We've watched him argue over pebbledash, lobby for pergolas and grapple with glass bathtubs - all that in just the most recent series of Room to Improve.

Now, Ireland's most famous architect is opening the doors to his most ambitious project yet, his own home, and the country is waiting with bated to breath to see how Dermot can improve on ... Dermot. 

In a new two-part RTÉ special, Room to Improve: Dermot's Home will see the celebrated architect try to separate his head from his heart, all in the pursuit of his dream family home. 

After 13 blissful years in the house where he and his wife raised their three children – the first rooms he improved, if you will – Dermot is moving on. Having fallen in love with and bought a run-down 1930s house in Drumcondra, he has planned a massive renovation, including a two storey extension that will triple its size. 

For the first time ever, Dermot is both client and architect – a dual role in which he’s far from comfortable. And as he struggles to realise his vision, he’ll need all the help he can get.

Dermot has brought in quantity surveyor Patricia Power to help. 

Reuniting with former Room to Improve regular, no-nonsense quantity surveyor Patricia Power, as well as architect Ciaran Deville, a college buddy of Dermot's, the usually forthright and decisive architect will fight to avoid everything "pedestrian and predictable". 

As it turns out, the only predictable thing about this build are the delays caused by Dermot's obsessive attention to detail. From the structure of the roof to windows and flooring, nothing happens on time, to the increasing frustration of builder Graham Byrne.

It's not surprising that when it comes to his own project, Dermot brings out the big guns and his vision makes for one of the most ambitious builds yet. Worn down by delays, Dermot high-tails it to Oxford for a last-minute masterclass with his hero, award-winning architect Niall McLaughlin.

But Niall's critique of the Drumcondra design throws Dermot a curveball, leaving him full of doubt and questioning a key part of his plan. 

Can Ireland’s most famous architect separate this head from his heart as he embarks on his most personal project yet – the family home of his dreams?

Watch part one of Room to Improve: Dermot's Home at 9:30pm this Sunday 5 January on RTÉ One.