uPVC vs Aluminium vs Wood Window Frames: A Material Guide for Kolkata's Climate Swings

Window frame material is one of those decisions clients often want to make purely on aesthetics, and we understand the instinct, because a frame is one of the most visually dominant elements on any facade and the sample swatches at a showroom all look convincing under showroom lighting. But Kolkata puts a specific kind of stress on a window frame that a lot of national buying guides simply do not account for, because our climate is not one condition, it is two extreme conditions stacked back to back every single year: a summer that pushes surface temperatures on a sun-facing frame well past 45 to 50 degrees Celsius by early afternoon in April and May, followed within weeks by four months of monsoon humidity that sits above 85 to 90% for days on end with sustained wall-wetting rain. A frame material that handles one of those conditions well does not automatically handle the other, and the honest answer to "which is best" depends heavily on which facade of your specific flat or house we are talking about, so we want to walk through how each material actually behaves under this specific swing rather than giving you a single blanket recommendation.

uPVC: Reliable Baseline, With One Real Weakness

uPVC (unplasticized polyvinyl chloride) has become the default recommendation for a large share of our residential projects over the last several years, and there is good reason for that, because as a fully synthetic polymer it does not rust, does not rot, does not need painting, and its multi-chamber profile design gives it genuinely strong thermal insulation compared to a solid metal frame, which matters on west and south facing units that take direct afternoon sun for hours at a stretch. Its moisture behavior is essentially inert since it does not absorb water at all, which makes it a strong performer through monsoon specifically, with no swelling, no fungal risk, and gaskets that seal reliably as long as they are installed correctly. Where uPVC does have a real and specific weakness in our climate is thermal expansion under sustained direct heat load, because the polymer has a notably higher coefficient of thermal expansion than aluminium or timber, and on large uninterrupted spans, particularly big fixed picture windows or long sliding tracks on a west-facing facade that bakes for four or five hours every summer afternoon, we have seen frames develop a slight bow or the sliding track resist smooth operation by the third or fourth summer if the profile grade was on the cheaper end or the installation did not leave adequate expansion allowance at the frame joints. This is manageable, and reputable uPVC brands account for it in their profile engineering, but it is exactly why we specify a heavier, reinforced profile with steel insert reinforcement for any uPVC window wider than about 4 feet on a west or south facing wall, rather than using the lightest profile grade purely to save on cost.

Aluminium: Strong and Slim, But It Sweats

Aluminium frames give you the slimmest sightlines of the three materials, which is exactly why we specify aluminium so often for larger glazed openings and full-height balcony sliding doors where the client wants maximum glass area and minimal visible frame, a look that has become common in newer New Town developments with expansive balcony glazing. Structurally, aluminium is extremely stable under heat, with a thermal expansion rate low enough that even large spans stay dimensionally consistent through summer without the bowing risk uPVC can show, and it obviously will not rot or host fungal growth the way timber can. Its specific weakness in Kolkata's climate is thermal bridging and the condensation that results from it, because plain aluminium conducts heat and cold extremely efficiently, and when a humid Kolkata morning meets a frame surface that has cooled overnight, particularly common during the shoulder months around October to November and again in February, that conductivity means the interior frame surface can drop below the surrounding air's dew point and you get visible condensation beading on the inside of the frame, sometimes running down onto the sill. Over years, that recurring moisture at the sill and frame edge, especially if the window is not opened and ventilated regularly, can lead to staining, mold at the sealant lines, and in poorly maintained installations, corrosion at fixing points if the anodizing or powder coating has been compromised. The fix we specify on every aluminium project now, and this is worth insisting on if a contractor is quoting a bare aluminium section, is a thermally broken profile, where a polyamide insulation strip separates the interior and exterior faces of the frame, because that single detail cuts the condensation problem dramatically and is a difference you genuinely cannot see once installed, similar in spirit to how a properly specified putty coat is invisible but determines the outcome years later, a theme we go into in our piece on wall putty quality and monsoon paint failure.

Wood: The Warmest Look, the Most Demanding Material

Timber window frames remain the material clients ask for most often when they want a specific warmth and character, particularly in renovation projects on older independent houses in the Salt Lake and Rajarhat belt where the original construction used wood and the client wants to preserve that character rather than switch to a modern synthetic profile. The honest tradeoff is that wood is the most climate-sensitive of the three by a wide margin, because as an organic hygroscopic material it physically absorbs and releases moisture from the surrounding air, expanding when Kolkata's humidity climbs through monsoon and contracting again as things dry out post-monsoon, and that expansion and contraction cycle repeated year after year is what eventually causes the warping, sticking shutters, and hairline cracking at joinery points that we get called to repair on older timber-framed homes across the city. Species selection matters enormously here, and this is where we push back hardest against budget substitutions, because a well-seasoned hardwood like teak, properly kiln-dried before fabrication and finished with a quality exterior-grade polyurethane or marine varnish reapplied every few years, can genuinely perform well for decades even in our climate, which is why you still see original teak windows in good structural condition in Kolkata houses built well before independence. A softer, poorly seasoned timber finished with a basic varnish, on the other hand, can start showing swelling at the bottom rail and sash within two or three monsoons, and once water gets into an open joint at the corner mortise, the deterioration accelerates because that moisture has nowhere to escape from inside the joint. Wood also demands the most ongoing maintenance of the three, with a fresh coat of protective finish genuinely needed every three to five years on exposed elevations, a maintenance commitment we make sure every client understands upfront before they commit to timber purely on the strength of how it looks in the design render.

Our Decision Guide by Facade Orientation

Because the three materials fail in different ways under different conditions, we do not give a single blanket recommendation across an entire house, and instead we look at each facade's specific sun and rain exposure before finalizing material per opening. For east-facing windows, which get strong but comparatively brief morning sun and are somewhat sheltered from the harshest afternoon heat load, all three materials perform reasonably well, and the choice usually comes down to budget and aesthetic preference rather than climate risk, so this is where we most often let client taste lead. For west and south-facing windows, which take the brunt of Kolkata's punishing afternoon summer sun for the longest sustained stretch, we lean toward either a reinforced uPVC profile with steel insert or a thermally broken aluminium section, and we actively steer clients away from unprotected timber on these elevations unless they are committed to a serious, disciplined maintenance schedule, because this is the exposure that ages a frame fastest regardless of material. For north-facing windows, which get the least direct sun but in an open plot can take significant wind-driven rain during monsoon storms, moisture resistance matters more than thermal performance, which puts uPVC and well-sealed aluminium ahead of timber unless the timber has a genuinely robust waterproof finish and generous roof overhang protecting it. And for larger openings anywhere on the facade, meaning anything wider than roughly 4 to 5 feet in a single frame such as a big living room picture window or a full sliding balcony door, we default toward aluminium or heavily reinforced uPVC over timber, purely because timber's dimensional movement becomes harder to manage structurally at that span regardless of species quality.

What This Actually Costs

For a standard 4 by 5 foot window opening, uPVC typically runs ₹450 to ₹750 per square foot installed depending on profile grade and glazing (single or double glazed unit), aluminium runs ₹500 to ₹900 per square foot with the higher end reflecting thermally broken profiles and powder-coated finishes, and solid teak wood frames run considerably higher at ₹1,200 to ₹2,200 per square foot depending on the grade of timber and finish quality, with lower-grade hardwoods coming in somewhat below that range but carrying the durability tradeoffs we described above. On a typical 3BHK apartment with eight to ten window openings across the facade, mixing materials by orientation the way we described rather than committing the whole unit to one material can meaningfully change the total budget while actually improving long-term performance compared to a single blanket material choice, which is a conversation worth having at the design stage rather than after the frames are ordered.

If you are working through a broader renovation where window replacement is one piece of a larger scope, our guide on structural repair costs versus renovation costs in Kolkata is useful context for where frame replacement fits into an overall budget, and if your project also involves rooftop solar planning, our piece on retrofitting rooftop solar into an existing New Town flat or independent house touches on some of the same facade and roof-load considerations that come up when we are also specifying window and glazing work.

Let's Match Your Facade to the Right Frame

Every facade on your home is having a slightly different argument with Kolkata's weather, and picking one window material for the whole building without accounting for that is how we end up doing warranty visits for warped sashes or condensation-stained sills a few years down the line. If you are planning new construction or a window replacement and want a facade-by-facade material plan rather than a single guess, reach out through our contact page with your floor plan or elevation drawings, and we will map out which material makes sense for each opening before you place a single order.