A well-designed green roof assembly, whether extensive or intensive, involves a series of functioning layers that must succeed in achieving the following:

The success of a green roof relies heavily on the performance of the waterproofing system. In addition to preventing water ingress, waterproofing systems must also be able to provide the building with thermal performance, roof drainage, air tightness & vapor control, and protection from any structural damage caused by root penetration. To ensure that the waterproofing membrane is protected, these systems will typically include a root barrier.

Root barriers can be used to create a protective barrier, either chemically or with a physical sheet, between the vegetation and the waterproofing membrane to protect from potential roof penetration. Physical barriers are made from dense, inorganic materials that will not break down due to bacterial activity or allow roots to penetrate. Chemical barriers contain a compound that stunts root growth on contact and therefore do not allow roots to penetrate the surface of the waterproof membrane.

Today, root barriers installed on green roofs are most commonly made of low and high-density polyethylene, often abbreviated to LDPE and HDPE. This doesn’t come as much of a surprise, especially when considering that HDPE makes up 47% of the material in all plastic milk, water, and juice bottles in the U.S. 

In addition to being a lightweight, pliable, heat weldable, and fully recyclable material, HDPE also offers outstanding tensile strength, moisture resistance, and the ability to withstand extreme temperatures. Naturally, it has proven to be a great material for green roof root barriers.

Barrett offers a number of root barriers to be used with our Greenroof-Roofscapes®, each offering their own features and benefits based on their recommended application.

Root Barriers for Low Profile (Extensive) Greenroof-Roofscapes®

RB20 (20 mil) is the most common root barrier product used for extensive green roof systems. It is a low-density polyethylene sheet that is ideal for systems that have typical green roof plants such as sedums, which have shallow roots and will not present a lot of penetration pressure.

Root Barriers for High Profile (Intensive) Greenroof-Roofscapes®

RB30 (30 mil) is a high-density polyethylene sheet most common in intensive green roofs and roof gardens that will have more aggressive and larger plants like perennials and grasses. The thicker sheet provides additional protection and peace of mind that roots will not penetrate.

Root Barriers for Specialized High Profile (Intensive) Greenroof-Roofscapes®

RB40 (40 mil) is a heavy-duty high-density polyethylene sheet that is recommended when very aggressive rooting plants are installed. This product has been used effectively with bamboo, but we recommend caution when installing bamboo on any roof due to the aggressive nature of the root system. 

*For questions regarding RB40 applications, please contact a Barrett technical representative directly.

All Barrett root barrier products are installed in a similar manner, typically lapping the proceeding sheets a minimum of 12 inches and taping all joints with Barrett’s RB 25 Seam Tape. The barrier is to be turned past the top of the growing media to avoid roots growing around the edges of the sheet. Taping the edges is an extra measure of assurance.

These products are not biodegradable when covered and are intended to provide protection from root penetration during the life of the green roof assembly. This type of root barrier is FLL compliant. Similar to ASTM in the United States, the German FLL is an organization that has been developing and standardizing green roof technology for over 30 years.

When properly installed within one of our hot asphalt RamTough 250 and/or cold asphalt Black Pearl® Greenroof-Roofscapes®, these root barriers provide a comparatively inexpensive solution for membrane protection without compromising performance or quality.  With warranties available for up to 20 years, the solution for any green roof assembly is Barrett’s Greenroof-Roofscape®.

NOTE: All product literature (i.e. technical & safety data sheets, specifications, application instructions, etc.) is currently available to download from the “Resource Library” on our website. 

Using ice melting compounds to clear snow and ice from plazas, drives, public entryways, and other pedestrian & vehicular traffic surfaces is virtually a universal practice today. Facility maintenance personnel learned long ago that to achieve safe surfaces in the shortest time with the least total cost, ice melters are a necessity.

This is also common practice for bridge decks. In regions where snow and ice are common during the winter months, deicing salts are used to treat hazardous road conditions. The chloride ions from the deicing salts can travel with the water through the permeable concrete structures and begin attacking the exposed steel underneath.

The corrosion caused by this attack leads not only to weakened steel but also can contribute to spalling of the surrounding concrete. This results in deterioration of the load-carrying capacity as well as the quality of the riding surface of the bridge. Waterproofing membrane systems are vital for combating this specific type of accelerated deterioration in bridge decks.

Unfortunately, whenever a product category gains such widespread acceptance, the market attracts a host of suppliers looking to capture a share. As a result, there are more than 100 brands of ice melters available today, many of which are packaged with no mention of their chemical composition.

Because of this, we cannot offer a simple, all-encompassing answer. We can, however, confirm that RamTough 250 membranes will withstand exposure to both calcium chloride and sodium chloride (or “rock salt.”), the two most extensively used deicing materials in applications around commercial, industrial, and institutional facilities.

We recommend exercising caution with liquid applied deicing agents, as some also contain solvent carrying agents that can be detrimental to the assembly. Since the installation of the Ram-Tough membrane is often in conjunction with extruded polystyrene insulation, concrete surfacing, paver systems, drainage mats, as well as other materials installed above the membrane system, consideration should be given to those materials as well. The same holds true for Barrett’s drainage mat products.

We have talked with the major suppliers of extruded polystyrene insulation and they have confirmed their product is unaffected by both calcium chloride and sodium chloride deicing agents. Because of the wide variety of concrete and paver systems available, if there is a concern, Barrett suggests the suppliers be contacted for their recommendations.

What about Greenroof Installations and other Vegetated Areas?

If deicing is necessary for traffic surfaces adjacent to vegetated areas, care should be taken to avoid having the deicing material come into contact with the plants and growing media. Alternatively, we recommend selecting a deicing product that is vegetation friendly.

There are a variety of newer materials coming on the market which claim to be more environmentally friendly. If there is an interest in any of these products, please provide us with the product literature and Material Safety Data Sheet and our Technical Services Department will review.

NOTE: All product literature (i.e. technical & safety data sheets, specifications, application instructions, etc.) is currently available to download from the “Resource Library” on our website. 

It is important to understand what may be encountered during cold weather applications and what material and manpower limitations exist. Following these cold weather suggestions will help provide greater application efficiency and system performance.

Acceptable weather conditions are based not only on the actual ambient temperature, but a total combination of elements (e.g., wind, humidity, frost, dew and precipitation). The “wind chill” factor will have a great deal of influence not only on materials, but also on workmanship. Careful planning of work during cold weather will improve the quality of the installation. Laying out the roof area and placing materials where they will be needed prior to application will lessen problems associated with cold weather application.

Where different grades of materials are specified for summer or winter use, the grade specified for cold weather should be used.

Applying RamTough KLB-100 Polymer-Modified Elastomeric Roofing Bitumen

At the point of application of the roofing plies, the mopping asphalt should be at the recommended temperature. Failure to keep the asphalt in the proper application temperature range will result in poor ply adhesion, slippage and over usage of material.

The maximum heating temperature in the summer should be 500°F and in the winter, 525°F. The EVT of 125 cP (centipoise) with KLB-100 is generally around 500°F. However, the ideal viscosity of SEBS modified asphalt is approximately 180 cP, which occurs at about 450°F.

To compensate for the rapid cooling of mopping asphalt in cold weather, it is extremely important to keep the asphalt within the specified range, but never less than 400°F and not greater than 525°F at the kettle.

SEBS modified bitumen material is heat sensitive and should not be held at elevated temperatures for prolonged periods of time. If bitumen usage throughout the day is expected to be of limited quantity, consider using a smaller kettle or keeping a smaller volume of material in the kettle to avoid prolonged heating of the bitumen that could occur in a large kettle or tanker.

Felts must be installed into the hot mopping as rapidly as possible to guarantee adequate embedment. Mopping should not precede the roofing plies by more than five feet to prevent premature cooling of the bitumen. Brooming the felts in place immediately is very important.

Proper insulation of all asphalt handling equipment is required to keep bitumen at an appropriate application temperature in cold weather. The use of insulated rooftop equipment for transporting asphalt across the roof, such as hot luggers and mop buckets, is recommended.

This is especially important when bitumen is being transported over long distances on the roof. Bitumen pumping lines from the kettle to the roof should also be insulated, as they tend to clog in colder temperatures.

Ultimately, Barrett does not recommend installing built-up roofing applications below 25°F under any circumstance.

Roof Membrane Application Precautions

Asphaltic base sheets, plies and cap sheets become less flexible in cold temperatures. Rolls should be stored on end and when possible, in a warm (>50°F) and dry location prior to application. As the work progresses on a day-to-day basis, it is essential that each section of the roof be completed as specified. “Phased construction is not acceptable”.

Applying RamTough 250 Hot Rubberized Asphalt Waterproofing Bitumen

RamTough 250 bitumen can be installed at 0°F. However, the installation techniques become critical. Use approved double-jacketed melters with mechanical agitation. Begin melter warm-up early enough to have hot fluid material when the work is scheduled to start. Cold weather start-up will take longer.

Regulate melter to maintain material temperature range of 375°F to 400°F, with constant agitation. Do not overheat RamTough 250. To compensate for the rapid cooling in cold weather, it is extremely important to keep the Ram-Tough 250 within its specified range, never less than 350°F and never greater than 425°F. It is important not to hold RamTough 250 material at elevated temperatures for prolonged periods of time. Generally, the upper limit recommendation is four (4) hours at 400°F.

At the point of application, the RamTough 250 bitumen should ideally be 325°F-375°F. Failure to keep the RamTough 250 at the proper application temperature could result in excess material usage.

When applying a RamTough 250DM system, the reinforcing ply must be installed before the bitumen cools to assure adequate embedment. RamTough 250 should not precede the reinforcing ply by more than five feet to prevent premature cooling of the bitumen.

Proper insulation of all RamTough 250 handling equipment is required to keep bitumen at an appropriate application temperature in cold weather. The use of insulated rooftop equipment, such as hot luggers and buckets, is highly recommended for transporting the bitumen to the worksite. This is especially important when bitumen is being transported over long distances. Bitumen pumping lines from the melter to the work location are not recommended with RamTough 250, as they tend to clog in colder temperatures.

Pail materials, such as cements and coatings, should be properly stored with tight-fitting lids to prevent moisture intrusion or other forms of contamination. Use winter grade material and store in heated space if possible.

Applying Ram Ultra-White® and Other Water-Based Coatings

Water-based coatings must be stored in a warm (>35°F) location to prevent freezing. Should any material freeze, be sure to properly discard it.

It is recommended that these products be applied when temperatures are 40°F and rising and that temperatures will remain above freezing until the material has cured sufficiently. Depending on weather conditions, cure time can range from 24 to 48 hours or more.

Applying Solvent-Based Coatings

• Ram Cold Tar® Plus
• CP-80 Cold Process Adhesive
• Ram Ultra-Silver®
• Ram Primer Surface Conditioner
• Ram Mastic

Although not susceptible to freezing, these bituminous based coatings will become stiff and harder to apply at colder temperatures. It is recommended that the application temperature for these products be 40°F and rising.

Storing materials in heated storage until the time of application will make application easier and require less material. Care should be taken not to apply these materials heavier than recommended. Heavy applications will effect cure time and contribute to other performance problems.

HANDLING RECOMMENDATIONS

NOTE: All product literature (i.e. technical & safety data sheets, specifications, application instructions, etc.) is currently available to download from the “Resource Library” on our website. 

APPLICATION LAYERS

• Ram 203 | Protection Course (1 Ply)

• RamTough 250 | Rubberized Asphalt (2nd Coat)

• PolyFelt 125 VP | Reinforcement Fabric (1 Ply)

• RamTough 250 | Rubberized Asphalt (1st Coat)

• Ram Primer & Surface Conditioner

• Concrete Substrate

The RamTough 250 formulation and manufacturing process yields a self-healing, elastomeric material with significantly better elongation, elasticity, low temperature flexibility, adhesion and toughness properties compared to all other types of membranes. 

RamTough 250 waterproofing is composed of SBS rubber polymers, specially refined unoxidized asphalt, recycled tires and mineral filler. It is melted on the jobsite, spread on the deck 90 mils thick, reinforced with polyester fabric, over-coated with another 125 mils of RamTough 250 and covered with an SBS reinforced protection course, creating a total membrane thickness of approximately 300 mils. Totally adhered, water cannot get under or through this four course application. With the protection layer in place, the membrane is ready to accept a variety of traffic bearing surfaces, insulation, aggregate ballast or a green roof assembly. 

The unique physical properties of the RamTough 250 DM system offers superior performance and durability, even in the presence of ponded water and extreme climate variations.

SLOPE & DECKS

Decks up to 1 in/ft incline require no special precautions. Contact Barrett Technical Services for slopes over 1 in/ft, vertical applications and decks other than concrete.

SURFACE PREPARATION 

Concrete decks must be made reasonable smooth, dry, free of dirt, laitance, curing agents, debris and other contaminants. Prior to installing the membrane, apply a coat of Ram Primer and Surface Conditioner at a rate of 300-500 sq.ft./gal to all surfaces to be waterproofed. Allow the coat to dry thoroughly. Before proceeding, treat all cracks, construction and expansion joints in accordance with Barrett recommendations or approved details.

MEMBRANE APPLICATION

Starting at the low points of the deck, apply a base coat of RamTough 250 no less than 90 mils thick and approximately 44” wide. While still hot, install one ply of PolyFelt 125 VP reinforcement fabric into the RamTough 250. Standing off to the side, use a broom or squeegee to press the fabric into the hot bitumen carefully, so as to not create wrinkles or fish-mouths. If the sheet is not set straight and begins to run off a straight line, cut the roll and reset it, overlapping the end of the sheet by 12”. 

After the first run has been installed, return to the same starting point and install a second run of RamTough 250 and reinforcement, overlapping the first course by 3”. All end laps shall be a minimum of 6”. Ensure that there is a solid coat of RamTough 250 between all laps. There should be no place where fabric touches fabric. All laps shall be laid to allow for the flow of water over the lap, not against it. Continue working up the slope. 

After the base coat of waterproofing and reinforcement have been completed, apply a top coat of RamTough 250, applied at a minimum thickness of 125 mils.

WATER TESTING

It is recommended that all sections of the completed membrane installation be flood tested in accordance with ASTM D-5957 for 48 hours. Any leaks shall be repaired and the area retested. Some applications may require an Electronic Field Vector Mapping Test (EFVM) conducted by an approved surveyor.

PROTECTION COURSE

Once the water test is complete, install 1 ply of Ram 203 protection course. Provide 2” side-laps and 6” end-laps. The protection course is to cover all horizontal surfaces, as well as all vertical flashings. If the base flashing is to be permanently exposed, install 1 ply of Ram 306 granulated cap sheet into the top coat of RamTough 250 in lieu of the Ram 203. Use RamTough 250 as an adhesive, as required, to hold the protection course in place prior to it being covered with the specified surfacing.

SURFACING

Carefully install surfacing overburden (e.g. insulation, filter fabric and ballast, pavers, green roof assembly. etc.) as per the project specifications.

PRODUCT SAFETY INFORMATION 

RamTough waterproofing products offer no unusual health or safety risks for products of this nature. As with any roofing and waterproofing installation process, proper ventilation, clothing and eye protection is important. 

For specific product information, contact the Barrett Company for a current Material Safety Data Sheets for any and all Barrett products. Obtain Material Safety Data Sheets from manufacturers whose materials may be used in conjunction with the Barrett waterproofing system. For installation safety information, consult the National Roofing Contractors Association (NRCA), the Occupational Safety and Health Administration (OSHA), and any other informed sources. 

The user should not assume that all safety measures are indicated or that other measures may not be required.

NOTE: All product literature (i.e. technical & safety data sheets, specifications, application instructions, etc.) is currently available to download from the “Resource Library” on our website.