Building regulations for two-storey extensions in Cardiff and the Vale of Glamorgan
Planning an extension in Cardiff and the Vale of Glamorgan? This is how our building regulations service works, with the Wales rules and typical fees.
Cardiff and the Vale of Glamorgan at a glance
- Nation
- Wales
- Price region
- Wales
- Postcode areas
- CF
- Towns covered
- 10 listed below, plus surrounding villages
- Site visits
- Free, no obligation
What a building regulations application involves
This service suits every two-storey extension, because each one needs building regulations approval wherever you live in the UK. You get technical drawings and a specification coordinated with the structural engineer, a full plans application, site inspections arranged at each stage, and the completion certificate you will need when you sell. We manage the process, and the work is carried out by vetted teams working under S&K.
Towns in Cardiff and the Vale of Glamorgan include Cardiff (CF10), Barry (CF62), Penarth (CF64), Llantwit Major (CF61), Whitchurch (Cardiff and the Vale of Glamorgan) (CF14) and Rhiwbina (CF14). If yours isn't listed, we still cover it.
Fees
Technical drawings and specification are a guide of £1,500–£4,000. The council's building control fee depends on the value of the work; we confirm every fee in writing before the design stage starts.
Rules in Wales
In Wales, building regulations approval follows the Welsh Approved Documents, which differ from England's in places, notably Part L for energy efficiency. Approval comes from the council's building control service or a registered approver. The structure, fire, ventilation and drainage checks are broadly similar, with a completion certificate at the end.
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
Full plans and inspections
Full plans approval checks the design before work starts, which we recommend for two-storey extensions. Building control then inspects key stages, such as foundations, damp-proofing, drainage and insulation, before issuing the completion certificate.
How we work in Cardiff and the Vale of Glamorgan
Look at the house
We start in Cardiff and the Vale of Glamorgan with a free visit: measurements, photos, a look at the loft and drains, and a frank chat about budget.
Choose the approval route
Some designs fit permitted development, most need a householder application. We decide which applies in Wales before drawing in detail.
Engineer it
Foundations sized for two floors, steels for any openings, and building control approval, all before anyone starts on site.
On site
One project lead runs the job, keeps you updated and arranges inspections at each stage until completion.
Towns we cover in Cardiff and the Vale of Glamorgan
- Cardiff
- Barry
- Penarth
- Llantwit Major
- Whitchurch (Cardiff and the Vale of Glamorgan)
- Rhiwbina
- Llandaff
- Dinas Powys
- Thornhill
- Rhoose
Building regulations for two-storey extensions in Cardiff and the Vale of Glamorgan: questions
Do I need building regulations if I have planning permission?
Yes. Planning permission and building regulations are separate. Planning covers what the extension looks like and how it affects neighbours; building regulations cover how it is built and whether it is safe, warm and healthy. A two-storey extension needs both, unless permitted development replaces the planning part.
What is a build-over agreement?
A build-over agreement is permission from your water company to build over or near a public sewer. Many rear extensions sit near shared drains, and the water company will want access protected and the pipe checked. We check sewer records early so the agreement does not delay the start.
Neighbouring areas
- Building regulations for two-storey extensions in Mid Glamorgan
- Building regulations for two-storey extensions in Gwent
- Building regulations for two-storey extensions in Somerset
- Building regulations for two-storey extensions in Bristol
All extension services in Cardiff and the Vale of Glamorgan · About building regulations for two-storey extensions
Ready to see what a second storey could do for your home?
Book a free site visit. We'll look at your house, talk through options and explain the approvals you'd need, then price the design stage in writing.