17 Top Advantages and Disadvantages of Flat Roofs House Design | Types of Flat Roofs Materials
What is Flat Roof House Design? | Advantages and Disadvantages of Flat Roofs | Flat Roof Construction | Types of Flat Roofs | Flat Roof Insulation
What is a Flat Roof?
A roof which is approximately flat is called as a flat roof. A flat roof is a roof which is almost level in contrast to the many types of sloped roofs. The slope of a roof is properly known as its pitch and flat roofs have up to approximately 10°.
Flat roofs are an ancient form mostly used in arid climates and allow the roof space to be used as a living space or a living roof. The flat roof is commonly constructed in reinforced concrete, flat stone supported on rolled steel joists, bricks, tiled, etc.
A flat roof is a roof with a surface that is level. As mentioned above, the term “flat” does not imply that it has no slope, but that the slope is very slight. A flat roof can be constructed in a variety of other ways, but the most common are sloping or standing seam roofing.
In modern buildings, a flat roof is built with the help of strong tar or rubber to cover any number of different materials.
In traditional buildings, a flat roof is more unlikely, as they are usually built with sloped roofs with inclined planes to help gather rainwater.
Current construction codes require a minimum two percent slope, or one-fourth unit vertical for every 12 units horizontal, for drainage considerations.
To put it another way, the roof must slope one-fourth of an inch for every 12 inches. To the naked eye, the slope is nearly invisible.
Flat Roof Construction
Flat roofs are becoming increasingly popular these days as they don’t require much maintenance when compared to a sloped roof.
They are very durable and capable of withstanding extreme weather conditions like heavy rain and strong winds. The construction is simpler than that of a sloped roof, which makes them more cost-effective than traditional roofs.
Flat roofs are seen as the best choice for many commercial and residential properties, but they are also installed on some office buildings.
This is because they not only help in minimizing the amount of maintenance required by your building, but also their visual appeal. The look of a flat roof is similar to that of a conventional roof. Hence, you won’t see any significant differences when comparing it with a sloped roof.
The demand for flat roofs is higher in cities with a relatively smaller population; this is because they are more cost-effective and can easily be built.
Flat roofs are available in many different styles and designs. Hence, you have a lot of options to choose from, depending on your requirement and budget.
There are two types of flat roofs materials
Asphalt & gravel (also known as hot tar) and synthetic slate.
Slating is the process of constructing a flat roof by installing long sheets of thin metal on an existing roof frame. The metal is secured with nails, screws or staples. The slates are usually rested on an overlapping shingle base.
Slates are typically made from granules of natural rock that are bonded together by heat and pressure. They are very durable and long lasting; however, they do not offer the same level of insulation as synthetic slate roofing.
Synthetic slate is made of polymer (a class of plastics) granules that, when compressed, have physical properties similar to natural slate, such as rigidity and durability.
Because the internal cellular structure of synthetic slate is not the same as natural slate, synthetic slates are able to withstand heat-related stress better than natural slates.
A key difference between synthetic and natural slate is that synthetic slate does not require an adhesive layer. Synthetic slates can be nailed or stapled to roofs in a similar manner as asphalt shingles.
Slate roofs were traditionally made from slate, a sheet-like rock which grew abundantly in Wales and England. Slate is formed when layers of shale, an early sedimentary rock, are compressed over many years.
Coal waste was often used as a binding material. Slate was once a popular roofing material in the United States and some isolated areas still use it today. U.S. slate roofs are increasingly being recycled for environmentally friendly projects or used as a substitute for granite countertops and floor tiles.
Concrete Flat Roof
A concrete slab flat roof is typically constructed of a structural layer of concrete finished with a smooth screed on top of which a water-resistant layer, such as a membrane, is laid. To prevent interstitial condensation, the roof should include insulation and, in most cases, a vapour control layer.
Flat Roof Design Replacement & Repairs
Knowing the pros and cons such as the price of flat roof repair, the roofing material required, potential ponding water and roof leaks help make a decision that is best suited for your building. Flat roofs construction consists of a top coat and underlayer
Flat roofs are usually found on commercial buildings rather than residential buildings, but this does not mean you cannot have a flat roof constructed on your home. There are several things to consider when choosing a flat roof, such as the materials, weather, and maintenance.
Most flat roof replacements are done using rubber, synthetic or fiberglass materials. The cost of a flat roof replacement is usually the same as that of a sloped roof, but you have to take into consideration other factors like location and material used.
There are some flat roofs that can be found in all regions of Australia, so they’re commonly installed on commercial developments.
Flat roofs are ideal for business establishments that require a durable and lasting roofing system. The problem with many flat roofs is their susceptibility to water pooling which makes them susceptible to leaks.
The weather protection offered by a flat roof is the main reason for its popularity today. Flat roofs are an ideal solution for building owners that require a durable roofing system that can withstand heavy rains and strong winds.
They are very economy and cost-effective compared to conventional roofs since they require less maintenance.
The other main benefit of flat roofs is the ability of them to prevent unwanted leaks in your building, which increases the longevity and durability of your structure considerably.
Flat roofs have earned a reputation for being a stronger, cooler and safer alternative to conventional sloped roofs. Flat roofing is used in a wide variety of locations, including public and commercial buildings.
A flat roof is an ideal choice for government or municipal buildings. These include community centers, city halls and public schools.
Flat roof replacement costs are much lower than that of a sloped roof, which means you are able to make the most out of your budget without compromising on quality.
Flat Roof Insulation
Insulation is an important part of a well-functioning home and can help to lower your energy bills. Installing insulation on your roof can also help minimize the amount of heat lost through your roof.
There are many types of materials that can be used to insulate your roof, including:
- -Shingles that, when laid down tightly, offer excellent insulation.
- -Rigid polyurethane foam insulation panels; A rigid foam that is installed between the roof deck and the roofing.
- -Spray Foam Insulation: A liquid foam that is injected in the voids and penetrations of a built-up roof.
- -A reflective roofing that is designed to be self-protective.
Flat Roof Membrane
The membrane is a building material. It is the most common material in flat roofing and involves placing a waterproof material on the roof.
This material may be synthetic or it may be rubber, PU, PVC or EPDM. The membrane can be bound to the roof with adhesive (sealant) or mechanically.
A properly installed membrane will prevent leaks and will not allow heat to transfer through it. Some membranes are more resistant to ultraviolet rays, heat and chemicals than others.
Types of Flat Roofs Materials
There are three types of flat roofs: single-ply, built-up, and modified bitumen.
- Built-up roof (BUR)
- Rubber Membrane Roof
- Modified bitumen roof
1. Built-Up Roofs
Built-up roofs are made of hot tar and gravel and are one of the most cost-effective flat roof designs, although they have several drawbacks.
They’re usually made of three or more layers of impermeable ply sheets sandwiched between layers of hot tar. For stability and endurance, these roofing layers are ballasted with a layer of gravel or smooth river stone.
Built-up roofs can pass higher fire ratings if you are concerned about the fire safety of your commercial building. Gravel is a non-combustible roofing material.
Roofs ballasted with rock, on the other hand, are very heavy, putting additional strain on the construction of your building.
This type of roof structure is also notoriously difficult to remove once its useful life has expired. This difficulty in removal raises the expense of later roof replacement.
Built-up roofs are frequently unsuitable for various applications because roofing installation is untidy and the molten tar emits a strong asphalt odor.
Pros of Built-up roofs
- Gravel is a great fire retardant.
- Suitable for windows and decks with a view of the roof.
- It is the least expensive of the four roof options.
Cons of Built-up roofs
- Quite heavy.
- Joists must occasionally be reinforced.
- The installation process was unpleasant and clumsy.
- It is not suggested to install in occupied residences.
- It is not a do-it-yourself installation, and locating the cause of leaks is difficult.
- Gravel has the potential to obstruct gutters and scuppers.
2. Modified Bitumen Roof
Modified bitumen roofs are comparable to built-up roofs in that they are constructed of asphalt rolls that are normally three feet wide, but a modified bitumen roof is usually only made of two piles or layers, a base sheet and a cap sheet. Modified bitumen can be applied in four ways:
- Hot tar applied,
- Cold applied solvent-based glue that does not require heat.
- Torched down with an open flame that melts the two sheets together
- Peel and stick base and cap sheets that self-adhere after a release tape is removed.
The cap sheet or top layer is commonly granulated and light gray in color, comparable to the grains on a shingle roof.
Because modified bitumen roofs employ only a single layer of adhesive roofing material, they are suitable for do-it-yourself installations.
Previously, modified bitumen was put with a torch; however, self-adhering solutions are now available.
Modified bitumen roofs are also lighter in color, which helps reflect part of the sun’s infrared radiation and lowers HVAC expenses in facilities.
Pros of Modified bitumen roofs
- Homeowners can install peel-and-stick material by themselves. Modified bitumen is the most easily installed of the options because it requires no special equipment or professional installation services.
- Its light-colored mineral surface reflects heat and reduces energy consumption.
- Its cost falls in the middle of the scale.
- Modified Bitumen provides the same roofing benefits as slate, such as durability, fire resistance, and insulation.
Cons of Modified bitumen roofs
- Torch-down applications are a fire hazard and should not be used in occupied buildings.
- It is not as resistant to scuffs and tears as rubber-membrane roofs
3. Rubber Membrane Roof
Historically, rubber membrane has been a common flat roofing material. EPDM (ethylene propylene diene terpolymer) is another name for a rubber roof membrane.
Membrane Roofs are installed as thin sheet materials that range in thickness from 0.030 (30 mils) to 0.060 inches (60 mils) and are applied to the roof in a single layer.
Because they are constructed of synthetic rubber or polymer, they are flexible and elastic, and can withstand temperature variations and some types of impact better than built-up roofs.
Rubber membrane roof leaks are easily fixed, and repair supplies are inexpensive. Rubber membrane roofs are lighter and more durable than older flat roof systems like as BUR and Modified, but they are less resistant to punctures than newer PVC membranes.
EPDM membranes, like PVC, have the advantage of being highly recyclable once the useful life of the roof has expired.
The naturally dark hue of rubber roofs makes them susceptible to heat absorption and, in some cases, may necessitate light-colored roof coatings, which will raise the cost of installation.
The visual aspect of the black rubber roof is frequently cited as its main detractor.
Advantages and Disadvantages of Flat Roofs
Advantages of Flat Roofs
1. Reduced building and repair costs.
Flat roofing systems are the clear winners in terms of cost-effectiveness. Flat roofs use less material and take up less area than sloped roofs. This reduces the cost of initial construction while also saving money if substantial repairs are required.
2. Simple to clean maintain
Because a flat roof is easier to reach than other systems, it is simple to maintain. To keep debris from accumulating on your roof, you should remove algae, mold, and stains on a regular basis.
Pressure washing is the most effective technique to clean your flat roof without damaging it, especially if it is made of concrete.
Some homeowners make rooftop gardens out of flat roof portions. Flat roofs are also great for building roof decks.
A flat roof can be used by homeowners to construct a stunning addition that also gives greater weather protection.
4. Flat roofs are long-lasting
Flat Roofs Are Long-Lasting: If longevity is paramount to you, a flat roof is the system for you. A waterproofed flat roof is water resistant, so you won’t have to worry about water damage.
If you have a flat concrete roof, you have a roofing structure that can withstand strong winds. When you choose a flat roof for your home, you reduce the possibility of a fallout.
5. Energy conservation
Flat roofs are excellent for keeping house utility expenditures under control, especially in warmer areas. A level roof offers less overhead room for air to stagnate, but sloped roofs can trap undesirable warm air or enable cooled air to escape.
6. Maximum space utilization
Installing a flat roof provides you with more usable outside area. If your house lacks a large yard, why not build a roof-top garden, BBQ area, or simply a place to sit on your flat roof?
The area on a flat roof may be used in an infinite number of ways, and this is by far the best advantage of having one.
7. Better roof acccessibility
Have you ever attempted to climb a slanted roof?! To say the least, accessing a steep pitched roof is difficult – even for professional roofers.
If you intend to maintain your roof on a regular basis, a flat roof is likely to be significantly more accessible than a pitched one.
8. Installation of solar panels
When flat roofs are compared to pitched roofs, flat roofs are the greatest places for solar panels.
Installing these energy-saving and ecologically beneficial solutions on a flat roof maximizes their effectiveness. You will be able to optimize the solar panel angles. Most importantly, you make the most of your money.
9. Faster and less disruptive installation process
Another benefit of going with a flat roof is that because they are easier to install, you won’t have to wait as long to move in!
Flat roofing systems, in general, need less time to install. A simple structure necessitates the use of fewer materials and tools.
As a roofing buyer and business owner, you’ll appreciate knowing that your regular activities will not be disrupted and temporarily halted for days.
Pitched roofing systems are known for taking a long time to install. You have to cope with additional labor and materials.
Choose a flat roof instead if you are not prepared or willing to deal with disruptions in roofing installations.
Disadvantages of Flat Roofs
1. Drainage issues
Because of potential drainage concerns, you’ll generally need to pay very close attention to a flat roof. Pitched roofs easily drain water.
If your flat roof is not professionally planned or built, you can expect puddling after a few days of rain.
Maybe better, engage a competent roofing firm to service your roof. They should develop a good maintenance plan, conduct frequent inspections, and provide guarantees for their materials and services
Though a flat roof is less prone to corrosion than a pitched roof, it is still vulnerable to water deposits.
If you have a flat roof on your home, you become more concerned about rainwater that might seep through the seams and depressions on your roof. This will cause some corrosion and deterioration of the roofing material.
3. Not as stylish and attractive
Flat roofs are not as stylish or attractive as pitched roofing. The lack of style is often cited as the most common negative aspect of flat roofs and one that may lead to a feeling of general dissatisfaction with the look and feel of your home.
4. Possible leaks and damage
A flat roof is less resistant to punctures than newer PVC membranes, so it’s more important to plan for proper installation during construction.
This means that you should never rely on the type of flashing provided to seal flat roofs in place. Instead, you should consider installing proper roofing and waterproofing material.
5. Different aesthetics
A flat roof is generally lighter in color than a pitched roof. This coloration can make a tough-to-maintain flat roof appear even less attractive.
In addition, this colored finish may make your house look different from surrounding homes that have more appealing colors and textures
6. Debris and dirt can build up
Snow and water aren’t the only things that might cause issues on a flat roof. Debris and dirt can also accumulate. Leaves, twigs, mud, and other debris can also plug the drain, causing snow and water to not drain properly.
You may avoid clogged drains by examining and cleaning the dirt and debris off your roof on a regular basis.
7. Less durable
Flat roofs that are older do not last as long as pitched roofs. The great majority are constructed of conventional felt, which is a low-cost, widely available material that is simple to install.
However, the lifespan of this roofing material is just about 10-15 years. What is the solution? To extend the life of the roof, polyurethane liquid, GRP fibreglass, or polycarbonate roofing can be put alongside EPDM rolled rubber.
These materials are slightly more expensive and may be worth considering, but it is difficult to determine how long they will survive. EPDM rubber roofing, on the other hand, can survive for up to 50 years if not damaged!
8. Higher repair costs
A pitched roof is more common because it is easier to work with. Flat roofs require more care when maintaining the lower level, so they may cost you a little extra in upkeep.
The best way to combat costs is by incorporating quality maintenance into your routine. Maintain your flat roof with care and this should be an advantage for you!
How To Convert Flat Roof to Pitched or Sloped Roof
A homeowner may choose to convert a flat roof to a pitched roof for a variety of reasons.
Pitched roofs are far less prone to leaking, can address some structural issues, and can give additional storage or living space if the homeowner so wishes.
However, before converting a flat roof, a roofing contractor must confirm that the home’s structure can withstand the conversion.
So, can a flat roof be change to pitched?
Yes, is the simple answer and it could make sense for a variety of reasons.
- Flat roofs are susceptible to rain ponding, which can lead to leaking in pipe penetrations or at un-protected scuppers.
- Flood damage as a result of heavy rainfall on a flat roof is much higher than that incurred by pitched roofs due to shallow eaves decreasing distance between water surface level on one side and the ground level on other side
- Less ventilation resulting in poor air quality conditions, increasing dry rot risks or timber decay, this risk can be mitigated by considering solar
While many homeowners enjoy the benefits of flat roofs, there are some severe issues with its structure.
To avoid leaks, for example, homeowners must be attentive about upkeep. Gravity might also cause the roof to sag over time. Puddles of standing water can form as the rubber membrane ages and settles.
Pitched roofs nevertheless require maintenance, however routine examination are frequently easier on pitched roofs.
Pitched roofs can also be ventilated and insulated. Roofing materials can last longer if properly maintained since they are less damaged by direct sunlight.
Many homeowners want to convert flat roofs to pitched roofs for aesthetic reasons. Pitched roofs can improve the exterior appeal and value of particular home types.
Several methods exist for converting a flat roof to a pitched roof. Roofers in the first way leave the flat roof alone and construct the pitched roof immediately on top of the existing roof.
This should only be done if the flat roof is in good shape. This strategy may save the homeowner money on construction costs, but it may limit the appearance of the interior of the home.
Custom attic space or cathedral ceilings can be built if the current roof is removed. If the home’s structure cannot sustain both the flat roof and the new pitched roof, the present roof may be removed.
If the previous roof is removed, the roofers will first replace any damaged structural components before constructing the new roof.
After that, the new trusses and rafters will be erected. After that, the roof decking must be joined to the framing.
Some people may re-use the decking if it is still in good shape, but it may be better to utilize new materials.
Finally, the shingles and other outside roofing components can be installed.
Professional roofers can convert a flat roof to a pitched roof relatively easily, depending on the construction and design of the home.
Having said that, there are several reasons to avoid a roof conversion. Before making a final decision, homeowners should have an open discussion with an experienced roofer.
Flat Roofs FAQs
1. Do I need to seal my flat roof?
Regardless of the type of roofing that you have, it is important to apply a sealant. This can help eliminate issues like leaks, puncture holes, and mold.
2. How much does a flat roof cost?
It all depends on the type of material that you choose for your roof. If the material is low-cost, such as felt or vinyl planks, then the price may go as low as $500-600 per square meter.
If you are on a budget, then you may have to do a bit of DIY to save money. However, expect more than $1,000 per square meter.
3. How long will a flat roof last?
If you choose PVC membrane or asphalt shingles then they can last for up to 30 years. Other flat roofs like Rubber Membrane Roof can last for 50 years.
4. Can I Install a Flat Roof?
No. You must hire a professional. Flat roofs are much more complex than some other roofs, and they should be installed by people who have the skills to make them watertight and per code. You can only have a flat roof installed if your house is constructed with a flat roof. If your house has a pitched roof, then you will be unable to install any type of flat roofing system.
5. What Is a Flat Roof?
A flat roof is a type of roof with no slope at all or one where the slope is very slight from the walls of the structure to its perimeter. These types of roofs are typically found in areas that experience low rain, snow, or hail on a regular basis.
6. How do I install a flat roof?
Always hire professionals for this job if you choose to install it on your home. The process is fairly complicated, as it requires two layers of roofing materials and waterproofing.
This can cost you more in the long run since you may have to pay more for the materials and labor.
7. What are some flat roof house problems?
A roof is the protective covering on a building that prevents water from getting inside and causing damage.
A flat roof is a type of roof in which there is no slant. These roofs have proven to be a problem because they are not able to shed water like a slanted or pitched roof.
If the roof becomes overburdened with rain, snow, and other water sources, water will eventually leak inside and cause damage to the inside of the house.
If the water is allowed to sit on the roof, it can cause damage to the shingles. “Standing water, especially if it enters your home through your ceiling insulation, can cause mold to grow.”
If you have a flat roof, you may experience problems like:
- Water damage
- Mold & mildew
- Stains & discoloration
- Corrosion & deterioration of roofing material
- Roof cracks or gaps in the flat roof that are bigger than a credit card
8. What is the recommended flat roof pitch?
A flat roof is any roof with a pitch of 1 to 10 degrees. As a result, flat roofs aren’t actually flat. It may appear horizontal; however it frequently has a minimum slope of 1/4 inch every foot. This allows water to drain off the roof and protects it from damages.
9. When is it time to replace your flat roof?
If the leak has appeared in an area that can easily be repaired, and you are going to repair it yourself, then follow these steps:
- Use pressure washer to clean the area with detergents and water. You do not need to rinse it until you are finished.
- Apply an adhesive-backed fabric patch over the hole or tear. The patch should be at least twice the size of the tear or hole. If possible, match the color of your roofing material as closely as possible.
- Use a spray adhesive or silicone adhesive to attach the patch over the tear or hole. Let dry overnight.
- Apply roofing cement over the patch, matching its color as closely as possible with your original roofing material.
The above process will take care of small leaks until you can replace your flat roof entirely.
If you are facing extreme repair costs, believe it is too costly to fix your leak, or if you retain a service provider to replace your flat roof, then you can consider replacing it with a new one.
10.What causes a flat roof to leak?
The most common causes for leaking roofs are poor maintenance and standing water pooling on the flat roof. It is important to regularly check for repairs or replacement if you own a flat roof.
If you experience leaking, the first thing to do is to make sure that all of your gutters are functional and free of leaves or other debris.
These elements can block water from flowing out of your roofing system and into your downspouts. Furthermore, make sure that the downspouts are draining properly and not clogged with debris!
They should extend past your house far enough to have no clogs in them.
Inadequate maintenance can lead to leaks on any type of roofing material, including concrete. Leaks can also arise from improper installation or poor installation techniques.
11. What is the life expectancy of a flat roof?
Typically, you would expect these flat roofs to offer a life expectancy of 15-25 years if properly maintained.
Most traditional flat roofs are built of mineral felt or asphalt and have a maximum life expectancy of ten to fifteen years. Unfortunately, they have a terrible reputation because of their proclivity to leak or become ruined as a result of pooling water.
12. Is it expensive to replace a flat roof?
The cost of the new roofing material (shakes, shingles, tiles) is higher if the pitch of your roof is high. Flat roofs are less expensive to install because they have less materials and labour involved in their installation. The cost of a flat roof replacement will vary based on other factors, such as:
- The size and length of the roof
- The type of material being used
- Number of layers required to cover your flat roof
- Your geographic location
13. What are some of the benefits of having a flat roof on my home?
The most important benefit of a flat roof is that it will keep your home safe from leaks and other damage.
They offer a warm and cozy space for you and your family to enjoy. Flat roofs are also quite durable, which means that they require less maintenance than sloped or pitched roofs.
They are also popular design choices for new homes because cheaper to build, accessible and they can be built without an actual ceiling, providing more space for living rooms or kitchens in the home.
14. Do I need insulation beneath my flat roof?
Despite the fact that most flat roofs are not insulated, it will help you to put a layer of insulation beneath your flat roof. The purpose is to keep the heat in during summer and out during winter.
The type of insulation utilized depends on your local weather conditions. You can use a reflective substance or fiberglass insulation to keep the heat out through the summer months.
15. What are Some Pros and Cons of Flat Roof
Pros of Flat Roof
- The roof can be used as terrace for playing or gazebo or for other domestic purposes.
- Flat roof construction and maintenance is very simple.
- It provides the better architectural appearance to the building
- Flat roofs are typically more accessible than roofs that are sloped and are easier to climb upon to inspect.
- It is easier to make the flat roof fire resistant.
- A flat roof also makes interior space more versatile and provide maximum interior space
- It possesses good insulating properties.
- It avoids the need of a interior ceiling eg. gypsum ceiling
- The construction work of upper floor can be readily taken up in case of flat roof, whereas in case of pitched roof, the entire roof has to be dismantled before the construction.
- Pitched roof need much more area of roofing material than flat roof.
Cons of Flat Roof
- Materials for flat roofs are scarce.
- Most flat roof waterproofing materials have limited lifespan with most of these materials having life expectancy of between 10 and 15 years before being replaced.
- Draining, or rather lack of it is the biggest disadvantage as the roof do not drain as efficiently as roofs with a pitch.
- Buildings with flat roofs are more affected by extreme changes in temperature because there is less space for installation.