Q: How much does a house cost to build per sq foot?

A: This must be the most debated topic outside of ‘Brexit’ and rising property prices in Ireland.

A good analogy is to think of what a car costs per square foot. It’ll depend on whether it’s new or second hand, a people carrier or a German luxury sports car, whether it leather seats, two doors or four. It is the very same for building. Almost every house is different, some have double glazed uPVC windows, some have quadruple glazed aluclad. Some have red deal floor boards some have American White Oak wide plank solid flooring. Some have fibre cement slates on the roof, some have copper or zinc.

In this context, a bog standard house could conceivably be built for approximately €80 per sqft plus VAT but this is for a simple design (rectangular, plaster finishes, fibre cent slate roof, double glazed uPVC windows) with no finishes (tiling, flooring, decoration, patios perhaps not even a kitchen sink!).

In NI you can claim VAT back so while the figure is around the same mark it excludes VAT. There are many examples of this type of house scattered in housing estates throughout the 32 counties.

Q: What drives up the cost per square foot?

A: As a general rule, the more complicated the design, the more expensive to build. More elaborate houses have more irregular shapes meaning more insulated external walls, more structural steel, more roofs, more tricky areas to weatherproof and finish, etc. Site conditions are also important. Is the site on a slope? Is it well drained? Is there rock in the ground? Do the foundations need to be piled?

Q: What about extensions?

A: Extensions will command a higher cost per square foot and are much more difficult to pin down but certainly well over the €100 / £80 plus VAT mark. In NI extensions are not VAT exempt. Costs can quickly rise with issues surrounding restricted access, demolition and propping, tricky detailing to connect the house and extension, drainage and service diversion, to name a few.


Selfbuild Live Dublin is the ultimate showcase for people who are building, extending, improving or simply decorating their home. Selfbuild Live Dublin, 13th-15th September takes place in the Citywest Convention Centre, Dublin.


Q: Why are my tender prices coming in at different rates?

A: Builders will price projects differently – some may use previous experience, others may employ a quantity surveyor. They may add a percentage to factor in risk factors which could price them out of the running. Sometimes they get it right, sometimes they don’t. Remember that a building does not cost the original estimate quotation, but the final account. So tender drawings and construction details are essential to get comparative quotes.

Don’t be lulled into a false sense of security, get the tenders in for the spec you want to see where you stand. And remember, if a quote looks too good to be true, it probably is. You do get what you pay for.

— Kieran McCarthy of kmchomes.ie


SelfBuild Ireland has just launched a range of build cost calculators powered by online budgeting tool ProntoCalc. The Build Cost Calculator gives you a rough idea of how much your project will cost, contractor led. It’s free, quick and easy. You can use it below: