The Irish DIY sector will face serious competition following a decision by the Supreme Court to clear the way for the giant British retailer B&Q to open a superstore at Liffey Valley retail park in west Dublin. The 150,000 sq ft retail warehouse will begin trading before the end of next year.

The court dismissed an appeal by the Irish Hardware Association against the refusal of the High Court to quash the planning permission granted last July.

The association had claimed the permission was materially different to the original planning application submitted to South Dublin County Council for five smaller retail units.

The association denies the legal challenge was designed to keep out competition. It claims the B&Q store would be in contravention of the retail planning guidelines, which state that large single-retail warehouse units attracting large volumes of carborne customers from a wide catchment area can have an unacceptable impact on smaller shops in town centres.

The Supreme Court decision is not expected to open the way for other developers to build superstores because the original planning application at Liffey Valley was lodged before the Government published the retail guidelines.

The Department of the Environment and Local Government planned to make an order before the end of the year implementing the guidelines but has had to hold off until the Government considers an independent study into whether the introduction of a cap on the size of retail houses and supermarkets is anti-competitive. Even if the study comes out in favour of the guidelines, it is possible the cap will be challenged in the courts.