Could I extend my garage below ground to create a separate dwelling?

I have a detached garage that I could convert into a separate dwelling as I have a large rear garden. My waste pipe and that of my neighbour’s extends the width of the garden and continues under the garage. I cannot (and would not) add an extra floor to the garage as it would block my neighbour’s light. Could I extend below ground?

Extending under ground is an interesting design solution but before we look at this we must first look at the potential of converting a domestic garage into a dwelling from a planning perspective. Converting a detached garage to a dwelling of separate use to your own dwelling will require planning permission. The best thing to do is to set up a meeting with the local planning officer.

Each authority has a pre-planning application form and you can add a map or your Eircode to this. The map or Eircode ensures that the planning officer for the area will be assigned your case. Explain what you’re thinking, and the planning officer will let you know if you are likely to be successful or not.

This will not be a guarantee of a planning grant because there will be so much to consider by the planning officer, and they will not have all the pertinent information that makes up a planning application. But they will give you an indication as to the likely success of your application.

That secret to choosing the perfect colour scheme for your home

---

Contemporary finish allows period features to shine on elegant D4 road, for €1.7m

---

What will €275,000 buy in Japan, Norway, Spain, the Bahamas and Carrick-on-Shannon?

---

Live like a lord: Wicklow estate that featured in The Tudors and Matt Damon film for €8m

---

Regarding the extension below ground, again, you will need to speak to the planning authority about this. Extending under ground in a domestic building is not always viewed favourably by authorities because it is not considered traditional construction. We are all familiar with basements in larger estate houses, or tall streetside properties that were built in the 1700s and 1800s around the country, but basements are not considered vernacular in Ireland. A lot of the reason for this may be related to our wet weather and the potential of flooding.

Adding a split-level rather than a basement may be viewed more favourably if, for example, the land slopes away from the building, creating a full storey at one aspect and a partial basement on the other. Perhaps the extension might be brought forward so that you add to the front of the existing building and avoid the mains pipe and avoid loss of daylight to the neighbour. Or perhaps if you add an upper storey but flatten the roof pitch to lower the overall height, you may get the room you need and your neighbour may not be impacted.

A good designer may offer a suitable site-specific solution. First things first, however, make your application and see if you can go forward in the first instance. If you get the green light, then you can appoint a designer to resolve any issues on site. There are always challenges to construction but some of these can be found in the neighbour’s back garden or the back garden of your friends. Keep your eyes peeled for solutions. It could well be an enjoyable project.

Brigid Browne is a chartered building surveyor and a member of the Society of Chartered Surveyors Ireland

Do you have a query? Email propertyquestions@irishtimes.com

This column is a readers’ service. The content of the Property Clinic is provided for general information only. It is not intended as advice on which readers should rely. Professional or specialist advice should be obtained before persons take or refrain from any action on the basis of the content. The Irish Times and it contributors will not be liable for any loss or damage arising from reliance on any content