Structural engineering for two-storey extensions in the Scottish Borders

The Scottish Borders at a glance

Nation: Scotland
Price region: Scotland
Postcode areas: EH, TD
Towns covered: 8 listed below, plus surrounding villages
Site visits: Free, no obligation

What a structural design involves

Structural engineering for a two-storey extension involves calculating how the new floors, walls and roof carry their loads down to the ground, and designing the beams, lintels, foundations and ties into the existing house to suit. The engineer's calculations and drawings form part of the a building warrant. They also tell the build team exactly what steel and foundations to install.

Towns in the Scottish Borders include Hawick (TD9), Galashiels (TD1), Peebles (EH45), Kelso (TD3), Selkirk (TD7) and Jedburgh (TD8). If yours isn't listed, we still cover it.

Fees

A structural engineer (calculations and beam design) is a guide of £750–£2,200, priced in writing once the design is known.

Rules in Scotland

In Scotland, structural calculations form part of the building warrant application, assessed against the Scottish Building Standards Technical Handbooks rather than Approved Documents. The council's building standards service must grant the warrant before any structural work starts, and a completion certificate is submitted when the work is finished.

Approval in Scotland: Householder planning application: £371. Councils have two months to decide a local planning application.

Building standards: A building warrant from the council's building standards service before work starts, and a completion certificate at the end. Scotland uses its own Technical Handbooks.

There is no Party Wall Act in Scotland. Shared walls and boundaries are governed by title deeds and common law, so we speak to neighbours early and record the condition of shared structures.

Getting the design right

Building on existing structure

When building over a garage or a single-storey extension, the engineer checks the existing footings, walls and lintels. Many were sized for one storey only and need underpinning, strengthening or replacement to carry the new floor.

Foundations for two storeys

Two storeys put more load on the ground than one, so foundations are usually deeper or wider. Clay soil, nearby trees, drains and made-up ground can all mean deeper trench fill or piles, which is why we dig trial holes before fixing the design.

How we work in the Scottish Borders

Understand the brief
At your home in the Scottish Borders we agree what you need: bedroom count, bathroom, kitchen space, and how much garden you want to keep.
Get it approved
Once you're happy with the design we submit it to the council for the Scottish Borders and deal with any questions from the planning officer.
Detail and price
Construction drawings, engineer's calculations and building warrant approval, then a written fixed price for the build.
Build it
The new structure goes up first, then we open into the house, finish inside and get the completion certificate.

Towns we cover in the Scottish Borders

Structural engineering for two-storey extensions in the Scottish Borders: questions

Can a steel beam be hidden in the ceiling?

Often, yes. A beam can sit within the floor depth so the ceiling is flat, but that may mean a deeper steel section or a different floor structure. Otherwise it shows as a downstand below the ceiling. We discuss the options with you and the engineer before the design is fixed.

How deep do foundations need to be for a two-storey extension?

There is no single depth. It depends on the soil, nearby trees, drains and the loads. On firm ground foundations may be around a metre deep, while clay near trees can need much deeper trench fill or piles. Trial holes and the engineer's design set the depth, and building standards inspects the trenches.

Do I need a structural engineer for a two-storey extension?

Almost always. Building standards needs calculations showing that the foundations, beams and walls can carry the loads of two storeys and a roof. A two-storey extension usually involves removing part of an outside wall and new steel, which needs an engineer's design.

Neighbouring areas

All extension services in the Scottish Borders · About structural engineering for two-storey extensions