Flat Roof Styles

There are different materials for flat roofs that are used throughout the Lower Mainland. Flat roofs can be single-ply or built-up using multiple layers of liquid tar or asphalt over tar/asphalt saturated paper; or have multiple layers of other types of waterproof membranes.

Tar and Gravel Flat Roof

This is probably the most common flat roof system, often, a Tar and Gravel roof will have a layer of pea-size gravel on top, to protect the tar from the sun’s UV rays. The tar and gravel style of flat roof is found on both residential and commercial roofs in the Lower Mainland. Applied with 4 or 5 plies of asphalt based organic felt paper, it is held together with layers of hot asphalt (tar); and then gravel is then placed on top to protect the asphalt from the sun’s effects.

Tar and Gravel Roof Life

Many years ago, Tar and Gravel roofs used to have a percentage of Coal Tar in them that made it last a very long time. I have personally seen a 35 year old tar and gravel roof still holding out. Others have told me they can even last over 50 years. The Coal Tar had a self sealing property that apparently was the secret. But it is a cancer causing agent and has since been removed. Now generally a Tar and gravel roof would last 20 years and quite often less. (Keith Kinvig, Manager of Absolute Roof Solutions)

Tar and Gravel roofs are still done today and, for some situations, might be the best roof. One of the drawbacks is that there is a very strong asphalt smell and smoke. There is a large propane powered Kettle that heats and liquefies the tar and pumps it up onto the roof, the smoke is oily and if mixed with dust in the air, it will stick to everything. In general it offends many people by its use.

Several benefits to Tar and Gravel is that there is no open flame used in its application on say, a wood frame building, and has a lower risk to fire than the more modern Torch-on systems (see next section).

Benefits of a Tar and Gravel Roof

Another benefit to Tar and Gravel is that the drains, in general, don’t have to be cleared as much as a Torch-on roof system, or other single ply roof systems. The reason is that leaves and tree debris is held in place by the “pea gravel”. As it rains, the water flows around the gravel and does not lift the leaf and carry it to the drain to create a blockage. Of course there are exceptions to everything but in general the debris just builds up on the Tar and gravel roof and for the most part does not flow to, and block the drain.

Torch-on Roof

The Torch-on, also known as Torch-down method of roofing allows the installer to eliminate the use of the offensive tar “Kettle” and strong smells. This product is made from either polyester or fiberglass base, then coated with asphalt that has been modified with a rubber additive.

Flexibility of a Torch-on Roof

The rubber gives the roof strength plus flexibility and makes it easy to work with at low temperatures. The Torch-on installer shows up with some rolls, a propane tank and torch, and is now installing a new flat roof system. It is more compact, easy to get up to the roof and overall, is not as messy.

The Torch-down roof now is probably the most common flat roof system, but other systems are making inroads. Before looking at other systems let’s talk about areas where the Torch-on roof system is good.

Where to Use the Torch-on Roof Method

Many new home construction patio flat roofs, and even concrete foundations, are being done using Torch-on systems. Many decks on houses may only be 50 to 100 square feet. Can you imagine trying to bring in a Kettle to do a 50 sq ft deck? Even harder could be trying to coat foundation walls with hot liquid tar. The Torch-on systems can be applied on small projects and even very large projects, so it has become a favorite amongst roofers as their “go to” flat roof system.

A Torch-on roof includes layers of fiberglass and polyester with bitumen. The 2 layer sheets are melted together with torches so that vulcanization (welding) occurs. It’s actually called modified bitumen – because of the mixing of asphalt with rubber compounds. The top layer of Modified bitumen has little rocks called granules added to the top coat which gives it UV protection and therefore does not need any loose gravel to protect it. It is pre-built into the materials. Its life span is often 20 years or more. But if applied poorly, it can be less than 10.

If you have any questions about whether a Torch-on roof would be the correct system for your roofing needs, please call us at 604-263-0334

EPDM Roof Method

EPDM is the acronym for a long chemical name for a special roof covering that is pretty well made up of Rubber. It is a thin sheet that comes in a roll and is laid out on a roof deck and glued at its edge and seams and runs up the wall to form a sort of “pool liner” on the roof. EPDM is an excellent roof system; lasts a very long time and does not require any UV protection as the rubber has been cured with its own protection. It is often used with “ballast” which would be 1” or 2” stones to weigh it down so as not to be lifted in strong winds.

Leaking Gutter Repairs for EDPM

In the Vancouver area on residential roofs, EPDM is often used as a built in gutter liner. A 24” or 36” wide roll is laid out into the gutter and glued or folded at the ends, corners or seams. Many people I have met who own a house with EPDM gutters have cursed them. If a seam or drain releases, it leaks into the soffit area and stains and rots out the wood. EPDM has to be handled and repaired correctly or else it will fail again. That’s why, when a home owner tries to repair his own EPDM gutters it lasts for the summer but then quickly leaks again in the Vancouver weather.

EPDM on Commercial buildings is not quite as common as Tar and Gravel roofs but definitely has its place.

TPO Roof

TPO is another single ply membrane similar to EPDM and is often made by the same manufacturers as EPDM. It generally comes in two colors, grey and white, and is considered a very “cool” roof. On a very hot summer day it is pretty well impossible to stand barefoot on a Torch-on roof. However the TPO is amazingly cool. This is a positive as big cites and metropolitan areas are trying to reduce the heat they give off.

Commercial Building Roofs

TPO also does not require an open flame, much like EPDM. However, the TPO is welded together at the seams and joints using a hot air welder. This is quite a reliable system and the rolls can come as wide as 10’ or more. Thus, it works well in large commercial environments.

Over the last few years TPO roofs have started to become more wide-spread on smaller commercial buildings, and even on residential houses and decks. It can be used in tight spaces and applied quite quickly. It can even be applied over an old tar and gravel roof without having to remove the entire old roof.

Richmond BC, Olympic Speed Skating Oval Roof

TPO is the roof system on the new Richmond Olympic speed skating oval.

Other Flat Roof Systems

There are other flat roof systems, like liquid applied or spay on liquids. Those are not as common on residential buildings as much as for Commercial buildings.

At Absolute Roof Solutions we have a variety of suppliers of the most up to date, flexible and useable materials, depending on each client’s needs.