It has become increasingly common for homeowners, building managers and architects to opt for a flat roof rather than a conventional sloping roof, because the results look fantastic, the prices are reasonable and the spaces can be versatile if the roof is installed properly by specialists.

Whether the aim is to design a modernist house, install solar panels, fit a green roof or simply have an outdoor upstairs space, a flat roof is a highly desired option, but eager homeowners often ask how long it can take to install one.

This is a question that gets asked a lot but is ultimately quite difficult to truly answer, as it can depend on a wide range of different factors.

An average-sized house roof will typically take at least a week, whilst the flat roofs of large commercial buildings can take at least three months.

These assume rather ideal scenarios, and that is not always possible when it comes to installing flat roofs, particularly given that a major factor that governs timescales is out of any of our control.

The size, shape and complexity of the roof are the biggest factors and ones that a specialist will typically use to give a baseline rough estimate. Small bungalow or garage flat roofs will typically take at least three days, the average is a week, larger roofs can take over 6 weeks and commercial roofs considerably longer than this.

These timescales are widely affected by the nature of the roof itself. If it is a tall building which needs a flat roof installed, this will necessarily make the project take longer to ensure that it is done safely and in keeping with health and safety legislation. This is also true if there is any confined space work involved.

There are multiple waterproofing and sealing materials that can be used, but the simpler it is to install, the faster it will be to apply and the less time a flat roof will take to finish.

Finally, the weather is a huge factor, as strong winds can make it unsafe to work at height, and heavy rain showers can affect the use of adhesives, the waterproofing of the building and can bring roofing work to a grinding halt.