What is the cost to replace a commercial roof?
The replacement of a commercial roof is inevitable. In many cases we have seen that a roof could have been repaired instead of replaced and if we are called in between those times, we would be able to remedy those repair issues, however, there are many factors we use to determine whether the current material that is on the roof is in a state of repair, or in a state of needing a total replacement.
Hot Tar and Gravel or Built-Up Roof (BUR)
This type of commercial roof is the oldest. If we find that your building still has the Hot Tar and Gravel or Built-Up roof or has been painted with aluminum asphalt coating, it is likely that this roof is over 30 years old and we would advise against repairs. If the surface looks, smooth with no visible cracks, bubbles or blisters, then you may have a chance to remedy it with only repairs.
Self-Inspection of a Hot Tar and Gravel or Built-Up Roof (BUR) System
- Find a gallon of cold tar at Home Depot, a utility knife and a small trowel. Cut a small square of the roof’s membrane; about 6″ x 6″ to determine the thickness of the material. If the membrane is over a 3/8″ thick and the cut edge feels slightly sticky, then the membrane is still good. Replace the piece and patch with cold tar.
- Look for big bubbles. They are normally 10″ x 10″ in diameter or bigger and the membrane has an upheaval. This is a very clear sign for roof replacement. These bubbles are caused by moisture entering the layers of the membrane and steam builds up and separates the layers.
- Look for physical cracks on the roof. One or two random cracks can be repaired. When there is an upheaval in the crack, then the problem is more serious.
- Brittle or disintegrating -when the entire roof shows signs of layers breaking apart, then replacement is recommended. If there are only a small sections where layers are just breaking up into small pieces of paper, then that section should be covered with a new membrane.
- When there are signs of many other repairs in the past, it’s time to replace.
- When the leaks are everywhere on the roof, and not confined to one area, then it’s time to install a new membrane. If there is only one or two leaks, then it’s possible to repair.
- If you have a Hot Tar and Gravel roof – and some problems start to show up, consider the age of the roof and replacing it may be more cost effective than intermittent repairs.
Watch the video below and you will notice the blistering or bubbles we mentioned above. This is a sign that the roof should not be repaired, but rather, replaced.
Modified Bitumen Membrane
Another type of membrane commonly found on Commercial roofs is the Modified Bitumen Membrane (MB). It is a 2-ply system and many times a contractor would have installed it over a old Hot Tar roof or a Hot Tar and Gravel roof, which is perfectly acceptable.
This type of rubber membrane is the most durable of all roofing membranes. The additional layer increases the roof life beyond 40 years. There is no comparison to any other roofing system to date.
Important! – The removal of an old MB membrane roof is not necessary!
Note – a Modified Bitumen Membrane almost never has to be removed before a new roof can be installed. If the current membrane has many leak issues, and it is determined that a new roof has to be installed, it is best to use the existing membrane as a base and install another Modified Bitumen Membrane over it to be fused together. It will have a doubled thickness of regular roof and will easily last for 50 years.
Self-Inspection of a Modified Bitumen Membrane Roofing System
- If the membrane is over 30 years old, and numerous repairs have been made, replacement is recommended.
- If many seams are loose due to faulty installation and or degradation, we recommend replacement.
- If the membrane was installed without a base, or not fused properly to a base, we recommend replacement.
- If the membrane did not include a mineral or ceramic protectant, or was never coated with an aluminum silver coating, ultraviolet light exposure has probably caused fine cracks over the entire surface if older than 15 years, and we would recommend a new MB install directly over the one that has been compromised.
- If there are many creases, and the membrane is not completely flat, it was installed incorrectly. We would recommend a new MB install directly over the old one.
- In our experience, the most common cause for leaking is where the membrane attaches to the metal flashing. Most contractors do not know how to tie the MB membrane to the metal edging and flashing around cooling units, skylights, and vents on a flat roof. The material must be cut back about 10″ and a new membrane must be installed to make the transition to the flashing.
- If previous attempts have been made to repair the roof, and tar is smeared over seams and the appearance is untidy in other areas, it is best to install a new MB membrane. It is much harder to assess where there may be potential leaks when a repair is messy, than to fix a roof properly.
- We also see obvious damage to a membrane due to wind storms or snow shoveling, but this type of damage is repairable most of the time.
Important! – Do not try to repair a roof with tar cheaply!
The most expensive mistake we see is in the attempts to fix a flat roof cheaply! When a proper repair can’t be done immediately, a tar application is the best remedy for emergency cases only. It is easier to repair leaks on a flat roof without having multiple applications of tar and silicone caulking to strip prior to a proper repair.
The EPDM single-ply flat roof system is the most popular roofing system used by contractors in the entire country, however, unbeknownst to potential clients or customers, it is also the worst roofing system. The single-ply membrane is only about 1/16″ thick and black making its life expectancy only 15 years. The rubber used is highly susceptible to punctures from foot traffic and the adhesives used to glue down the seams weaken and break down because of the all-black membrane absorption of ultraviolet light which accelerates the degradation process.
Self-Inspection of an EPDM Single-Ply Roof System
If you are having problems with your EPDM roof, here are a few tips on what to look for to help you make a decision about whether you should be repairing or be replacing it.
- If the roof is over 10 years old, install a new Modified Bitumen Membrane 2-ply over the EPDM.
- If there have been many intermittent repairs done, then it’s time to replace it.
- If the seams around A/C units, skylights, and vents are separating, replacing the roof would be less expensive over time.
- If the membrane is pulling away from the edges because of shrinkage or degradation, replacing the roof is highly recommended.
- If the roof is fairly new, 7 years old or less, it’s possible to salvage the roof with some repairs by a professional EPDM technician.
- If you able to separate the seams easily, we recommend a flat roof replacement.
Important! Regular inspections are key to the longevity of an EPDM roof system
If you already have the EPDM system installed, self-inspections or regular professional inspections will be needed. Before a leak finds its way into the interior of a building, it can saturate the substrate or soft board under the membrane, causing it to rot. When the soft board is destroyed, the entire roof may need to be replaced.
This video was made several years ago, but it can give you an idea about where to look for leaks on a EPDM roof.
TPO Roofing Systems
Like the EPDM roof system, the TPO system is also a single-ply membrane that is less than 1/16″ thick. This system is popular because the manufacturer provides a guarantee on the roof. The installer is certified and an inspection of the installation is performed. The roofing contractor can be gone and the roof will still have a warranty, but only for 15 years. A Commercial roof should last well over 30 years with no maintenance.
The process to install a TPO roof system is costly and timely. The roof is installed by adhering the entire membrane with glue to the substrate with a hot-air heat gun that welds the seams together. Regular flashing cannot be used with a TPO install. A special flashing has to be pre-made in the factory and installed on a roof that must first be properly prepared, which means the existing roof must almost always be removed so that the new, special flashing, can be installed.
Self-Inspection of a TPO Roof System
- Age – If the roof is older than 12 years, and starting to show signs of degradation or there are leaks, replace it by installing a Modified Bitumen 2-ply membrane on top of it.
- Seams -The long straight seams are welded with a walk behind welder, but the seams around skylights and other objects are welded with a handheld air gun. Check these handheld transition areas where many problems can be seen.
- Traffic Areas – Assess traffic paths for premature damage from punctures.
- Ultraviolet Degradation – Although TPO is white in color, it is important to inspect areas where there is more sun exposure; we have seen the TPO membrane prematurely fail in such areas.
- Flashing and Metal Drip Edges – In our experience, we have seen that this material shrinks over time and causes tension in the edging. It can pull the edging completely up and away. This normally happens after 10 years of a TPO’s life.
- If the membrane is over 15 years, it is better to replace it by installing a 2-ply Modified Bitumen membrane over it.
Conclusion – The single-ply systems are great from an aesthetic point of view. They are smooth, easy to clean, and as in the case of the white TPO, which reflects heat, it only reflects a portion or ultraviolet rays. For a fraction of the cost, you can have a 2-ply Modified Bitumen System that will give you more than double the roof life and less maintenance over time.
1 thought on “When Should a Commercial Flat Roof be Repaired or Replaced? – Video”
The article makes a good point about the eventuality of having to replace a flat roof, so it is important to know what costs what. I love that the article does such a thorough break down of this very topic. After all, every business owner needs to work this into their building’s budget for the future.