Second-storey addition to an existing dwelling

A first-floor addition over an existing single-storey house, used here to demonstrate how residential alteration projects are presented.

Placeholder entry. This page demonstrates the project detail layout. The project name, location, year, scope and any client attribution are outstanding and must be confirmed by the practice before publication.

Role

Structural engineer

Structural system

Timber-framed addition over verified existing footings, with steel transfer beams at removed walls

Structure type

Addition to existing dwelling

Existing structure

Verified by inspection before load was added

Stage

Design and documentation

Scope

Verification of existing footings and wall framing
Transfer beam design where walls were removed below
New floor and roof framing design
Documentation for building approval

The constraint

Adding a storey means the existing footings and walls have to carry loads they were never designed for. Assuming they can is the single most common way this work goes wrong.

Verification first

Existing footings were exposed and inspected, and the existing wall framing was checked, before any of the new structure was designed. Where capacity was short, it was addressed directly rather than designed around.

Structural approach

The addition is timber-framed to keep loads low. Where walls below were removed to open up the ground floor, steel transfer beams pick up the new load and carry it to points where a supported load path could be demonstrated.