This extension by Cast Architecture shows how important it is to get your materials right when they dominate the structure

SOME IRISH architects have recently played with white, slight, light while others have embraced the shaggy eco look and we have all learned valuable design and living lessons from this.

Although there are those who are still going around in the equivalent of 1970s flares - the small windowed, pitched roof standard stock of house that has been around for ever and tends to duck below architectural movements such as Modernism and High Tech although it did have a bit of a passing chat with Post-Modernism.

Now what are architects to do? White boxes will take their place in Ireland's architectural history but that trend is so last decade. And while the grander international designers have pushed computer design packages and materials technology into looped, twisted and deconstructed buildings it may take a while for house owners to demand same from their architects.

Yet a warm but calm extension in Glenageary, Dublin, by Cast Architecture does bring in influences from larger jobs that at least one of its two directors has worked on. Emmett Scanlon spent nine years with Grafton Architects who used tiles on the dark hatted Soltice Arts Centre in Navan; its upper half is clad in dark limestone marble tiles from Italy. "So there is that continuous thread," says Scanlon. "Architects are informed by every project they do."

On this house, the red clay klinker tiles (hard-wearing tiles often used on commercial buildings) are warmer than those on the Navan arts building and, despite the extensions' north-facing aspect, they give it a Mediterranean feel, a sort of Costa del Glenageary.

The way the material can wrap the structure, across walls, floors and soffits, is what Scanlon and practice partner Sarah Cremin liked about it. And that wrapping makes even the stairs feel part of the furniture, you can imagine perching on them with a book in hand. The architects also wanted a structure that contrasted with the existing house, a pitched roof brick and plaster building in a street of similarly profiled properties.

The couple who live in this 1970s house have been here for 20 years and wanted to stay for longer. Their son had grown up here and, in adapting the interior of the original house, the clients wanted something that would keep him close - now that he is at college - but to give him independence also.

So the garage to one side of the house came down and a room for him went up. This is part of the extension structure which essentially clasps the house, running along the back and around to this side.

The teen room has its own front door - so no 4am after-party disturbances - but connects into a new shower room and on into the main kitchen/living space at the back of the house.

There used to be an office where this open-plan area is now, but the home worker was happy to move to the west side of the house to allow the kitchen to have a relationship with the garden, where there was none before.

The orientation is not ideal; the garden faces north-westand large neighbouring trees darken the already sun-free light. The clients were keen to have a roof terrace: if the sun wasn't coming to them then they would go to the sun.

The architects wanted an extension with as strong a profile as the A-frame house and to articulate the difference between old and new, with both materials and shape. They have certainly managed that with the existing pitched roof contrasting sharply with the 90 degree angles of the extension.

"We wanted the new extension to feel like one piece," says Scanlon. When you are working with one material, it must be a beautiful one that sits on a form that is neither too complex nor dull.

That has been achieved here with the use of those klinker tiles all beautifully applied by hand and in vertical courses to underline the fact that they are non-structural. "From the moment we began looking for a contractor we told them that this would be a really important part of the job." Pat Comerford was the builder and the tiler was Tadas, from Poland, who took great care over the project. "He would sponge down the tiles with a smile on his face," says Cremin.

If there is contextualism here then it comes from the sea seen beyond the rooftops of Monkstown (there are also echoes of Dublin's redbrick homes) but while the tiles remind you of the Med, the irony is that this sea is nearer the North Pole than that and the aspect is north-facing. But that is what makes this such fun, a hot shot in a cold spot.

There is necessary layering of private and public spaces here, largely due to planning requirements that the terrace not overlook neighbours - we have become a private society. So the glass wall at the edge of the balcony is opaque, screening the neighbours but also shielding the residents and this terrace feels like an outdoor room as a result.

Its other screens are the bookends at each edge which are part of the klinker-clad extension structure.

They comprise box-like 'persicopes' that rise up from the main form and have windows that gather in light to the rooms below. One splits to allow light into both a hallway and bathroom and the other upright brings light into the edge of the open-plan living space. These light-catchers offer another example of complexity being tempered by simplicity in this structure. On the ground floor, away from neighbours' eyes, things become more open with large glass doors embracing the garden.

The concrete patio paving is in a similar colour to the clinker tiles and was a compromise where the tile budget ran out.

Scanlon, who teaches architecture and advises the Arts Council, set up Cast in 2006 and this project was designed for people he knew. Cremin joined the practice soon afterwards, having worked for Herzog and de Meuron on projects in New York and China.

In the Big Apple she worked on the Prada HQ and on an Ian Schrager hotel and apartments (called 40 Bond) while in China she worked with artist Ai Weiwei on a masterplan for the town of Jinhua, the birth place of his father, the poet Ai Qing.

Ai Weiwei later worked with Herzog and de Meuron on the Olympic stadium - known as the bird's nest - in Beijing.

While extension yearners and planners may not yet be ready for nest-like extensions, should the time come then Cremin could perhaps help them out. Meanwhile, it looks at if Cast will continue to explore materiality and wrapping on less twig-like, woven forms.