Modern Granny Flat Extension Broughshane, County Antrim, Northern Ireland

Architect Slemish Design Studio Architects
Quantity Surveyor Dessie Boyce Quantity Surveyor

Modern granny flat extension attached to 1930's traditional house

Raceview Granny Flat Extension

Buying his parents house & adding a modern granny flat extension, turned out to be the best decision we made as a family.

My parents have lived in this house for the past 31 years and put a lot of time, effort as well as money into it. The area. just outside broughshane is first class, they didn’t want to leave it, but they needed to downsize.

During one of our get-togethers, I suggested buying it off them and putting a granny flat on.
My wife and children always loved the house, so it was sort of a no brainer.
They wanted enough space to enjoy retirement, so I designed the new rooms around what they currently used in the house.

This is what we replicated in the granny annexe. There was no need for anything other than the mains rooms because of all the space that there is in the house.
Dad wanted something in keeping with the house (it was built in 1930) and I wanted something that was different from the house to stop it looking like an old people home.
Since my dad retired he’s too much time on his hands and like myself has too many mad ideas running about his head. We argued over him wanting a two-storey extension and me wanting something more subtle.

We’d used timber cladding in our first house and loved the thought of using it again, only this time the plan was to char/burn the larch.
This was an aspect we all really enjoyed, my dad, got right into it. He’d be out burning the cladding most of his spare time and myself and my daughters helped clean/stain/move it about in the evenings.
Keeping the alleyway through to the annexe was important too, we can all use it, along with mum still having access to the utility – handy as well for them when they’re looking after our kids and dog.
For this project, both planning permission and building control were required. We had to apply for a change of use for the garage space and that was approved within four weeks. With using burnt larch the planners wanted to see how the material blended with the house, and we produced 3D renders to showcase this.

Building control was within the same timeframe – we made a few calls to ask them to get the construction drawings approved as soon as possible. We’d been moved into the house two months at that stage and were eager to get started.

We specified standard cavity wall construction for the new parts with a 150mm cavity fully filled with board insulation.
For the garage conversion, we applied 120mm spray foam insulation to the walls, which consisted of a single block on the flat. We put in 150mm board insulation over the flat roof and 400mm mineral wool insulation over the garage ceiling. There are new floors throughout insulated with 150mm

The only change during the build was moving the living room an extra foot. Dad had this sorted when I wasn’t there as he thought the room wouldn’t be large enough. Now he reckons the room might be a foot too long! Apart from that everything that we set out to do was followed to the letter and worked very well.

The downside is that it took a long time, 10 months, which was due to my workload in the office. It was frustrating at the time running the site and my business. It consumed more time than I’d of liked, but it saved us money which was the main thing. Everyone involved with the project has been pleased with how it turned out, which I feel very proud of.

The one thing that should have been sorted and was left to the end was the landscaping. This was mainly due to money but also due to the fact that one of my best mates who is a landscaper and who said he’d help me on it, is flat out.

Next year will sort it all out, and I want to get it just right for everyone in the family in the long term.
My advice for anyone considering a similar set-up is to talk it over and over and over (and over) again with your parents or in-laws – everyone has to get on living this close together.