Built-Up Asphalt Roof Systems in Florida Commercial Buildings

October 13th, 2011 • By: Rick Brown Roof Types

Conventional built-up roof systems have been in use as an industry mainstay for over 100-years. These applications typically use coal tar pitch or asphalt as the waterproofing material which is installed in successive layers and reinforced with ply felts. With multiple plies, a contractor is essentially “building up” the roof, hence the terminology. This post covers the asphalt side of BUR systems.

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..

Commercial Roof Insulation

October 5th, 2011 • By: Rick Brown Roofing Insulation

Exploring the elective components of a commercial roofing system in Florida, we now take a look at types of insulation.

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..

All Area Follows OSHA Roofing Safety Regulations

May 2nd, 2011 • By: Rick Brown Uncategorized

One hundred years ago, 146 people perished in the fire at the Triangle Shritwaist garment factory because of overcrowded conditions, absence of fire alarms, inadequate fire escapes, and locked escape doors. The event is widely regarded as a majo

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r catalyst for workers rights groups fighting for safe labor conditions that eventually culminated in the establishment of Occupational Health and Safety Association (OSHA). Its mission is to make sure all United States Workers can go to work without fearing for their health, safety, or lives.

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 casino spiele online 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.

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Florida Commercial Roof Decks

April 5th, 2011 • By: Rick Brown Roof Deck

The basis of any roof assembly is the roof deck. Its primary function is to provide structural support for the roofing system with adequate strength to support all anticipated live and dead loads. The deck must not deflect, must be secured to p

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rovide resistance to wind uplift and should be a clean, uninterrupted surface that provides for insulation or membrane securement.

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..

Roofing Components

April 5th, 2011 • By: Rick Brown Roof Components

In order to make decisions about the care of your roof, you need to be familiar with its critical components.  By building a virtual system, we will examine the “pros and cons” of each component, providing you with the knowledge base to ultimately receive full value for your capital expenditure and maintenance dollar.  Below is a real-time outline of currently published articles.

A. Roof Deck

  • Plywood or Wooden Plank

 

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