Butterfly Roof Structure – What is it?


What is a Butterfly Roof?

A butterfly roof (sometimes referred to as a ‘V roof’ or ‘inverted pitch roof’) is a form of roof that is shaped similar to a butterfly. It is where two roof adjacent gable slopes downwards towards the centre as opposed to traditional roofs you draw as a child which slopes upwards like a pyramid.

They tend to have no gutter as rainwater will run off in either end of the valley often running down a downspout. Unlike a gable roof where this would require a gutter to prevent rainwater falling down on to the surface where pedestrians maybe walking. Depending on the architect it can be designed to be symmetrical slopes and the valley is centred, or can be found having a slightly quirky feel, with the valley being of centre and the pitched surfaces being different sizes.

With the nature of the roof it allows the perimeter of the walls to be higher, providing a use of large windows that can be installed above eye level (also know as clerestory), which helps light to come through yet keeping privacy. This works well for certain buildings such as P.E. halls for schools and leisure centres.

Depending on the construction of certain buildings this type of roof structure can sometimes look similar to a flat roof depending on the angle of the pitch.

Butterfly roof on a residential home


History of the Butterfly Roof

Butterfly roofs are fairly modern compared to other roofing structures. It is the early to middle 20th century saw a change in the way architects designed buildings to bring forward thinking and unique style to their designs. Now this style has survived and can be seen to be quite common to see in new builds, more so in commercial office spaces and building rather than houses.

It is commonly credited to be created by Dan Palmer and William Krisel in the late 1950s in California.
As much as popularised the form with creating of 2,000 houses using this roofing structure it turns out that Krisel nor Palmer were the originators.

It began in the 1930’s, Le Corbusier who was a Swiss-French Architect who used the butterfly roof in his design of a vacation house in Chille. There were other designs and project within the time of the late 1950’s such as Antonin Raymond, Oscar Niemeyer and Marcel Breuer.

Butterfly Roof


What are the benefits of a butterfly roof?

There are a range of advantages of butterfly roofs. For architects it adds an extra dimension to their design, providing eye-catching displays and straight lines.

As mentioned above butterfly roofs provide multiple options such as having large, stylish windows that still maintains privacy or the building could have windows installed that fall eye-level to also see the interior of the building. With the perimeter walls being higher can also open up other options for structural elements within the interior of the building.

By having large windows this also increase natural light in the building. Natural has been proven to help with health and wellbeing but also provides options to install solar PV panels, making it more efficient when it comes to heating bills.

Due to the design this can also be used to collect water and can then be used in a variety of ways such as; watering plants showering, or even drinking after using a purifier. This leads on to drainage. If the use is not to use water for any efficient purposes than still butterfly roofs are fantastic way to drain the water off the roof ensuring it is easy to flow off the roof and into one direction. This means that no guttering is needed to be installed – just a down pipe.
This means low maintenance when it come to cleaning the gutter every 6-12 months.

Wind resistant is also an advantage for a butterfly roof structure. It is very aerodynamic causing it to resist from heavy winds and storms, again saving time in maintenance and repairs.

So here is a recap of the benefits:

  1. Design: Adds an extra dimension to the building and very eye-catching.
  2. Large Windows: Provides options to have large, stylish windows due to the wall perimeters.
  3. Efficiency: Having large windows can improve natural light and also heat depending on the window choose – Saving on the utility bills.
  4. Drainage: One central drainage valley making it easy to maintain as no gutters are required.
  5. Commercial / Eco-Friendly Uses: Due to the water flow it can be collected and used for other uses such as watering plants, showering and plumbing.
  6. Aerodynamic: Due to the design of the structure it prevents damage from high winds and storms.
  7. Maintenance: Maintenance and repair costs can be very minimal and save time and money with the structure being aerodynamic and no gutters to clean.

Butterly roof on a commercial building.


Now what about the cons?

The advantages hold a lot of weight on why you would go for this type of roof structure. However, there are some disadvantages to this beautiful designed structure.

A factor of why you may not see many butterfly roofs is the initial cost to have it installed. It is very labour intensive due to it being a lot more demanding to install and provides more equipment to do so. With it’s complexities with the pattern and aerodynamic requirements the installation time is more time consuming, but the price can vary depending on whether a contractor has been employed to do carry the project or if it can be done by yourself.
If it is a contractor that you are hiring ensure you shop around but not necessarily go for the best deal as it is a complex structure so go for a reputable contractor who has done this before with a track record.

Temperature control is also a factor of why you shouldn’t have a butterfly roof. It is difficult to regulate the temperature throughout the building making certain areas warmer than others. It is recommended to use specific solid membrane to keep the roof more secure and sealed.

Due to the design of the roof structure with the roof indenting it causes the space in the loft very minimal if any space at all. This can minimise the value of the property and also miss out on storage space if it is on a commercial property which may need such space to store items such as Christmas decorations etc.
Many residential properties have extended the house by renovating the loft space and adding a stair case for ease of access. With a butterfly roof however, it would mean having to build another floor to have the capabilities of another room as their may not be any loft space with this type of structure.

Butterfly roof on a home in an open area

An advantage of butterfly roofs is maintaining them however, if the roof does ever need repairing it can come at cost. Due to the design and layout it can cause pools of water that is undetected in the valley of the roof as it isn’t easy visible from looking from the ground level. This can put extra pressure and load on the roof and can cause damage in the long-haul, leading to leaks and other damages.
As much as it is a desirable structure to have for the appearance and also no guttering to maintain, there is maintenance needing to be had for the valley of the roof. The valley acts like a gutter and so needs to ensure that no debris is preventing water flow from getting stuck.

As the centre of the roof is a vital part to keep clear to prevent damages, it is important that this type of roof is not installed in areas where it is common for heavy rain and snow. Having this type of roof structure can increase the risk of collapsing or leaks with a load-baring due to snow or heavy rain. If this happens it wouldn’t just mean a repair to the roof but also causes damages to the interior meaning further costs, not to mention the health and safety risks.

So here is a recap of the disadvantages:

  1. Installations Costs: It is a very labour-intensive and complex structure to build meaning that the installation costs can be very high.
  2. Loft Space: The design of the roof will reduce / minimise space within the loft, which can reduce the cost of the property when it comes to sell.
  3. Temperature Control: The structure can affect the temperature circulation causing certain areas to be hotter than others.
  4. Heavy Rain and Space: If the property is in a location where it has heavy rain or snow, reconsider this roof structure as it can cause severe damage and the roof to collapse.
  5. Costs of Repairs and Maintenance: With such a complex structure it can cause the cost to repair and maintain the roof to be a little pricey than normal. Be aware that to have a beautiful looking roof it may bite you when it comes to repairing it.



If you are looking to go a head with a butterfly roof ensure that you compare the pros and cons and do your research. Make sure that you are in a location that don’t have serious weather that will cause damage to your property. Evaluate your budgets to make sure it is an affordable option for you to go for. Finally, if it is affordable for you and it is in a perfect location to do so, enjoy showing off your property as it can truly make the building structure look stunning.