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How much does it cost to install a green roof? Gardening pros answer your burning questions

 Green roof.
Green roof.

Green roofs, also known as living roofs, as the name suggests, cover the top of the roof with greenery and vegetation. But if you are considering building a living room system on your property, you’re probably wondering how much does a green roof cost.

As this gardening trend essentially consists of turning your roof into a small garden, although there are many benefits to it, you do need to tread with caution to avoid any damage to your home. This means that help, or at least a consultation with, the professionals is advised. Therefore the costs of green roofs change depending on how much you involve these pros and how big your roof is, along with a few other factors.

According to Google Trends, searches for ‘green roof’ peak every spring in the UK. And this spring season is no exception as both ‘green roof’ and ‘living roof’ are currently breakout terms.

So if you’re one of the (many!) people researching everything about green roofs and you want to know how much you could end up paying for one, you’ve come to the right place. We’ve consulted our gardening experts to have them break down the expenses that come with building a green roof.

Green roof
Green roof

How much does a green roof cost?

Firstly, if you’re not quite sure what a green roof is, then let’s clear that up.

‘A green roof is a roof of a building that's either partially or fully covered with vegetation,’ says Steve Chilton, garden expert at LeisureBench. ‘It's also often known as a living roof, an eco roof or a grass roof. It's not as simple as just throwing some turf on your roof, however. The roof must have a waterproof membrane and a proper drainage system in order to prevent the moisture from the roof coming into the property.’

If you’re wondering whether you should build a green roof, then you should know there are both benefits and downsides.

Green roof
Green roof

‘They can provide a wide range of public and private benefits, such as aesthetic improvements, waste diversion, improved stormwater management and improved air quality,’ explains Petar Ivanov, Fantastic Gardeners' gardening expert.

‘They’re also more energy-efficient and have good noise-reduction properties. Green roofs can support a variety of plants and organisms and they provide habitat for many bird species as well as improve health and well-being by reducing pollution and providing a local food system.’

In terms of downsides, the cost is an obvious one, even though it varies. And the other is the danger of property damage if not installed properly. That risk is of course higher if you decide to install a green roof yourself without the assistance of experts. But if you do opt to get professionals in, then the overall cost rises.

Pitched grass roof with black cladding and white windows
Pitched grass roof with black cladding and white windows

‘To get a green roof professionally installed, it all depends on the company and what type of green roof you want when it comes to the cost. It also depends on how much roof you have that you want covered, as you'll usually pay in terms of square metres. You're probably looking at anywhere from £50 to £200 per square metre, although the average cost is probably between £75 and £150 per square metre,’ Steve reveals.

Petar adds, ‘The cost can be a lot lower if you decide to do it yourself with simpler materials, such as around £7 to £12 per square metre depending on how large you want yours to be.’

So now that you know how much it will cost you, this is what you’ll be spending your money on, besides the manual labour.

A building with a curved green roof
A building with a curved green roof

What you’ll need to build a green roof

Installing a green roof is about a lot of layering. And the first layer is a waterproof membrane.

‘You’ll need to lay a waterproofing membrane,’ says Fiona Jenkins, gardening expert at MyJobQuote.co.uk. ‘The membrane is there to manage the moisture.’

Then comes the geotextile. ‘A geotextile is then laid over the top to stop plant roots interfering with the integrity of the roof,’ Fiona says.

Next, your plants will need enough drainage so laying down a drainage layer like mesh is key. ‘You'll need a good drainage system that allows water to flow away from the roof and prevent water buildup which would make the roof heavy and dangerous,’ Steve says.

A red brick house with a green roof
A red brick house with a green roof

After that comes the growing medium like soil. ‘Some sort of growing medium, whether it's soil or sand is really important as this is where your plant roots will grow,’ Steve explains.

Finally, your plants. ‘Your plants are laid over this. Readymade mats and trays can be bought to save you the hassle of planting the roof up yourself. These typically contain sedums and grasses that are low maintenance.’

It’s up to you what kind of plants you go for or whether you opt purely for grass. Either way, we hope that you’ll give the beauty of a green roof a try.