Sales were up 68.8 per cent on last year at £784.9 million and 20.3 per cent on 2019 before the pandemic.
The group, which has sites in the Black Country and at Cannock, Kidderminster and Telford, went from a £14.2m loss in the first half of 2020 to a £119.2m profit.
Chief executive Andrew Livingston said: "Howdens delivered a very strong performance in the first half of 2021, with sales and profit before tax at record levels for the period."
He explained that sales of "everyday" and promotional items were particularly strong.
"This robust performance demonstrates the strength of our trade only, in-stock, local business model and the benefit of pent-up demand as people choose to spend more on their homes. With that in mind, we now believe there is potential for at least 900 depots in the UK, including 20 to 25 in Northern Ireland, and plan to start testing the Howdens model in the Republic of Ireland in 2022.
"While we are aware that economic uncertainties persist and also of the strong comparatives we will trade against in the second half, we are encouraged by the progress made so far in 2021 and remain confident in our business model for the future," added Mr Livingston.
Seven new depots opened in the first half of the year and there are now 754.
Howdens has revamped 28 of its older UK depots revamped and eight have been re-racked without other modifications.