Structural Engineers · Cardiff
Structural Engineers in Cardiff
Need structural calculations and drawings for a loft conversion, extension, load-bearing wall removal or steel beam in Cardiff? Xponexus Engineering provides clear, buildable structural design support for homeowners, architects and builders. Share your postcode, drawings or photos and we will confirm the most suitable route for your project.
Bristol-headquartered structural engineering support for projects in Cardiff, delivered remotely with coordinated local site attendance where required.
How we help in Cardiff
Loft conversions & dormers
Structural calculations and drawings for loft conversions, dormers and roof alterations, including steel beams, joist checks and load paths.
Learn more →Extensions & renovations
Foundation, wall and roof support design for single and double-storey extensions, plus refurbishment structural checks.
Learn more →Load-bearing wall removals
Assessment, beam specification and support arrangements for opening up rooms and creating open-plan layouts.
Learn more →Steel beams, lintels & alterations
RSJ, lintel, post and bearing design for structural alterations, with calculations and practical construction notes.
Learn more →Structural engineering support across Cardiff
Cardiff’s housing is dominated by Victorian and Edwardian bay-fronted terraces, particularly through Roath, Canton and Cathays, where solid brick walls, suspended timber floors and hipped roofs all shape what is structurally possible. Closer to the centre, Pontcanna’s grander townhouses and the villas of Penarth often carry larger spans, higher ceilings and decorative masonry that deserve careful assessment before any opening-up work begins. A common question in these streets is whether a rear wall or chimney breast can be removed to create an open-plan kitchen, and the answer almost always depends on how the upper floors and roof are tied into the wall being taken out.
North of the city, areas such as Whitchurch and Llandaff mix period cottages and substantial inter-war semis, where single-storey rear extensions and loft conversions are frequent projects. Around the docks and the city centre, converted properties can introduce steel frames and party-wall considerations that need checking before works are scoped.
Wales has its own Building Regulations approved documents, and Cardiff projects are dealt with through the relevant Building Control route. We prepare information suitable for Building Control submission, tailored to the actual property rather than a generic template. Whether your home sits in CF10 or CF11 near the centre, CF14 to the north, CF23 and CF24 across the east, or CF64 around Penarth, we scope each project from your drawings, photographs and a short brief, and confirm what a site visit would add before any design work begins.
Areas we support across Cardiff
Postcode districts covered: CF10–CF11, CF14, CF23–CF24, CF64 and surrounding areas.
Typical project scenarios in Cardiff
These are typical project scenarios we support in Cardiff—not case studies. Every project is scoped individually from verified information.
Typical project scenario
Open-plan alteration in a Roath bay-fronted terrace
A homeowner in Roath wants to remove the wall between the front and rear reception rooms and open the back of the house into a kitchen extension. The key question is whether the wall carries the upper floor joists, the roof, or both, and what size steel beam with what bearing arrangement is needed. We would ask for existing layout sketches or architect’s drawings, photographs of the wall, ceilings and loft, and confirmation of any chimney breasts nearby. The output is a calculation pack with beam specification, bearing details and construction notes, ready for your builder and suitable for Building Control submission.
Typical project scenario
Loft conversion in a Canton or Cathays terrace
A mid-terrace in Cathays is being converted into an extra bedroom with a rear dormer. The common engineering question is whether the existing ceiling joists can support the new floor and how the trimmed openings and ridge support should be handled. We would need photographs of the loft structure, approximate house dimensions, and any drawings showing the intended staircase position. The expected output is a set of structural calculations and drawings covering new floor joists, steels, trimmers and bearing points for the dormer and stairs.
Typical project scenario
Rear extension to a Penarth villa or Whitchurch semi
A family in Penarth or Whitchurch is planning a single-storey rear extension with a wide corner opening and roof lantern. The recurring question is how the extension foundations, steels over the new openings and any removed section of the original rear wall work together as one load path. We would ask for the architect’s layout drawings, photos of the existing rear elevation and garden levels, and any drainage or ground information available. The output is foundation and steelwork design with calculations, drawings and practical notes your builder can follow on site.
What you receive
Structural calculations
Clear calculation packs covering beams, joists, posts, lintels and bearing checks, prepared for your specific project.
Drawings & construction notes
Buildable drawings and practical notes your builder can work from, with steelwork, lintel, post and bearing details where within scope.
Building Control-ready information
Information suitable for Building Control submission, subject to confirmed information and project requirements.
Follow-up support
Responses to follow-up technical queries from your builder or Building Control after the pack is issued.
How it works
Share your details
Send your postcode, drawings, photographs and a short project brief.
Confirm scope
We confirm the scope and the information required for your project.
Prepare the design
We prepare your structural calculations and drawings.
Issue & support
You receive the agreed pack, and we respond to follow-up technical queries.
Frequently asked questions
Can you assess walls in a Victorian bay-fronted terrace in Roath or Canton?
Yes. Bay-fronted terraces across Roath, Canton and Cathays often have walls carrying both floor joists and parts of the roof, so the assessment looks at the full load path, including any chimney breasts and party walls. Good photographs and a sketch of the existing layout are usually enough to confirm the scope before any site attendance is arranged.
Wales has its own Building Regulations — does that change what you produce?
Wales has its own set of Building Regulations approved documents, and Cardiff projects follow the relevant Welsh Building Control route. We prepare information suitable for Building Control submission, with calculations and drawings prepared for your specific project; approval itself is always a matter for the Building Control body.
What types of project do you cover in Cardiff?
Our core residential scope covers loft conversions and dormers, single and double-storey extensions, load-bearing wall removals, and steel beam, lintel and post design for alterations. If your project falls outside this scope, tell us what you are planning and we will confirm whether it is something we can support.
How is the work delivered if you are based in Bristol?
Xponexus Engineering is headquartered in Bristol and supports Cardiff projects remotely: you share drawings, photographs and a brief, we confirm scope, and the design is prepared and issued digitally. Where a project genuinely needs a site visit, we coordinate local site attendance as part of the agreed scope.
What information do you need to quote for a Cardiff project?
Your project postcode, any architect’s or layout drawings, photographs of the areas affected, and a short description of the work you want to do. With that we can confirm the information required, the most suitable assessment route, and provide a scoped quote.
Related services & resources
Structural Engineering · Loft Conversions & Extensions · CAD & BIM · Remote Engineering Support · All Locations · Loft conversion structural calculations explained
Talk to a structural engineer about your Cardiff project
Send your postcode, drawings or sketch, photographs and a short description of the work. We will confirm the information needed for an accurate scope and quote.
Request a quote
Complete the secure enquiry form below and include your postcode, drawings or photographs where available.
