Window Water Tightness Test: How Aluminum Windows Are Checked

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A window water tightness test checks whether rain driven by wind can pass through the window frame, sash and seals under controlled pressure. Air infiltration testing measures how much air leaks through the unit when it is closed. Both checks depend on correct measurement, sound profile design, quality seals and careful installation.

Why water tightness and air infiltration matter

A window can look perfect and still let rain and draughts into a room. Water tightness describes how well the unit resists water pushed by wind, while air infiltration describes how much air passes through closed joints. Both affect comfort, dampness, noise and energy use in an apartment or office.

For building inspectors and clients, these two properties are the real test of whether an aluminum window was made and fitted properly, not only how it looks on the day it is delivered.

Measurement and site survey before production

Every window starts with an on-site measurement. We check the opening width and height at several points, the depth of the wall reveal, the sill condition and the direction the building faces. Wind exposure on a high floor differs from a sheltered courtyard, and this changes the demands placed on the frame and seals.

Photos taken during the survey help us record the surrounding finishes, so the frame junction with the wall can be planned before the aluminum is cut.

Drawing and written specification

After measurement we prepare a drawing and a written specification. It lists the profile system, glazing, gasket type, drainage route and the fixing method. The specification also states the performance the client expects for water tightness and air infiltration, so both sides agree on the target before work begins.

Profile depth and wall thickness
Glazing build-up and gasket positions
Drainage slots and weep holes
Fixing points and anchor type

Production and in-factory checks

Aluminum profiles are cut, mitred and assembled in our factory on Rival Street. Corners are welded or mechanically joined, and the drainage channels are checked so that any water entering the frame can leave again. Gaskets are fitted continuously and inspected for gaps before the sash is glazed.

Finishing, including powder coating, is completed before dispatch so the surface is protected during transport and handling on site.

Installation and sealing on site

Most leaks come from installation rather than the window itself. The frame must be level, plumb and square, and the gap to the wall must be filled and sealed correctly. We recommend installing a continuous sealant or membrane at the perimeter and making sure the sill slopes outward so water runs off.

Inspectors should look at the junctions between the frame and the masonry, as these are the most common points of failure.

Inspection and testing procedures

Water tightness is usually assessed by spraying the unit with water while applying air pressure, then observing whether water appears on the inner face. Air infiltration is measured by pressurising the closed window and recording the airflow through it. Results are compared with the performance agreed in the specification, and with the requirements of the relevant Israeli standards, which our engineer reviews for each project.

Where exact values are needed for approval, they are confirmed with the project engineer rather than estimated on site.

Frequently asked questions

What is a window water tightness test?

It is a test where water is sprayed onto a window while air pressure is applied, to see whether any water passes through the frame or sash. It shows how well the unit resists wind-driven rain.

What is the difference between water tightness and air infiltration?

Water tightness concerns rain being pushed into the window, while air infiltration concerns air leaking through a closed unit. A window can pass one test and fail the other, so both matter.

Can I check water tightness myself?

A simple visual check of seals, drainage slots and the wall junction helps, but formal testing requires controlled spray and pressure. For approval, ask for a documented test with the results recorded.

Who is responsible when a new window leaks?

Responsibility depends on whether the fault lies in the product, the measurement or the installation. A written specification and documented installation make it much easier to identify the cause.

Common mistakes to avoid

The most common mistake is focusing only on the window unit and ignoring the installation junction with the wall. Skipping the written specification of performance targets also leads to disagreement later.

Our recommendation

Agree the water tightness and air infiltration targets in writing before production, and inspect the frame-to-wall junction before the finishing trades cover it.

Summary

Window water tightness and air infiltration are controlled by accurate measurement, sound profile design, quality seals and careful installation, and they should be verified by testing rather than assumed.

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