Chicago Flat Roof Company: Chlorinated Polyethylene and Chlorosulfonated Polyethylene Sheets Roofing

Commercial buildings generally have flat roofs. In fact, we seldom see, if ever, buildings with pitched or sloped roofs. On the other hand, most residential houses have pitched roofs. What are the reasons for this basic difference?

Flat Roofs versus Pitched Roofs

There are at least three reasons why commercial buildings have flat roofs. First, flat roofs are more economical or cost efficient than pitched roofs. Why? They require less material and labor, which translates to lower cost. Second, they provide additional space that may be used for different purposes such as storage area for equipment on the roof deck. Third, they are easier to inspect. Since commercial buildings have to be inspected regularly, a flat roof design makes inspection very convenient.

While most residential houses are still capped with pitched roofs, an increasing number of residential homeowners are resorting to flat roofs for their homes. Flat roofs are pleasing to look at and conform to most modern designs. They also offer flexibility that is conspicuously absent in pitched roofs. Some issues are, however, persistently connected with flat roofs – leaks and repairs.

If you own or manage a commercial building, chances are you are already familiar with the different roofing membranes used on flat roofs. However, if you are yet to install one but plan to do so, acquiring some ideas about the different types of flat roof systems will prove helpful in the future.

Different Types of Flat Roof Systems

1. Built-Up Roofing System (BUR):

It consists of multiple layers of fabrics, felts or mats with layers of bitumen and topped by mineral aggregate, liquid-based coating or other cap sheet. The resulting membrane is semi-flexible and continuous. The aggregate consists of either water-worn gravel, crushed stone or similar materials.

2. Modified Bitumen Roofing System (MB):

Composite sheets made of bitumen modified by polymer and reinforced with different types of films or mats. The installation of MB is made through the use of torch or heat welding.

3. Single-Ply Roofing System:

A single layer of flexible membrane is used to cover the roof as opposed to the multiple-layer of BUR. The membrane is either thermoset or thermoplastic. To strengthen the membrane, reinforcing materials are added such as polyester mats, nylon and glass fibers. Many types of single-ply roofing system are available including Thermoplastic Olefin (TPO), Polyvinyl Chloride (PVC), Ethylene Propylene Diene Terpolymer (EPDM), Chlorinated Polyethylene (CPE) and Chlorosulfonated Polyethylene (CSPE).

Unlike EPDM that is well-known to most people who have experience in flat roof systems because of its extensive use in the construction industry, CPE and CSPE are relatively unknown. We provide a brief description below what these two flat roof systems are to introduce homeowners and managers to these two types of roof membranes.

General Strengths and Weaknesses of CPE and CPSE

In general, people who chose CPE and CPSE do so because these roofing membranes are highly resistant to deterioration from ultraviolet rays. They can also be produced in light and heat-reflective colors, which lessens the rate of absorption of the sun’s heat on the roof. CPE and CPSE are also ideal for use on roofs where aggregate ballasting is not possible because of the high slope of the roof or for aesthetic reasons.

Roofing professionals agree that welding and repairing both CPE and CPSE entail more difficulty compared to other single-ply membranes such as TPO and PVC. The shares of CPE and CPSE in the single-ply market have been diminishing through the years.

Chlorinated Polyethylene

Chlorinated Polyethylene (CPE) belongs to the family of single-ply roofing thermoplastic membranes. This type of roofing material is made of high molecular weight polyethylene that is subjected to chlorination to produce a flexible rubber-like material. The chlorine content normally ranges from 25% to 42% by weight but could be as high as 70%.

The main purpose of CPE is as modifier that greatly enhances the impact resistance of PVC. It also lowers the cost of the brittle and rigid material.

Desirable Traits

CPE offers distinct advantages, including:

Inherent resistance to oxidation, ozone and heat because of its molecular composition augmented by chlorination and molecular modification

Durability against the weather

Good anti-combustion

Tolerance to low temperature

Resistance to chemicals

Easily shaped

Stable

Undesirable Traits

The product is known to emit hydrogen chloride, carbon dioxide and carbon monoxide when heated. The fumes released upon reaching melting point is understandably irritating.

Chlorosulfonated Polyethylene

Chlorosulfonated Polyethylene (CSPE) is a synthetic thermoset rubber-like membrane composed of high molecular weight polyethylene formulated with chlorine and sulfur dioxide to produce synthetic elastomer that is self-vulcanizing. The process converts the thermoplastic polyethylene to a synthetic polymer. Chlorine content is generally from 27% to 45% by weight.

CSPE is marketed as Hypalon, a well-known trade name used by its developer DuPont.

Desirable Traits

Some of the desirable qualities of the CSPE are:

Resistance against moisture
Non-reactive to chemicals
Strong dielectric properties
Fire and oil and microorganism-resistant
Adheres to most surfaces
UV stable
Durable against the weather

These diverse qualities made CSPE one of the most popular flat roofing membranes in the construction industry. Its uses is not limited to being installed as a reliable roofing membrane; it is also extensively used in other products such as cable wire sheathing, tank linings, acid-resistant protective layers and rubber gaskets.

Undesirable Traits

Emissions resulting from burning the product include carbon monoxide, organic acids, alcohols, hydrogen chloride and sulfur dioxide.

Obtaining more Information on these Products

If you are looking for more information about Chlorinated Polyethylene and Chlorosulfonated Polyethylene roofing systems, reading about these two flat roof membranes on journals and articles may not be enough to give you a thorough understanding of their strengths and weaknesses. We suggest talking to the professionals themselves and consult them to find out if these roofing systems are suited for your roofing needs.

If you live in the Chicago or Northwest Indiana areas or own properties there that you plan to equip with flat roofs, we highly recommend getting in touch with the Chicago Flat Roof Company before committing to any roofing system or closing deals with any roofing contractors. The company has been around for years and earned the reputation of a trustworthy and professional roofing contractor that provides excellent quality and workmanship in their work. They even provide free inspection of your house and estimates of the cost involved.