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Budget between €1,900 to €2,300 per sqm for an extension using traditional materials and construction methods; more unusual finishes or methods push up costs to around €2,000 to €2,500 per sqm

Budget between €1,900 to €2,300 per sqm for an extension using traditional materials and construction methods; more unusual finishes or methods push up costs to around €2,000 to €2,500 per sqm

Budget between €1,900 to €2,300 per sqm for an extension using traditional materials and construction methods; more unusual finishes or methods push up costs to around €2,000 to €2,500 per sqm

Q We are thinking of building an extension but are concerned about costs and how to keep them under control? What is your advice?

A Extending your home is an exciting project but also daunting, as it can involve considerable disruption and cost. It's probably one of the biggest investments you will make other than the original purchase of your home and your money should be spent wisely to make sure you get the maximum benefit. The more research you do beforehand and the clearer you are on what you want your extension project to deliver, the smoother it will progress.

Where to Start

Establish a brief - I recommend that you consider employing a registered architect early on in the process.

An architect has the qualifications, vision and experience to take you expertly through your building project. They will help set a viable brief and budget, guide you through the planning process, obtain quotes for the work, manage consultants like surveyors and engineers, monitor the budget and administer the construction contract.

At the outset of the process, you and the architect will establish your main hopes and aspirations, such as the size, extent and configuration of the extension. This may affect whether or not it would require an application for planning permission.

Establish a budget

When you have identified your list of requirements and the potential size of your extension, your architect will help you to work out a preliminary budget. The RIAI publishes a Cost Guideline Document (2019) on their website (riai.ie) which can form the basis for working up a budget.

Generally, if you're thinking of adding a single or two-storey extension, using traditional materials and construction methods such as concrete strip foundations, insulated cavity walls, flat or pitched roof, a moderate amount of services, new kitchen/bathrooms, renovations to the existing house and services, then allow for a cost range of €1,900-€2,300 per sqm. With smaller projects, the figures may increase as much of the preliminary work is required regardless of the project size. Adding an expensive kitchen will also adjust the cost significantly upwards.

Where the new work involves non-traditional construction methods or requires high quality finishes or materials, put aside a figure more like €2,000-€2,500 plus per sqm. These figures are based on Dublin suburban area figures so keep in mind that costs vary around the country. The new NZEB Part L Regulations (insulation and ventilation) will also impact on costs. All these figures would be exclusive of VAT, which for construction works is 13.5pc and for professional fees is 23pc at present rates, and of inflation (currently around 7pc).

You may also have to budget for expenses such as planning costs (if planning is required), development levies/ contributions, fees for the architect, quantity surveyor, engineers and assigned certifiers, as well as health and safety costs. Your architect will advise on these.

Control Costs

n Sign an agreement with your architect and a contract with your builder prior to commencement of works. Your architect can advise on the best RIAI building contract to use.

n Spend time in the design process and try to decide/choose as much as possible before starting on site. If you have a ''significant other'', both of you should attend the key meetings to avoid revisiting the designs after you have signed the contract - something that is costly.

n Be realistic about the overall scope of the work. For example, it's easy to overlook what needs to be done to your existing house, which might then become an issue when a project is mid-way through. At the very least, you might want to paint some of the rooms off the extension.

n Allow for a good contingency figure of 10-15pc for alterations and unforeseen items.

n Tie down the bigger ticket items before you sign the contract so that the provisions you've made are realistic. For example, windows and kitchens can significantly affect your budget as the cost and types vary so much. Secondly, they tend to have long lead times and if they hold up the construction, it can have financial consequences.

n Ensure you have sufficient funds in your account. Projects can get suspended while a client has to wait for the mortgage top-up.

n Supplying materials or services yourself may not be as cost or time efficient as getting your contractor to do so. Remember their VAT is at 13.5pc, whereas your purchases will be made at 23pc. If you order things and this causes delays to your building, the fault (and cost) lies with you.

n Try to move out of your home for the critical phase as least. If the builder has to work around you and keep the site safe and clean every evening, you will pay for it.

While this may all seem daunting, I've never experienced a project where the client has regretted the work they've done. It is usually the work they have chosen not to do that exercises them while sitting in their ''new'' home!

Best of luck with the project.

If you are considering changes to your home, work with a registered architect on riai.ie, the registration body for architects in Ireland.

Paula M Murphy MRIA is a registered architect working mainly in Tipperary and Dublin paulamurphy.ie; houzz.ie

Sunday Independent