Roof Repair 101 – Flat Roof Repair. Materials and Option to Choose From.

Flat Roofing Repair Toronto, Mississauga, Winnipeg, Calgary, Edmonton, Saskatoon, Regina, Vancouver and all points between. British Columbia. Alberta. Saskatchewan. Manitoba. Ontario.

July 26, 2016 by Tyler Sinclair | 1.877.497.3528 24 Hour Service

Leaky Flat Roof? Below are the options for flat roof repair and replacement.

While I write this I am looking out my office window at corner of John Street and King Street downtown Toronto and there is a massive rain storm – I am watching the water levels rise on many of the flat roofs and wondering about their drainage and how many are leaking right now.

Toronto, Roof, Repairs, Leaky
From office at 50 John Street (John and King Street) looking at likely Toronto flat roofing repairs and leaky roofs from rain storm.

Flat roofs leak. Even new flat roofs can leak because they are custom installed and expansion and contraction or improper installation can cause leaks. Storms, ice dams, the suns rays, aging low slope membranes, plugged drains, flashing problems and more can cause roof leaks.

What to do if your flat roof is leaking.

The first thing to do is to assess whether it is an emergency roof repair or if the repair can wait until the next business day (if it happens on the weekend or at night). If there is a concern with patron or pedestrian safety or the roof may collapse due to weight loads from water or snow loads then it is best to call our emergency roof repair dispatch that is available 24 hours a day.

Emergency, Roof Repair, Calgary, Metal Roof
Our roofers at an Industrial Metal Roof – Emergency Roof Repair in Calgary, Alberta.

While you are waiting for our crew to arrive to inspect and repair the leak be sure to catch any water you can coming in the ceiling with buckets and mop up the area to protect public safety (if commercial building). If the roof could collapse you may have to have people evacuate (this occurred with many buildings in 2011 in Edmonton, Alberta). If you attend to the roof be safe and always be careful with using ladders.

How Our Roofers Will Help With Your Roof Leak.

The first step is to inspect the flat roof. Our flat roofing expert will attend to your roof to assess the roof and provide you a verbal and/or written report and options for repair, replacement and pricing options.

Roof Drain, Repair, Roof, Inspection, Edmonton
Flat Roofing Repair Inspection in Edmonton, AB. Roof drain problems.

When your roof has been inspected and you have the report with costs for repair or replacement you can then make decisions. Sometimes this needs to be done immediately so our roofer will provide you with verbal inspection results and pricing and you may want to authorize the repairs at that moment.

Flat Roof Problem Areas – What to Inspect When Experiencing a Roof Leak.

When inspecting a flat roof check the sealants to be sure they are not dried out and cracked. Be sure roof drains are clear and allowing water to flow down (or scuppers and downspouts). Sometimes leaves or snow and ice can plug roof drains. Check all mechanical units such as air conditioner curbs and any roof tie-ins and parapet walls flashing.

Mississauga, Roof, Inspection, Torch-On
Flat roof inspection of torch-on roof in Mississauga shows improper installation.

A common place for problems on a flat roof are at rooftop unit curbs and flashing. Also check membrane for holes, punctures, blistering, splitting, ridging and any other irregularities.

Typical Flat Roof Repair Costs and Options

Most flat roof repairs are fast and relatively inexpensive, unless you have allowed the roof to deteriorate over the years without proper annual maintenance.

Most repairs a simple repairs to blisters on tar and gravel, torch on patches on SBS modified bitumen roofing, quick rubber patches on EPDM and for TPO and PVC roofing the repair is usually a quick heat weld to seams or rooftop penetrations.

Metal roofs can usually be repaired and maintenance with roof coatings and spot repair to the fasteners, seams and rooftop vents.

Metal Roof Leaks, Coating, Liquid Rubber, Regina
Liquid Rubber Roof Coating in Regina Repairs Metal Roof Leaks for a Reasonable Cost.

Materials Available for Flat Roofing

Modern membranes include many options not available when most flat roofs in Canada were originally installed. Over recent decades there are many options beyond traditional built-up tar and gravel.

Our main website has a complete article dedicated to flat roof membranes.

When we prepare pricing for flat roof repairs and replacement we include all options. Some are as follows:

Tar and Gravel, Roof
Picture of a tar and gravel flat roof on mall in Calgary.

Tar and Gravel Roofing (Built-Up).

Tar and gravel is the standard flat roof (old school style) you may have seen. There are pebbles (pea gravel) on top to protect the layers of mopped on bitumen from the suns UV rays. If the rocks are larger then it is not likely a standard tar and gravel built up roof (BUR) – it is most often a ballasted EPDM or inverted roof system.

Torch-On Roofing (SBS Modified Bitumen).

Torch-On, Membrane, 2 Ply, Toronto
Picture of 2 Ply SBS Modified Bitumen Torch On Roof Membrane in Toronto, Ontario.

SBS modified can also be applied as a cold application or mopped on. Typically SBS Modified is torched on however.

This product choice is newer than tar and gravel systems and comes in rolls that are usually torched on. The granules are on top and many customers refer to it as the shingle looking roll style when they call me for service.

Single-Ply Membranes.

EPDM, Membrane, Single-Ply
Picture of an Edmonton EPDM roof on a commercial building.

Next came the single ply roof membranes. Standard in Canada are EPDM, TPO and PVC.

EPDM is a rubber roll usually 10 x 100 (but comes in many sizes) that is applied by way of glue, mechanically fastened or with rock ballast (a rock similar to river rock). The picture to the right is a fully adhered EPDM membrane in Edmonton, AB on a commercial property.

TPO and PVC.

TPO, Membrane, Vancouver
Vancouver TPO roof inspection shows improper welding of seams.

TPO (thermal plastic olefin) is another type of single ply membrane and is usually white in color. The rolls are welded together with a heat welder vs. using adhesive as with EPDM (above).

PVC (poly vinyl chloride) is similar to TPO and the seams are welded in the same fashion as TPO. The chloride in the PVC caused some issue with the market when it was released so TPO was brought to market shortly after.

Roof Coatings. Fluid Applied.

Another category of products are the liquid applied products such as liquid rubber (which is a cold application coating), Spray Foam (SPF) and there are also hot applied rubberized asphalt coatings.

Liquid Rubber, Roof Coating, Metal, Industrial
Leduc, AB. Roof Coating being installed on an industrial metal roof (liquid rubber).

Liquid rubber / elastomeric roof coatings are typically used to coat metal roof systems. Liquid rubber is available in various colors.

In Canada it is best to stay with a darker coating but lighter coatings such as white and reflective are also available. You can click here to learn more and visit our roof coatings repair website.

And finally spray foam (SPF) is available which is a spray foam that is applied over top of the roof and a coating (usually polyurea but also silicone and liquid rubber are used) is sprayed on top of the spray foam.

Spray Foam, Roof, SPF, Cracking, Peeling
Leaking spray foam roof (SPF). Top coat on spray foam was not applied properly and it is cracking and peeling.

The biggest challenge with spray foam roofing in Canada is that spray foam expands and contracts and the top coating can peel if not the right top coat or if done improperly. Be sure you have a good contractor if you choose spray foam – it has to be right or there can be big problems.

Our inspection report and pricing options will detail the pros and cons of each product and provide pricing for each membrane type. Our quotations also provide pricing details for replacement of insulation, metal flashing for parapets and deck (substrate) sheathing if required.

Toronto green roof installed at 80 Front Street East.
Green Roof at 80 Front St E in Toronto.

Eco Roofing.

Eco-roofing is a green roof (low slope / flat roof) that supports vegetation or is a cool roof (reflective white roof) that reflects the sun’s thermal energy away from the building.

A green roof (eco friendly) is one that has growing vegetation over a significant proportion of the area of the roof. Water and energy conservation is the goal with a green roof. The low slope assembly is made up of a waterproofing membrane (such as above – EPDM, TPO, or PVC), a drainage layer, an organic growing medium (soil) and vegetation.

A cool or white roof is one that reflects solar and thermal emissivity and reduces heat build – up in the building. A white reflective roof (or cool roof) is applied as a coating over an existing system such as a low slope metal roof or over an existing or new waterproofing membrane (listed above) on a flat roof.

Toronto has grants for green and cool roofs. Since 2009, the City of Toronto’s Eco-Roof Incentive Program has helped fund the installation of more than 100 green and cool roofs on buildings across the city. You can find the Toronto Eco Roof program here.

Patio Membrane - DecTec Installed at Condo on 100 Ave in Edmonton.
Google Earth Image of Balcony Membrane Repairs at 11618 100 Ave Edmonton, Alberta – DecTec Rooftop Patio Membrane

Balcony Waterproofing Membranes / Rooftop Decks / Patios.

If you have a balcony membrane that is leaking (also used on rooftop decks or patios) our journeyman install material such as DecTec to deck areas.

If your deck or patio is above a living area (including a garage) then you need a waterproofing membrane material such as DecTec (a PVC product) that is suitable as both a flat roof and a patio membrane. It is very important to choose a material that is suitable for both uses.


If your flat roof needs repair or replacement my best suggestion is to be sure that you are provided with ALL options for replacement material and methods. Ask for a complete and detailed report and pricing explaining the pros and cons of each material type and method.

For more reading I will direct you to our main website at or visit these links:

Wikipedia –

Different Types of Flat Roof Material Options –

Thank you for considering us for your roof repair needs! Call anytime 1.877.497.3528 and speak to our local expert in your area.


Tyler Sinclair

Flat Roof Repairs in Toronto, Mississauga, Winnipeg, Calgary, Edmonton, Saskatoon, Regina, Vancouver and all points between. British Columbia. Alberta. Saskatchewan. Manitoba. Ontario.


Metal Roof Repairs | Flat and Metal Coating & Restoration

General Roofing Systems Canada Repairs metal roofs throughout Canada. Metal Roof Repair; Calgary, Red Deer, Edmonton, Fort McMurray, Lloydminster, Saskatoon, Regina, Medicine Hat, Lethbridge, Canmore, Banff, Cranbrook, Kelowna, Vancouver, Whistler, Winnipeg, Toronto and points between. British Columbia. Alberta. Saskatchewan. Manitoba. Ontario.

Repairs to metal roofs are quite often due to metal seams expanding or contracting, screw holes that have expanded over time, or roof penetrations that are improperly flashed.

The first step is to assess the repairs from a repair or remediation perspective. Some high end caulking, underlayment, and flashing knowledge is required. We use a journeyman that can assess the conduct the repairs to this end.

Once the repairs are done, you may have to consider one of the many options in metal roof coatings if your roof is low slope or irreparable.

Flat Metal Roofs – Low Slope Roofing Considerations

A roof coating or restoration will likely be required in addition to the repairs, especially if you have a flat or low slope system. We often service these types in commercial and industrial facilities.

Flat roofing is more difficult as “waterproofing” becomes key. A high slope roof can be looked at as a “watershed”, so are a little easier in terms of this type of maintenance.

There are many different options for metal roof restorations/roof coatings. A proper metal roof restoration, with the right people doing the application coupled with the right materials, should get you (conservatively) about ten years or more out of your metal roofing system. As well, a high quality coating will cost you about half the price of a brand new metal roof. In the meantime, you will have another decade free to plan for your roof replacement when it has reached end of life.

The reason a roof coating or restoration is typically required when you have run into metal roof issues especially flat ones) is that the issues are most often installation or design issues that cannot be permanently fixed. Any fix we do to mitigate a roof leakage, for example, will most often be temporary repairs.

For more information on roof coatings, flat roofing, industrial and commercial coatings, and metal roof systems, visit our website for roof repair and re-roofing information. At the bottom of the main page you will find links that discuss various issues, repairs, systems, hiring contractors, and related topics. You can also search this blog by keyword using the built-in search function.

Contact Us:
General Roofing Systems Canada (GRS)

24 Hour Emergency Roof Repair: Call +1.877.497.3528 toll-free.

British Columbia | Alberta | Saskatchewan | Manitoba | Ontario

Flat Roof Membranes: Sample Customer Query

Below you will find a customer inquiry we had in Fall 2011 referencing flat roof membranes for a new inner-city home our customer is having constructed in Calgary, Alberta.

This fellow was the unfortunate recipient of what occurs in the flat roofing industry every year – there is a year-end tsunami we as roofers experience when panicking clients need to have their flat roofing systems maintained, replaced, or repaired. It turns into an “all hands on deck” period of time during this so-called tsunami, especially for our commercial roof and industrial roof clients. This particular flat roof membrane query unfortunately took some time to return, but the client was gracious nonetheless. Please note that the quoted blocks in italics are our responses to the client’s questions.

< Start of Email >

Well thank you very much for the in-depth follow-up, it is much appreciated.
I do have several questions, some of which may overlap with others. Please bear with me, my inexperience with flat-roofing necessitates a bit more research, and there seem to be so many systems that it is difficult to know which is more appropriate than the next.
1. With the liquid rubber roof coating system, will the membrane simply seal around any punctures in the roof (i.e. irrigation line for the planter box, roof skylight openings, scuppers in the parapet), or does this require separate attention?
Liquid Rubber roofing, at least the specification GRS applies liquid rubber roof coating to is a process of steps. The first being cleaning the substrate or roof deck, next is preparing all roof penetrations, fasteners, expansion joints, connections, etc with a scrim fabric sheet (polyester woven scrims) and trowel grade liquid rubber (done by hand with trowel, squeegees, and rollers), then a flood coat of liquid rubber (sprayed), and then the final stage of liquid rubber roof application is a final spray coat of liquid rubber. Another coat is optional to add colour. This is done with an acrylic top coat. The liquid spray on acrylic roof coat can be specifically tinted to the desired color.
2. Do you recommend, as per the liquid rubber system, a 2-layer approach (using the Sealroof A-100 over top the Sealroof B-200), in the same way you would do a 2 or 3-layer torch on system? In this way, you could apply a white top-coat < GAF Top Coat > to help reduce the heat island effect on the roof and help alleviate the temperature variation in Calgary?
The GRS process of application for liquid rubber roofing, flat roofing, and pitched roofing is typically more involved than most specifications our roofers see day-to-day in the marketplace. Specific to Liquid Rubber roofing, our system of application is detailed at point 1 above. Top coating the liquid rubber is also detailed above and there is an article linked to our website specific to the white and black decision with flat roof membranes found here (Carlisle-Syntec Article).
3. My current details include a sloped insulation for added R-value, over top of a ventilated ceiling cavity with vents in the parapet wall. Who do you get your sloped insulation from, and is it custom made for the project, or does it require labour to adjust it? Is it possible to simply install sleepers above the roof joists to achieve slope and sheath the roof and apply the membrane overtop of that, and sacrifice the added R-value of the sloped insulation? Is that normal?
Sloped insulation for flat roof structures is a common method. Many designers will specify the framing of the substrate to be sloped also as an alternative. We source our sloped roof insulation from a number of companies. One we often use in your area is Plasti-Fab. It is a pre-engineered sloped insulation that is delivered with a diagram for installation. We would have difficulty answering to the roof sleepers question until on site or more discussion was had.
4. You mentioned custom metal flashings, and I am wondering what the scope of your roofing will entail (in other words, do you also provide flashing around skylights, and around scupper holes for drainage)?
Various roof flashing required we provide to our flat roof customers. Typically, roof skylights will have flashing kits, but various designs will have us custom fabricating metal. Whether it is flat roof cap flashing, cant flashing, edge flashing, or various custom flashing for roof membranes… we fabricate and install it.
5. You mentioned the TPO system (which I have been recommended to use from a colleague) is more suited for Vancouver than for Calgary. What are the reasons for this? Is it strictly based on freeze/thaw considerations or total precipitation, snow loads, or some other reason? One of my biggest concerns is that the roof membrane will not stand up to the temperature differentials we all know that Calgary is susceptible to.
Answering to the environmental impact to various roof membranes (such as freeze thaw) is a complicated topic. SBS Modified Bitumen (torch on) and Built Up Roofing (Tar and Gravel) has been a mainstay for so long, with Alberta holding to it longer than most other areas of the world. My comment to TPO or any roof membrane that is reflective or light colored is more specific to the energy efficiency of roofing systems or flat roof membranes. In Alberta, many see it as counter productive to have a reflective roof as more often than not we have our heat on than we do the air conditioning. This too is a diverse conversation. Our web site under the flat roofing section on the right column has links to articles. With respect to how each membrane will hold up specific to Calgary, that is a difficult question. TPO, PVC, EPDM single ply flat roof membranes are being installed every day in Calgary, as are the traditional SBS modified and BUR flat roof membranes. SPF – Spray Foam Roofing is another roof membrane option and then the Liquid Rubber roof membranes. At issue is that most roof membranes have not been installed for a long enough duration in the Calgary market for an excellent evaluation of performance. For example, the liquid rubber we are referring to in this instance has only been available for shy of a decade and not widely used until very recently. Our comfort is in that we simply add more liquid rubber membrane if there were to be failures. When single ply membranes were first introduced the remediation of early failures in the membrane was much more complicated than with liquid rubber roof membranes – with liquid rubber we simply apply more liquid rubber if failures were to occur. In saying all of that, we have significant liquid rubber roof membrane applied over the last 3 years with no failure to date.
6. Is a Torch on SBS system the only one which requires a ballast? Or does the liquid rubber also require a covering to reduce UV penetration, etc? Would adding Ballast prolong the life of some of these other systems?
Ballasting a roof membrane is for the purpose of keeping the roof membrane to the roof deck – wind uplift etc. For example, a ballasted EPDM roof membrane holds the EPDM down so the wind doesn’t take the membrane away. The EPDM is adhered at the seams and loose laid to the insulation or roof deck with the roof ballast (rock) covering the membrane. Inverted loos laid systems have the roof insulation laid on top of the EPDM roof membrane with the rock or roof ballast on top of the insulation. Single ply roof membranes (EPDM, TPO, PVC) can be mechanically fastened (not requiring roof membrane ballast), Loose Laid (requiring roof membrane ballast), or Fully Adhered (not requiring roof membrane ballast). With SBS Modified Torch on roofing their is no ballast required as the SBS membrane is torched or fastened to the system by way of torching or with adhesives etc. The UV is not an issue also with SBS Modified Roof Membranes as the cap sheet (or second layer of roof membrane) has granules attached that keep UV away from the Bitumen. With Built Up Roof Membranes (or BUR) the layers of bitumen are covered with an inset top layer of gravel to keep the UV away from the bitumen in the roof membranes (typically a four layer membrane system). The gravel in this instance is not for ballasting, it is only for the purpose of UV resistance. In the case of Liquid Rubber Roof Membranes, the liquid rubber manufacturers claim UV resistance with-out the requirement of granules as with SBS membranes or gravel as with BUR or Built Up Roof Membranes.
7. Do you have specific price per square foot values for each of these products, or is the quote system more complex than that (in terms of metal flashing, scupper detailing, etc.)?
Specific pricing for flat roof membranes is wisely derived after review of the construction drawings and discussion with the parties that can affect construction processes. In your instance, specific pricing for the various roof membranes can be accomplished by way of the construction drawings provided.
It seems from your email that the liquid rubber system is more costly initially and less costly over the lifespan of the roof. Can you list the roof systems according to their initial cost for installation? I am very interested in the liquid rubber system, but a little hesitant regarding the price. My understanding was that a modified Torch-on SBS was cheaper than some of the other systems, like a TPO membrane or a soprema system.
Pricing for all flat roof membrane systems are similar. Tar and Gravel Roof membranes (or BUR) will tend to be more costly due to the extensive labour, SBS Modified should be similar or perhaps a touch more than the Single Ply roof membranes (TPO, PVC, EPDM), TOUGH ROOF (which is a concept built on the strength of the traditional Built Up Flat Roof with an elastomeric top coat) would be on the higher side of the pack, and Liquid Rubber systems (if done per the specification of membrane application that we use) will be in line with Single Ply. More often than not, with roof membrane choices and pricing, you will receive varying opinions that are usually specific to what the roof membrane applicator installs most, what roof membrane the roofer is certified to install, etc. The widest divergence we see in flat roof membrane pricing is not necessarily the roof membrane material that will be used, but the process of application of the roof membrane itself and whether the flat roofing company has all the other operating costs that credible flat roof companies can have due to safety, staff remittances, benefits, company vehicles, licensing, insurances, etc.
My roof works out to be about 1150 sq. ft. (inside parapet), with the planter on the second storey being about 23 sq. ft. Would you be able to work out a few prices using the Torch-on SBS, liquid rubber, EPDM, and Soprema systems that you install?
As it applies to SBS Modified, we typically use when available to us the IKO SBS Modified Bitumen products vs Soprema. Not that we see IKO superior, it is just what our company typically uses for SBS roof membrane unless specified otherwise. I am personally a Soprema certified installer and I don’t see much of a difference either way – both IKO and Soperma produce a quality SBS Modified Roof Membrane as I see it. With EPDM, we regularly install Firestone and Mulehide EPDM (I believe Carlisle manufacturers the Mulehide EPDM, but I could be wrong). With TPO we install Firestone and Mulehide regularly also. Liquid Rubber roof membranes come in various forms, because we are installing so much of the liquid rubber roof membranes we have various specifications for application and material for the membranes. I will price yours specific to how we see it best applied and according to the manufacturer(s) we see as best for your roof membrane.
The pricing for the various roof membranes I will forward in a separate email.
Thanks again for your comprehensive response. You’ve been most helpful.
< End of Email >
Contact Us:
General Roofing Systems Canada (GRS)

24 Hour Emergency Roof Repair: Call +1.877.497.3528 toll-free.

Calgary, Red Deer, Edmonton, Fort McMurray, Lloydminster, Canmore, Lethbridge, Medicine Hat, Vancouver, Whistler, Cranbrook, Saskatoon, Regina, Winnipeg, Toronto and all points between. British Columbia, Alberta, Saskatchewan, Manitoba, Ontario.