Over half the world’s population lives in urban areas, and the share of city dwellers is projected to reach around 68% by 2050. Space scarcity means many people are looking for ways to enjoy their outdoor space and create different types of gardens in new spaces. A roof terrace is one such space, as it provides a usable outdoor space in suitable climates.
However, this roof choice also has its disadvantages. For instance, flat roofing membranes cost up to $12 per square foot installed and usually need major recoating or replacement every 15 to 20 years.
Pitched roofs, on the other hand, can last over 35 years with a much lower need for replacement. Cost, homeowners find, is just one consideration when choosing between the two options.
The Space and Flexibility Offered by Roof Terraces
Roof terraces are walkable, load-rated flat or low-slope decks (with a 1º to 10º fall) that can support occupancy, green-roof layers, and furniture.
They essentially add an entire room to a home, making an ideal setting for parties and gardening activities, and a good base for future vertical extensions. These roofs are finished with tiles, non-slip polyurethane coatings, or timber. They contain a core layer of materials such as EPDM rubber, TPO and PVC, modified bitumen, or fiberglass.
Their design makes them highly compatible with HVAC equipment or solar panels, and they enable green-roof layers that improve insulation and stormwater retention. While the slanted nature of pitched roofs lets homes shed water efficiently, this function comes at the cost of creating an entirely new space for a host of activities.
Differences in Costs
The cost of tiling a flat roof is generally lower because it requires simple horizontal joints and less timber framing. Its surface area is also smaller, as it matches the room immediately beneath it.
Finally, flat surfaces are easier for building crews to work on and quicker to build because they require less scaffolding. Base estimates range from $4 – $13/sq ft for waterproof membrane installation vs. $10 – $25/sq ft for concrete, clay, or slate tiling.
Weather Considerations
Depending on the local climate, flat roofs can carry risks. In rainy zones, they can accumulate water, leading to membrane degradation and leaks. Drainage systems must be on point, and regular inspection and recoating may be necessary in homes with roofed terraces.
In areas with heavy snow, pitching also reduces long-term risks by using gravity to shed snow. One reason pitched roofs tend to require less replacement is the materials they are made of.
Concrete tiles, clay tiles, and slate depend on gravity and overlapping courses to shed water, meaning they require a minimum slope. To help flat roofs last longer, consider fiberglass or high-quality membrane systems, which can last several decades when properly installed and maintained.
Planning Height Limits
Many cities worldwide, including New York, London, and Barcelona, have strict planning rules that impose maximum building heights. Flat roofs are a perfect way to create a useful terrace or amenity space without adding height to a building.
However, they do introduce new considerations, such as additional noise and overlooking neighboring spaces, particularly in dense residential areas. Features such as privacy screens, railings, and acoustic measures may be required to keep noise down and avoid overlooking issues.
If you are seeking inspiration for how to keep your flat roof compliant, check out Casa Malaparte in Capri (which has a curved white wall that provides privacy) or Tyra Banks’ former Pacific Palisades home (which has a large roof terrace with glass balustrades, seating, a spa, and outdoor areas).
When choosing the perfect roof style—flat or pitched—factors such as taste, cost, and legal requirements matter most. Flat roofs are ideal for urban areas that experience relatively little rain or snow.
They are also an affordable option for those who want to add an extra room to their home without increasing height or width, and they offer greater space for socializing and enjoying hobbies such as gardening.
However, flat roofs also require excellent drainage systems and, in some cases, features such as glass balustrades and perimeter railings to comply with noise and privacy regulations.
