Order of works when windows are replaced

01 When should windows actually go in?

The safe rule is that windows go in once the building is weathertight but before finishes are applied, and after any work that changes the openings themselves. In practice that means:

• After structural alterations. If an opening is being widened, a new lintel inserted or a bay created, the structural work, building control inspection and making good of the inner leaf must be complete first. A frame fixed into a wall that is still moving will rack, and the sealant will fail within months.
• After damp and rendering work outside. External wall insulation or re-rendering changes the reveal depth and often the position of the frame relative to the insulation line. Fitting windows first and insulating afterwards is a common and costly sequencing error, because the frame should sit within or against the insulation layer to avoid a thermal bridge.
• After first fix electrics and plumbing where cables or pipes run near reveals, but before second fix. This keeps trades out of each other's way and prevents damage to finished surfaces.
• Before plastering and decoration of the reveals. The plasterer needs the frame in place to form the reveal and to make good the gap between frame and wall, typically with expanding foam, a flexible seal and a bead or skim.
• Before flooring and skirting in the same room, so the fitter can level the cill and the joiner can scribe skirting and architrave around the new reveal.

Kitchens and bathrooms complicate the order. Worktops, wall units and tiles should not go in before the window behind them, so the sequence there is windows first, then fit-out. Where a whole house is being renovated, phasing room by room, the window order usually follows the plastering order.

02 What does window access require, and how is it planned?

Window replacement is an access-heavy trade that other trades underestimate. Before signing, check what the fitter expects and what the contract says about it:

• Inside clearance. Furniture, curtains, blinds and radiators under the window must be moved. Radiator removal is sometimes the fitter's job, sometimes not; it should be written down. Floor protection is standard on a professional job, and old frames coming out as single units leave debris and dust.
• Scaffolding and external access. Upper-floor windows on a terraced house may need scaffolding, which is a cost and a neighbour conversation, particularly over a shared passage or a party fence. Scaffolding on the public highway in England requires a licence from the local highway authority, so it needs lead time.
• Party walls. Cutting into a wall that shares a boundary line, or work on a wall subject to the Party Wall etc. Act 1996, triggers notice obligations to the adjoining owner. A straightforward frame swap in your own reveal usually does not, but widening an opening on a terrace or semi often does.
• Listed buildings and conservation areas. These change the order of decision, not just the paperwork: a listed building consent application must be granted before any window is touched, and conservation area rules may dictate like-for-like styles. This is decided at design stage, months before any trade arrives.

03 Who makes good, and to what standard?

Making good is where disputes concentrate, because two trades each assume the other is responsible for the gap. The frame fitter is normally responsible for fixing the frame, foaming the perimeter, trimming and sealing inside and out. The plasterer is responsible for the reveal finish. External making good, whether cement sills, render patching or trim, sits somewhere between them and must be assigned in writing.

Three checks close this out properly. First, internal making good should be to a paintable standard, not just a filler bead, unless the contract says otherwise. Second, external sealing should be a proper weather seal, with a compressible backing and sealant, not a bead squeezed over dust. Third, if the wall around the opening is damaged during removal, agree before the job whether repair is in the fitter's price or is a separate plastering item. A written schedule of what is included, checked line by line against the quote, is the only reliable protection.

04 Which documents must be kept after the work?

Window replacement is notifiable building work in England, and the paper trail matters decades later, at resale. Keep the following, physically or scanned:

• The FENSA certificate, or a building control completion certificate if the work was done through the council or another registered competent person scheme such as Certass. This is the evidence a solicitor asks for when the property is sold, and it confirms compliance with heat loss, safety glazing and ventilation requirements under Approved Documents L, K and F.
• The contract and the final invoice, showing what was supplied and fitted and any guarantee wording.
• The written guarantee itself, including the insurer-backed guarantee where the installer offers one, and the deposit protection or insurance details if the company later ceases trading.
• The specification sheet, glazing Ug values, frame colour and hardware, so that a future repair matches rather than guesses.
• Any party wall award, listed building consent or planning permission that the window work depended on.
• A dated photo record of each opening, inside and out, taken on completion day. It costs nothing and settles later arguments about whether a crack or a stain predated the job.

For work in France, the equivalent trail differs, with urbanisme authorisations, the devis and the réception de chantier with réserves playing the corresponding roles, which is why cross-Channel renovators are advised to map the documents of both systems before starting.

05 How is the work checked at handover?

At the end of the fitting day, before the fitters leave, a structured walk-through catches defects while they are cheap to fix. Check every opening opens, closes, locks and stays put in a partly open position. Check each sash sits square in the frame, with even margins all round. Look for glazing without scratches or trapped debris between panes, and safety glass marked in critical positions such as low panels and side panels to doors. Run a hand over internal trims and check that foamed joints are sealed, not left open. Outside, check that every frame perimeter is sealed continuously and that sills drain forward, away from the wall.

Note any defect on the invoice or job sheet before signing, with a date, and photograph it. Minor making good, such as a plaster patch awaiting decoration, should be listed as an outstanding item with an agreed completion date. Items recorded this way stay within the contract; items raised after the fitter has left become negotiations. The receipt stage, with its list of reservations and follow-up, is standard practice in French renovation contracts and is just as useful a habit in England, whatever the paperwork calls it.

A window is a small part of a renovation budget with an oversized paperwork and sequencing footprint. Fix the order of trades early, write down access and making good, and file the certificates on completion: those three habits outlast the fitter, the plasterer and even the owner.

Once sills, thresholds and surrounds are fixed, the sequence of the remaining work decides whether they survive intact. Trades that follow can chip a dressed edge or load a threshold before the bedding has cured, and dust from cutting stone settles into fresh mastic. Before the next lot starts, note what has been fitted, photographed and signed off, and keep those records with the certificates. A companion entry on the order of trades sets out where window replacement sits inside a renovation, covering access, making good and the documents worth holding before the following stage begins.

Once the street work is finished, the same discipline applies inside each home. A resident who has just had frames fitted will soon face plastering, flooring and decorating, and the order in which those trades arrive decides how much making good is needed. The Ledger sets out that sequence of a renovation in its own entry, covering access, dust and the documents worth keeping before the next lot begins. Reading it alongside this page helps a household plan the weeks after installation rather than react to them.