** Shares of HSS Hire Group HSS.L rise as much as 10.6% to 6.9p, their highest since October 2024
** Stock among top pct gainers across London
** International building materials distributor and DIY retailer Grafton Group GFTU_u.L to buy HSS Hire's Ireland unit for 31.6 mln euros ($34.2 mln) on a cash-and-debt free basis
** After completion of the deal, Grafton plans to operate the unit as part of Chadwicks, its distribution business in Ireland
** Grafton stock down 1.1%
** Including session's gain, HSS up ~15% YTD
($1 = 0.9251 euros)
(Reporting by Aby Jose Koilparambil in Bengaluru)
((abyjose.koilparambil@thomsonreuters.com))