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Denver Flat Roofing

Flat Roof Construction

With the advance in quality of roofing materials, flat roofs can be a good option for homes in any part of the country. Flat roofs offer an unique aesthetic and opportunities for utilizing roof-top spaces.

Benefits of Flat Roofs

The primary benefit of a flat roof system is its efficient use of available space. Creating a second floor or eliminating attic space may be desirable options.

Denver gets over 300 days of sunlight a year — put your roof to use for such things as a recreational garden or sun deck. Solar panels are much easier to install on a flat roof.

Flat roof installation consists of putting down multiple layers of water resistant materials. Interestingly, flat roofs are not flat: they are angled to direct water to gutters and downspouts.

Types of Flat Roofs

  • Built-up-Roofing (BUF) consists of laying down several layers of tar and water resistant materials and then covering with gravel. Once made of tarpaper, these types of roofs now use more advanced materials such as fiberglass membranes. 
  • Modified bitumen roof system is an asphalt hybrid BUF. It used to be laid down by heating an adhesive (a “torch-down” system), but a newer peel and stick variety is much easier to install.
  • Rubber membrane - EPDM (short for ethylene propylene diene monomer) is a singly ply roofing material made from ethylene propylene rubber. EPDM roofs are typically used for industrial, institutional and commercial buildings. They can be installed by ballasting (stabilizing with gravel), mechanical fastening or full adherence.
  • Thermoplastic Polyolefin Roofing Membranes (”TPO”) is regarded as the new-generation of single-ply roofing materials. Even though it’s referred to as single ply, it consists of three components or layers: a structural deck or outer skin; a thermal insulation barrier, then a waterproofing skin that adheres to the roof.
  • Polyvinyl chloride or PVC roof membranes have been in use since the early 1960s, giving PVC the distinction of having the longest track record of usage among any thermo plastic roofing membranes.
  • Mastic asphalt is the most durable waterproofing membrane on the market. Also referred to as stone mastic asphalt (or SMA), it has a coarse stone aggregate content interlocked with mastic (a paste-like cement) to form a tough surface.  Some SMA mixtures are used in surfacing residential streets and highways.

Flat Roof Cost

Historically, flat roofs rarely lasted as long as a good sloped roof. However, modern materials have improved considerably over the past two decades. Some flat roofs carry warranties of up to 20 years, approaching warranties for sloped roofing.

  • BUF is the least expensive flat roof. The cost of installation may be a bit higher simply because it’s messy and more difficult to work with than other materials. Repairs are relatively easy but if original installation was done poorly and a leak develops, repairs can be quite costly. 
  • Modified bitumen is the next least expensive flat roof choice. Modified bitumen offers light color selections which reflect the heat and sun better, effectively helping with energy bills.
  • Although generally more expensive, EPDM ,TPO, Mastic asphalt and PVC offer more protection and longer life. Thus they may prove cost-effective in the long run.

Flat Roof Care

Gravel (BUF roof) is an excellent fire retardant but is heavier than other choices so support structures may need reinforcement. Gravel can also come loose and clog drains.

Modified bitumen has the benefits of the built-in redundancy of a BUF roof and is stronger. Additionally, the membrane of asphalt and polymer provides more UV resistance. Because there are several surfacing options for this system, maintenance and repair can be more difficult.

EPDM is light yet highly resistant to scuffs and tears. Leaks are easy to patch. The durability of EPDM equates to an average lifespan of 20 plus years. One problem with EPDM sheets is they’ve been known to shrink in certain circumstances. If ballasted or mechanically applied, EPDM can be reusable.

TPO is very durable and has low toxicity. TPO has petrochemical in it, so it’s not recyclable. It can, however, be reusable if installed properly or applied with water or pebbles. Since TPO has been around for only 10 years, maintenance requirements and life span are still being evaluated.

Mastic asphalt is recyclable, non-toxic, and odorless and can withstand extreme temperatures. It can last over 60 years.

PVC is highly resistance to perforation and impact, and fire retardant. It has great flexibility and tolerance to extreme temperatures. The problem with PVC is it’s not reusable or recyclable. The average life span of PVC flat roofing material is 25 years.