Choosing a Window Installer or Fabricator: Questions That Sort the Field

Two identical window systems can perform completely differently five years on — because one was fabricated square, glazed correctly and fitted plumb by people who do it every week, and the other wasn't. SIVAL supplies through a network of 180+ approved fabricators and installers precisely because the hands matter as much as the aluminium. Here is how to judge them, whoever you buy from.

The paperwork that should exist

• System accreditation: fabricators should be approved by the system company whose profiles they cut — approval means trained staff, correct tooling and access to genuine components rather than lookalike gaskets and hardware.
• Compliance route: replacement windows in England and Wales must be certified through a competent-person scheme (FENSA or Certass) or signed off by Building Control. A firm vague about which route they use is a firm to avoid.
• Insurance-backed guarantee: a workmanship guarantee is only as good as the company behind it; insurance backing means it survives even if the installer doesn't. Ten years is the respectable norm.
• Product documentation: CE/UKCA marking, U-values stated per window (not one flattering brochure figure), and PAS 24 certificates where security is claimed — see our PAS 24 explainer for what that paperwork means.

Questions worth asking to their face

"Who surveys, and when?" A proper technical survey after deposit but before fabrication is non-negotiable for made-to-measure frames. "Who actually fits — your employees or subcontractors, and who stands behind the workmanship?" Subcontracting is normal; unclear responsibility is not. "Can I see a job from two years ago?" Fresh photos flatter everyone; aged installations tell the truth. "What happens if a sash drops or a seal fails in year six?" The answer reveals whether aftercare is a department or a shrug.

Red flags, briefly

Prices that only hold "if you sign today"; surveys done by tape measure from the drive; guarantees mentioned but never shown in writing; "we can start Monday" on made-to-measure aluminium (good fabricators have lead times because they have order books); and quotes that name no system at all — "aluminium windows" is a material, not a specification.

How our network works

Homeowners can order supply-only or be matched with an approved installer local to the project; trade customers and self-builders get fabricated systems, technical support and delivery to site. Either way the specification, the U-value reports and the guarantees are stated in writing on the quotation — start one through the quote form and judge us by our own checklist.