Cardiff price guide
House extension quotes in Cardiff
Typical local pricing runs £1,650–£2,750 per m² of new floor area, excluding VAT and kitchen fit-out. Here is what drives that range in Cardiff, and what to check on the quotation in front of you.
Indicative Cardiff range
£1,650 – £2,750
per m² of new floor area, excluding VAT and kitchen fit-out. Based on a local cost index of 0.94 against the UK average.
Why Cardiff pricing differs
Reasonable availability with rates below the English average; roofing and rendering demand is high due to exposure and rainfall.
Victorian bay-fronted terraces in Roath and Canton, 1930s semis in Llanishen, and modern estates to the north.
Planning and consent
Cardiff Council operates conservation areas across Pontcanna and Roath; Wales has its own building regulations differing from England.
What to check on a house extension quotation
- Foundation depth allowed for, and the rate if a deeper dig is needed
- Whether structural steel, engineer's fees and building control are inside the price
- The glazing allowance, stated per m² or per unit
- Which items are provisional sums rather than fixed prices
Areas we see quotes from
Homeowners across Pontcanna, Roath, Whitchurch, Penarth, Llanishen and the wider Cardiff area use KnowMyQuote to understand what a contractor has actually priced before committing.
Frequently asked questions
How much does house extension work cost in Cardiff?
Local pricing typically runs £1,650–£2,750 per m² of new floor area, excluding VAT and kitchen fit-out, based on a lower-than-average cost index of 0.94 for Cardiff.
Why do quotes in Cardiff differ so much?
Because they rarely cover the same scope. Reasonable availability with rates below the English average; roofing and rendering demand is high due to exposure and rainfall. Two quotes for the same job can exclude different items, which is why comparing exclusions matters more than comparing totals.
Do I need planning permission in Cardiff?
Cardiff Council operates conservation areas across Pontcanna and Roath; Wales has its own building regulations differing from England. Always confirm with the local authority before committing, and apply for a Lawful Development Certificate where the work is permitted development.
How many quotes should I get?
Three, all priced against the same drawings and written specification. Without a common document you are comparing three different buildings, not three prices.
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