Established in 1979, GRM Windows has grown to become one of South Wales most experienced and trusted manufacturers of quality windows and doors to both trade and homeowners alike. We have developed a close working relationship with our key suppliers and to this end we are delighted to be Rehau authorised partners. We pride ourselves in having the customer focussed and flexible approach to design that is required to achieve the Passivhaus standard.  We manufacture Passivhaus Windows and doors, tested to PAS-24 and certified Secured by Design. This year we launch the new ARTEVO window & door system to the Passivhaus Market place.