Window Position and Reveal Decision Checklist

Ask whoever is designing the openings whether the position of the frames within the wall depth has already been settled, and if so, when and by whom.

This decision is frequently made silently inside a standard detail, which is why owners meet its consequences rather than the choice itself.

Ask what positions are actually available in the wall you are building or altering, rather than assuming the full range is open in every construction.

What the wall is made of limits where a frame can go, so the realistic options are narrower than a general discussion suggests.

Write down, in the designer's own words, what each available position would change about the perimeter, and keep that note with your drawings.

A written record of the reasoning survives long after the meeting, and it is what you will want when somebody later questions the detail.

Ask a qualified professional to set out the thermal, structural and water consequences for your particular wall. None of them can be generalised here.

Note clearly for yourself which parts of this are yours to prefer, such as how the reveal looks, and which parts belong entirely to the designer.

Owners who express a preference on a technical point can inadvertently take on responsibility for it without anyone saying so.

Ask at what point the position can no longer be altered without reworking something already built or already ordered, and put that date in your own notes.

Openings are often formed and units ordered well before installation, so the window to raise anything closes earlier than owners expect.

Photograph how the existing windows in the building sit within the wall, from inside and outside, so the discussion has a reference in front of it.

An existing building already demonstrates one position and its consequences, which is far more useful than describing options in the abstract.

Look at every window in the house and note what currently sits on the internal sill, from plants and radios to keys, and whether you would miss that surface.

Internal sill depth is a daily convenience that nobody thinks about until it disappears, and it follows directly from frame position.

Note where a radiator, a bench, a desk or a run of units sits beneath a window, and whether anything currently overlaps the reveal.

Furniture and heating below a window frequently assume a particular reveal, and that assumption is rarely written down anywhere.

Ask what the internal reveal will be finished in, and whether the finish is the same material as the surrounding wall or something set into it.

Reveal finish affects how the opening reads from inside and how easily it can be repaired or redecorated later.

Note where the opening handle would sit relative to the reveal, and whether anyone in the household would struggle to reach it across a deep return.

A deeper internal reveal puts the handle further away, which matters most to whoever finds reaching difficult.

Stand at your existing windows at different times of day and note how the reveal shapes the light at the edge of the opening.

Reveal depth changes the quality of light entering a room, and this is the consequence owners are least able to picture from a drawing.

Write down what you want the internal reveal to do in each main room, as a plain sentence, and give that to the designer rather than a dimension.

Stating the use leaves the technical decision where it belongs while still letting your requirement reach the detail.

Walk round your own building and nearby ones and photograph the marks below the windows, noting where dirty water has run down the face.

Staining patterns below openings are visible evidence of how water leaves a cill, and they vary noticeably between positions.

Ask what the external cill or sub-sill is to be made of, how far it projects beyond the face, and whether it returns into the reveals at each end.

The external cill is the component that decides where water leaves the opening, and it is often chosen late and for appearance alone.

Whether a cill arrangement can be jointed to the surrounding construction without becoming a route for water is a design determination.

Note how deep the external reveals look on buildings with windows set at different depths, and record which reading you would want on your elevation.

Depth of shadow at the opening is one of the strongest characteristics of an elevation, and it is settled by this single decision.

Ask what the wall directly beneath each window is finished in, and whether that finish is one that shows marks from water running off the cill.

Some finishes carry run-off almost invisibly and others record every drip, which makes the surface below part of the same question.

Note what sits below each window outside, such as a bed, a path or a gravel strip, and whether water leaving the cill would land there.

Where run-off lands is worth naming early, because it affects splashing back onto the wall as well as the planting itself.

Photograph each elevation squarely from outside before any work, so the existing rhythm of openings and shadows can be compared with a proposal.

A square-on photograph is the simplest way to hold a conversation about how a new opening will sit among the existing ones.

List, window by window, what you intend to fit, whether that is blinds, shutters, curtains, a pole, secondary glazing or nothing at all.

This list is the single most useful thing an owner can bring to a window discussion, and almost nobody brings it.

Ask whoever supplies blinds or shutters what they need behind the face of the wall to fit inside the reveal rather than in front of it.

Supplier requirements differ, and asking them before the opening is detailed is far easier than discovering the constraint afterwards.

Note which windows open inward, and whether anything mounted in the reveal would foul the opening leaf or its handle when in use.

Inward-opening units and reveal-mounted coverings compete for the same space, and this clash appears late and expensively.

Note whether any ventilation opening is formed in or above the frame, and ask whether a covering fitted in the reveal would sit across it.

Coverings that block a designed ventilation route are a common outcome of two separate decisions made by two separate people.

What ventilation provision your building needs is confirmed with a qualified professional and the relevant local authority, not assumed.

Note where a curtain pole or track would fix at each window, and whether the fixing would land in the reveal, on the wall, or into the ceiling.

Where a pole fixes depends on what is behind the finish there, which is a question worth asking while the wall is still open.

Put the window-by-window list into your written brief rather than mentioning it in conversation, so it reaches whoever details the openings.

Verbal requirements do not survive the gap between design meetings and detailing, whereas a written list usually does.

Ask whether every opening in the project is to follow the same position strategy, and if not, which ones differ and why.

A single consistent approach is easier to detail and easier to explain, and a deliberate exception is very different from an accidental one.

Note every place where new openings will sit on the same elevation as existing ones, and photograph how the existing ones currently sit.

The junction between old and new windows on one face is where a mixed approach becomes visible from the street.

Ask what happens where the project includes more than one kind of wall, such as an extension built differently from the original house.

Different wall build-ups impose different constraints, so one strategy may need different detailing in each to read consistently.

Note whether doors and rooflights in the same project are being treated as part of the same family of details or handled separately.

Doors and rooflights have their own requirements but still read as part of the same envelope, and owners often see them together.

Where an opening is deliberately treated differently, record what was said about it, so the exception is not mistaken later for an error.

Undocumented exceptions get corrected by someone who assumed they were mistakes, which is worse than the original inconsistency.

Ask plainly what mixing approaches would mean at the junction between them, and write the answer down rather than relying on reassurance.

Naming the junction makes it somebody's responsibility, which is the entire point of an owner asking the question at all.

Junctions between differently detailed openings are a matter for a qualified professional. Record the question; leave the resolution to them.

Ask, window by window, how the outside face is expected to be cleaned, and note which ones could only be reached from outside the building.

Cleaning is an owner obligation from handover onwards, and it is decided by the design rather than by the person doing it.

Note any window standing above a roof, a lightwell, a planted bed or a neighbour's land, where reaching the outside would not be straightforward.

What is below a window decides what can stand there, which is why this is a plan question rather than a maintenance one.

Work at height is a matter for qualified people with the right equipment. Record the constraint rather than planning the access yourself.

Ask whether any window is intended to be cleaned from inside, and what that depends on, such as the way the unit opens or reverses.

Inward cleaning is a property of the unit and its opening arrangement, and it should be confirmed rather than assumed from a picture.

Note how a broken unit would be got to and taken out at each window, including whether anything would have to be removed to reach it.

Replacement route is part of the same access question and is almost never discussed while the building is still on paper.

Ask which parts of the opening perimeter can be looked at later and which are permanently concealed once the reveals are finished.

Knowing what has been made permanent tells you what has to be right first time and what could be revisited.

Write the cleaning and replacement route for each window into the record you keep for the building, alongside the product information.

This information is obvious on the day and completely lost a few years later, which is exactly what an owner record is for.

Ask which drawing actually shows the frame position, keep a copy of it, and note the date and revision marked on it.

Owners routinely hold general arrangement drawings and not the detail that settled the question they later want to revisit.

Photograph each opening after the frame is fitted and before the reveals are finished, from inside and outside, and date the images.

This is the last moment the perimeter can be seen at all, and the photographs become the only record of what is behind the finish.

Note any opening where the position ended up different from the drawing, and write down what you were told about why it changed.

Site changes to openings are common and sensible, but they only become part of the record if somebody writes them down.

Ask whether the first window can be looked at by everyone involved before the rest are fitted, and note what was agreed at that review.

A first-of-type review is the standard moment to catch something that reads wrong, and owners often do not know to ask for one.

Keep the documentation supplied with the windows, including anything about the perimeter and the drainage openings in the frames, in one place.

The product's own documentation governs a good deal of what the perimeter has to do, and it is easily lost during a project.

Do not seal or paint over drainage openings formed in a frame. What those openings require is set by the manufacturer's documentation.

Write down who made the position decision, when it was made, and which meeting or email it appears in, and keep that note with the drawings.

A short provenance note is worth more than a long argument later about what was agreed and by whom.