Have you thought of how you want your flat roof installed? It’s crucial that you do because the installation part will affect your entire roofing project. Yes, if you don’t match your type of roof with the right method of fastening, it’s likely to develop issues later.
Now, there are several ways of attaching flat roofs but the two most commonly used are fully adhered and mechanically adhered. Each of these two alternative methods has its pros and cons. This is why you should learn everything there is to them so that you make the appropriate decision when installing your flat roof. With that said, check out the pointers below:
What is a mechanically adhered roof?
A mechanically attached roofing system consists of a membrane roof that gets attached to a substrate such as wood, steel, concrete, etc. by mechanical means. This mechanical attachment can be via concrete nails, screws, augers, etc. If anything, the fastener used is dependent upon the type of roof decking (the substrate).
Many builders prefer mechanically adhered single-membrane roofs to the fully adhered ones because they offer a faster and cheaper installation process. When installing this type of roofs, the contractor first sets in place the deck, followed by the insulation layer, and then the roof. When the membrane roll gets laid down, the roofer mechanically drives the screws through the insulation boards and into the deck below.
Take note that the fastening screws get drilled at the membrane roll’s edge before getting covered with the next sheet’s edges as the contractor successively puts down the next rolls. Once all the rolls are in place, a hot-air gun is used to heat-wield the membranes together, creating a water-tight seal.
Mechanically fastened roofing installation
Pros
- Rarely flop over time
- No foul smell during the installation stage
- Ease of FM (Factory Manual) compliance
- Can improve a roof’s wind rating
- Obtainable with any kind of roofing system
Cons
- This method can easily cause penetrations in the structural component
- Mechanically adhered installations can create flutter within the roofing system
What is fully adhered?
Fully adhered refers to flat roofs that are glued directly to the insulation layer below. For this type of roofing system, the 4’x8′ insulation boards serve the role of insulating the roof as well as connecting it to the metal deck. The fully adhered method is slower, more expensive, and can result in additional challenges since the roofer has to apply large quantities of glue at exactly the right temperature and time.
What’s more, if the glue doesn’t first dry sufficiently, the roofer can’t achieve the right tackiness level. Once the glue is in place, a weighted roller presses the membrane, attaching it to the insulation layer below. Many builders believe that fully adhered roofs are more resistant to leaks due to the belief that water can’t travel past the glue layer under the roof membrane.
Even so, the reality is different because when leakage occurs in these kinds of roofs, chances are you won’t realize there’s a hole until water pools underneath it, degrading the glue adhering to the insulation layer. With fully-adhered roofing systems, the roofer must fasten down rigid insulation thoroughly. As a result, these systems feature 12-24 patterned fasteners while the mechanically attached ones only require 5-8 fasteners.
Fully adhered roofing installations
Pros
- Proven and tested over time
- Aesthetically attractive
- The roofing system doesn’t flatter
- Offers desired manufacturers wind ratings
- Can work with all kinds of single-ply systems
Cons
- Increased chances of fasteners hitting a lighting system or conduit that’s close to the deck
- Because of the use of adhesive, a foul smell is produced during installations
- It’s relatively expensive compared to all other single-ply membrane roof installation methods
- Potential FM compliance issues, especially where there’s a ‘bubble test’
- Fully adhered roofs can blow off or peel up when the wind gets under the roofing system
Choosing the most appropriate installation method for your roof
So many factors determine the best installation method to use for your particular roof. As such, it’s best to contact a trustworthy roofing contractor for help while selecting the appropriate method. However, here are some of the pointers to consider before settling on any of these two attachment methods:
Time of year
As you know, the fully adhered method works best in specific conditions. It’s, therefore, vital to consider the temperatures and weather conditions that will be present during the installation process, otherwise, the whole project will fail.
The roof substrate
While there are many different types of roof substrate materials, both the fully adhered and mechanically adhered processes can only work perfectly with some of them. For instance, it’s not advisable to go for mechanically adhered when you have a softer deck as the fasteners can penetrate through to the structural components.
The contractor’s experience
If you have a preferred roofer, it’s best to choose a method that he or she is most familiar with. Some contractors will be quick to assure you that they can perform certain procedures, only to mess up everything when you give them the job.
The seaming method
Always ensure that the seaming method used with your selected materials is effective for your particular roofing design. Remember, the seams are the weakest link in any kind of roof.
If you’re installing a roof that will be in the public’s view, it’s best to go for a fully adhered flat roof since it’s more aesthetically pleasing than the mechanically adhered one. This type of system is also excellent in buildings with high wind ratings. On the other hand, if you prefer a faster and less disruptive roof installation method, go for the mechanically adhered.
It not only requires less labor but also works well in a variety of weather conditions. Even so, contact a reliable roofer to help you decide which method fits best based on your specific roofing needs. This way you can ensure that whatever choice you make is fool-proof.
TIPS FOR FLAT ROOF MAINTENANCE IN TORONTO
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