Re-Roofing? Consider Converting a Flat Roof to a Pitched Roof

General Roofing Systems Canada re-roofs low slope residential roofing systems throughout Canada. Our roofing services are available in Toronto, Calgary, Red Deer, Edmonton, Lloydminster, Saskatoon, Regina, Medicine Hat, Lethbridge, Canmore, Kelowna, Vancouver, Whistler and points between.

Low Slope Shingle Re-Roofing to Flat Roof Membrane Edmonton, AB

Low Slope Roof Membranes

One common challenge homeowners have when considering re-roofing a flat roof or a low slope roof on their home, and we receive many inquiries about, is homes with a low slope pitch that currently have shingles on the roof and the homeowner is considering a conversion to a flat roof membrane when they re-roof instead of the shingles, or homeowners considering converting a flat roof on their home to a pitched or sloped roof instead.

Some considerations for low slope re-roof planning for your home:

Low Slope Residential Re-Roofing

Today there are many more options than once available for homeowners considering flat roof or low slope roofing membranes for re-roofing. We can remove the shingles on your home and apply a number of different systems.

Homeowners call us with concerns over the cost of low slope or flat roof membranes (relative to shingles) and this becomes a serious consideration when planning for a residential re-roof project.

Low slope roofing has changed and many options are now available for re-roofing your home that are much less costly than the traditional low slope tar roofing or torch down roll roofing.

The other thing that homeowners often call about is taking a low slope or a flat roof and having it turned into a pitched roof or a high slope roof instead of a flat roof.

Today, solutions are available for low slope residential roofs that don’t require the cost of traditional flat roofing or the expense to go from a flat roof to a pitched slope roof on a home.

Newer low slope roofing membranes are “single ply”. EPDM is a single ply low slope roofing membrane that has a 20 year membrane warranty (the membrane warranty is available for residential re-roofing as well as commercial re-roofing) and some flat roofers will tell you they expect the newer single ply roofing membranes to last 30 or 40 years, TPO is a single ply low slope white roofing membrane, PVC is similar to TPO in that it is single ply and white, and then there are the older style systems being the torch down sbs modified bitumen roofing membrane (or roll roofing) and Tar and Gravel flat roofing. All of these systems work on low slope re-roofing projects. And finally, there are metal roof or steel roofing systems for low slope re-roofing and even shingles for slopes to about a 4/12 pitch. Some roofing contractors are applying low slope shingles to 3/12 but we consider it tentative.

The residential low slope roof in the pictures of this post are of a residential low slope roof that we are re-roofing this week. The low slope shingles are being torn off and replaced or re-roofed and converted to an EPDM flat roof membrane. The EPDM roofing membrane system carries a 20 year manufacturer warranty. Also in the re-roofing process, we are removing the sheathing from this home and an attic insulator is blowing in insulation, then we are re-sheeting and adding a low slope insulation board, and then EPDM low slope roofing. All the roof flashings are being replaced in the re-roofing process – the eave, gable, chimney etc will be replaced as will all roof penetrations. The two low slope skylights are being replaced. The venting of this low slope re-roofing project will be re designed and installed at the ridge or peak of the roof with a custom made ridge ventilation system that will have a curb framed in first and then the ridge vent along the ridge. This will allow for proper attic/roof space air flow and ventilation, it will keep snow from covering the ridge vent, as well the custom framed curb for the vent will keep snow from entering the roof system.

You can follow this residential re-roof project by checking back regularly on our roofing blog as we will post pictures showing the process of re-roofing from a low slope shingle roof to a low slope flat roofing membrane.

If you have any questions about low slope roof membranes or re-roofing you can call us any time at +1.877.497.3528 or email us at or click here to fill out an online roof repair or replacement request form.

Until Next Time,

The Team at GRS

General Roofing Systems Canada (GRS)

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

British Columbia | Alberta | Saskatchewan | Manitoba | Ontario

Low Slope Roofing: Metal, Shingles

Low Slope Flat Roof & Metal Roof
Low Slope Flat Roof & Metal Roof

General Roofing Systems Canada installed low slope roofing systems throughout Canada. Roof installation; 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.

When re-roofing low slope roofing systems it is important to be sure you are using the right material for the right roof slope, local building code, and roof material manufacturer specification.

Below we provide a guideline for low slope shingles, roof membranes of flat roofs, and metal roofing.

Low Slope Roofing Shingles

Serious consideration is required when you are considering re-roofing a sloped system that is less than a 4/12 pitch.

For roofing with a 3/12 pitch, regular shingles can usually be installed with a two-ply 15 lb. roofing felt paper as underlay.

The GRS specification for installing roofing shingles is to never use felt paper. Instead, we use Ice & Water protector on eaves, valleys, around chimney flashing, etc. and use synthetic roof underlay such as titanium. In this instance (with a 3/12 roof), I would consider seriously using only an Ice & Water membrane versus the two-ply roofing felt. This is especially important around chimney and skylight flashing, and any roof vents, valleys, and openings.

A roof that has a 2/12 – 3/12 slope is more tentative and the risk increases. Some shingle manufacturers such as IKO with the Cambridge shingle will put a 12-year warranty on low slope roofs. Malarkey shingles will honour a 30-year warranty.Malarkey Roofing

A roof that is 2/12 or less in slope should have a “flat roof” or traditional “low slope membrane” installed. We like to see any roof that is less than a 4/12 slope get a low slope membrane that is fully adhered, mechanically fastened, or ballasted.

Other information (PDF):

Malarkey Shingle Installation Guide – Includes Install Instruction for Low Slope 2/12 – 4/12

IKO Low Slope Shingle Bulletin – Installation of Asphalt Shingles on Low Sloped Roofs

IKO Roofing – Applying Asphalt Shingles on Low Slopes (covers 3 tab shingles, eave protection, etc)

IKO Shingles
IKO Shingles

Low Slope Roof Membranes (Flat Roofing)

Low slope membranes for flat roofing come in a few categories:

  1. Single-ply membranes in the form of EPDM (rubber), TPO (thermal plastic), or PVC (polyvinyl chloride). They are either fully adhered, mechanically fastened, or ballasted.
  2. Two-ply membrane, the primary choice being SBS modified bitumen that can be torched down or cold applied.
  3. Built-up roofing (BUR). Another way of describing multilayer roofing. An examples would be the traditional tar and gravel roofs, or flat-top tar roofs.
  4. New BUR. More recently, modern technologies have advanced the built-up roof so that they utilize environmentally friendly products and modifiers versus the tar or bitumen commonly used in tar roof systems. These newer versions are extremely tough, will outlast almost any other roof (in our opinion), and are VOC-free, making them sustainable offerings to low slope roof assemblies. The GRS liquid rubber built-up flat roof is an example of a modern system with 800% elasticity and environmentally-friendly synthetic fabric between layers, as opposed to employing the use of traditional tar felt paper.
  5. Spray Foam Roofing.
Low Slope Roof
Low Slope Roof

Low Slope Metal Roofing

Low slope metal roofing (steel, cladding, standing seam) has been used primarily in industrial and commercial settings for decades.

With residential roofing, metal is more typically found on steeper residential roofs. We install a lot of metal systems at mountains villages like Squanism, Canmore, Banff, Cranbrook, Fernie, etc. We also do a lot of residential metal roof shingle installations in cities like Vancouver, Edmonton, and Calgary. Residential metal panel and shingle installations are growing in popularity, but the greatest volume of metal work is on industrial facilities by far.

Low Slope Metal Roof
Low Slope Metal Roof

At issue with metal roofing is that no other form of roofing material expands or contracts as much as metal does. The seams between roof panels, the fasteners, roof openings at vents, chimneys, flashings, and skylights are expanding and contracting all the time. Ultimately, metal roofing leaks due to this expansion and contraction.

Also, condensation with metal or steel roof systems can be an extremely frustrating situation. Many roof leaks with homes or businesses are actually not leaky roofs. Instead, it is water coming through the ceiling as a result of condensation.

Dealing with the potential leak or condensation issues with metal roofing in advance of installing a new system is key.

We solve the problem of metal roof leaks with installing a premium roof membrane under the metal roof system, using a premium caulking tape at the seams, and installing hidden fasteners. If you really want to solve the potential of leaks or condensation in advance, torch an SBS modified membrane or spray liquid rubber in advance of putting the metal roof on.

For commercial roofing and industrial roofing that already has a metal roof on that is leaking, typically we will coat the roof with liquid rubber and it will be good for another 10 years or more. Trying to locate metal roof leaks and deal with them in an isolated way is not usually a good investment of time. Click here to visit the roof coating section of our website.

Until next time,

The Team at GRS


General Roofing Systems Canada (GRS)
24 Hour Emergency Roof Repair: Call +1.877.497.3528 toll-free.

British Columbia | Alberta | Saskatchewan | Manitoba | Ontario