Shares in builders' merchanting group Grafton - which operates 15 stores in Northern Ireland - tumbled more than 4% in early trading yesterday after it experienced weaker trading in March.
Grafton Group is the parent company of MacBlair, which has 15 branches in Northern Ireland.
It said the slowdown was due to bad weather and unseasonably low temperatures.
That cut the growth rate in its average, daily, like-for-like revenue to 1.3%. But it left its full-year forecasts unchanged and group revenue was still 7% higher at £907m in the first four months of the year.
Revenue was 6.2% higher on a constant currency basis.
Chief executive Gavin Slark said the group should continue to benefit from buoyant economies in Ireland and the Netherlands.
"We should continue to benefit from exposure to strong growth markets in Ireland and the Netherlands and, consistent with our view coming into the year, expect underlying demand in the UK RMI (repair, maintenance and improvement) market to remain subdued but house building to perform strongly," he said.
Grafton, which held its AGM yesterday, said that average, daily like-for-like revenue growth at its Irish builders merchanting business was 4.6% on a constant currency basis for the first four months of the year.
Revenue at its Irish merchanting business was up 7.6% in the first four months on a constant currency basis, while revenue at its Woodies DIY chain was also up 4.7%. Woodies accounts for just 6% of Grafton's overall revenue.
A strong start to the year at Woodies was the result of an improved economy, store upgrades and new and extended product ranges, according to Grafton.
In the UK, Grafton said it had anticipated the softer underlying activity in the first four months of 2018 in its merchanting business there, with competition denting pricing.