Ethylene Propylene Diene Monomer or EPDM, is a compound whose principal components are ethylene and propylene.  This form becomes a flexible rubber when diene is added.  EPDM is classified as a thermoset membrane, meaning it is cured prior to installation.  The uncured form is used as flashing material and cures during the natural weathering process.  Seams are chemically welded with solvent borne adhesives or specialty seam tapes with adhesive primers.

One of the early appeals of EPDM was the relatively low materials cost.  The membrane is typically 25 per cent-30 percent less expensive than modified bitumen and half the cost of built-up roofs.  The uncured flashing materials and lap adhesives tend to drive the price higher, however the overall cost can be considerably less than conventional roofs and this is especially attractive for large scale distribution centers or manufacturing plants.

Three choices are available in EPDM system design:

1. A mechanically attached system with fasteners through the laps and into the substrate;
2. A fully adhered system glued to either suitable insulation or substrate and
3. A loose laid or ballasted system, fastened only at the perimeters and penetrations with either pavers or stone holding the system in place.  As of the revised 2004 Florida Building Code, system 3 is no longer applicable in the state, but is used extensively in large facilities requiring less stringent wind uplift standards due to its extremely low installation costs.

As the early EPDM systems aged, several issues became apparent.  First and foremost is shrinkage.  Most notable is ballasted systems, shrinking membranes displace gravel, can distort wall or edge flashings and will ultimately tear the membrane itself allowing water intrusion.  There are no universal methods of addressing shrinkage as the repairs required range from minor tension relief cuts to complete re-roofing.  The second problem is lap failure, often due to shrinkage or improper adhesive installation.  The latter problems have been addressed with the advent of seam tapes providing more uniform lap strength.

If your property is currently covered with an EPDM system, please contact All Area Roofing & Waterproofing for a free evaluation with maintenance recommendations.

In addition to providing greater tensile strength and elasticity, the introduction of these polymers allows for a single roll with coverage of 100 square feet, including the surfacing, resulting in significant labor savings during application.  Modified can be installed with conventional hot asphalt, modified adhesives, open flame torches, hot air welders or most recently, self adhered.  Several of today’s systems, such as Derbigum, combine the superior uplift of adhesives with the immediate watertight lap provided when torching or heat welding.

All modified bitumen membrane rolls rely on an inner scrim or reinforcement mat to hold the asphalt in place.  Scrims are typically polyester or fiberglass or both and these mats are dipped into the molten modified mix, processed through a rolling cylinder and then a surfacing table and cooking bath.  These mats are chosen because of their ability to accommodate the modifying polymers elongation properties.  The type and weight of the mat determines the final characteristics of the roll and ultimately the price.

Since the introduction of modifieds in Florida in the 70’s, their market share has increased steadily culminating in almost 30 per cent in the 90’s.  Several factors play a role in the recent decline seen in this market over the last decade.  A few of these include:

• Widespread acceptance of thermoplastic systems requiring minimal slope with accompanying reduced installation cost.
• Increased insurance costs associated with open flame and 500 degree molten asphalt for SBS cap sheet installation.
• Rising petroleum costs translating to higher manufacturing prices and ultimately more expensive end user cost.
• Increased demand for environmentally sensitive “cool roofs” and more awareness of potentially harmful fumes.

Despite the items listed above, modifieds have proven performance on residential, commercial and industrial applications.  The granular surfacing requires no costly maintenance coatings while making inspections and repairs very easy.  Tough and long lasting, these systems are designed for Florida Owner/Managers that wish to keep and maintain rather than sell.

Coal tar pitch is a distillate of coal tar and is formed of primarily aromatic hydrocarbons.  This complex linking makes coal tar inherently stable chemically and allows a broad range of softening temperatures vs. the defined melting point found in asphalt products.  In short, coal tar is an extremely durable roof membrane which softens at very low temperatures and this cold flow property allows the roof to “heal” itself from minor punctures and voids.

Coal tar roof systems consist of alternating layers of roofing pitch with reinforcing felts and are “built-up” in a similar fashion to asphalt BUR roofs.  Because of the unique chemical composition of coal tar, it can be installed on “dead level” or poorly drained flat roofs with no ill effects on the system.  Prior to the widespread use of mechanical air conditioning units, many buildings were”water cooled’ by providing raised edge details to impede water run-off and coal tar pitch was the roof system of choice for these locations.

Coal tar pitch is also utilized in several other areas of the construction industry including a below grade waterproofing mastic and pavement sealants. 

Unfortunately, the past few decades have revealed some serious health concerns with coal tar products.  Side effects from the vapors range from minor skin, nose and throat irritation to nosebleeds, changes in skin pigmentation, rashes, fainting and comas. 

Additionally, the price of pitch has been a prohibitive factor as the installation cost is typically 2-3 times that of asphalt products and special design criteria must be met to accommodate the cold-flow characteristics.

The combination of health and cost concerns has created a marked decrease in the cold tar market.  Several manufacturers’ have vacated this segment of the industry and as health insurance costs continue to rise, we’re doubtful coat tar pitch will rebound. 

If you have a coal tar roof on your building and require assistance in managing this specialized system, call All Area Roofing & Waterproofing, Inc. today.

Built-up asphalt roofs are field fabricated using hot applied asphalt in alternating layers with Type IV, Type VI or organic ply sheets.  The entire assembly is then surfaced with protective coverings such as gravel, fibered aluminum or other coatings to avoid UV degradation of the asphalt in the assembly.  A built-up roof is greatly enhanced with additional plies and redundancy is the key to its performance. 

Layers of a Build-Up Roof

A typical BUR assembly might consist of an anchor or base sheet installed over a lightweight concrete deck or multiple layers of tapered insulation.  The next step is the alternating felts and asphalt mopped in place at an application temperature within 25 degrees F of the EVT for the particular type of asphalt.  Most contractors today use Type 4 asphalt with an EVT of around 472 degrees so the temperature at the mop should be within the 450-500 degree range for the optimum roofing.  The asphalt is spread to allow approximately 23-25 lbs. of asphalt per 100 square feet per ply.  Too much asphalt and the roof can “slip”, too little and the system will fail prematurely.  The fiberglass ply sheets are porous and allow the asphalt to saturate at this temperature and this combines to form a “ply”.  Four of these layers constitute a “4-ply BUR”.  Finally an additional layer of asphalt is spread and gravel is broadcast while still hot at the rate of 400-600 lbs. per 100 square feet.  A minimum standard is 50 per cent embedment of the surfacing gravel.  This system then becomes a “4-ply BUR/G”.

Other alternatives for surfacing include a clay/asphalt emulsified coating, fibered aluminum coatings or acrylic/elastomeric coatings.  All of these are acceptable, however, each is subject to deterioration and will require “recoats” at 5-7 year intervals and none have the protective properties or excellent fire ratings of gravel.

Build Up Roof Challenges

As is easily noticed from the installation guidelines, built-up roofs are extremely labor intensive.  Kettles at ground level to heat the bitumen allowing it to be pumped onto the roof must be constantly monitored.  Moving hot asphalt safely around a roof surface requires additional personnel and specialized equipment and to physically install ply sheets and surfacing requires a substantial team.  A typical built-up crew can easily involve 10-12 men or more.

Combining the high labor costs with volatility in the petroleum market, increasing awareness of open flame and fume hazards and building department concerns over gravel surfacing becoming airborne projectiles has led to a decrease in market share for this roof type.  Additional concerns include the aesthetics of a “hot kettle” at ground level and the stringent safety procedures that must be followed when dealing with open flames and super-heated asphalt with its’ resultant fire potential.  Lastly, when the cost of tapered insulation (asphalt fares poorly in  ponding water) are combined with high labor and increasing bulk asphalt prices it is east to have a 15-year BUR system at double to triple the cost of other systems with the same warranty period.  In today’s economy, many Owners and Managers are increasingly in search of alternative systems for their properties. 

For further information concerning your built-up asphalt roof, we suggest the Asphalt Roofing Manufacturers’ Association .  Or please contact All Area Roofing and we will be glad to visit your site, evaluate your BUR and provide maintenance or design/build insight as needed.

Roof insulation performs two basic functions:

• Acts as a thermal barrier for the top of the building.
• Serves as the base for the roof sytem.

Secodary functions include:

• Enhancing drainage through the use of tapered insulation systems and stiffened roof decks.

Poly-isocyanurate

Far and away the most common roof inulation installed, ISO is available in flat or tapered panels and is the base for many roof systems with an average LTTR value of 5.56 per 1″ of product.  Polyisocyanurate features a closed cell iso core integrally laminated to fiber reinforced felt factors.  Iso has a perforated facer on one side for use with hot asphalt applied systems while the non-perforated side is for use with single-ply systems.

Pros

High R value of 5.5 per inch and good compressive strength.  Excellent dimensional stability and very lightwwight.

Cons

Contains CFCs or HCFCs which may be released into the environment, causing ozone depletion.  It is also expensive in comparason to other insulations.  Contains a petroleum by-product increasingly in demand worldwide, resulting in availability problems and lengthy lead times for orders.

Perlite

Perlite insulation is an inorganic, rigid board insulation available in 2′ x 4′ or 4′ x 4′ panels.  The panels are composed of expanded volcanic glass and wood fibers bonded with asphaltic binders.  Until recently, perlite was the most common insulation used in roofing.  Although still popular, its low R-value of 2.78 per inch and tendency to absorb moisture have diminished its frequency of use.

Pros

Perlite has an excellent fire protection resistance rating.  It also has good compressive strength which allows normal roof foot traffic.  It also has great dimentional stability and the ability to absorb outgassing common in foam and iso insulations.  It is often used  as a cover board in hot asphalt sytems.

Cons

Very friable and relatively easy to break panels.  Complete deterioration when in contact with moisture.  Low R value and poor tensile strength.

Expanded/Extruded Polystyrene

As the lead times required for isocyanurate insulation increases, EPS has risen as a low-cost alternative for roofing insulation.  Both types are manufactured from polystyrene, one as a fused board made of beads while the second is formed from a molten sheet pressed into shape.

Pros

• Dimensionally stable with lower water absorbtion. 
• Extremely lightweight, minimizing roof dead loads. 
• Easy to handle, cut, and form.
• The extruded form is used widely as a base for achitectural shapes at wallsand parapets.
• Decent R values between 4-5 depending on type.
• Relatively inexpensive

Cons

• Poor fire resistance
• Low compressvie strength equates with poor wind load resistance
• Releases potentially toxic combustion product if ignited

Dens-Deck

Dens-Deck is an ever increasingly popular roof insulating product in roof assemblies.  It is the roofing version of an exterior board used most commonly as an exterior stucco backer board.  This board is a mold resistant roof panel that consists of a moisture-resistant, non-combustible core of specially treated gypsum with glass mat facings.

Pros

• Approved by all manufacturers.
• Highest performance rating for fire, wind uplift, and moisture resistance.

Cons

• Very heavy board increases handling costs and deck requirements.
• Difficult to cut and form
• Primed version must be used in hot applications to avoid blistering membrane.
• Low R value

Wood Fiber

The final insulation we will examine is wood fiber.  It is the oldest type designed for roofing.  It is normally found in a “high density” form and is inexpensive and durable.  It is also often used as a cover board over iso in hot applications to reduce outgrassing.

Pros

• Durable, easy to handle, and relatively easy to cut and form.
• Decent compressive strength provides reasonable wind uplift ratings.

Cons

• Dimensionally unstable in contact with moisture. 
• Rapid deterioration when wet, also providing possible medium for mold growth.
• Poor fire rating with low R value of 1.9 per inch.

Other types of roofing material used in commercial roofs across Florida are foam-glass, gypsum wallboard, and mineral board.  Please call us if you have any questions or would like a further analysis of the insulation in your roof system.

Each project and roof assembly has its’ own subtle differences that may lend itself to a particular size, type, or thickness of insulation.  Additionally, the expense at insulation should be cost-factored in comparison to heating or cooling billd over the expected life of the assembly to determine the most effective insulation for a particular project.  Your contractor, consultant, or manufacturer can all play vital roless in helping with the final decision based on R value needs, anticipated length of ownership, and local codes.

It has now been 40 years since OSHA opened their doors.  Democrats and Republicans can both celebrate the successes of the program since it was passed by a Democratic congress and signed into law by a Republican President.  Since opening it doors in 1971, OSHA has fostered a decrease in workplace fatalities and injuries have dropped 65% over the past 40 years.

In 1983, 10,000 health care workers contracted Hepatitis B, largely due to the accidental contact with needles used on patients.  As OSHA began to investigate the situation and eventually released guidelines and regulations, instances dropped to fewer than 400 by 2000.  Countless stories such as this one are a testament to our countries commitment to safe workers.

OSHA regulations play a large part in making the roofing industry a safe place to work despite the inherent risks involved.  All Area Roofing and Weatherproofing is proud to uphold all of the regulations provided for the safety of our employees and efficiency of the construction sites and residential homes in Florida.

Some of the regulations meant to provide a safe environment for roofing projects include:

• Requirement of roof strength testing to insure it can support construction workers safely
• Roofs higher than six feet must either have a guardrail or employ one or more of the following:  safety nets, fall arrest systems, or toe boards.
• Protection from holes on roofs over six feet.
• Elimination of impalement hazards below the edges of roofs under construction.
• Monitoring for inclement weather during the entire construction process

Following all the rules and regulations is always a challenge for small business.   Here is an excerpt from the budget hearings for the Small Business Administration and what they are doing for us to help everyone utilize the OSHA requirements.

Why am I concerned with the roof deck type,” you might ask.  Three reasons:

• The deck type determines if insulation is required and what load it may carry
• The deck type mandates mechanical attachment or adhesion of your roof.
• The deck type determines how difficult repairs will be as your system ages

We will include the relevant factors in our basic instruction on the following types of roof decks:

• Plywood or Wooden Plank
• Steel Deck
• Lightweight Insulating Concrete
• Structural Concrete
• Tecum/Cementitious Wood Fiber

Plywood/ Wooden Plank

Used most frequently in residential construction or in commercial sloped roof applications, wood decking is secured directly to wood or steel framework and is available in thickness from 1/2″ to 3″.

Pros

Readily accepts most fasteners, is quick and easy to cut and form and is relatively inexpensive.

Cons

Low wind uplift resistance when nailed and rapid deterioration when moisture is encountered.

Steel Deck

The most common form of deck on commercial projects is steel. Metal decking is puddle welded to the structural steel framework and is available in 18-22 gauge, with profiles 1″-1-1/2″ in height.

Pros

Rapid installation in 24′ x 3′ panels welded to a steel frame. It is also cost effective due to low labor resources needed at the time of installation. There is super wind uplift ratings and good long-term resistance to moisture.

Cons

Metal decking is costly to replace becaue of the need to remove the closest frame member. It also requires either structural concrete or lightweight insulation to perform properly.

Repair investigating is also difficult with a steel deck roof because of possible water migration under the roof through the lenght of each panel.

Lightweight Insulating Concrete

Another common form of decking for commercial projects is lightweight insulating concrete (LWC). It can be found on many buildings in the form of plank using gypsum, or monolithic pours over corrugated/fluted metal deck or a form board such as fiberglass. LWC is an air entrained mixture of cement, water, fly ash, sand, or other additives depending on density required. When poured over preformed foam, it allows drainage to be built into the deck.

Pros

Rapid installation with taper in deck to enhance drainage. It also has a high fire resistance. The lighter deck weight results in savings from footers thru the the wall structure due to less dead load at deck level.

Cons

LIC has low wind uplift resistance and fastener pull out values in comparison to steel or structural concrete. There is also rapid deterioration once moisture intrusion occurs.

Structural Concrete

The next form of decking in commercial applications in Florida is structural concrete.  It is found in three common types:

• Monolithic Pour – uses “forms” and is poured in a slurry, similar to the foundation in residential construction.
• Pre-stress or “twin tees” – a pre-cast plank with steel reinforced built into the material at the plant and shipped in various lengths and widths.
• “Hollow Core” – also a factory formed plank, it is hollow inside with internal supports similar to masonry blocks

Pros

The most secure form of decking with superior wind uplift and fire ratings.  Structural concrete is virtually indestructible and is found on most high-rise buildings and hurricate rated shelters.

Cons

Extremely heavy decking requires extensive supporting walls.  Concrete decks allow water saturation, eventually deteriorating the reinforcing steel enough to require epoxy injections to restore.

Tectum/Cementitious Wood Fiber

The last form of commercial roof deck covered in this post will be tectum or CWF.  These planks or panels are factory formed and comprised of wooden fibers bonded by hydraulic cement.  CWF was used widely during the 1950s – 1970s but has since become a marginal player in commercial applications.

Pros

Superb sound absorbtion and acoustical properties.  A Class A/I interior rating requires no additional finish for exposed deck applications.  Fabricated from sustainable natural resources meets “green” building requirements.

Cons

Poor wind uplift ratings.  Requires extensive 2-step fastening system to meet Florida wind loads.  Deteriorates rapidly when wet.

For a more detailed examination of your roof deck and entire roofing system, please call us to set up an appointment.

A. Roof Deck

• Plywood or Wooden Plank

We will clarify those terms in a language the lay person can understand and shed light on how they can affect your budget, capital expenditures, and maintenance funds.  This should provide an easy seque into the design/build and maintenance process as you encounter the inevitable need to deal with roofing and waterproofing issues.

We will also provide you timely updates on the dynamic world of  OSHA and EPA regulations and compliance, storm preparedness and disaster response, and permitting issues.

Questions, comments on individual blog posts, and blog topic requests are welcome and appreciated.