The quality of a composite door installation determines whether the door achieves the thermal and security performance its specification promises. A high-quality composite door slab badly installed — poorly fitted frame, compressed seals, misaligned multi-point lock — will draught, leak, and offer worse security than its specification suggests. The survey and installation process is as important as the door selection, and understanding what a good installer does helps homeowners distinguish between quality contractors and those who treat every installation as a production-line job.
The Pre-Survey — What It Should Cover
A proper pre-survey visit before a composite door installation covers: accurate measurement of the existing opening (width, height, depth of reveal, any deviation from plumb or square in the existing frame); assessment of the existing frame condition (whether frame retain is viable or full frame replacement is needed); identification of any drainage issues in the threshold; confirmation of the hinge positions relative to the brick or blockwork; and discussion of the desired configuration, colour, glazing, and hardware. An installer who quotes from a phone call and photographs without a site visit is either assuming a standard installation or planning to deal with any complications as a variation charge on the day.
"The pre-survey is where the installation is planned, not the day the door arrives. An experienced door fitter can identify in fifteen minutes whether a frame is plumb, whether the threshold will need packing, whether the existing reveal has any unusual profile that requires non-standard framing, and whether the planned door configuration will work as ordered. These are not things that should be discovered when the new door is already on the drive."— FENSA — What to Expect From a Door Installer
Installation Quality — the Frame Fit Is Everything
A composite door frame must be: plumb (vertical — a frame that is even slightly off plumb will cause the door to swing open or drift closed on its own, and will put uneven stress on the multi-point locking points); level at the threshold (a threshold that is not level will not seal correctly on one side); correctly packed and fixed at the structural surround (the frame must be fixed to the masonry or timber structure, not just wedged into the opening); and correctly sealed and pointed at the reveal (expanding foam filling the gap between frame and masonry, with external sealant or mortar pointing over it). An installer who rushes the frame setting is creating a door that will move and gap over its first few thermal cycles as the fixing settles.
Handover — What You Should Receive
At installation completion, a good installer will: demonstrate multi-point lock operation and provide two sets of keys; adjust the door to ensure it seals correctly at all points; explain the maintenance requirements (annual lubrication of lock points, periodic check of seals); provide the FENSA certificate or confirm when it will arrive; and leave the site clean and dry — no expanding foam residue on the brickwork, no cement smear on the new frame, no rubble from the removed old door left in the garden. These are not unreasonable expectations: they are what a competent professional installation looks like.
"The two-key handover, the lock operation demonstration, and the seal check are the minimum a homeowner should expect at the end of a composite door installation. A door that is not sealing correctly on day one will not improve on its own. The time to identify this is while the installer is still on site, not three months later when the draught becomes noticeable in winter."— Which? — Composite Door Installation Standards
Looking for a Composite Door Specialist?
Firquote connects you with qualified, insured composite door installers in your area — free quotes, no obligation.
Get Free Quotes →