The renovation began with opening the bedrooms at the back of the house to the large private rear garden.
"We wanted light as much as flow - and the house, as it had been built, had neither," Beattie says.
"Installing french doors not only gave the illusion of more space by allowing light to penetrate, but meant we could enjoy the garden effortlessly. We love the framed bits of garden we get through the windows on either side of our bed."
He made it a priority to retain the mid-century appearance of the original sloping ceilings and white beams that recalled distinctive mid-century houses.
This stage of the renovation also included a rationalisation of space that saw two modern bathrooms created and the laundry and storage expanded, all with the addition of only 3sq m to the original footprint.
"This was one of the areas where we thought hard about what to do, yet in the end it all worked out really well," Beattie says.
"Extending outside the footprint adds to the budget but this was absolutely worth it for what we gained."
With their one-year-old son Jack now on the scene, Beattie and Stather are in no hurry to embark on renovating the front half of the house.
They have given the walls a fresh coat of paint and had new carpets laid, but they are taking their time to consider options for reworking the kitchen, living and dining areas so they interact better with the front garden.
"We have a liveable home," Beattie says.
"The most important thing is to create a home that gives us daily pleasure to live in it."
Style tips
If it works, keep it: If your home has a distinctive style, try to retain it where you can by preserving key elements. Beattie identified simplicity of detail, use of texture and light, sloping beamed ceilings and the simple forms as important.
Spend time, save money: By planning well in advance you can save money by making fewer mistakes and coming up with cost-effective design solutions.
Devil in the detail: Echo materials and style details from the old parts of the house into the new. For example, replicate the appearance of tongue and groove panelling on the ceilings by using grooved ply and battens.
Leanne Moore is the editor of Your Home & Garden. For the full story see the latest issue of the magazine.