What Actually Happens on Installation Day? A Realistic Two-Day Timetable for Replacing Windows in a St Clement Home
Photo: Internet Archive Book Images, No restrictions, via Wikimedia Commons
Most of us can picture the end result of a window upgrade without much trouble: quiet rooms, frames that actually close, a house that holds its heat on a January evening. What people rarely picture is the bit in the middle — the vans on the drive, the furniture pushed into the centre of the room, and that slightly alarming half hour when there is a hole in your wall and a bloke on a ladder outside it.
That gap in expectations is where a lot of unnecessary worry lives. So here is a plain-English run-through of what a professional two-day installation typically looks like in a St Clement home, and what a good crew should be doing at each stage.
Before anything arrives: the survey that prevents surprises
The most useful thing you can do happens a fortnight before the fitters turn up. A proper survey should measure every opening, check how the current frames are fixed, look at the condition of the walls and lintels, and confirm whether the reveals are square. It should also flag the awkward stuff early — a rotten sill, a window with a radiator hard up against it, restricted access at the back of the house.
Ask directly: will the new windows be fitted from inside or outside, how much making good is included, and who takes the old units away. If a company cannot answer those three questions before you have signed, that is worth noting.
Day one, 7:45am: arrival and room preparation
A good crew arrives early and gets the protection down before any tools come out. Expect dust sheets over floors and furniture, and anything breakable moved a sensible distance from the work area. Curtains, blinds and tracks usually come down first — they get in the way, and there is no point having them covered in dust.
Most fitters will ask you to clear a metre or so around each window the night before. That single bit of homework saves an hour over the course of the morning.
Mid-morning: the old frames come out
Removal is the noisy, messy, faintly dramatic part, and it is also the quickest. Beads come off, glass comes out first (far safer than wrestling a whole unit), then the frame is cut clear of its fixings and lifted out. A typical bedroom window takes thirty to forty minutes to strip at this stage.
This is also the moment when discoveries get made. Rot behind a reveal, a lintel with a crack in it, plaster that crumbles at a touch. A decent installer will stop, show you, and explain the options before carrying on. Budgeting a contingency of a few hundred pounds for exactly this sort of thing is not pessimism — it is just realistic in older housing stock.
Afternoon: new frames levelled, packed and fixed
Fitting is quieter but slower. The new frame is offered up, packed, checked for plumb and level, then fixed through the frame or via the reveal depending on the system. Diagonals get measured to confirm the frame is not racked. It is genuinely fiddly work and rushing it is how you end up with a window that drags on one corner for the next twenty years.
By the end of day one, most two-person crews aim to have every opening glazed and weathertight, even if the final sealing is finished the following morning. That way the house is secure and dry overnight. Ask about this when you get your quote — a company that leaves your kitchen open to the elements overnight is not one to book in November.
Day two: glass, seals and the fiddly finishing
The second day is all about the details most people never notice until something goes wrong. Silicone lines to the outside, trims and beading inside, handles and locking mechanisms checked, trickle vents confirmed as opening and closing, drainage slots left clear so water can escape rather than pool on the sill.
Making good comes next. Some plaster patching around the reveals is normal, and most installers will fill and sand small areas as standard. Larger repairs should have been discussed at the survey stage, not sprung on you as an extra.
The snag walk: twenty minutes well spent
Before the last van leaves, walk round every window with the fitter. Open and close each one, turn every handle, check the locks engage without force, and look at the glass in daylight for scratches or marks. Outside, check the sealant line is continuous and that sills slope away from the wall so water drips off rather than sitting against the brickwork.
Ask them to show you how the trickle vents work and how to adjust the hinges. Note anything that feels slightly off — a stiff opener, a seal that looks thin at one corner — and get it written down on the job sheet there and then. Snags are far easier to sort while the crew is still on your road.
The first few days afterwards
Expect a bit of dust in unexpected places, even with good sheeting. Give it a few days before hanging curtains back if fresh silicone has been used near the tracks. Clean frames with warm soapy water rather than anything abrasive, and keep the drainage slots clear of grit.
It is also normal to notice a little condensation on new glass in the first week or so while rooms dry out. Condensation that forms between the panes, though, is a different matter altogether and should be reported straight away.
Two days, a bit of noise, and a surprising amount of tea. That is the honest shape of a well-run installation — and knowing it in advance is most of the battle.
