When Should You Order Windows During House Construction?

A Stage-by-Stage Planning Guide for Homeowners

Homeowners often treat windows as a finishing-stage decision — something to sort out once the walls are up and the house is starting to look like a house. It’s an understandable assumption. But by the time windows come up for discussion, several of the choices that shape them may already have been locked in.

Opening sizes, wall finishes and sill levels may already be decided before the window requirements are fully discussed. These decisions can affect details such as mosquito mesh and sliding door tracks.

So the real question isn’t when do I buy windows. It’s when do I start planning for them — and the answer is: much earlier than you’d think.

The process that actually works looks like this:

Plan early → Finalise the system → Measure at the right moment → Manufacture → Install at the right stage

Here’s how that plays out, stage by stage.

Why Windows Deserve Early Attention

A window today isn’t just glass in a frame. Depending on the room, it might need to handle:

• Large, uninterrupted glass spans
• Sliding or multi-track shutters
• Fixed glazing panels
• Mosquito mesh (sometimes on a dedicated track)
• Safety grills
• Toughened or laminated glass
• Double glazing for heat or sound
• Corner or wraparound configurations
• Balcony-height openings
• Ventilators
• Space for curtains or blinds later on

Leave all of that until after the walls are finished, and you’re no longer designing a window — you’re negotiating with a wall that’s already decided the answer. The better approach is to fold window planning into the building process itself, not bolt it on at the end.

Stage 1: Architectural Planning

Timing: Before construction begins

This is where the window concept takes shape — not the final spec, just the intent. Your architect will rough out opening positions and sizes based on elevation, light, and airflow. But this is also the point where you, as the homeowner, should start asking yourself some practical questions:

• Do I want this window to slide, or swing in or out?
• Does this room need strong cross-ventilation?
• Is an unbroken outside view a priority here?
• Will this opening need mesh? A grill?
• Does this room need better acoustic insulation?
• Should the elevation carry larger glass panels?
• Are there balcony doors or floor-to-ceiling sections involved?
• Will curtains or blinds go up here eventually?

These aren’t cosmetic questions — they affect the opening dimensions themselves. A wide opening drawn for a basic two-track slider may require different opening details and structural coordination if you later choose a slide-and-fold configuration, depending on the selected system. Better to know that now than after the lintel is cast.

You don’t need every technical spec nailed down at this point. You just need to know, room by room, what each window is for.

Stage 2: Masonry Stage

Timing: While walls are going up, before openings are finished off

Once the structure starts rising, it’s worth pulling out the window schedule and checking it against what’s actually being built. Changes are generally easier to coordinate at this stage than after plastering and tiling.

Worth checking at this point:

• Opening width and height, as built
• Sill height
• Lintel level
• Whether windows line up across the elevation
• Position of large doors and windows
• Corner conditions
• Clearances around structural columns
• Room for shutters to swing or slide freely
• Space for grills or mesh tracks

Sill height in particular gets overlooked, and it shouldn’t. It governs how the outside view looks, where the kitchen counter or study table can go, bathroom privacy, child safety — even where furniture can sit. A kitchen window set without reference to counter height, or a bedroom window that ends up fighting with the bed placement, is the kind of thing nobody notices until they’re living with it.

Reviewing these details now can help avoid rework after plastering and tiling.

Stage 3: Choose the Window System

Timing: Before final plastering and finishing work wraps up

By now you should be narrowing down the manufacturer and the broad system — sliding, casement, fixed, combination, sliding doors, slide-and-fold, ventilators. Different rooms will likely need different answers.

This shouldn’t be an aesthetic decision alone. Opening size, required ventilation, wind and rain exposure, how easy the window is to operate and clean, safety, mosquito protection, and the physical space around the opening all matter just as much as how it looks in a photo. A qualified window consultant reviewing your drawings at this stage — before civil finishing gets too far along — can flag issues that are still easy to fix.

Stage 4: Plan the Glass

Timing: Alongside the system decision

Not every window in the house needs the same glass. Match the glass to what the opening is actually doing:

• Clear glass — where light and view take priority.
• Toughened glass — heat-treated for extra strength; a common choice where openings are large or safety is a concern.
• Laminated glass — uses an interlayer that helps retain glass fragments if the glass breaks. It can contribute to safety and security when appropriately specified for the application.
• Tinted or solar-control glass — can help manage glare and heat on sun-exposed elevations, depending on orientation and the selected glass.
• Single glazing — the standard one-pane setup.
• Double glazing — two panes with a sealed gap between them, which can meaningfully improve thermal and acoustic performance depending on the overall configuration.

This decision matters more in some rooms than others: large windows, bedrooms facing a busy road, west-facing rooms that catch the afternoon sun, balcony doors, staircase glazing, kids’ rooms, anywhere security is a concern. At Ascendia, we look at glass, frame, and application together rather than treating glass as something you pick off a shelf at the end.

Stage 5: Decide on Mesh and Grills

Timing: Before the window goes into production

A surprising number of homeowners only think about mesh and grills after the windows show up on site — at which point the options have narrowed considerably. Decide in advance, opening by opening, whether you need:

• Mosquito mesh
• A safety grill
• Both
• Neither

Sliding windows often need a dedicated mesh track built into the frame from the start. For slide-and-fold systems where it’s appropriate, a pleated mesh may be worth considering.

Safety needs also vary across the house — ground floor windows, kids’ rooms, and easily reached openings may have different safety requirements from upper-floor windows. If you’d rather avoid the visual clutter of a grill, laminated glass can sometimes serve as part of the safety strategy, depending on the application. Either way, the goal is to plan this as part of the window system, not add it on afterward as an afterthought.

Stage 6: Get the Opening Properly Finished

Timing: After plastering, before final measurement

This stage gets skipped more often than it should. Window manufacturing runs on precise dimensions, and measurements taken too early can be quietly wrong by the time internal plaster, external plaster, sill work, tiling, cladding, and waterproofing are all done.

Before anyone takes final measurements, confirm:

• The opening is square and properly finished
• Internal plaster is at its final thickness
• The external finish around the opening is settled
• Granite or stone sill details and their effect on the final opening dimensions are confirmed
• Finished floor level is known, for doors
• Cladding thickness, if any, is confirmed
• No further dimensional changes are expected

Balcony doors and floor-level sliding systems are especially unforgiving here — even a small shift can throw off installation and finish quality.

Stage 7: Take Final Site Measurements

Timing: Once openings are genuinely ready

This is normally when the supplier should take final production measurements; preliminary site checks can happen earlier. Treat the architectural drawing dimensions as a guide, not a manufacturing spec. Site conditions drift: masonry tolerances, plaster thickness, structural tweaks, flooring changes, sill adjustments. The only dimensions that matter for production are the ones taken physically, on site, at this stage.

For larger projects with many windows, it’s worth having your supplier prepare a proper window schedule — reference number, location, final dimensions, opening type, frame configuration, glass spec, mesh, grill, and finish for each one. It sounds like paperwork, but it’s the difference between a smooth handover and a site full of mismatched openings.

Stage 8: Place the Final Order

Timing: As soon as specs and measurements are locked

Once measurements are approved, get the order moving. Don’t wait until painters, electricians, and interior contractors are all on site at once before placing it — windows are engineered products, and they take time to manufacture. Lead times shift depending on quantity, sizes, profile availability, colour or finish, glass spec, hardware, and how custom the design is.

Order at the right point and manufacturing runs quietly in parallel with the rest of the finishing work. Order late, and it becomes the thing everyone’s waiting on.

Stage 9: Prepare the Site for Installation

Before the windows arrive, the site needs to be genuinely ready — accessible, free of major obstructions, plastered where required, structurally sound, and not a hazard zone. It’s worth having a direct conversation with your contractor and window team about scaffolding, exterior access, sill finishing, sealant zones, waterproofing, adjacent cladding, and final floor levels.

Good windows installed carelessly still perform poorly. Frame, glass, hardware, anchoring, and sealing only work as a system if they’re installed as one.

Stage 10: Install Before the Final Touch-Ups

Coordinate window installation before the final painting and finishing touch-ups, following the agreed installation sequence. Installation may involve drilling, anchoring, sealant, minor adjustments, and moving glass and frames around an active site. Painters and finishing crews can then complete the final touch-ups around the openings.

At the same time, don’t install too early either. A window sitting through months of active cement work, welding, or grinding is a window that’s going to show it later. Timing this stage well matters more than people expect.

Stage 11: Protect the Windows Through the Rest of Construction

Once installed, windows need to be treated as finished elements, not construction material. Keep them away from:

• Cement splashes
• Paint overspray
• Plaster buildup
• Grinding sparks
• Welding heat near glass
• Dust getting into hardware and tracks
• Being used as a support for scaffolding or materials

If protective film is applied, follow the manufacturer’s instructions for its use and removal. A little care here saves permanent stains and damage before you’ve even moved in.

Stage 12: Final Inspection and Handover

Before signing off, go through every window individually:

• Operation — does every operable shutter move and lock smoothly in its intended modes?
• Glass — any visible damage or installation marks?
• Hardware — handles and locks working properly?
• Sealing — is the perimeter seal intact?
• Mesh — moving freely and fitted correctly?
• Alignment — do frames and shutters sit true?
• Drainage — are weep holes and drainage paths clear?
• Cleaning — has construction residue been cleared off?

It’s a slower process than just glancing at the windows and moving on, but it’s far better than finding these issues after you’ve moved in.

A Simple Planning Timeline

Mistakes Worth Avoiding

1. Waiting until plastering is fully done to think about windows — by then, changing the opening means real rework.
2. Ordering off architectural drawings alone — always verify at site.
3. Leaving glass selection to the last minute — it affects safety, heat, sound, and privacy.
4. Forgetting mosquito mesh — retrofitted mesh rarely integrates as cleanly as mesh planned from the start.
5. Ignoring grills until installation — position affects appearance, access, and how the window operates.
6. Not coordinating kitchen and bathroom windows with counters, tiling, plumbing, and privacy needs.
7. Installing too early — active construction damages frames, glass, and hardware.
8. Ordering too late — this delays everything downstream, including handover.

When Should You Actually Call a Window Company?

Before the masonry openings are fully finalized — but you don’t need to place the order that day. An early consultation just gives a window specialist the chance to review your opening sizes, configurations, glass requirements, mesh and grill needs, sill conditions, and installation details while there’s still room to adjust.

The final order can wait until the site actually reaches the right measurement stage. For anyone building in Kerala, where rainfall, humidity, strong sun, and coastal exposure all factor into window performance, that early technical input tends to matter even more.

Windows Are Part of the Building, Not an Afterthought

The right time to think about windows isn’t when the house is nearly finished — it’s when it’s still being planned. At the same time, don’t rush to manufacture from early drawings before the openings are actually ready. The right approach sits between those two extremes:

Plan early. Measure at the right stage. Manufacture accurately. Install carefully.

At Ascendia Window Systems, we treat each window as part of the building envelope — not a standalone product dropped in at the end. Coordinating the frame, glass, hardware, mesh, safety features, and installation timing from the right stage is what actually produces windows that look right, work properly, and hold up over the years.

A bit of planning during construction saves a lot of compromise after you’ve moved in.