Read your window schedule before requesting a quote
Understanding window planning
At first glance, a window schedule can look like a table of abbreviations, dimensions and item numbers. In fact, it determines whether three suppliers are pricing the same scope or simply offering similar-sounding windows. Reading it before requesting quotes reveals missing details early: Is the dimension the structural opening, external frame size or clear opening? Is the opening direction viewed from inside or outside? Does the U-value apply to the glass or the complete window? And are the drawn glazing bars decorative or glass-dividing? These are not formalities. They affect function, appearance, installation planning and comparability. Work through every item, flag uncertainties and issue every supplier the same corrected version. This turns a planning document into a reliable basis for your quote request.
Check before requesting quotes 1
Use the window schedule as a shared benchmark
A sound enquiry starts with one simple rule: an item number represents one clearly described specification. Item F-01 may appear several times where identical windows are planned in different rooms. In that case, the quantity and identical configuration must be obvious. If even one detail changes, such as opening side, division, finish or glass, it will usually need its own item or an explicitly documented variant note. Otherwise, one supplier may assume a simplified version while another prices every variation separately. The resulting quotes can appear comparable in total, even though their actual scope differs. Start by marking all rows where a description could allow more than one possible configuration.
Keep all relevant documents alongside the window schedule: floor plans, elevations, sections, detail drawings where available, and a specification. The schedule often states what is to be supplied; drawings show where the element sits and its context. Do not quietly reconcile conflicting information yourself. Write, for example, “F-08: schedule single-leaf, elevation double-leaf” rather than choosing a version independently. For renovation work, also record whether the schedule contains existing dimensions, design dimensions or order dimensions already checked on site. Decide which document must be checked when information conflicts. That clarification belongs in the enquiry, not as a surprise at order confirmation.
Check item numbers, rooms and quantities
Begin with a checklist: every item number should have a location, quantity, element description and traceable drawing reference. Room names are especially useful where sizes recur. A bathroom window may need different privacy, ventilation and usability features from a visually identical living-room window. Without a location, an item can be priced, but important use questions remain unanswered. Check whether doors are included in the same schedule too. A patio door is easily grouped under “windows”, yet needs additional details about threshold, handle side and clear passage. Use consistent room names rather than changing abbreviations from different drawing revisions.
Check quantities not only line by line, but also by building elevation and storey. This can reveal elements missing from an elevation or counted twice by mistake. Identical windows on different façades can share an item if every feature truly remains the same. If they do not, split the items. For an enquiry, a single-leaf inward-opening window may describe a suitable product type, but that label does not replace the exact dimensions, handing, glass, finish or hardware requirement. Always include the item number. A small subtotal for each storey also makes it easier to compare the quote, order confirmation and actual delivery later.
Check before requesting quotes 2
Put dimensions in context before comparing
Numbers without a dimensional reference are a common source of misunderstanding. Width by height may mean the external frame size, opening size, structural opening or clear opening. The notation 1,235 × 1,485 mm does not explain that reference. For each item group, ask: Which dimension is stated, from which side is it read, and is it a design dimension or one verified on site? For windows with sidelights, toplights or coupled parts, also clarify whether the number describes the overall size or the individual sections. Record whether the order is consistently width × height so rotated dimensions do not go unnoticed.
Do not copy dimensions uncritically from a façade elevation when the window schedule gives different values. Elevations may be simplified for design purposes; conversely, a schedule can contain a transposed number. Check slopes, arches and special shapes particularly carefully. A triangular or sloping fixed-glazed window is defined by its outline geometry; width and height alone do not fully describe it. For these items, request a dimensioned sketch with clear reference points and the position of the slope. Installation planning also includes connection details and the intended position of the element within the wall build-up. The responsible design professional should assess these points for the particular installation situation.
Read views, opening types and handing correctly
A window symbol does not always explain everything. First clarify whether the drawing is read from inside or outside. Only then can left or right handing be interpreted reliably. For certainty, also describe in words which side the hinges are on in the stated view and the direction in which the sash opens. A tilt-and-turn window also needs its intended operating function. For a double-leaf version, record which leaf carries the handle, which opens first and what division is required. Where the floor plan and window elevation use different viewing directions, label both clearly rather than relying on arrows alone.
The opening type must suit how the room is used, not simply the façade drawing. An inward-opening sash can clash with furniture, curtains, fittings or a benchtop. An outward-opening sash, by contrast, needs sufficient clear space outside. A double-leaf inward-opening window describes the basic opening direction and number of leaves, but it does not automatically answer every detailed question. Mark possible clashes for each affected element on the floor plan and furniture layout. Also ask whether fixed and operable sections are labelled clearly. A visible division does not reliably show which section opens or which sash is used first in everyday life.
Check before requesting quotes 3
Do not confuse fixed glazing with a fixed sash
A window schedule should clearly distinguish fixed glazing from an opening sash. A fixed-glazed element is designed as a non-opening part; it may provide daylight, views or a calm façade division. An operable sash also provides operating and ventilation functions. Where a room has only fixed glazing, the planned ventilation method should therefore be raised as a project question. It should not be replaced by an assumption that a section will “somehow” open. Also check access for cleaning and maintenance from the intended installation situation. For high-level or externally inaccessible sections, this practical issue can influence the selected arrangement.
For combined elements, a field sketch is particularly useful. Show, for example, a fixed light on the left, an opening sash in the centre and another fixed light on the right. Add division dimensions, or clearly note when the supplier should propose these as an alternative. This prevents the overall external width alone being priced while the internal arrangement is interpreted differently. For a purely non-opening version, a fixed-glazed window is an appropriate description. Still check the actual schedule for mullions, transoms, division dimensions and glazing bars. With round or arched windows, it should also be clear whether the entire form is fixed glazed or whether adjoining rectangular sections are intended to open.
Compare glazing and U-values on the same basis
Terms such as double or triple glazing are a starting point, but not yet a complete basis for comparison. State in the enquiry which glazing is intended for each item and which additional properties are specifically required, such as privacy, patterned glass or a particular safety specification. A blanket statement for “all windows” is risky when individual rooms or door panels are planned differently. Create a separate glass column and have unclear requirements confirmed. For patterned glass, the designation, required appearance and assigned field should also be unambiguous. Always review quotes item by item: special glazing may have been allowed for only one line, even if the summary sounds more general.
The reference basis must be stated for a U-value. A value for the glazing is not automatically the value for the complete window. Ask: Which performance value is quoted, to which exact element and dimensions does it apply, and does it genuinely apply to every item offered? A Super Low Uw passive-house window, outward-opening names a product configuration, but does not replace item-specific confirmation of the required specification and values. Do not compare a single number alone. Dimensions, frame proportion, opening sashes, divisions and glazing all affect assessment of the particular element. If suppliers use different reference bases or sample dimensions, request an explanation before ranking offers. The energy design of the whole building should be handled by suitably qualified professionals.
Check before requesting quotes 4
Describe glazing bars precisely, not only with an image
“With glazing bars” is too vague for an enquiry. Bars alter a window’s appearance, but their construction can differ. Describe decorative glazing bars clearly as decorative, while bars that genuinely divide the glazing must be specified as glass-dividing. State the quantity, orientation, position and grid, for example two horizontal bars in the upper section. An elevation image is useful but cannot replace the written specification. For asymmetrical layouts, give dimensions or clear reference lines. If the grid must align across several elements, show that design intention in the elevations and describe it consistently for every affected item.
Check the glazing-bar layout separately for fixed lights and opening sashes. What looks symmetrical across the whole window elevation can end differently at sash edges, mullions or transoms. For a historic design intention, assess the frame effect, sash division and glazing-bar pattern together. A double-leaf historic-style casement window, outward-opening can serve as a starting point, but the precise glazing-bar design remains a separate specification. Also ask whether the drawing and description show the same quantity. If you do not want glazing bars, write “without glazing bars” explicitly. This avoids a schematic illustration being treated as a binding division, or a decorative version being offered when glass-dividing bars were actually intended.
Record doors fully as separate items
External and patio doors usually need more context in a window schedule than a standard window. Along with width, height, opening direction and handing, clarify their relationship to the finished floor build-up, the required passage arrangement and handle side. For a door to a patio, the threshold can be crucial to use; however, its exact construction must not be inferred from a symbol. Keep this as a question and coordinate it with the connection and floor design. A door leaf with a sidelight is not a simple individual dimension, but an assembly. State the overall width, divisions, fixed and movable sections, and the sidelight position clearly.
Large openings require especially clear identification of moving and fixed sections. For Patio Life lift-and-slide doors the schedule should show, for example, which panels are fixed and which move, from which internal view the operating side is defined, and whether the dimensions apply to the full assembly. Add the required opening side in words and check whether furniture, an external step or an adjacent wall section affects use. The same applies to folding or multi-leaf solutions. Request an item-specific drawing where the floor plan does not clearly show the sliding direction. This ensures every supplier prices the same system and the required passage does not end up on the wrong side because a view was misunderstood.
Check before requesting quotes 5
Assign finishes, handles and accessories explicitly
A window schedule is ready for enquiry only when visible and operable details do not appear solely in general notes. Check the desired colour or finish inside and out if these sides are to differ. Assign handles, hardware finishes, ventilation accessories, window sills, roller shutters or other components to clear items. If individual components are excluded from supply, this can also be recorded as a boundary. Where decisions are missing, ask for separately priced alternatives rather than allowing the supplier free choice. That keeps the base version comparable. Also check whether a global colour specification really applies to special shapes, doors and differently designed internal rooms, or whether exceptions need their own lines.
Operating height and accessibility also deserve a look at the floor plan and section. A high-level window may be planned as an top-hung outward-opening awning window but the enquiry needs to specify its operation and the required method of control. For hard-to-reach items, ask how the element is intended to be operated in daily use rather than defining only its form. Also document whether insect screens, privacy screening or sun protection need coordination. These components are not automatically part of a window quote, but can affect space, operation and connections. List separately what is to be quoted, merely prepared for, or planned by another trade. This prevents missing ancillary work from becoming visible only after price comparisons.
Turn unclear details into a quote comparison matrix
Rather than sending several emails with individual corrections, create a compact quote comparison matrix. Each row should include item number, room, quantity, dimensional reference, element type, opening type, view or handing, glass, glazing bars, finish and outstanding decision. Add a column headed “Supplier to confirm”. Put specific questions there, such as “Dimension understood as external frame size?” or “Decorative or glass-dividing bars allowed for?”. Another column can refer to the governing drawing and its revision. The matrix does not replace a drawing, but shows which details are binding and which remain open. Send the same dated version to every supplier. When questions are answered later, issue a new revision rather than overwriting individual cells without a change note.
Request feedback item by item, not merely as a total. On receipt, check that every item is included, quantities and dimensions have been adopted, and alternatives are separately identifiable. A lower quote is not automatically better value if an opening type, sidelight, accessory or required glazing is missing. Compare the scope first and prices afterwards. For differences, request a clear list rather than a blanket price adjustment. Windows and doors from Bloomcabin carry a five-year guarantee. Delivery takes 4–6 weeks, subject to order confirmation. Still check the specific order confirmation line by line against the final window schedule and document all approved changes.
Frequently asked questions
What is the main difference between a window schedule and a window drawing?
A window schedule organises item numbers, quantities and properties in a structured form. A drawing shows location, view, shape or installation situation. You need both for a reliable enquiry: the schedule supports comparison, while the drawing clarifies spatial relationships and divisions. Contradictions should be resolved in writing before requesting quotes and allocated to an unambiguous drawing revision.
Do I need to state left or right handing?
It can be helpful, but is not always sufficient on its own. Also state the view being considered, such as the internal view, and describe the hinge side and opening direction in words. For double-leaf windows, the handle side, first-operated leaf and intended use should also be clear from the schedule or a field sketch.
Is it enough to give only width and height in millimetres?
No. The supplier needs to know what the dimensions refer to, such as external frame size, structural opening or clear opening. Special shapes also need dimensioned geometry. State whether these are design dimensions or dimensions already checked on site, and whether the order is consistently width × height.
How should I specify glazing bars in an enquiry?
First name the type: glazing bars for a decorative version, or glass-dividing bars for genuinely separate glass panes. Add the number, horizontal and vertical position, grid and assignment to fixed light or sash. If no division is wanted, write “without glazing bars” clearly in every affected item.
What should I do if not every detail is decided yet?
Separate fixed requirements from outstanding decisions. For open points, ask for clearly labelled alternatives rather than silent assumptions. Have the base version priced fully and item by item. You can then compare variants later without retrospectively aligning several quotes or trying to break down unclear lump-sum prices.
Next step
A window schedule is not good because it contains many abbreviations, but because every item can be understood without guesswork. Check quantity, location, drawing revision and dimensional reference first. Then clarify opening type, handing, fixed and movable sections, glazing and glazing bars. Add finishes, operation and accessories only with clear item assignments. A short, visible list of open questions is more valuable than apparent completeness. When every supplier receives the same version-controlled document and identifies differences item by item, scopes and alternatives can be compared purposefully. Release the specification only when the window schedule, drawings and order confirmation all match.
