Will a new conservatory roof add value to your house? What can be counted and what cannot

The honest starting point

If someone tells you a new conservatory roof adds a set percentage to your house price, ask where the figure comes from. We have looked, and no reliable UK figures pull a roof apart from everything else that moves a sale: the street, the kitchen, the garden, the market that month. So we will not give you a number for sale price.

What we can do is show the parts of value you can count. There are three kinds, and they behave differently.

1. Sale price: what a buyer pays. Real, but impossible to pin to one change.
2. Saleability: how easily the house sells, and how much gets knocked off after the survey.
3. Use: what the room is worth to you while you live there, in months of use and in heating bills.

Saleability: the survey conversation

Buyers rarely fall in love with a roof. They do notice problems. A buyer's surveyor who sees brittle polycarbonate, stained sheets or water marks on the floor will usually note the roof as an item to budget for. That note turns into a conversation about price.

Here is how it tends to play out. Say the survey flags an ageing roof on a Victorian measuring 4 m each way. The buyer does not know what a replacement costs, so they ask for a generous figure off the price to be safe, perhaps £6,000 or more. If you had fitted the roof yourself, a medium Victorian panel roof sits in our band of £4,350 to £5,150. The buyer also gets a room without the problem, which is easier to sell than a discount.

A panel roof only helps a sale if the paperwork is in order. Keep these together:

• Building control's completion certificate. Going solid brings building control in, and a buyer's solicitor will ask to see the sign off.
• Your 10 year insurance backed guarantee, explained on our guarantee page.
• The written quote or invoice, showing the date, the 75 mm panel and its U-value.

We lodge the building control application on every job, so the certificate comes as part of the work rather than something you chase afterwards.

Use: the value you can measure

Months you can sit in the room

Plenty of conservatories are used from April to October and turned into a storeroom for the rest of the year. If a 16 m² room is unusable for five months, you are heating, insuring and cleaning space you only get seven months out of. A roof that keeps the room comfortable in winter and stops it overheating in summer turns part-time floor space into a full-time room.

Cost per square metre

Put the panel roof price against the floor it brings back into use. For that 4 m by 4 m Victorian, £4,350 to £5,150 over 16 m² works out at roughly £270 to £320 per m². Rebuilding the same floor as a single storey extension is commonly quoted at around £2,000 to £3,000 per m² before finishes. We compare the two routes properly in conversion against extension.

Heating bills

In most conservatories the roof is the biggest single stretch of glazing, and it leaks heat fastest. The table shows yearly roof heat loss for an 18 m² roof, which is about what a 4 m by 4 m Victorian carries once you allow for the pitch. Each row multiplies U-value, area, 2,150 degree days (the England average) and 24 hours, then divides by 1,000. Energy is priced at the October to December 2026 Ofgem cap: 26.32p a kWh for electricity and 7.97p for gas, with the boiler 90% efficient.

The table takes it that the heating runs in there right through winter. Heat it less and the saving falls. They also ignore the walls, which lose the same heat under any roof. Even so, swapping old glass for panels on this roof saves about 2,200 kWh a year, which is close to £580 on electric heaters or about £195 on gas.

What can take value away

• No sign off. A solid roof without a completion certificate gives a buyer's solicitor something to worry about.
• A dark room. Losing the see-through roof changes the light. A glazed roof light or two, £395 apiece, put daylight back where you sit.
• A colour that fights the house. Buyers see the roof from the garden before they step inside. Our guide to choosing white or grey panels helps you pick one that suits the building.
• A tired frame left as it is. A new roof on a failing base does not fix the base. The survey covers it, and you hear from us if it needs work first.

So, is it worth doing before you sell?

If you are listing next month, a new roof is unlikely to return its full cost in the sale price alone, and nobody can promise that it will. It can still make sense if the old roof is leaking, the survey is likely to flag it, or the room photographs as a cold store rather than a living space.

If you are staying for a few years, the case is stronger, because you collect the use and the lower bills yourself. Most of what a new roof is worth lands with whoever lives under it.

Price it for your house

Swapping old glass? Start with replacing a glass roof. See your figure in build your roof, then use get my price for a survey and a fixed written quote.