The old aluminium-framed units at the back of a 1970s house in Hiltingbury have gone misty, the draughts are whistling through the kitchen, and you’ve had three quotes that all say roughly the same thing. How do you tell them apart? Start with the paperwork, because the rules on replacement windows have tightened and a few firms haven’t caught up.
Part L of the Building Regulations sets the thermal performance for new windows. Trade guidance this year puts the target at around 1.2 W/m²K for windows and 1.4 for doors, down from 1.6 and 1.8 under the older standard. Lower is better. In practice that means a quality A-rated UPVC frame, a warm-edge spacer bar instead of old-fashioned aluminium, and a low-E coating with argon fill between the panes. Ask for the U-value on the quote. If the salesman can’t tell you, that tells you plenty.
Then there’s FENSA, or an equivalent competent person scheme. A registered installer self-certifies the job, and you get a certificate to hand over when you sell. Without it, you could be chasing building control for a retrospective sign-off from Eastleigh Borough Council, and that’s a headache nobody wants halfway through a conveyancing.
Fit matters as much as the frame. Frames should sit on packers at the quarter points, fixed back to the reveal through the frame rather than relying on silicone, and finished with expanding foam and a proper internal seal. Egress is another one: bedroom windows above ground floor need an openable area of at least 0.33 square metres, with no dimension under 450mm. Quiet details, but they’re the ones inspectors check.
Fortress UPVC fits windows and doors across Eastleigh, Chandlers Ford, Bishopstoke and Hedge End, and they’ll happily show you the U-value, the glass spec and the certification before a single frame comes out. Have a look at fortressupvc.co.uk/ or ring them for a no-pressure survey.