On a west-facing terrace, the first monsoon tells you everything about the roof you chose for the pergola. A cheap single-skin sheet drums like a tin shed and bakes the seating by April; a well-chosen multiwall polycarbonate stays quiet and cool; a toughened glass roof sparkles but shows every leaf and water spot and asks to be cleaned. The pergola frame — timber-look aluminium, mild steel, WPC — gets most of the attention, but the roof is what decides whether the space is usable in heat and rain, and the real choice there is almost always polycarbonate versus glass.
Both can be beautiful and both can be a mistake. Glass fails when it is specified as ordinary annealed glass overhead, or when it is laid flat so water and dust sit on it; polycarbonate fails when the cheapest UV-unprotected sheet is used and yellows within a few summers, or when it is laid flat so it sags and pools. Chosen and detailed well, each has terraces where it clearly wins. This comparison sets them side by side on the things that matter on an Indian terrace — heat, light, rain, safety, cleaning, lifespan and cost — and then says which to use where.
Side by side
The table compares the two across the criteria that decide comfort and cost on a real terrace. "Polycarbonate" here means a quality UV-protected sheet — multiwall (hollow, insulating) or compact solid — and "glass" means toughened or laminated safety glass, which is the only kind acceptable overhead.
| Criterion | Polycarbonate (UV-protected) | Glass (toughened / laminated) |
|---|---|---|
| Weight | Light — easy frame, wide spans | Heavy — needs a stronger frame |
| Breakage / safety overhead | Near unbreakable; safe if hit | Must be toughened/laminated; laminated holds if it breaks |
| Clarity / view of sky | Translucent to clear; slight haze | Crystal clear, stays clear |
| Heat gain | Multiwall insulates well; stays cooler | Clear glass lets heat in unless tinted/low-E |
| Rain noise | Audible, louder on single-skin | Quieter |
| Scratch resistance | Scratches more easily | Very scratch resistant |
| Yellowing / ageing | Cheap sheets yellow; good UV sheets resist | Does not yellow |
| Spanning / supports | Spans wide with few purlins | Needs more support, smaller panes |
| Cleaning | Easy, but marks show on haze | Easy to wipe; spots very visible |
| Lifespan (good quality) | Roughly 10–15 years | Longer if undamaged |
| Indicative installed cost | Lower (see cost table) | Higher (see cost table) |
If the table reads as a draw, decide by the one thing that matters most on your terrace. The quick guide below takes the common priorities and names the clearer winner for each — a faster way to choose than weighing eleven criteria at once.
| Your top priority | Better choice | Why |
|---|---|---|
| Lowest cost | Polycarbonate (multiwall) | Cheaper sheet and a lighter, cheaper frame |
| Widest span, fewest posts | Polycarbonate | Light, so it spans far with little support |
| Coolest space underneath | Polycarbonate (multiwall) | Hollow structure insulates against the sun |
| Clearest, unchanging view of the sky | Glass | Does not haze, scratch or yellow |
| Quietest in heavy rain | Glass | No drumming; polycarbonate is audible |
| Near-unbreakable safety overhead | Polycarbonate | Will not shatter onto furniture below |
| Least maintenance over 15 years | Glass | No yellowing; very scratch resistant |
Where polycarbonate wins
Polycarbonate wins wherever size, budget or safety lead. A large terrace or a long car porch roof is far easier and cheaper to build in multiwall polycarbonate: the sheets are light, so the aluminium or steel frame can be slimmer and the spans wider, and a quality multiwall sheet insulates against the Surat sun far better than clear glass, keeping the space under it usably cool. It is effectively unbreakable, so there is nothing to shatter onto furniture below in a storm or if a cricket ball lands on it, which matters over a play area or a seating zone. It also curves, so a barrel or lean-to profile is simple. The things to get right are the sheet quality — insist on genuine UV-protected sheet from a known maker, not an unbranded one that will yellow — and the slope and sealing, so it drains and the open flutes of a multiwall sheet are taped and capped against dust and insects.
Where glass wins
Glass wins on a small, premium pergola close to the house, where clarity and a sense of permanence are the point. A compact toughened or laminated glass roof over a 6-to-10-foot seating nook gives a clear, unchanging view of the sky, stays looking new for far longer than polycarbonate, does not yellow or scratch, and is quieter in rain. Within reach of a terrace tap and a long squeegee, it is easy to keep clean. The price of all this is weight and cost: glass needs a stronger frame and more intermediate support, the panes must be smaller, and it must always be safety glass overhead — laminated is the safest choice beside seating because it holds together if it ever breaks. Clear glass also lets solar heat straight through, so a west-facing glass roof usually wants a tint, a low-emissivity coating, or an openable louvre or shade above it to stay comfortable.
There is a third way worth naming, because many Surat terraces use it: a mixed roof. A mostly polycarbonate roof with one or two glass panels over a seating nook gives the cool, wide, affordable span of polycarbonate where it is walked under and the clear view of glass exactly where people sit and look up. It keeps the budget and the structure light while buying the premium feel only where it is seen, and is often the honest answer when the verdict feels like a tie.
Cost
The indicative October 2026 bands below are for the roofing sheet or glass with its fixing on an existing pergola frame, per square foot; the frame itself is a separate cost. Polycarbonate sits clearly below glass, and the gap widens on larger roofs, where glass also forces a heavier, costlier frame. Remember that the frame is sized for the roof it carries, so a glass roof quietly adds structure cost beyond the per-foot figure, while a light polycarbonate roof lets the same posts and rafters span further.
| Roof option (supplied + fixed, on existing frame) | Indicative cost (₹/sq ft) | Note |
|---|---|---|
| Single-skin / corrugated polycarbonate | ₹80–160 | Budget; noisier, less insulating — use good UV grade |
| Multiwall polycarbonate (6–16 mm) | ₹150–350 | The sensible default; insulates, spans wide |
| Compact / solid polycarbonate sheet | ₹300–600 | Clearer, tougher, heavier than multiwall |
| Toughened glass roof (10–12 mm) | ₹450–900 | Safety glass overhead; needs more support |
| Laminated glass roof (10.76–13.5 mm) | ₹700–1,400+ | Safest overhead; holds together if broken |
Read the bands against the span, not just the area. A large roof in glass needs a heavier frame and more supports, so its all-in cost climbs faster than the per-foot figure suggests; the same large roof in multiwall polycarbonate stays light and simple. For a small roof the frame difference is minor, which is another reason glass makes most sense at small sizes.
Getting either one right
- Slope the roof at least about 5° so monsoon water and dust drain instead of pooling and staining.
- For polycarbonate, insist on genuine UV-protected sheet from a known maker; cheap sheet yellows within a few summers.
- Tape and cap the open flutes of a multiwall sheet so dust, water and insects do not fill them.
- Use only toughened or laminated glass overhead — never ordinary annealed glass; laminated is safest beside seating.
- On a west or south roof in glass, add a tint, a low-E coating, or a shade/louvre above to control heat.
- Detail the fixing and gaskets for thermal movement — both sheet and glass expand; rigid fixing cracks or leaks.
- Size the frame for the material: glass needs a stronger frame and closer supports than polycarbonate for the same roof.
Frequently asked questions
Which is cheaper, polycarbonate or glass, for a pergola roof?
Polycarbonate is cheaper — roughly ₹150–350 per square foot for a quality multiwall sheet versus about ₹450–1,400 for a toughened or laminated glass roof, supplied and fixed in October 2026, on an existing frame. Glass also needs a heavier frame, so the gap in the all-in cost is larger on bigger roofs.
Does a polycarbonate roof get too hot?
A good multiwall polycarbonate sheet actually stays cooler underneath than clear glass, because the hollow structure insulates against the sun. A single-skin or thin sheet, or clear glass, lets more heat through; on a west-facing roof, choose multiwall polycarbonate, or a tinted or shaded glass, to keep the space comfortable.
Is glass safe as a pergola roof?
Only as toughened or laminated safety glass, never ordinary annealed glass. Laminated is the safest choice overhead and beside seating, because the interlayer holds the pieces together if the glass ever breaks, rather than letting them fall. The frame and fixing should be sized by the supplier's system and, for larger roofs, checked by a structural engineer.
How long does a polycarbonate roof last?
A good UV-protected polycarbonate sheet typically lasts around 10–15 years before it begins to haze or discolour, depending on sun exposure and quality. A cheap, unprotected sheet can yellow within a few summers. Glass lasts longer if it is not damaged, which is part of why it costs more up front.
Sources & standards
- Bureau of Indian Standards — IS 2553 (safety glass) and IS 14900 (float glass); manufacturer data for multiwall and solid polycarbonate sheet
- National Building Code of India 2016 — general guidance on overhead glazing and roof drainage
- Polycarbonate and glass manufacturers' installation guidance — slope, fixing, thermal movement and flute sealing
- This site's guides to toughened vs laminated glass and to balcony and terrace design
- Price ranges: indicative October 2026 estimates for supplied-and-fixed roofing — confirm locally before budgeting
