IN OUR NEW series, The Big Reno Clinic, Houses to Restore QS Shay Lally provides answers and solutions to the big (and little, but important) questions you may have about making the most of your home.
Send your question to reno@thejournal.ie.
This week’s question:
We had our extension designed 16 months ago — 3m x 7m off the kitchen-diner, flat roof, glazed on two sides, a couple of roof lights, and a large steel to open up the back wall. Our site’s on a slope, so we wanted it built on our upper patio level rather than disturbing the whole garden. We went with a recommended architect, but it’s dragged on — flip-flopping on planning, two failed submissions, endless promises that never materialised. 16 months later we have a €6,000+ bill from him and a first quote of €130,000 plus VAT plus glazing, against the €100,000 we were told to expect. The builder says the slope means heavy groundworks and possibly pulling up the whole garden. Is this just where extension costs are now, or has this gone wrong somewhere?
Site conditions, structural work and glazing can all add substantially to the final cost. Shutterstock
Shutterstock
Shay says:
Short answer: both. The number itself isn’t mad for what you’re building — but there’s a lot in your 16 months that should have been flagged a long time ago.
Let’s take it in three parts: the architect, the budget and the slope.
The architect. Hiring one was the right call. But 16 months is a long time, and it sounds like they were either overloaded or not prioritising you. Here’s the trap people fall into: once you engage an architect, it’s tempting to hand over the whole process and stop checking in. Don’t. You still need to set deadlines, follow up on decisions, and know exactly what service you’re paying for — some architects just design, others manage the whole build through to sign-off. Get that scope agreed at the start, in writing, with a timeline attached.
The budget. €100,000 was set 16 months ago — and costs haven’t stood still since. Materials, labour, waste and transport have all gone up, partly due to wider geopolitical pressures affecting fuel and transport costs. A budget that was tight then is tighter now, and no one revisited it with you along the way.
This is where a quantity surveyor earns their fee before a single block is laid: getting realistic costs for your actual scope tells you straight away whether your budget matches your ambition, or whether something needs to give. If it doesn’t match, you defer what you can — wardrobes, decorating rooms you’re not using yet, landscaping — and value-engineer the rest.
The slope. This is the part that should never have been a surprise. A sloping site can push groundworks costs to two or three times those of a flat site — it’s labour- and plant-heavy no matter how you slice it. Stepping down into the extension instead of levelling the ground can bring that cost right back down, though not everyone wants a step in their house. Either way, this should have been priced and discussed the day you were quoted €100,000, not 16 months later in a builder’s site visit.
So what should this actually cost?
Based on what you’ve described, here’s roughly where I’d land:
That €4,400/m² rate is on the higher side to reflect the glazing you’re planning — the final number could climb further depending on the roof finish and glazing spec. In other words: your €130,000 quote isn’t the world gone mad. It’s close to where this project should sit — the problem is nobody walked you to that number gradually, so it landed as a shock. Worth noting, I didn’t allow for any works other than the knock to the existing house – any works you intend to do would be in addition to the above
Key takeaways
- Set a deadline with your architect, in writing, from day one — 16 months for design and planning on a project this size is too long, and you’re entitled to push back long before that.
- Agree the scope of service upfront — know exactly whether your architect is just designing, or managing the build to completion, so nothing falls through the cracks.
- Re-cost your budget if time has passed — a figure agreed 16 months ago needs revisiting; materials, labour and site costs move.
- A sloping site should be priced early, not discovered late — expect 2–3x the groundworks cost of a flat site, or ask about stepping down into the extension to save money.
- Get an independent cost check before you commit — a quantity surveyor’s estimate against your actual scope tells you fast whether you’re on budget or need to defer and value-engineer.
- €130,000+VAT for this spec isn’t unreasonable — the shock here is the process, not necessarily the price.
Shay will be back answering your questions next week. Send him your pressing queries on managing a renovation to reno@thejournal.ie.