The Different Types Of Flat Roofs

The Different Types Of Flat Roofs

In general, there are two types of roof terraces, including the accessible roof terrace and the inaccessible roof terrace. Unlike a sloping roof or a rounded roof, the installation of a flat roof does not require the installation of a frame, but of a load-bearing part. However, making a roof terrace yourself requires adherence to building standards.


This page tells you more about the different types of patio roofs, and their uses:

Table of Contents

Roof terrace: definition

The roof is the stage, which completes the external construction of a house; it is part of the major works. The roof terrace is one of the possible options when building a roof.

Composition of a roof terrace

The roof terrace is one of the possible roof styles. This type of cover is composed of a single panel. It differs from other types of roofs by the absence of a frame. On the other hand, it has a load-bearing element, which comprises:

  • Slope,
  • An insulation element,
  • Opening,
  • Protection,
  • Vapor barrier.

These are the main elements that make up a flat roof.

Different Types of Flat Roofing Materials To Choose From

Good coverage is essential to protect your roof from leaks. Here is an overview of roofing options used in most flat roofs along with their pros and cons.

Choosing the right flat roofing material

If you are planning to build a flat roof house, or want to renovate your current flat roof, there are several material options available to you. Here are the different materials that are usually used to cover flat roofs:

1. EPDM or Elastomeric membrane

Elastomeric membranes are composed of two layers, where the base layer is made is fixed with screws or glued or a second covered with hot tar and gravel (white, light gray, brown, or green), while the top layer has beautiful finishing.

The relevance of applying a granulated topcoat is linked to the fact that it provides great resistance to the entire installation against sunlight, shocks, and tears. The joints are welded by fusion with a torch, which ensures a great seal to the whole installation

Note that the elastomeric membrane can also be installed without the aid of heat, using sections of self-adhesive membranes. Particularly resistant to shocks and temperature variations due to its high elasticity, the membrane requires few repairs during its life, which is a great advantage in its favor.

Even if the membrane will remain waterproof during its life, be aware that it is still sensitive to stagnant water which can reduce its life by at least 10 years. In addition, be aware that algae and ice present on its surface may deteriorate the aggregate on the topcoat if they are not removed within a reasonable time.

Ideally, the drain on the roof should be at least 4 inches in diameter to drain water properly. The cost of the elastomeric membrane is higher than that of asphalt roofing, but you should keep in mind that the former has more service life, which is around 25 to 40 years.

Due to its long service life, EPDM rubber is a rather popular coating for flat roofs. This rubber roof can withstand heavy foot traffic, provided the roof is properly installed. In addition, this material is elastic, and therefore it does not tear easily.

EPDM requires very little maintenance and any damage is easily repaired. Since this material is usually installed on the existing roof cover, the installation can be done very quickly.

2. Bitumen or asphalt

bitumen roofingThe bitumen, which is also known as asphalt is another popular choice for covering a flat roof. As for the laying, the bitumen is fixed using a gas torch.

The big advantage of bitumen roofing over EPDM is its price. Otherwise, EDPM rubber has a longer life, is easier to install, and presents less risk of damage. This is why most people favor EPDM over bitumen for coating flat roofs. But, all the shortcomings of Bitumen roofs have been fixed in modified Bitumen, so you can expect easier installation and lesser damage in modified bitumen roofs.

3. Green roof

green roofAs its name suggests, the green roof is made up of all kinds of vegetation: plants, grass, mosses, etc. It is aesthetic and practical since this plant layer offers additional protection against weather conditions. Moreover, you can contribute to the environment by having a green roof, but then, it requires thorough maintenance or else, the roof starts to leak, and then, you will have to look for roof replacement, which will increase your expenses.

The disadvantage of this type of roof is that it is more difficult to detect leaks. In addition, an underlay (in EPDM, for example) must be laid beforehand. The roof structure should also be strong enough to support the weight of the vegetation.

4. PVC Membranes (Single Ply Membrane)

pvc membrane roofingPVC is a ubiquitous polymer in the construction world. The material is coated using heat-welded seams that create a watertight seal. It doesn’t need adhesives, sealants, or tapes as with other types, which helps save some money. Moreover, it has amazing heat-reflective properties that make it energy-efficient as well. However, PVC coating is less durable than EPDM.

Also, it can start degrading after only a few years, which increases the risk of cracks, with all the consequences that entail. In addition, plasticizers, which are believed to improve the flexibility of the material, are said to be unhealthy. Therefore, this material won’t last for too long and you may have to redo the entire roof or replace it with a different flat roof material.

5. TPO membrane

tpo membraneTPO (Thermoplastic Polyolefin) is a reflective single ply roofing membrane made from polymerized polypropylene rubber and ethylene-propylene. The joints are usually fusion-welded as with the elastomeric membrane, although the TPO membrane can also be mechanically attached.

In addition, TPO roofing has a glossy surface, which makes it easy to maintain. It is widely used in the construction and renovation industry due to its multiple advantages.

This material is not the most expensive when you compare it with other materials, so you can consider it for your roof.

6. Built Up Roof

built up roofingThis type consists of 2-3 layers of bitumen sheet that are bonded together with the help of hot bitumen or adhesives. Crude oil is distilled to produce the bitumen. The reinforced bitumen sheets are made using several materials such as glass fiber, organic fiber, or bitumen-saturated polyester. The material undergoes a bath of molten bitumen followed by giving a coating of sand to prevent adhesion. The material is durable and waterproof, but a lot depends upon how precisely it is installed. During the manufacturing process, a toxic by-product is produced by the name of Methyl Bromide.

What about shingles?

Unfortunately, traditional asphalt shingles cannot be installed on a flat roof. The reason behind this recommendation is directly related to the presence of interstices between the shingles, which make possible a possible water infiltration.

This risk is rather limited on sloping roofs, as water can drain off them normally. For a flat roof, water will collect on the surface and eventually enter the interstices.

How much does a flat roof cover cost?

The total cost of the work may vary since it depends on different factors. Here is what you need to consider if you are planning to cover a flat roof:

  • Can the new cover be placed directly on top of the old one? Or does the old cover have to be removed first? In the second case, it may require laborious work, which will be reflected in the final cost.
  • Whether it is new construction or a renovation, it is also an opportunity to insulate the roof. It’s an additional investment, but it’s worth the effort. In the long run, you will be able to save a lot of energy and therefore money.
  • The total area of the roof, of course, influences the price of the work.
  • If the roof is difficult to access, it will be necessary to mount scaffolding, which means an additional fee.
  • Finally, the degree of difficulty of the work also plays a role.

The different types of flat roofs

In addition, the roof terrace comes in two forms, namely an accessible roof and a non-accessible roof.

The accessible roof is typically designed in stone, wood, concrete, and tile. As a result, the places are well equipped for the various trips.

Whether accessible or inaccessible, the roof terrace requires:

  • Support that does not require complicated materials;
  • Masonry consisting of concrete, steel, or other slabs;
  • An assembly of the reinforced concrete slab, sheet steel;
  • Woodwork, most often in solid wood.

The 3 main supporting materials for a flat roof

For any construction of a roof terrace, there are 3 types of support materials. The latter is essential in this kind of work.


Wood is an essential element in the design of a flat roof. To do this, you will only have to build a rigid structure in wood or one of its derivatives such as plywood. The latter must be treated externally. You can also build panels from compressed wood particles treated with water repellent products. It is a much more expensive option, but more durable and aesthetic.


This is most often composed of a simple solid slab of concrete or composite material. This solution is heavier and requires a house with a solid foundation. But, when it comes to the construction of flat roofs, this solution remains the most efficient.

The carrier part

This part includes several elements. It is important that it incorporate a slope. Admittedly, the slope is not very steep but allows the rainwater to drain properly. Generally, the slope varies between 1 and 5% and depends on the accessibility or not of the roof. Note that the surface also plays a role in the shape. If the surface of your terrace is not large enough, the shape will come out a little rounded. On the other hand, if it is more important, it will be tilted. However, in both cases, small cavities are needed for water drainage.

Insulation for a flat roof

insulating flat roofFor good drainage of rainwater, a flat roof must not be completely flat. Indeed, it is necessary to respect a slope of 1 to 5 degrees at least. For an accessible roof, a slope of 1.5 to 2 degrees is recommended. In addition, to avoid humidity, a vapor barrier should be installed. The latter helps to stop water vapor and protect the roof insulation. You have the choice between vapor barriers in aluminum foil or bitumen felt. The choice depends on 2 factors, including the humidity and the heating mode of the house.

In addition, to maintain heat and prevent heat loss from above, good insulation is needed. It is still a strict rule, which the roof terrace must meet. Unlike a sloping and rounded roof, the insulation of a flat roof is done from the outside.

To have the most suitable coating on your flat roof, you should consult a professional roofing company. Let the experts have their say about your flat roof because they take into account all the factors, the roof construction, weather conditions, budget, and time before finalizing the best material for your flat roof. Southern Premier Roofing offers quality roofing, siding, and gutter services in several areas, Fayetteville, Hope Mills, Charlotte, and Boise to meet commercial and residential needs. If you are looking for roof installation services in Boise, work with us today!

"*" indicates required fields

This field is for validation purposes and should be left unchanged.

Request Estimate