Installation day is the one part of the double glazing installation process that actually happens in your home, and for a standard house it is a 1 to 2 day job. A little preparation the night before makes the whole thing go faster and cleaner. Take down your window dressings, clear access to every opening, and the fitters can get straight to work instead of waiting on you.
Before the day: how to prepare your home
Everything that hangs on or near a window needs to come off before the old frame can be removed. That means curtains, blinds, poles, rails and any window-mounted accessories such as shutters or trackers. Clear a path to every window on both the inside and, where you can, the outside, because the fitters work from both sides. Move furniture back from the openings or cover it with sheets, and lift anything valuable off the sills. Finally, keep pets secured somewhere away from the work, because doors will be open and there is broken glass about. None of this takes long, and doing it the night before means the crew is not standing around while you clear a room.
| Before the fitters arrive | Why it matters |
|---|---|
| Take down curtains, blinds, poles and rails | They sit against the window and must come off before the frame does |
| Clear access to every window, inside and out | The team works from both sides of each opening |
| Move or sheet nearby furniture | Protects it from dust and gives room to lift frames |
| Secure pets away from the work | Doors stay open and there is broken glass about |
Doing this the night before means fitting can start the moment the crew arrives.
The jobs that run late are almost always the ones where nothing was ready. If the curtains are still up and the sofa is under the window, I lose the first hour before I have touched a single frame. Ten minutes of prep the night before genuinely saves you a slower, messier day.
Tom Bradley, FENSA-registered installer
On the day: what the fitters do
A reputable crew arrives with its own dust sheets and covers your floors and remaining furniture first. They then work one opening at a time: removing the old unit, offering up the new frame, levelling and fixing it square, and sealing it inside and out before moving on. Trickle vents and hardware go in as they go. Because they work room by room, your home stays secure and weatherproof throughout rather than being thrown open all at once. The old windows are taken away as part of the job on a fully-fitted contract, which we cover in our guide to old window removal and disposal.
How long it takes and the tidy-up
A standard house is a 1 to 2 day job, and a good crew clears up after itself: offcuts bagged, old sealant and debris removed, floors swept, and your sheets lifted. Clearing up is part of a proper fitted price, not an extra to chase. If you are comparing prices before you book, the uPVC window calculator gives you a fair benchmark for a fully-fitted job that includes removal and making good.
I leave a house cleaner than I found it. Dust sheets down, offcuts bagged, every window wiped and working. If a fitter leaves you sweeping up glass and old frames in the garden, that tells you everything about how they run a job.
Tom Bradley, FENSA-registered installer
After the fit: sign-off and your certificate
Before the crew leaves, walk the job together and check that every window opens, closes and locks smoothly, and note anything that needs adjusting. The installer then self-certifies the work under a Competent Person Scheme and registers it with the council, which is what produces your FENSA certificate (or a CERTASS one if that is their scheme). It does not arrive on the day; it usually follows by post within a few weeks. Once the windows are in, keep an eye on the simple upkeep in our double glazing aftercare guide to protect the seals and hardware for the long haul.
Frequently asked questions
Take down curtains, blinds, poles, rails and any window-mounted accessories. Clear a path to every window inside and out, move or sheet furniture near the openings, and keep pets secured away from the work. Doing this the night before means the fitters can start straight away.
Yes. Curtains, blinds, poles and rails all attach to or sit against the window, so they have to come off before the old frame can be removed. Taking them down yourself protects them from dust and damage and saves the fitters time.
There will be some dust, but a good crew brings its own dust sheets, protects your floors and furniture, and clears up before leaving. Removing old windows creates debris and offcuts, so tidy-up at the end should be part of the service, not an extra you chase.
A standard house is a 1 to 2 day job. The team works room by room, taking out one window, fitting its replacement and sealing it before moving on, so your home stays secure and liveable throughout rather than being opened up all at once.
Move or sheet anything close to the windows so the fitters have clear working space and your belongings stay clean. You do not need to empty the room, just create access to every opening on both the inside and, where possible, the outside.
Not on the day itself. After the fit, the installer self-certifies the work under a Competent Person Scheme and registers it with the council. Your FENSA or CERTASS certificate then usually arrives by post within a few weeks.