How much does a house extension cost in Dublin?

While there are a number of elements that can influence the cost of a house extension in Dublin, the most significant thing to consider is the extension’s size. This is because the project’s size (which is usually measured in square feet) is directly proportional to the total cost.

When deciding on the size of your extension, there may be planning policy problems to consider. Your architect will be able to tell you the maximum size that is likely to be allowed under authorized development laws (if applicable) or through a planning application for your property.

We can begin estimating costs using some common square metre rates after you know the required size of your extension. All of the pricing listed below are for construction only and were last updated in 2019. VAT and professional costs are not included.


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The expense of extending your home is:

  • Single story – In Dublin, a single story extension costs between €2,000 and €3,000 per square meter (€185 and €280 per square foot). Finishes and goods that cost €2,000 per sqm would be considered cost-effective. You may expect to pay between €1,200 and €1,500 per square metre (€110 and €140 per square foot) elsewhere in the Dublin. Add 50 to 60% to the guideline price of a single storey extension to get a rough estimate of the cost of a two-story extension.
  • Two story- additions save money because just one set of foundations is needed, for example. Two-story expansions can be more difficult to obtain planning approval for.
  • Basement – A basement is more expensive due to the complexity and risk of construction. In Dublin, a basement extension costs between €4,000 and €5,000 per square meter (€370 and €465 per square foot).

What is the purpose of the extension?

Many people seek to extend their homes to incorporate a kitchen or a bathroom. When compared to additional bedrooms or living spaces, these will automatically raise the entire cost.

  • Kitchens – If you want to include a kitchen in your extension, plan on spending an extra €15,000 to €40,000. A low to mid-range design, complete with units and some appliances, will normally cost €15,000.
  • Bathrooms – The cost of adding a bathroom will range from €5,000 to €10,000. The cost will rise as the quality of the fixtures and fittings improves.

Fees for a house extension consultant

The cost of all professional services will typically be 15% to 20% of the total construction cost:


Architects are frequently the first point of contact for a project, and they are a wise investment. They’ll take care of the important aspects of the project, such as design and obtaining planning approval.

There are other costs


The charge for submitting a planning application for a house extension is €206. Some house additions may not require planning permission since they come under the Permitted Development category. In this instance, applying for a Lawful Development Certificate, which indicates that the work does not require planning, is still recommended. This is especially significant if you intend to sell the property after the renovations are completed. A potential buyer is likely to want evidence that the works are legal.


Many homeowner’s insurance policies do not protect you while construction is underway. This could make you accountable if there is any structural damage as a result of the modifications. As a result, it’s critical to tell your insurers before starting work, and you may need to get a separate coverage for your peace of mind while construction is underway. Non-negligence insurance, for example, can help to cover you in the event that your extension causes structural damage to your neighbor.


Extensions are normally subject to the full VAT rate, which is presently 20%. There are a few projects where the VAT rate will be altered. Any property that has been vacant for more than two years, for example, may be eligible for a 5% VAT reduction.

Request advice from your architect to help you understand the cost of VAT for your house extension. Architects will be aware of the various tariffs and whether you qualify for a discount.

Costs of major items

Doors and windows

Windows are costly; in general, the larger the window, the higher the cost per square metre of the unit. The quantity of glazing you want, the amount of insulation you want, and the style and installation of the window will all effect the price of the window.

Doors are an additional cost, especially if you want huge sliding patio doors or bi-folding doors, for example. However, the amount of light in your property may greatly improve your enjoyment of it, and the flexibility to open up living spaces to gardens can drastically change how spaces are used throughout the summer months.

Heating is provided through central heating

Your boiler and central heating system may not be able to cope with the extra rooms and space depending on the size of your extension. To accommodate the extra space, you may need to improve your system or add a second heating system to the property.

Constraints of the location

If there are any concerns with the extension’s location, the cost will almost certainly rise. For example, the soil type may necessitate the use of more expensive building materials.

Trees, drainage, plumbing, steel work, gas meters, sheds, conservatories, and fuse boxes may all need to be moved, which may add to your extension costs. If you’re working on a listed building or a property in a conservation area, you’ll need to budget more for costs and construction.

Specifications in general

The level of customization you desire to achieve will influence the cost of your house extension. You can choose from basic, off-the-shelf items and high-end luxuries. Finishes such as tiling, paint, wallpaper, and flooring can have a big impact on the price.

Lighting and electronics add to the expense of a home, especially if smart home systems for heating, energy, and audio and visual control are necessary.

External work and finishing touches

Consider the expense of external work such as garden landscaping as well as the reconstruction of pathways and driveways. To finish the areas internally, you may need interior design services.

Costs of a house extension expressed as a percentage

The following example will give you a fair sense of all the things you need to examine and how much you should be spending on each:

  • The cost of builders, materials, and construction: 60%
  • 10% for the architect (15 percent on top of the construction cost)
  • Other consultants account for 5% of the total
  • Permission and administration for planning: 1%
  • Agreements on party walls: 3%
  • The cost of insurance is 1%
  • VAT is charged at a rate of 20%

What role may an architect have in budgeting?

A qualified architect should be able to point out the majority of the concerns that could effect the cost of your extension’s construction. They might be able to suggest cost-cutting alternatives or give recommendations on where the effort and costs should be focused. Most architects will be able to identify any prospective difficulties before they emerge, which could boost your budget unexpectedly, by examining your property and having a complete understanding.