Structural engineering for two-storey extensions in Powys

Powys at a glance

Nation: Wales
Price region: Wales
Postcode areas: LD, NP, SY
Towns covered: 8 listed below, plus surrounding villages
Site visits: Free, no obligation

What a structural design involves

This service suits every two-storey extension, because each one needs foundations sized for two storeys and usually steel beams where walls are removed. You get a structural engineer's calculations and drawings for beams, padstones, lintels, foundations and connections, coordinated with the architectural drawings, submitted for building control and followed through on site by our build teams.

Powys towns we list: Newtown (SY16), Brecon (LD3), Welshpool (SY15), Llandrindod Wells (LD1), Knighton (LD7) and Llanidloes (SY17). Every other address in Powys is covered as well.

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 Wales

In Wales, structural design is checked under the Welsh building regulations, Part A, as part of a full plans application to building control. The engineer's calculations and drawings are submitted with the architectural drawings, and the building control surveyor inspects foundations and key structural stages on site.

Approval in Wales: Householder planning application: £585. Councils normally decide householder applications within 8 weeks.

Building regulations: Building regulations approval under the Welsh Approved Documents, which differ from England's in places (notably energy efficiency).

The Party Wall etc. Act 1996 applies in Wales, so notices may be needed for work on or near a shared wall or boundary.

Getting the design right

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.

Beams and padstones

Steel beams carry the first floor and roof over openings, and they sit on padstones that spread the load into the walls. The engineer sizes each beam and checks the walls can take the point loads, which affects ceiling heights and where posts can go.

How we work in Powys

Free site visit
We visit your home in Powys, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
Detail and price
Construction drawings, engineer's calculations and building control sign-off, then a written fixed price for the build.
On site
One project lead runs the job, keeps you updated and arranges inspections at each stage until completion.

Towns we cover in Powys

Structural engineering for two-storey extensions in Powys: 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 control inspects the trenches.

Will the engineer visit the site during the build?

Not usually at every stage. Building control inspects the foundations, steelwork and other key stages against the approved calculations. The engineer is called back if site conditions differ from the design, such as unexpected ground, hidden beams or weak existing walls, and issues revised details before that part of the work continues.

Neighbouring areas

All extension services in Powys · About structural engineering for two-storey extensions