Polycarbonate sheet cracked in Gurgaon: why sheets split and what to do

Polycarbonate is tough; it's the material used for riot shields. So it surprises people in Gurugram and Noida when a terrace shed sheet cracks within a year or two. Almost always, the sheet itself wasn't the weak point. How it was fixed, and how it was allowed to move, decides how long it lasts.

The short answer

Look at where the crack starts. A crack radiating from a screw hole is a fixing problem: overtightened, no oversize hole, or no washer. A star-shaped crack in the middle is impact. Fine crazing all over with yellowing is UV ageing, covered in polycarbonate sheet yellowing.

Why polycarbonate cracks

No room for expansion

Polycarbonate expands and contracts much more than steel. A sheet on a terrace goes from cold winter mornings to a summer surface temperature far above the air temperature. If screw holes are drilled to the exact screw size, the sheet can't move, and stress cracks start at the holes.

Overtightened screws

A screw driven hard crushes the sheet, especially multiwall sheets, and starts a crack. The right fixing uses a washer that seals without crushing.

Wrong screws and washers

Screws without proper washers, or with hard washers, point-load the sheet. Some sealants and PVC washers also react with polycarbonate and make it brittle.

Impact

Hail, falling branches, a cricket ball, or someone stepping on the sheet can crack it, particularly thinner or older sheets.

Too few supports

A sheet spanning too far between purlins flexes in wind and fatigues at its fixings. See shed roof sagging.

What you can check

• Find where each crack starts: at a screw, at an edge or in the open sheet.
• Check whether screws are tight enough to dent the sheet, or if there's a washer under each one.
• Look at the sheet edge: multiwall sheets should have end tape and closures, and their channels should run down the slope.
• Note any leak below the crack; that tells you how urgent replacement is.

Patch or replace?

A short crack can be sealed with a compatible clear sealant or tape as a stop-gap to keep water out. It won't stop the crack growing. The lasting fix is replacing the sheet and fixing the new one properly: oversize holes, washered screws tightened just enough, correct purlin spacing, and UV-protected side up. Our polycarbonate sheet glossary entry explains solid and multiwall types, and polycarbonate vs metal sheet roof compares them. If you're rebuilding, see polycarbonate terrace shed or, for a crisp entrance, a glass canopy. Pricing factors are in the terrace shed cost guide.

How FabWise handles it

Send photos of the crack, close-ups of the screws near it and a wide shot of the shed on WhatsApp. We'll tell you whether one sheet needs changing or the fixing method across the roof needs correcting. A site visit, if needed, costs ₹99 in our Delhi NCR cities and is adjusted against the bill; replacement work is quoted after the visit.

Prevention

Ask for oversize holes and proper washers on any new polycarbonate roof. Keep trees trimmed back from the shed. Never use the roof as a walkway for cleaning water tanks; build a separate access. Check fixings before each monsoon.

Related: shed noisy in rain, shed gutter overflowing and terrace shed leaking. Browse sheds and pergolas or see sheds and pergolas in Greater Noida.