We seal window gaps across Bengaluru. Between every window frame and the wall it sits in, there is a joint, and in many buildings that joint was filled once with mortar or cheap sealant and never again. It cracks, crumbles and opens, leaving a running slot around the window. Fine dust drifts through it daily, ants and mosquitoes use it as a road, traffic noise rides through it, and in a storm it whistles. Sealing the full perimeter properly, inside and out, starts at ₹1,400 per window.
Where the gaps are, and why they open
A window frame and a masonry wall move differently. Concrete and brick barely move, the frame expands and contracts with every hot afternoon, and whatever rigid filler was packed between them cracks along that line within a few years. That crack is the gap, running the frame's whole perimeter.
Builders' mortar fill fails fastest, because mortar has no flex at all. Old sealant fails next, chalking and pulling away from one side of the joint. And in a surprising number of flats, sections of the joint were simply never filled: the top edge above the frame, hidden from sight, is the classic miss.
Run a torch around your frame's edge at night. Light from outside, or a visible dark slot, is the confirmation.
What comes through an unsealed joint
Dust, endlessly. Bengaluru's fine construction and road dust settles on sills and shelves near the window however often the room is cleaned, because the supply line is open all day.
Insects, deliberately. Ant trails around a window almost always start in the frame joint, and mosquitoes find slot-shaped entries that mesh on the shutters cannot help with, because the gap bypasses the mesh entirely.
Noise, constantly. A slot is an open sound path, and sealing the perimeter takes a real edge off traffic and street noise, more than most people expect from so thin a line.
And during storms, whistling and fine spray. The joint is the windward face's weak line, and the gap-sealed window is also drier in the monsoon.
Sealing done properly
Loose material comes out first: crumbled mortar, dead sealant, dust in the joint. Sealant bonds to clean surfaces or not at all.
Deep gaps are packed with backer rod, a foam cord that fills the depth so the sealant sits at the right thickness instead of sinking into the void. This step separates sealing that lasts a decade from beads that split in a season, and it is the step skipped in most quick jobs.
Then exterior-grade sealant, gunned into the joint and tooled to a smooth, slightly concave line that flexes with the frame's daily movement. Outside face and inside face both, because each does a different job: outside carries the weather, inside stops the dust and noise that get into the wall cavity by other routes.
The line is paintable once cured, and it disappears into the wall within a repaint.
Cost per window and per house
One window, sealed on both faces with preparation and backer rod, starts at ₹1,400. Larger openings, balcony-door-sized frames, price up modestly by their perimeter length.
Gaps rarely afflict one window alone: the same builder filled every joint in the flat the same way in the same year. The usual booking, after the torch test travels the house, is most of the windows in one visit, and the per-window figure works out lower that way.
One scope note: this service seals the frame-to-wall joint. Gaps between shutter and frame, the moving parts, are the territory of our seal replacement and air sealing pages, and if your draught is coming from there, we will say so and point at the cheaper right answer.
