​The pros and cons of a flat-roof house

Johannes van Graan Johannes van Graan
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South Africa is home to numerous designs and styles when it comes to residential structures, including the all-too familiar flat-roof house. But saying that a roof is 100% flat is actually inaccurate, as a flat-roof design usually has pitch/slant of about 15° to allow for rain drainage. 

Although flat-roof houses are great options for those living in low-rainfall areas, one cannot deny that it also makes for a unique, modern look when it comes to visual aesthetics – definitely one of the reasons why so many people opt for a flat-roof design.

But like all things when it comes to architecture, decent research is required (yes, even when it comes to the roofs and floors of a structure), which is why we’ve taken it upon ourselves to find the pros and cons of the flat-roof house.

​1. The pros of a flat roof: Usable space

Modern double storey family house homify Modern houses architectural design,draughting

Modern double storey family house


Probably the biggest advantage of flat-roof houses in South Africa (and worldwide) is that they allow for more space, which would have been lost had a pitched roof been used. With a flat-roof, one has the option of adding an extra floor or storey, with no slanting or angled walls to intrude on the space. 

This also makes it possible to use the extra space on smaller structures such as extensions, porches, and garages. From the outside, a flat roof can allow for socialising/relaxation spaces like a rooftop deck or patio. And don’t forget about rooftop gardens, which are very much on trend in the 21st “green” century! 

​2. The pros of a flat roof: Pricing

Generally speaking, a flat-roof house is cheaper, since it requires less material for the roof. Of course this also depends on various other factors (such as the size of the house, location, etc.), but at the end of the day the reduced cost is thanks to the fact that no rafters (required for pitched roofs) are used. 

Additionally, the property’s footings are not required to be as deep as with a pitched-roof design, for flat roofs don’t place nearly the same amount of load onto the building’s foundations. 

homify hint: The insurance of roofing/building companies is generally cheaper when installing a flat-roof design, for it’s harder to fall off a flat roof than a pitched one!

​3. The pros of a flat roof: Additional factors

Replacement cost: The complete replacement of a flat-roof design requires much less time, thereby heavily reducing the costs. 

Quick installation: Because they lack pitch, flat roofs are easier to install. And as they lack the rafters and trusses that are used with pitched roofs, this allows for quicker installation as well.  

Compact design: Since they save on space and have excellent compact designs, flat roofs are also the popular choice for smaller structures, like extensions.

​4. The cons of a flat roof: Leakage

Those living in high-rainfall areas would be best advised to steer clear of a flat-roof house, as water on the roof builds up much quicker before soaking into the house. When a flat roof leaks, the damage often goes unnoticed for quite some time. The water first soaks through the roof, then seeps through the insulation and any structure below before it is noticed, and by then the major damage has already been done. If left for too long, this can result in: 

• A weakened roof structure 

• A total removal and replacement of the roof (if the insulation is affected), as it would end up becoming too mouldy 

• Mould sores, which can become a health risk when breathed in 

• Escalated damage costs.

5. ​The cons of a flat roof: Additional factors

Insurance: Insurance companies definitely take into account the fact that a flat-roof house is more prone to leaking. This results in raised rates for the homeowner. 

Heat absorption: A flat roof is designed to absorb heat. Because there is no roof pitch, the entire surface is exposed to the sun all day long. And although this sounds like a great idea for winter, the winter sun is at the lowest point; thus, there is a minimal amount of sun compared to the summer months, when your home will receive a full-on scorch from the overhead sun all day long.  

Maintenance: All roofs require regular maintenance. However, due to the nature of the slope, flat roofs often require more maintenance throughout their lifetime. Remember that, when it comes to drainage, a flat roof is not nearly as effective as a pitched one. Thus, without regular inspection, drains can become blocked, resulting in damage and leaks. 

Repairs: As a roof is exposed to the elements, it needs a waterproof seal, which must be maintained regularly to prevent leaks and expensive repairs. A lot of flat-roof leaks are due to a lack of regular inspection and maintenance, which is why, if you live in a flat-roof house, it is crucial that you make the time to regularly check your roof.

Did you know: Flat roofs are energy efficient

Umhlanga house 7 bloc architects Modern houses
bloc architects

Umhlanga house 7

bloc architects

Flat-roof materials are quite energy efficient, and many of them are also very reflective of light, allowing the heat to be reflected off the roof and thereby cooling down the interiors in summer. And forget what you may have heard about flat roofs and insulation: they are also able to be insulated, meaning your flat-roof house can continue to keep your home warm and cosy during the winter.  

Did you know: Flat roofs make great gardens

HOUSE SEALION | FRESNAYE Wright Architects Skylights Aluminium/Zinc Black
Wright Architects


Wright Architects

As they ensure some extra space, many homeowners and apartment complexes use their flat-roof design for a rooftop garden, gym, home office, skylights, balcony/terrace, and in some cases even a swimming pool.  

Did you know: Flat roofs can last for almost 50 years

Just like pitched roofs, your flat-roof design can last for nearly half a century with proper maintenance. Just commit to regular inspection (in spring and autumn, plus after heavy weather conditions like hail and rainstorms) and fixing leaks as soon as possible.

Next up: 33 ideas to renovate your house on a budget

What are your thoughts on flat-roof houses versus pitched-roof designs?

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