Understanding the labour vs materials split
Frame and glazing unit costs are often the largest share of a window quote, but fitting labour, old window removal/disposal and making good around the reveal add up too. If a quote looks cheap, check it specifies the same glazing spec as competing quotes, not a lower-grade unit.
Window and door guarantees, what to check
Frame guarantees commonly run 10 years, glazing unit guarantees are often shorter — ask specifically, since a failed seal (misting between panes) is a glazing unit issue, not a frame issue, and needs to be covered by the right guarantee. Installation workmanship guarantees are usually separate again.
Double vs triple glazing
Double glazing is standard for most UK homes and meets current Part L requirements on its own. Triple glazing further reduces heat loss and noise but costs more and adds weight to the frame — usually only worth the extra cost in an exposed or noisy location, or a new build aiming for very high efficiency.
Window energy ratings, explained
Windows are rated A++ to E based on their whole-window performance (frame and glass together), similar in concept to appliance energy labels. A higher rating generally means better heat retention, but the U-value figure is the more precise technical spec worth asking for if comparing quotes closely.
Three steps to hiring the right window installer
First, confirm FENSA or CERTASS registration and ask to see the number. Second, get a written quote specifying frame material, glazing spec (U-value) and whether the certificate is included. Third, ask about the guarantee — on both the glazing units and the installation work separately.
Background checks and identity verification
Before booking, check an installer's registration number directly on the FENSA or CERTASS website, not just take their word for it — window and door sales has historically had more than its share of doorstep sales pressure, so independent verification is worth the two minutes it takes.
Common window and door jobs
Window specialists handle full window replacement, double glazing unit repairs (a fogged unit usually means a failed seal, not the whole frame), door replacement, conservatories, and draught-proofing. Composite and bifold doors are increasingly common alongside standard uPVC window replacement.
Front door security features worth knowing
A composite front door typically offers better security and insulation than a standard uPVC door at a similar price point. Multi-point locking, a door viewer, and anti-snap cylinder locks are all worth asking about specifically rather than assuming they're included as standard.