To specify a facade for a Telangana project correctly, write to the composite climate first: target vision glazing with an SHGC of 0.25-0.35 and a low-e double-glazed unit for U-value, design wind pressure from IS 875 Part 3 at a 44 m/s basic wind speed, declare an ECBC compliance path, and call ASTM E283/E331/E330 as the test suite. Everything else on the drawing flows from those five decisions. Hyderabad's long hot-dry summers, an intense monsoon and a short mild winter mean your envelope has to reject solar heat and driving rain while still passing usable daylight.
This guide is written for the drawing, not the brochure. It walks through the performance criteria, standards and detailing language that turn a design intent into an enforceable specification - the clauses a fabricator can price and a project management consultant can hold you to. The aim is a facade section that leaves no ambiguity about glass, framing, movement, interfaces or testing.
Whether the project is an office tower in the Financial District, a showroom on the Outer Ring Road, or a mixed-use block in Kokapet, the same specification discipline applies. If you want a specification pressure-tested against buildability before tender, our facade consultancy team works alongside architects across Hyderabad and Telangana.
Why does the composite climate drive the numbers?
Hyderabad and Secunderabad fall in India's composite climate zone, where the envelope has to cope with three seasons that each stress the facade differently. Your specification should open with the environmental basis so every downstream criterion is traceable back to a real load, not a habit copied from another project.
- Summer: peak dry-bulb temperatures cross 40-44 degrees C in April and May, so solar heat gain and material expansion dominate. A dark ACP or aluminium surface in Gachibowli sun can reach 70-80 degrees C, driving large thermal movement.
- Monsoon: the south-west monsoon delivers wind-driven rain that will find any unsealed joint, so water penetration and drainage are the priority from June to September.
- Winter and dust: a short mild winter is easy, but year-round airborne dust from construction corridors like Kokapet and the Financial District settles on horizontal ledges and abrades gaskets, so detail self-draining, cleanable profiles.
State the glazing thermal and optical targets as a matched set rather than in isolation. Chasing one number in isolation - usually SHGC - is how facades end up too dark to daylight or too clear to cool. Our reflective glass facade and DGU facade options let you balance these without resorting to a blanket tint.
What thermal and optical targets belong in the spec?
Write the four glazing performance metrics together, with target bands rather than single points so the fabricator has a compliant window to specify glass within:
- SHGC (solar heat gain coefficient): target 0.25-0.35 for vision glass to limit cooling load without over-tinting. Spandrel zones can go lower.
- U-value: specify the vertical fenestration U-value to align with your ECBC compliance path - typically 3.0 W/m2K or better. A double-glazed unit with a low-e coating and a 12-16 mm air or argon cavity is usually needed to meet it.
- VLT (visible light transmittance): 0.40-0.60 keeps interiors daylit and supports IGBC or GRIHA daylight credits. Avoid dropping VLT to chase SHGC when a spectrally selective coating can do both.
- Light-to-solar-gain ratio (LSG): call an LSG above 1.25 to reward spectrally selective coatings over blanket body tints. This single clause quietly upgrades the whole facade.
For a west-facing elevation in Madhapur or Hitec City, where late-afternoon sun is punishing, the SHGC and LSG clauses do more work than any shading device you can bolt on afterwards. Pair the glass spec with aluminium louvers where solar geometry needs a physical cut-off rather than a coating.
Which standards should you cite by name and number?
A specification is only as strong as the codes it references. Vague phrases like 'as per relevant IS codes' are unenforceable - name each one so testing and compliance are non-negotiable. For Telangana work, cite these explicitly:
- IS 875 Part 3 for wind load; Telangana's basic wind speed is 44 m/s, which you factor by terrain category, height and topography to a design pressure.
- NBC 2016 for the overarching building-envelope, fire and life-safety provisions that govern facade design.
- ECBC (Energy Conservation Building Code) for envelope U-value, SHGC and window-to-wall-ratio limits - state whether you are on the Prescriptive or Whole-Building Performance path.
- IS 2553 Part 1 for laminated safety glass, and IS 2553 for toughened glass at thermally stressed and impact-prone locations.
- ASTM E283 (air infiltration), ASTM E331 (static water penetration) and ASTM E330 (structural performance) as the mock-up and system test suite.
- IGBC, GRIHA or LEED as applicable to the project's green rating, since facade SHGC and daylight feed those credits directly.
Whichever system you land on - structural glazing, unitized glazing or a curtain wall - the same code stack applies; only the test pressures and joint details change.
How do you write the wind-load and structural criteria?
Give the fabricator explicit load and deflection language so the framing is engineered, not assumed. The wind pressure is the single most consequential number on the sheet, because it sizes mullions, glass thickness and every anchor.
- Design wind pressure: derive it from IS 875 Part 3 for the 44 m/s basic wind speed, then adjust for terrain (Category 2 for suburban ORR sites, Category 1 for exposed high-rise), the building's height factor and any topography multiplier. A 100 m tower in Kokapet sees materially higher corner-zone pressures than a 4-storey showroom in Kondapur.
- Framing deflection: limit member deflection to L/175 of the span, or 19 mm, whichever is less, under design wind - the common serviceability benchmark for glazed curtain wall.
- Glass deflection: cap unit deflection so edge bite and seals are never compromised under peak load.
- Structural silicone: where used, size the glue-line (bite) to the wind load and design it to the sealant manufacturer's stress limit - do not leave bite dimensions to the shop.
- Corner and parapet zones: call out the higher local pressure coefficients so the fabricator does not size the whole facade to the mid-field pressure and under-build the edges.
This is where a spider glazing or bolt-fixed system needs particular care: point fixings concentrate load, so the glass and fitting must be checked at each node, not averaged across the pane.
What movement and tolerance language prevents failures?
Facades move - thermally, under live load, and as the structure drifts between floors. A spec that ignores movement locks stress into the glass and the sealant until something cracks.
- Thermal movement: accommodate service-temperature swings at every stack joint. A dark ACP or aluminium surface in Hyderabad sun can swing 60-80 degrees C over a day, so a 4 m unit can move several millimetres.
- Inter-storey drift: state the drift the facade must absorb without glass-to-frame contact, using the structural engineer's seismic and wind drift figures.
- Slab-edge tolerance: specify slotted, adjustable brackets so a +/-10 to 15 mm concrete slab tolerance is absorbed at the anchor, keeping the facade plane within +/-3 mm.
- Tolerance schedule: reconcile structural slab, blockwork and facade tolerances in a single table - they differ by an order of magnitude and must never be additive.
The rule to write on the drawing is simple: reconcile tolerances at the bracket, not the glass. Adjustable custom aluminium frames and aluminium fabrication give the installer the shimming range to hold the facade plane true even when the concrete comes out of tolerance, which on a fast-track Hyderabad slab it often does.
How do you detail interfaces, waterproofing and drainage?
Facades fail at junctions, not in the middle of a panel. In Telangana's monsoon, wind-driven rain tests every lap and every sealant joint, so your details must resolve how the system meets the structure and the wet trades before a single panel is fabricated.
- Drained and pressure-equalised design: detail a rain-screen principle so any water that enters is channelled back out, rather than relying on face sealant alone as the only line of defence.
- Continuous barrier: show continuity of the air and water barrier from the facade into the slab, parapet and window-wall transitions - the weakest lap defines the whole envelope.
- Flashings and weeps: specify sill flashing, end dams and weep paths at every horizontal transom and transition.
- Performance mock-up: require a PMU for large projects, tested to the ASTM suite before the first production panel is released, so leaks are found on a test rig and not on the fifteenth floor.
The same discipline governs where the facade meets ACP cladding, a cladding and elevation transition or a front elevation glazing band - every material change is a potential water path. You can see how we resolve these junctions across completed projects in and around Hyderabad.
What acoustic, fire and safety clauses complete the spec?
Round out the specification with the criteria that protect occupants and satisfy the authority having jurisdiction. These are the clauses that get scrutinised at the fire NOC and occupancy stage, so write them precisely.
- Acoustics: for facades on arterial roads or near ORR and airport corridors, specify a weighted sound reduction index (Rw). Asymmetric laminated IGU makeups typically reach the mid-30s to low-40s dB; acoustic glass partition logic carries into the facade here.
- Perimeter fire-stopping: detail the slab-edge gap between floor slab and curtain wall spandrel as a rated, continuous barrier per NBC 2016. Consider fire rated glazing where the elevation demands a rated vision area.
- Safety glazing: mandate laminated or toughened glass to IS 2553 at all guarding, overhead, sloped and full-height glazed locations, including any glass railing integrated into the facade line.
- Fall protection: where glazing acts as a barrier, specify the imposed horizontal line and area loads it must resist without failure.
- Maintenance access: specify facade access (BMU, cradle or ladder points) and confirm glass can be replaced from outside without dismantling adjacent units - a clause future facility managers will thank you for.
What does facade specification cost in Hyderabad?
Budget numbers belong in the specifier's thinking early, because the performance clauses above have direct cost consequences. Indicative Hyderabad rates (2026, material plus installation, subject to design and quantity) help you set client expectations before tender:
- Aluminium composite panel (ACP) cladding: roughly INR 350-650 per sq ft depending on grade and fire rating.
- Structural and semi-unitized glazing with DGU low-e glass: roughly INR 900-1,600 per sq ft.
- Spider and cable-net glazing for lobbies and showrooms: roughly INR 1,400-2,800 per sq ft given the fittings and toughened glass involved.
- Unitized curtain wall for high-rise towers: roughly INR 1,300-2,200 per sq ft, offset by faster site installation.
These are directional, not quotations - glass makeup, wind zone, height access and quantity all move the figure. The bigger cost lesson is that specification quality is cheaper than rework: a leak found on a mock-up costs a fraction of one found after handover. To convert your specification into a costed, buildable system for a specific Telangana site, get a free quote and we will review the drawings, propose a compliant makeup and flag any interface risks before you go to tender.
