* H1 net loss 8.9 million euros, vs 5.9 million loss in 2008
* H1 EBITDA 8.9 million euros, vs 18.3 million euros in 2008
* CEO says company "turning a profit" in past few months
* Says 85 million euro capital increase in upcoming weeks
* CEO sees stabilisation in UK, U.S., shares soar 24 percent (Updates with background, detail, share price update)
By Anne Jolis
BRUSSELS, August 20 (Reuters) - Belgian PVC window frame maker Deceuninck said its first-half net loss had widened 51 percent to 8.9 million euros ($12.6 million) but said the market appeared to be stabilising, boosting its shares.
Deceuninck, which has been hammered by the slump's effects on the construction sector, said on Thursday it had been turning a profit in the past few months and signalled its planned capital increase would be launched in coming weeks.
Chief Executive Tom Debusschere said the worst may be over.
"Deceuninck is turning a profit again during the last few months, and this at a monthly sales volume of 20 percent below last year's level. We notice the first signs of a bottoming out in the United States and the United Kingdom," Debusschere said in a statement.
Deceuninck shares leapt 24 percent to 3.35 euros in early trading.
Debusschere did, however, strike a note of caution, saying raw material prices had been rising again since May, and that even if sales stabilised, the timing of a recovery remained unclear.
"This is why Deceuninck will continue the implementation of its restructuring plan: Cash-flow generation and debt reduction remain the priority objectives for the coming years," Debusschere added.
Deceuninck, which makes a range of PVC-based products for the building sector, has already predicted a difficult year, with third- and fourth-quarter like-for-like sales expected to be substantially below levels in the same period of 2008.
It said its planned 85 million euro ($119.9 million) capital increase would be launched "in the upcoming weeks," once it had finalised the restructuring of its debt. Deceuninck's net financial debt came to 189.3 million euros at the end of the first half.
Deceuninck has said the capital increase would be supported by two core shareholders and ING Belgium NV, KBC Securities NV and Dexia Bank Belgie.
The company reported its net loss for the first six months of 2009 grew 50.9 percent to 8.9 million euros from a net loss of 5.9 million euros in the same period last year.
It said its first-half earnings before interest, tax, depreciation and amortisation dropped 51.4 percent to 8.9 million euros from 18.3 million euros in the first half of 2008. (Reporting by Anne Jolis; Editing by Dan Lalor and Rupert Winchester) ($1 = 0.7091 euro)