A pane has cracked, the hardware has broken, cold air seeps from under the frame or it is simply time to upgrade the glazing — and you need an installation. It looks straightforward: pull the old window out, slot the new one in, foam the gap. But get the measurements wrong, set the frame out of level or skimp on the foam and within six months you will have gaps, condensation and draughts. We install uPVC and timber windows across Warsaw: standard, roof, non-standard sizes. If the existing window is still sound but draughty, adjustment or resealing without a full swap may be enough.

How much does window installation cost and what affects the price

The cost depends on the window size, the construction type and the condition of the reveal. A standard two-leaf window in a panel block is one situation. A large floor-to-ceiling balcony glazing is another. A roof window in a pitched roof is a third, with an entirely different fixing method.

The labour charge covers removing the old window (if present), fitting the new one, levelling, anchoring, foaming the perimeter joint and checking the opening action. The window itself is supplied by the client. A sill, reveals and external flashing are separate jobs. Waste removal is extra. Current prices below.

Send a photo of the window and the reveal dimensions — the technician will calculate the exact cost.

How window installation works: step by step

Fitting a window is not just a matter of inserting it and foaming the gap. Every stage affects airtightness, thermal performance and the lifespan of the unit. Here is how the technician works:

1. Measuring the reveal. The technician measures width, height and depth at several points. A 5 mm variation is normal, but if the discrepancy is larger the reveal needs preparation.
2. Removing the old window. We take off the sashes, undo the fixings, cut through the old foam and carefully extract the frame. If the reveals are crumbling, we cut back to a solid substrate.
3. Preparing the reveal. We clear away leftover foam, plaster and debris. We check that the surfaces are flat. If badly damaged, we level with cement mortar and allow it to set.
4. Setting the frame. We place the frame on support packers and level it horizontally and vertically. This is the critical step — a crooked frame means sashes that will not close. We fix with frame anchors or through-bolts every 60–70 cm.
5. Foaming. We fill the perimeter gap with expanding foam — evenly, with no breaks. Excess is trimmed after curing. Outside we apply vapour-permeable tape; inside, a vapour barrier.
6. Hanging the sashes and testing. We fit the sashes, check that they open, close and tilt smoothly. We inspect the seals all round and adjust the hardware.
7. Final check. We test airtightness by running a lighter along the seals — the flame should not deflect. We verify that the handle locks the sash in every position.

Common mistakes during window installation

Mistakes during window fitting are expensive. Reworking an installation is harder and costlier than getting it right first time:

• Wrong measurements. The window was ordered 2 cm too large — it will not fit. Or 3 cm too small — the gap is too wide and the foam cannot bridge it. Measure at least three points across width and height.
• Frame not levelled. A 2–3 mm deviation per metre — and within six months the sash drops under its own weight and stops closing.
• Skimping on fixings. The frame is held by foam alone with no anchors. The first strong wind shifts it. Frame anchors or through-bolts every 60–70 cm are essential.
• Poor foaming. Foam applied with gaps or in too thick a bead. The result — thermal bridges, condensation on the glass in winter, mould on the reveals.
• No vapour barrier. The foam is exposed on both sides. Outdoors it degrades under UV; indoors it absorbs moisture. Within a year or two the joint loses its performance.
• Sill without a slope. Condensation water pools on the sill and seeps under the frame. A 2–3 degree slope towards the room is needed.
• Forgetting the external flashing. Rainwater gets under the frame, destroying the foam and the wall. An external sill with sealant is essential.

What to prepare before the technician arrives

Window installation is dusty work — preparation saves time and stress:

• Move furniture at least 1.5 metres from the window — dust and plaster fragments fly during removal.
• Take down curtains, curtain rails and blinds beforehand.
• Cover the floors with sheeting — construction dust embeds itself in laminate and parquet.
• If the window is on an upper floor, warn the neighbours below (pieces can fall during removal).
• Make sure the new window has been delivered and the dimensions match the reveal. Check completeness: frame, sashes, hardware, seals.
• Ensure access for carrying the window in — large units do not fit in lifts.
• Have access details ready: entry code and parking information — the technician arrives with tools.
• Decide in advance whether you need reveals, a sill and flashing — cheaper to do in one visit.
• If there are children or pets in the flat, keep them away from the work zone.
• In winter, bear in mind that the opening will be exposed for 30–60 minutes. A heater in the next room is a good idea.

A real case: window replacement in a Praga-Poludnie flat

A client in Praga-Poludnie decided to replace three windows in a 1970s flat. The old timber frames had dried out, the seals had turned to dust, and the draughts were strong enough to move the curtains. The reveals turned out to be uneven — up to 15 mm difference in width between top and bottom.

We had to level the reveals with cement mortar and wait a day. On day two we fitted all three windows: two standard double-leaf units and one balcony door-and-window set. Each frame was set with a laser level and anchored every 50 cm — the reveals were old, the walls silicate brick that crumbles easily. We foamed with professional winter-grade foam (it was +3 °C outside) and applied tapes inside and out. Sills were fitted with the correct slope and external flashings sealed. The sashes were adjusted — all close smoothly. The client noticed the difference immediately: the flat became quiet and warm. The takeaway: in older Warsaw buildings window installation takes longer because of uneven reveals, but the result is well worth the wait.

Frequently asked questions

Who does the work and what guarantees we offer

Windows are handled by tradespeople experienced in fitting in panel blocks, brick-built period buildings and new developments across Warsaw. We work with uPVC and timber units of any size. We arrive fully equipped: rotary hammer, laser level, expanding foam, anchors, tapes. We guarantee that after installation the window will be airtight, the sashes will operate smoothly and the perimeter joint will be protected from moisture and UV. If you find a draught caused by our work, we fix it free of charge. Call or message us — we typically reply within an hour.