GlassKrafts Knowledge Centre

The practical guide to façades, glass and aluminium windows.

System selection, engineering principles, materials, fabrication, installation, testing, defects, maintenance and safety—organized for architects, builders, consultants, contractors and property owners.

20 technical chaptersSelection tablesSite checklistsIllustrated details

Technical guidance

Start with the building conditions—not only the product.

Opening size, elevation, wind exposure, water path, glass makeup, fixing substrate and expected use must be assessed together. Final design requires project-specific calculations and approved drawings.

Building envelopes

Facade systems and structural glazing

Curtain walls transfer wind pressure and dead load back to the building while controlling air and water penetration. Unitized panels support rapid high-rise installation; semi-unitized and stick systems suit different grids and site sequences. Structural glazing creates a flush appearance, while spider glazing supports transparent entrances and atriums.

Check anchors, brackets, mullion deflection and slab-edge tolerance.
Coordinate movement joints, drainage paths, glass supports and compatible sealants.
Select the system for module size, access, performance and architectural intent.

Performance mock-ups help verify air, water and structural behaviour before repetitive installation.

Residential openings

Aluminium sliding-window systems

Two-, three- and four-track systems are selected by opening width, number of shutters, wind exposure, glass weight and required weather performance.

Use adequate track, shutter and interlock depth for the design pressure.
Keep weep holes and drainage chambers clear and directed outside.
Specify corrosion-resistant rollers, locks and fasteners for coastal locations.
Check fabrication tolerance, frame squareness, roller capacity and track level.

Large or high-level panels may require reinforced interlocks or additional structural members supported by calculation.

Insect protection

Pleated mesh systems

Pleated mesh folds into a compact side channel and suits windows, balcony doors and wide openings where a conventional sliding mesh would occupy track space.

Confirm clear opening, stack position and operating direction before fabrication.
Select UV-resistant mesh and durable cords for frequent movement.
Keep bottom channels clear and coordinate the closing profile with the window.

Pleated mesh is insect protection—not a safety barrier, fall-protection screen or railing.

Glass selection

Toughened, laminated, DGU and Low-E glass

Type	Primary benefit	Typical use
Toughened	Higher strength and safer breakage	Doors, windows and facades
Laminated	Interlayer retains broken fragments	Overhead, railing and acoustic glazing
DGU	Insulating cavity improves comfort	Air-conditioned homes and offices
Low-E	Coating reduces radiant heat transfer	Energy-conscious external glazing

Thickness and makeup depend on panel size, support, wind, thermal stress, safety location and applicable codes.

Structural performance

Wind load and profile-deflection basics

Wind pressure changes with building height, terrain and exposure. Load moves from the glass through gaskets, beads, shutters, mullions, brackets and anchors into the structure.

Establish project design pressure from the applicable code and consultant criteria.
Check glass stress and deflection for actual supported dimensions.
Verify aluminium profiles in both axes, plus joints, anchors and fasteners.

Indicative pressures and catalogue sizes never replace project-specific engineering and approved shop drawings.

Weather protection

Water leakage prevention and sealant detailing

Reliable weatherproofing uses overlapping barriers, drained cavities and controlled pressure paths. Sealant alone cannot correct a poor joint or blocked drain.

Provide outward falls, sill end-dams and open weep paths.
Use compatible primers, backer rods, gaskets, blocks and sealants.
Maintain designed sealant proportions and clean bonding surfaces.
Seal interfaces between frames, civil openings, flashings and cladding.

Site water testing can reveal interface problems before the installation is repeated.

Comfort and efficiency

Thermal and acoustic performance

Frame design, glass makeup, seals and installation quality work together. Thermal-break aluminium limits heat flow; Low-E DGU controls solar and conductive heat; acoustic laminated glass and continuous seals reduce noise transmission.

Specify whole-window targets, including U-value, SHGC and acoustic rating.
Control perimeter gaps and maintain continuous compression seals.
Select glass and frame as one tested or engineered assembly.

High-performance glass cannot compensate for air leakage around the frame or poorly sealed joints.

Long-term care

Maintenance and facade-safety guidance

Planned inspection protects performance, appearance and public safety. Frequency should reflect height, coastal exposure, pollution, system age and access.

Inspect sealants, gaskets, glass edges, flashings, fixings and corrosion.
Clean tracks and drains; adjust rollers, handles and locks.
Record defects by elevation and prioritize loose panels, cracked glass and leakage.
Use controlled access, barricading and approved replacement procedures.

Work at height requires an approved method statement, risk assessment, access plan and applicable safety controls.

Engineering essentials

Calculations begin with the load path.

Every design must trace wind, glass dead load, operating load and building movement through each component to the primary structure. These equations explain the method; project values must come from the governing code and appointed engineer.

Wind velocity pressureq = 0.6 V²

A common SI expression producing N/m² when V is in m/s. Design pressure still requires applicable risk, terrain, height, topography, pressure coefficients and load combinations.

Uniform line loadw = p × tributary width

Converts façade pressure into line load on a mullion, transom or window member. Use actual geometry, including corner and local-pressure zones.

Deflection conceptδ ∝ wL⁴ / EI

Deflection grows rapidly with span and reduces as elastic modulus or second moment of area increases. Use the correct support condition and project limit.

Thermal movementΔL = αLΔT

Estimates aluminium movement from coefficient, length and temperature change. Joints, anchors and gaskets must accommodate it.

Important: These formulas are educational summaries, not a calculation certificate. Do not select a section, glass thickness, anchor or fixing without project-specific verification.

Detailed technical rules

What must be resolved before construction

Interface engineering

Most failures occur where systems meet: façade to waterproofing, window to masonry, curtain wall to roof, glazing to ACP, fire stop to slab edge, and sill to balcony finish. Each interface needs a drawn water path, air barrier, structural fixing, movement allowance and installation sequence.

Show who supplies every membrane, flashing, closure and seal.
Define the primary weather line and secondary drained zone.
Avoid exposed face sealant as the only defence.
Confirm access for tooling, inspection and replacement.

Structural silicone glazing

Silicone bite and thickness are engineering dimensions based on design pressure, glass size, support, design strength and movement. Adhesion depends on approved substrates, cleaning, primer decision and process control.

Obtain project adhesion and compatibility testing.
Control spacer position, joint fill, cure and batch traceability.
Prevent three-sided adhesion and contamination.
Never substitute products without approval.

Glass edge and support

Glass strength is affected by edge quality, holes, notches, heat treatment and support. Setting blocks transfer dead load without point contact; edge clearances allow movement and tolerance.

Locate blocks according to glass and system design.
Use compatible hardness and prevent migration.
Protect edges from impact and metal contact.
Agree visual-quality criteria before production.

Fasteners and corrosion

Fasteners must resist calculated tension and shear in the actual substrate. Coastal moisture and dissimilar metals can accelerate corrosion where water becomes trapped.

Match grade and coating to exposure.
Verify embedment, edge distance and pull-out capacity.
Isolate aluminium from incompatible materials.
Keep drainage away from unprotected steel.

Fire and life safety

The façade fire strategy includes spandrel zones, perimeter fire barriers, cavity barriers, combustible components, falling-glass risk, fire-service access and opening restrictions. It must match the approved building strategy.

Maintain slab-edge fire-stop continuity.
Use tested systems within their approved application.
Coordinate brackets and movement with barriers.
Do not conceal unapproved substitutions.

Quality records

An inspection and test plan defines hold points, criteria, sample frequency, responsibility and corrective-action records.

Track extrusion, glass, sealant, gasket and fastener batches.
Record dimensions, diagonals, anchor torque and sealant checks.
Photograph concealed membranes, fire stops and drainage.
Close snags by elevation, grid and panel identity.

How the systems work

Three details every project team should understand.

These simplified diagrams explain the design intent. They are not fabrication drawings; profile geometry and dimensions must follow the selected system supplier and approved project details.

Load pathEvery component must carry load continuously to the building structure.

Drainage pathWater must be collected and discharged; sealing every opening can trap it.

Insulating glass unitGlass, cavity, spacer and edge seals function as one manufactured unit.

Complete project lifecycle

From concept to handover

Design inputs

Building location, height and terrain
Grid, opening and glass sizes
Structural movement and tolerances
Thermal, acoustic and safety targets
Cleaning and maintenance access

System selection

Stick, semi-unitized or unitized façade
Captured or structural silicone glazing
Fixed, casement, tilt-turn or sliding windows
Thermally broken or non-thermal frame
Pressure-equalized or drained construction

Material specification

Aluminium alloy and temper
Extrusion wall thickness and tolerances
Powder coating, anodizing or PVDF
Glass heat treatment and edge quality
EPDM, silicone, fastener and isolation compatibility

Shop drawings

Plans, elevations and setting-out
Horizontal and vertical sections
Anchors, brackets and embeds
Interfaces at slab, parapet, roof and cladding
Drainage, fire stopping and movement joints

Structural checks

Glass stress and deflection
Mullion and transom capacity
Shutter and interlock stiffness
Anchor and fastener reactions
Building and thermal movement allowance

Fabrication control

Approved cutting lists and identification
Machining, drainage and pressure holes
Corner joints and cleat assembly
Gasket continuity and sealant tooling
Dimensional and finish inspection

Installation control

Survey opening and reference lines
Verify substrate and fixing zones
Set line, level, plumb and diagonal
Protect drainage and isolate dissimilar metals
Record concealed work before closure

Testing and handover

Laboratory or project mock-up testing
Field air and water checks
Sealant adhesion and compatibility records
Glass, coating and hardware certificates
As-builts, warranties and maintenance manual

Quick decisions

Selection guides

Use these tables to frame the design discussion. Final selection remains subject to calculations, samples, testing, supplier limitations and consultant approval.

Requirement	Commonly considered solution	Verify before approval
High-rise repetitive façade	Unitized curtain wall	Panelization, anchors, stack joints, movement and mock-up criteria
Transparent entrance or atrium	Structural or point-fixed glazing	Glass support, fittings, silicone design, access and redundancy
Large luxury-residential opening	Minimal or lift-and-slide system	Sash weight, roller rating, threshold drainage and wind performance
Improved room comfort	Thermal-break frame with selected DGU/Low-E glass	Whole-window U-value, SHGC, edge spacer and installation continuity
Traffic-noise control	Acoustic laminated glass or asymmetric DGU	Target spectrum, seals, vents, perimeter gaps and wall flanking
Leakage repair	Diagnosis before resealing	Entry point, drainage, interfaces, sealant compatibility and test method

Troubleshooting

Common symptoms and likely checks

Water at sill

Check blocked weeps, missing end-dams, reverse fall, failed perimeter seal or wind-driven water beyond the pressure barrier.

Shutter difficult to slide

Check track level, frame squareness, roller damage, panel weight, interlock alignment and debris.

Glass edge fogging

Possible insulating-glass edge-seal failure; confirm the moisture is inside the sealed cavity.

Sealant cracking

Check joint movement, bite, depth, adhesion, primer, contamination and material compatibility.

Whistling or air leakage

Check gasket compression, interlock engagement, drainage-slot exposure and perimeter discontinuity.

Glass breakage

Preserve evidence; examine impact, edge damage, setting blocks, nickel-sulphide risk, thermal stress and frame contact.

Industry language

Essential façade glossary

Mullion: Primary vertical framing member.
Transom: Horizontal framing member between mullions.
Vision area: Transparent glazed area providing outward view.
Spandrel: Opaque zone concealing slab edge or services.
IGU / DGU: Two or more glass panes separated by a sealed cavity.
SHGC: Fraction of incident solar heat entering through a glazing assembly.
U-value: Rate of heat transfer through an assembly; lower generally insulates better.
Structural silicone: Engineered silicone that transfers specified glass loads to a frame.
Weather seal: Exterior joint seal intended to resist weather and accommodate movement.
Pressure equalization: Use of compartments and vents to reduce pressure across the inner air seal.
Deflection: Movement of a member under load.
Dead load: Permanent gravity load, including glass self-weight.

Frequently asked questions

Answers project teams look for

Which façade system is best for a high-rise?

There is no universal choice. Repetition, construction programme, access, movement, performance targets, factory capacity and commercial strategy determine whether unitized, semi-unitized or stick construction is appropriate.

Is thicker aluminium always stronger?

Not by itself. Alloy, temper, profile geometry, unsupported span, connection detail and load direction determine capacity and deflection.

Can silicone stop every leakage problem?

No. Water management depends on the complete barrier and drainage arrangement. Extra sealant can block weeps or trap water if the root cause is not identified.

Is toughened glass the same as laminated glass?

No. Toughening changes strength and breakage pattern. Lamination bonds panes with an interlayer that can retain fragments after breakage. A glass makeup may use both.

How often should a façade be inspected?

The interval should be set by the owner and competent professionals based on system type, age, height, exposure, previous defects and local requirements. Critical symptoms require immediate inspection.

What information is needed for a window quotation?

Location, opening schedule, dimensions, quantity, system type, finish, glass makeup, mesh, hardware, wind pressure, waterproofing interfaces, access and installation scope.

Standards and references

Use current project documents.

Standards change. Confirm the edition required by the contract, local authority and façade consultant. Purchase or access full standards only through their authorized publishers.

IS 875 (Part 3):2015Wind loads — Bureau of Indian Standards NBC 2016: Glass and GlazingBIS technical programme and glazing aspects ASTM E06.51Windows, doors, curtain walls and related performance methods AAMA 501.2Diagnostic water checks for installed façade systems

Editorial note: This library explains general industry principles. It is not a substitute for project specifications, statutory approvals, laboratory testing, structural calculations or advice from the appointed architect, structural engineer, façade consultant and fire consultant.

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