Engineering
Nine things decide how a uPVC window performs in Indian conditions. Here is what each one does and who is responsible for it. These are explanations of how the parts work, not test results.
Parts and responsibility
TF 201, a published Casement 60 section. The hollow cells inside the outline are the chambers.
01 / MATERIAL
TruFrame
uPVC is unplasticised polyvinyl chloride. It is rigid, does not rot or rust, and conducts heat poorly. A raw PVC resin still needs stabilisers, impact modifiers and pigment before it can be extruded into a window profile. That recipe is the compound.
Older compounds used lead-based stabilisers. TruFrame's compound is formulated lead-free.
02 / UV
TruFrame
Ultraviolet light breaks down PVC at the surface. On a poorly pigmented profile this shows up as yellowing and a chalky finish within a few years, faster on south- and west-facing walls.
Titanium dioxide (TiO₂) is a white pigment that screens UV. How much is in the compound is given in parts per hundred resin (phr). It is one of the most useful questions to ask any profile supplier.
03 / CHAMBERS
TruFrame
A profile is not solid. Internal walls divide it into chambers. Each chamber holds still air, and still air conducts heat poorly, so heat has to cross several layers to get through the frame. The walls also stiffen the section and create separate cavities for reinforcement and drainage.
More chambers usually means a slower heat path, but chamber count alone does not give a thermal value. That needs a test on the finished window.
04 / SEALING
TruFrame supplies · Fabricator fits
Noise and dust come in through gaps before they come through glass. The gasket between sash and frame closes those gaps. TruFrame systems use TPE (thermoplastic elastomer) gaskets.
What matters is continuity. A gasket that is broken or badly joined at a corner leaves a path for air, and with it sound and dust. Casements press the sash onto the gasket when they close. Sliders seal along the moving panel edges, which is usually less tight.
05 / DRAINAGE
Fabricator
In a monsoon storm with wind behind it, some water will get past the outer line of any window. A good system expects this. Water collects in an outer chamber and drains back outside through slots in the frame.
The profile provides the chambers. The slots are machined during fabrication. They need to be in the right place and kept clear, or water sits in the frame and eventually reaches the wall.
06 / REINFORCEMENT
Fabricator
uPVC is less stiff than aluminium or steel. For larger openings, and to hold hardware fixings firmly, a steel section is inserted into a dedicated chamber of the profile.
When reinforcement is needed depends on the opening size, the system, wind exposure and the hardware. The system specification sheet refers reinforcement to approved project-specific documentation, so confirm it with the technical team for each job.
07 / HARDWARE
Fabricator
Handles, hinges, friction stays, rollers and locking points set how a window opens, how firmly it closes onto the gasket and how secure it is. Hardware has to be compatible with the profile's hardware groove and sized to the sash weight.
Hardware is chosen and fitted by the fabricator and usually carries its own warranty, separate from the profile warranty.
08 / FABRICATION
Fabricator
Fabrication means cutting, reinforcing, welding corners, cleaning the welds, machining drainage and fitting gaskets, hardware and glass. Each step affects the finished window. A weak weld, a missing drainage slot or a sash out of square will undo what the profile was designed to do.
This is why TruFrame's partner programme includes a machine compatibility check and fabrication training.
09 / INSTALLATION
Installer
Even a well-built window will leak at the wall if it is fixed out of plumb, packed badly or sealed with the wrong material. The gap between frame and masonry needs a proper fixing, packing and a weather seal.
Ask who installs the window, and who is responsible if the joint between window and wall leaks. It is often a different party from the one who made the profile.
Where windows fail
Most complaints about windows come down to a handful of causes. Here is each one, and what the TruFrame system does about it.
Noise
Sound gets in through air gaps first and glass second. A sash that does not close evenly onto its seal lets traffic noise straight through, whatever glass is fitted.
TruFrame response
A TPE gasket runs between sash and frame. Casement systems press the sash onto it when closed, which is why they are usually the first choice when noise matters most.
Read the detailHeat
A frame that conducts heat well lets it bypass the glass. Aluminium without a thermal break is the common example.
TruFrame response
uPVC conducts heat poorly, and the multi-chamber section holds still air. The range runs from three chambers (Casement 50) to five (Peafowl, Casement 60).
Read the detailDust
Dust follows air. Any break in the seal, at a corner, a joint or a worn brush, is where it gets in.
TruFrame response
The same gasket that deals with noise keeps dust out. It needs to be fitted without breaks at the corners.
Read the detailWater
In driving rain, some water gets past any outer seal. If the frame cannot drain it, water collects and finds the wall.
TruFrame response
Chambered sections leave room for drainage. Where the drainage slots go and how they are cut is decided during fabrication.
Read the detailUV
Strong sun breaks down a poorly pigmented compound. The frame yellows and turns chalky within a few years.
TruFrame response
The TruFrame compound is stated at 8 phr titanium dioxide, the UV-screening pigment, and is formulated lead-free.
Read the detailOperation
A good profile badly welded, reinforced or adjusted will stick, drop or leak. Most complaints about finished windows start here.
TruFrame response
TruFrame supplies the profile and drawings. Fabricators turn it into the finished window, so partner training covers reinforcement, drainage and gasket fitting.
Read the detailIndian conditions
India does not have one climate. Each region stresses a window in a different way, and each stress points to a different part of the system. These are mechanisms, not test results.
Rajasthan
Sun degrades a weak compound first. Pigment loading decides whether a white frame stays white.
8 phr titanium dioxide
Delhi NCR
Dust comes in with air, through gaps at the sash. The seal matters more than the glass.
TPE gasket
Coastal India
Salt attacks exposed metal. uPVC itself does not corrode, but steel reinforcement and hardware still need the right specification.
Lead-free uPVC compound
Monsoon, nationwide
Water gets past the outer line of any window in a storm. What matters is whether the frame drains it out.
Multi-chamber, drained sections
From profile to window
| Step | Stage | Responsible | What happens |
|---|---|---|---|
| 01 | Compound | TruFrame | Lead-free formulation with 8 phr titanium dioxide. |
| 02 | Extrusion | TruFrame | Profiles are extruded at the works in Alwar, Rajasthan. |
| 03 | Dispatch | TruFrame | Lengths leave in TruFrame-printed protective film. |
| 04 | Cutting | Fabricator | Profiles are cut to the opening schedule. |
| 05 | Reinforcement | Fabricator | Steel is inserted where the opening size calls for it. |
| 06 | Welding | Fabricator | Corners are fusion-welded and cleaned. |
| 07 | Hardware | Fabricator | Handles, hinges, rollers and locks are fitted. |
| 08 | Glazing | Fabricator | The glass unit is bedded and beaded into the sash. |
| 09 | Installation | Installer | The frame is fixed, packed and sealed to the wall. |
Size, floor, which way it faces and what you want to keep out. That is usually enough for our technical team to point you to the right system.