beams and headers
2. The trimmed joists must be supported by the trimming beam, which must be designed for the additional loads
3. Steel or timber trimmers must be specified by the structural engineer

Building Regulations

1. A Building Regulations application (full plans or building notice) is required for all structural alterations
2. Structural calculations must be submitted to Building Control
3. Building Control will inspect the temporary works, the new structural elements, and the final installation

Practical Compliance Tips

1. Never remove a wall without first confirming whether it is load-bearing
2. Appoint a structural engineer before starting any structural work
3. Obtain Building Regulations approval before commencing demolition
4. Install temporary propping in accordance with the structural engineer's instructions
5. Do not overload temporary props; they must be positioned on solid supports (not on suspended floors without additional support)
6. Photograph the temporary works and beam installation for the building file
7. If the property is a flat, check the lease for restrictions on structural alterations and obtain freeholder consent