Replacing Old Nako Windows
Options, Ventilation and Costs

What a nako (louvre) window is

A nako window, also called a louvre or jalousie window, is a frame holding a stack of narrow glass blades in metal clips. A handle tilts all the blades together, like a Venetian blind made of glass. The doors and windows guide sums up its place in Malaysian homes: excellent ventilation, less secure, and traditional in Malaysian terrace houses, especially in kitchens, bathrooms and service areas.

Many older terrace houses and flats still have their original nako windows. They are often not broken, just tired: blades that no longer close tight, clips that have rusted, and a gap that lets in dust, insects and wind-driven rain.

Why owners replace nako windows

• Security. Loose glass blades can be slid out of worn clips, and the doors and windows guide rates louvres less secure than other windows.
• Rain and dust. The blades overlap but do not seal, so driving rain and dust come through even when the window is shut.
• Aircon and noise. A room that is being air-conditioned loses cool air through the gaps, and traffic noise comes in the same way.
• Worn hardware. Rusted clips and stiff operators make the window hard to open and close, and a loose blade can fall.
• Cleaning. Many narrow blades mean many edges to clean.

Before replacing, it is worth asking whether the problem is the window or the frame around it. The window repair guide puts the rule simply: the decision is made by the frame, not by the fault. A sound frame can often take new hardware; a corroded one is a replacement.

Keep the ventilation the by-laws expect

The reason nako windows were fitted in kitchens and bathrooms is airflow, and the Uniform Building By-Laws 1984 (UBBL) still expect it. By-law 39 in the consolidated text published by KPKT says every room used for residential or business purposes must have natural lighting and ventilation through windows with a total area of not less than 10 percent of the room’s clear floor area, and not less than half of that must be openable so that air can pass through freely.

For bathrooms and toilets the same by-law asks for openings of not less than 0.2 square metre per water closet or bathroom, through which air can pass freely. That text is a model by-law, and your state’s UBBL is the one that applies, but the practical lesson holds: do not replace a bathroom or kitchen nako with fixed glass. Choose a replacement that still opens, and keep the opening area.

What to replace a nako window with

For a kitchen or service yard the doors and windows guide still recommends a louvre for maximum ventilation and steam release, so replacing a kitchen nako with a new, better-made louvre is a reasonable choice. In a bathroom, a top-hung window gives airflow while keeping most rain out.

What the replacement windows cost

Indicative Klang Valley ranges for 2026, quoted unchanged from the doors and windows guide:

Removing the old frame, making good the plaster around the opening and repainting are usually separate lines. The window count, their sizes, the floor level and access all change the price.

Bathroom and kitchen windows

Bathrooms and kitchens are where most nako windows sit, and where the choice matters most. Steam and cooking smoke need somewhere to go, and a window that is kept shut because it leaks or rattles does not ventilate at all. Frosted or patterned glass keeps privacy in a bathroom without giving up the opening.

If the room has an exhaust fan, the window still matters: the by-law rule is about natural ventilation. For wet-area damp that has already marked the walls, look at the source first; a new window will not dry out a wall that is wet from a leaking pipe or failed waterproofing.

Frame, glass and hardware to specify

• Frame thickness. The doors and windows guide recommends specifying a minimum 1.2 mm frame wall thickness for aluminium windows, and 1.4–2.0 mm for larger openings or high-wind exposure.
• Frame material. Aluminium is the usual choice; uPVC costs more and seals better.
• Glass. Frosted or patterned for bathrooms, clear or tinted elsewhere. Ask for the glass type in writing.
• Hardware. Friction stays, handles and locks are often priced separately by cheaper suppliers.
• Colour. Match the rest of the house, or the building’s approved colour in a strata scheme.

Sealing and drainage: fitting it so it does not leak

A new window is only as dry as its installation. Window frames must be sealed with a flexible sealant at the perimeter to prevent water ingress, one of the most common causes of wall dampness in Malaysian homes. At the same time, the frame has to drain: the window repair guide warns never to let anybody run sealant across the bottom of the outer frame, because that blocks the weep holes.

If an old opening already leaks around the frame, sort out the cause as part of the replacement; the window leak repair guide explains how to tell a frame leak from a wall leak.

Grilles and security

Replacing a nako window improves security by itself, because hinged and sliding windows lock and have no loose blades. Many owners add a grille at the same time. The doors and windows guide notes that at least one quick-release emergency grille per floor is needed for fire escape under UBBL and local authority rules, so plan which window that will be. Casement windows that open outward need a grille that still lets them open; see invisible grilles for an option that sits inside the frame line.

Flats and condos: approval first

In a strata building the outside face of the window is part of the elevation. The window repair guide notes that any change to the appearance of the elevation, including a different frame colour or a new grille, is normally a permit matter under the house rules. Ask the management office for the approved window design and colour before ordering, and check strata renovation rules for working hours and deposits.

What the quotation should list

1. Each window by room, with its measured size and the replacement type.
2. Frame material, profile and wall thickness, and the finish colour.
3. Glass type for each window (clear, tinted, frosted).
4. Hardware: stays, handles and locks.
5. Removal and disposal of the old nako frame and blades.
6. Perimeter sealing, making good the plaster and any repainting.
7. Grilles, if included, and which one is the quick-release emergency grille.
8. For a strata unit: who obtains management approval.

How ClickBina quotes nako window replacement

ClickBina is an experienced KL & Selangor contractor. We handle whole-house refurbishment and coordinate the trades.

WhatsApp us your job details for a quote. A site visit is RM150, waived if you go ahead. The price is flat, with no hidden charges, and we reply within the hour. ClickBina is SSM-registered.

Sources & methodology

Prices and specification points are quoted unchanged from the site’s doors and windows guide (window types, indicative price table, frame thickness, perimeter sealing and emergency grilles). Repair versus replace, drainage and strata points come from the window repair guide. The ventilation rule is by-law 39 of the Uniform Building By-Laws 1984 (KPKT consolidated text), which is a model by-law; your state’s UBBL applies. Prices are typical Klang Valley ranges for 2026, not fixed rates; the final price depends on the number and size of windows and access, confirmed on site.