How to Compare Window and Door Quotes Line by Line
UK window and door buying guide
A retrofit quotation can look complete while leaving the difficult work between the old opening and the new frame largely undefined. This matters where access is tight, rooms remain occupied, reveals need making good or a new patio door must meet existing floors and paving. The answer is not to begin with the lowest grand total. Turn each proposal into the same opening-by-opening brief, then mark what is included, assumed, excluded or still undecided. Start with existing conditions: who measures, removes the old units, protects finishes and coordinates related building work? Only then compare the window or door specification. A disciplined line-by-line review makes differences in GBP understandable and helps prevent an attractive initial figure becoming an incomplete project after the order is confirmed.
01 / Map the openings
Start with the site rather than the catalogue
Establish what information each supplier has priced before comparing products. Is the quotation based on your measurements, drawings, photographs, a site visit or a future survey? Record whether dimensions are structural openings, frame sizes or provisional figures, and whether the old frames remain in place. In an occupied retrofit, upper-floor carrying routes, restricted parking, floor protection and temporary weather protection can all affect scope. A supply estimate may be useful without being a complete replacement proposal. Put the pricing basis at the top of your worksheet so an early estimate is not mistaken for a final measured quotation.
Give each location an unambiguous reference, such as GF-Kitchen-W01 or FF-Bedroom-W02. Add a marked plan or labelled photographs, including exterior views where useful. Note radiators, blinds, tiled reveals, alarms, furniture and other features that could affect removal or refitting. Ask who moves possessions, protects surfaces, removes the existing units and takes waste away. If one supplier includes careful protection while another says nothing, their totals are not yet comparable. Request the same site-work scope from both and retain the written replies with each revised quotation.
Build one opening schedule for every supplier
Create one row for every opening. Include the room, quantity, requested width and height, product type, opening direction, hinge side or handing, number of opening sections, glass description, colours, decorative bars and notes. Add columns for each supplier’s reference, quoted amount, measurement status and unresolved questions. This exposes changed quantities hidden within grouped lines such as “ground-floor windows”. It also shows whether adjacent units are priced as separate frames, a coupled arrangement or one combined product. Drawings remain useful, but every quotation line should lead back to a unique schedule reference.
Use a neutral description when suppliers apply different names. Write “single operable outward-opening side-hung sash”, for example, and record whether the offer corresponds to a single-sash outward-opening side-hung window. Place alternatives on separate rows instead of allowing silent substitutions. An opening sash, a fixed pane and a two-sash arrangement may fit a similar space but offer different ventilation, cleaning access and furniture clearance. If an alternative is proposed, ask why and request a separately priced version of the original brief where feasible. This preserves a genuine choice and keeps the comparison intelligible.
02 / Match the details
Confirm operation, handing and clearance
Opening direction is a functional choice, not a minor annotation. For windows, establish whether each sash opens inwards, outwards, from the side, top or a pivot point, or is fixed. For doors, record swing or slide direction, the active leaf, any passive leaf and the approach from inside. Test the arrangement against daily use: nearby chairs, kitchen worktops, curtain tracks, radiators, narrow paths and patio furniture. Do not infer these details from a small elevation. Where two rooms appear mirrored, confirm each item separately rather than assuming matching labels also mean matching handing.
Large glazed openings make this check especially important. A side-sliding patio door is not equivalent to a hinged or folding arrangement simply because the overall aperture is similar. Ask for panel movement and the everyday passage route to be marked on the schedule, rather than receiving only the overall frame size. With a double-leaf hinged door, identify the leaf intended for daily use and how the second leaf operates when required. If the layout changes after pricing, request an amended line describing the revised operation. A verbal assurance that it will be resolved later is not an adequate order record.
Compare dimensions and frame arrangements
Place quoted dimensions beside the requested figures, but ask what every measurement represents. Similar numbers may refer to different points, such as an opening size and a proposed frame size. Establish who determines the final manufacturing dimensions and when you approve them. For wider compositions, check whether the price covers individual frames, a coupled arrangement or a single assembly. Mullions, transoms and sightlines influence appearance and glass area but may be shown only loosely in an estimate. A line reading “window, 1800 mm” needs a fuller description before it can be compared confidently.
Special shapes need a confirmed orientation as well as dimensions. A fixed triangular or angled window should be compared with the same geometry and fixed configuration, not a rectangular allowance with a similar area. Verify where opening sections sit within composite designs and how neighbouring frames align. Ask whether the price includes a template, final survey, approval drawing or an assumption taken from preliminary plans. Retain earlier dimensions when revisions arrive so a reduced size or altered proportion remains visible. The aim is a clear route from preliminary measurements to the dimensions eventually authorised for manufacture.
03 / Separate the scope
Read glazing as a complete specification
A short glazing phrase rarely supports a proper comparison. Ask suppliers to describe the proposed glazing consistently, including any obscurity, visual treatment, decorative effect or glass-dividing bars. Confirm which panes are fixed and which sit in opening sashes. If daylight, privacy, glare or an uninterrupted garden view is important, record that requirement against the relevant opening instead of expecting a generic glass description to capture it. Do not compare headline performance values unless they relate to the same complete product configuration and use the same basis. A fixed non-opening window, for example, remains an alternative to an opening window rather than an interchangeable line.
Separate decorative choices from the core glazing description. Quotations should state where decorative bars appear, their layout and how patterns align across adjacent windows and doors. Request an elevation where the pattern is important. If one offer uses glass-dividing bars and another decorative bars, flag the difference rather than assuming they create the same construction or appearance. Apply the same discipline to obscured glass: identify the specific pane and opening instead of accepting “bathroom glass” as a catch-all. This shows whether a difference in GBP reflects a deliberate visual decision or an incomplete specification.
List finishes, hardware and thresholds separately
Compare colour by side and component rather than accepting a broad description such as “grey”. Record exterior and interior colours, frame finish, any contrasting sash treatment, handles, hinges and other visible hardware. Ask whether hardware colour is selected or assumed and whether door furniture is a named set or a later choice. For an entrance, list requested handles, lock-related hardware, letter plate, viewer and other accessories individually. A panelled outward-opening entrance door identifies a panelled outward-opening configuration, but the quotation must still define the finish and hardware included in your particular order.
Thresholds connect the door system to surrounding floors and external surfaces, so vague wording can create late coordination problems. Ask what threshold is proposed, what it meets on each side and who prepares adjoining levels or finishes. This is particularly relevant where a patio door meets decking, paving, tiles or a raised internal floor. For windows, identify whether internal boards, external cills, trims, sealant and making good are included, supplied only or excluded. Keep these items separate in the worksheet. A lower frame price is not like for like with a line that also covers trims, cills and completion work.
04 / Resolve assumptions
Separate supply, delivery and installation
Treat a product quotation and an installed-project quotation as different documents. Identify whether each price includes supply, delivery, unloading, removal, installation, perimeter sealing, trims, making good, waste disposal and final adjustment. Ask who provides any access equipment and whether preparatory work to the opening is included. “Installation included” is only a starting point. Where a builder or decorator is involved, require a clear boundary between trades. If folding doors are being considered, record a set of outward-opening bifold doors as that specific alternative and compare its installation and surrounding work with the requested arrangement.
For delivery, confirm the address, vehicle-access assumptions, unloading responsibility and whether units are left at the delivery point or moved nearer the openings. Bloomcabin states a delivery period of 4–6 weeks, subject to order confirmation, so plan dependent work from confirmed order information rather than an early estimate. Do not arrange premature removal of existing units around an unconfirmed date. Where delivery is a single amount, ask whether restricted access, split consignments or revised quantities would change it. The purpose is not to anticipate a problem but to identify the assumptions beneath the figure.
Convert allowances and exclusions into decisions
An allowance is a placeholder rather than a guaranteed final inclusion. Mark every provisional sum, estimate, “if required” phrase, TBC note and blank field. Ask which condition could change the amount or scope, who determines that condition and how a variation would be approved. Unseen repairs, altered openings, access needs and unfinished selections may reasonably remain uncertain. Do not demand certainty about concealed conditions; ask the supplier to distinguish the priced base work from events that would lead to a change. Compare the fixed scopes first, then consider whether each remaining uncertainty is acceptable at the present project stage.
Give exclusions equal attention. Use precise entries for structural alterations, plastering, redecoration, electrical relocation, blinds, alarm reinstatement, paving and disposal where relevant. Do not assume excluded work will be completed without charge by someone else. For a double-leaf inward-opening patio door, clarify both the internal swing around furniture and the responsibility for adjoining floor finishes. Assign every necessary task to the supplier, installer, another trade or yourself before choosing. The meaningful project cost comes from these combined scopes, even where some work will be contracted separately.
05 / Confirm the order
Review commercial terms and approvals
Read the commercial terms beside the specification. Check quotation validity, payment stages, deposit terms, what triggers final measurement, how drawings or schedules are approved and how requested changes are recorded. Ask whether the configuration remains subject to survey and whether survey changes produce a revised document before manufacture. Bloomcabin provides a 5-year warranty for windows and doors; request the applicable warranty wording with the order documentation and check that the final schedule identifies the products being ordered. Do not rely on an informal description of cover that is absent from the paperwork.
List every decision still open, including colour samples, handles, glazing patterns, handing and final dimensions. Give each one an owner and target date, especially where a delayed selection could postpone order confirmation. If the quotation contains one configuration while you are choosing between alternatives, ask for each alternative to be separately described and priced rather than leaving an oral option. Keep clarifications, revised drawings and final schedules together. The preferred quotation should be one whose scope and approval route can be explained to everyone coordinating the project, not simply the document with the most appealing first total.
Hold a final opening-by-opening review
Place the final quotations beside the master schedule and work through every row. Confirm what is supplied, how it operates, its dimensions, glazing, finish and hardware, and who completes work around it. Highlight unresolved points instead of filling them mentally. Compare separate subtotals for products, delivery, installation and site work where available. This reveals whether a difference comes from a genuine product choice, a service difference or an omission. It also allows you to accept a suitable alternative consciously rather than discovering after ordering that suppliers interpreted the same opening differently.
Send a final written confirmation request using the opening references and ask each supplier to identify any departure from the schedule. A pivot roof window should be confirmed as a pivot roof configuration at the relevant roof opening, not buried within a general “roof glazing” line. Apply the same discipline to every unusual item. Once questions are resolved, save the dated quotation, approved schedule and drawings as the baseline for manufacture and installation coordination. A short revision before commitment is more valuable than a quick decision based on assumptions that cannot later be traced.
Common questions
What is the quickest way to compare two window quotations?
Create one row for every opening and map each supplier’s line to it. Compare operation, dimensions, glazing, colour, hardware and installation scope before price. If a line cannot be matched to an opening, request clarification. Grand totals become meaningful only after the schedules describe equivalent work.
Should I reject a quotation containing provisional items?
Not automatically. A provisional item can be reasonable when a choice or site condition remains unresolved. Ask what is provisional, what could change it and how approval will work. Compare the fixed base scopes separately, then decide whether the remaining uncertainty is acceptable at that project stage.
Why can similarly sized patio-door quotations differ?
Overall size does not define the arrangement. Opening method, panel layout, active leaf, glazing, finish, hardware, threshold, delivery and fitting work may differ. Compare the intended route through the door and the adjoining floor details, then ask each supplier for a complete opening-specific description.
Is a survey the same as a final order specification?
No. A survey checks site dimensions and conditions; the final order specification records what will be supplied. Ask when the post-survey schedule will be issued, which changes need your approval and whether final dimensions, handing, glazing and finishes will be shown before order confirmation.
Which documents should I retain after choosing?
Keep the accepted quotation, final opening schedule, approved drawings or elevations, written clarifications, colour and hardware selections, delivery confirmation, warranty information and records of agreed changes. Together, they document the scope more reliably than a headline total or a collection of informal messages.
Next step
A dependable quote comparison is an audit of scope rather than a contest between totals. Record the existing site conditions, give every opening a reference and require consistent descriptions of operation, size, glazing, finish, fittings and surrounding work. Separate delivery, installation, exclusions and allowances so omissions remain visible. Request revisions where necessary and keep alternatives distinct. Approve the order only when every line is understood and the responsibilities around it are assigned. That process makes differences in GBP explainable and creates a useful record for measurement, manufacture, delivery and installation coordination.
