Cracked or broken conservatory roof panel

A cracked or broken panel is one of the few conservatory roof problems with a simple, contained fix: take the damaged sheet or glass unit out and put a matching one in. The rest of the roof can stay. The questions are how to keep the rain out until then, how to match the old panel, and whether the roof is worth repairing at all.

First: make it safe and dry

• Stay off the roof. ConservatoryLand says you should not walk on a polycarbonate roof, and Ultraframe says it is not safe to stand directly on any conservatory roof. Work from a ladder.
• Glass: keep people out from under a broken glass unit until it is dealt with. Modern conservatory roof glass is normally toughened safety glass (Ultraframe says all of its roof glass is), which breaks into small fragments rather than long shards, but a broken unit can still drop pieces.
• Polycarbonate: a crack can be sealed temporarily with weatherproof sealant, which Which? suggests for cracks, joints and vents, to keep the rain out until the sheet is replaced.
• Photograph the damage before anything is moved, in case you claim on your insurance.

Can you replace one polycarbonate roof sheet?

Yes. Each sheet sits between two glazing bars, held down by caps along the bars and an end cap at the bottom, so one can come out without disturbing the others. The job, drawn from installer and DIY accounts of re-sheeting:

1. Measure the old sheet: thickness (conservatory sheets are commonly 10mm, 16mm, 25mm or 35mm), width, length and tint.
2. Order a matching sheet, cut to size, with the correct end tapes.
3. Take off the bar caps either side of the damaged sheet, and the end cap. Ultraframe warns that the cap clips are likely to be damaged when caps come off and will need replacing, so have spares ready.
4. Slide out the old sheet and check the bars, gaskets and seals underneath.
5. Fit the new sheet with the flutes running downhill, solid tape at the top and breather tape at the bottom, so condensation inside the flutes can escape.
6. Refit the caps and end cap, and seal any screw holes.
7. Check from inside the next time it rains.

A sheet that has slipped down the roof is dealt with the same way: caps off, re-seated or replaced, caps back on. On an older roof, slipped sheets are one of the signs that re-sheeting the whole roof is due. Our guide to polycarbonate thickness explains the sizes, and can you replace a conservatory roof yourself covers the wider DIY question.

Expect the new sheet to look different. If the others have yellowed, the new one will stand out as clearer and brighter. That is cosmetic, but it is also a reminder of how far the rest have aged; see our page on discoloured polycarbonate.

Replacing a cracked glass roof unit

Glass roofs are made of sealed double glazed units, and a cracked one is replaced whole. Match the size, thickness and specification of the original, including any solar control tint or self-cleaning coating, or the new unit will look and perform differently from its neighbours. Ultraframe’s installation guide says self-cleaning glass must be sealed with MS polymer sealant, not ordinary silicone.

Two related problems: mist between the panes means the unit’s seal has failed and it needs replacing, while surface scratches can sometimes be repaired. The Glass and Glazing Federation says repairing surface damage can be more economical than replacement and has less environmental impact.

Swapping glass in its existing frame does not need to meet the energy efficiency rules: Approved Document L says it is not providing a controlled fitting.

What does it cost to replace one roof panel?

We found no reliable published price for having a single sheet or glass unit replaced, so get a written quote. What we do have:

• Polycarbonate sheet from hardware stores costs from around £35 to £50 or more per square metre, according to Green Space.
• MyJobQuote puts a typical conservatory roof leak repair at around £375, and Home Improvement Quote Today gives £500 to £2,000 for repairs. These are general repair figures, not panel prices, but they show the range roofers work in.
• One couple’s DIY re-sheet of a whole lean-to with 25mm polycarbonate cost £324 in materials.

Will insurance pay for a cracked roof panel?

It depends on the cause. Sudden damage, such as from a storm, may be covered by buildings insurance; damage from wear and tear or lack of maintenance usually is not. If a storm claim is disputed, the Financial Ombudsman Service asks whether there were storm conditions, whether the damage is consistent with a storm, and whether the storm was the main cause. Claims can fail where the roof was already in poor condition. Our conservatory roof insurance guide has more.

One panel or the whole roof?

Replace the panel if the rest of the roof is sound. Consider the whole roof if:

• the other sheets are discoloured or brittle, so more will crack
• this is not the first repair, or the roof also leaks elsewhere
• the room is also too hot, too cold or noisy

New roof	Typical cost, medium conservatory
Insulated panels	£1,800 to £4,600
New polycarbonate	£2,700 to £5,200
Glass	£3,500 to £7,000
Tiled	£7,400 to £12,100

Installers usually quote including VAT, but check. A new polycarbonate roof is the like-for-like option, while the others fix comfort problems too; see conservatory roof costs for prices by style and size.

When you get quotes, ask each roofer to name the replacement sheet or glass unit, confirm it matches the existing thickness and specification, and say what guarantee comes with the work.