Kieran McCarthy: 'How do I convert my garage into a living space?'

A garage stuffed with junk can easily be transformed into a living space, writes Kieran McCarthy

Converting a garage into a home office is becoming very popular.

Mon, 24 Apr, 2023 - 14:05

Kieran McCarthy

Hello Kieran,

As someone who has a garage attached to my home, I would like your opinion on how best to go about converting it into a living space. It’s a single-block build with a slanting, corrugated roof (I think there is asbestos in the roof). Our home is a three-bed semi-d, with side access to the rear via a passage down the other side of the garage which I would like to retain.

When we bought the house, we made provisions to install a door between the hallway and the garage. This is currently blocked off, but I don’t think it would be a major job to reinstate it. The garage is mostly full of ‘stuff’ (half of it junk) but it does house the washing machine and dryer as my kitchen is not that big.

Ideally, I would like to convert it into a den/office space, while retaining room for the washing machine and dryer. A shower room would be a great addition too. The garage is standard size and there’s a boiler room attached to it. If we had to move the boiler, is that a major job?

Also, is it possible to estimate what a single-storey conversion of the garage might cost? Or would it cost much more to do a double-storey extension and add an extra bedroom?

Thanks for your time,

Julia Smyth.

Hello Julia,

Thank you for your question here. I guess as life changes, either as children grow older or as we begin to work from home more often, our needs in terms of usable space at home change.

I am assuming that as you feel you potentially have asbestos in your roof that your house was built some time ago, likely even before the 1970s.

This would certainly be consistent with the type of brickwork you are indicating. So, as space is clearly at a premium, let’s see what would be involved to make your garage habitable.

The first thing you need to be aware of here is that you will need planning permission. Changing the use of this space (from garage/storage to den/office) does require planning permission and you are likely removing a garage door and replacing it with a window, which alters the front elevation of your home. I wouldn’t be overly concerned with this as it is likely a formality but I would advise getting it checked out all the same by contacting your council local planning office.

The next consideration of course is the layout of your new space.

I feel that as you need a small laundry room and a shower room, I would be more inclined to put these to the rear as I am imagining that placing windows to the rear might be more difficult for locations of patios, boilers, external storage etc.

What I am seeing at this point is a window to the front which would serve your den/office area and we may need to consider a door to the side or rear if you use a clothesline to make outdoor access easier. We would ideally need to consider some built-in storage to house the ‘stuff’ that you feel needs to remain in this area.

So, what would be involved in the building/conversion of this space and how much would it cost?

I am hoping that the existing external walls are in good enough condition that they do not need any structural reinforcement (as they will not be called upon to carry any substantial new load). In this case we need a new roof and we need to impose a new insulated floor.

The new roof entails the removal of the existing asbestos (by a licensed asbestos company) and a new timber roof structure and a ‘warm roof’ insulated covering installed. I am assuming your garage concrete floor is low enough to install insulation, radon membrane and a new concrete screed on top. We will of course need to install drains and water service for the laundry and shower rooms too.

Next we need to install internal partitions (which I would soundproof) and then add the new windows and electrical, plumbing and ventilation services (single rooms HRV units would work well in the laundry and shower rooms). Now it’s time to dryline your external walls and slab your ceilings to allow plastering to commence.

Once complete and dry you can begin the exciting phase of finishes including tiling, flooring carpentry and painting. If you were to look at moving the boiler, I would look at fitting a new and much more efficient condensing boiler which could in fact be fitted internally to an external wall, perhaps in the new laundry room.

So how much would all this cost? It really depends on how you go about it. Do you manage this project yourself or do you hire a building contractor. I feel the project would cost in the region of €35-50k.

If you were to consider another bedroom on top I feel it would dramatically change the price of the project as I do not see an engineer being happy that an new first floor could sit on the existing garage walls so I feel you would end up demolishing the garage and building a full, new two-storey extension.

This is more than twice the cost of the garage conversion I outlined above, and that’s before we even get into the ‘ah sure’ list.

Ah sure now that we have built the two-storey extension, we might as well fit a new kitchen, ah sure if we are fitting a new kitchen we need to redo the tiling, ah sure now that we have redone the kitchen we might as well repaint the whole house!

Kieran McCarthy is a building engineer and director of KMC Homes bespoke A-Rated new home builder, serving Cork and Limerick. He is also co-presenter of the RTÉ property show Cheap Irish Homes.