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Waterproof Sealants and Coatings For
Various Metal Roof Structures

How To Waterproof, Coat and Seal Metal Roofs

Our elastomeric, waterproofing and rubberized coatings for metal roofs provides unmatched flexibility and protection against the harshest conditions. Our products when combined, form a Seamless Monolithic Roof System that will last. Our products will cover tin, corrugated, aluminum, steel and many more types of metal roofing. Even old rusty and damaged roofs can be repaired at a lower cost with better results. Information to help is contained in the following page, from preparation to final coat, along with some Frequently Asked Questions to help, remember to call or email us if you need further assistance.

Temp Difference
Blue Max coated over by Maximum Stretch

Products in this Project

Blue Max® Liquid Rubber Waterproofer is a water-based, strong and highly adhesive elastomeric coating & sealant with 1200% elongation that moves with the surface to resist cracking & peeling. Blue Max® is ideal for waterproofing above & below grade foundations, basements, roofs, floors & more.

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Maximum-Stretch® is a white, elastomeric, acrylic, rubberized roof coating & sealant with 650% elongation to resist cracking & peeling. With 88% light reflectivity, the bright white finish reduces surface temperatures resulting in lowered cooling costs.

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Ames® Peel & Stick™ Seam Tape is a contouring, high strength, self-adhesive, seam tape for the reinforcement and prevention of water infiltration over seams, cracks, roof vents, flashings and more. Must be top-coated for UV exposures.

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A detailed inspection of the application area must be performed before beginning any work in the installation process. This can be done independently or with your contractor. This is to ensure that your project conditions and AMES installation guidelines match.

After inspection, repair, and the pre-filling of joints, corners and cracks, you can begin the application of AMES Liquid Membrane. Although most application processes will only require two coats, please pay careful attention to mil thickness and condition of your substrate.

Application Guidelines

Surface Preparation

Initial Cleaning

    • Proper initial cleaning of your substrate includes removing dirt, contaminants, and debris from existing surfaces. All loose contaminants that could prohibit proper adhesion of the AMES Liquid Membrane to the substrate can normally be removed with a stiff bristle broom, vacuuming or other means unless the buildup is severe then a pressure washer may be required. TIP: Leaf Blower

Inspection of Substrates

    • Inspect substrate for suitability to proceed with AMES Liquid Membrane.
    • If there are substrate issues, bring these issues to the project supervisor, architect, customer or AMES Research Laboratories tech services attention for recommendations.

Substrate Conditions - are specific to the type of surfaces you are working on. Incorrect conditions can cause installation deficiencies that could affect the performance of your waterproofing installation.

Inspect Substrates for:

    • Protruding or missing fasteners
    • Loose or broken backer board
    • Excessive gaps between backer board panels
    • Excessive gaps at intersections of backer board to other adjacent items
    • Excessive gaps at cutouts for water pipes, shower heads
    • Rough, sharp ridges in mortar sloping material
    • Dried crumbs of mortar slag on the surface of the shower base.
    • Mortar blocking mounting holes between drain base and clamping ring
    • Presence of mold or mildew on walls or sheathing due to extended exposure to the elements or other pre-existing conditions.
    • Wood moisture content – at or below 20% as tested at core of substrate. This will typically be a consideration when the floor sheathing has been properly pre-sloped and is the intended substrate for the AMES Waterproofing Membrane.
    • For remodeling projects, all types of existing substrates being protected with AMES Liquid Membrane Waterproofing need to be inspected for any possible need to repair or replace before proceeding with new applications.
    • Structural and environmental integrity is important in the underlying material as it will become a base for the new AMES Waterproofing System. An example of when aged and deteriorated substrates may be encountered could be when an aged existing shower or tub is being removed and a tile system is being installed.
General Guidelines
    • AMES Research Laboratories, Inc. recommends that these application suggestions be used as a guideline for applying AMES’ products. Please remember these are only suggestions.
    • Product durability depends upon surface preparation and sufficient material usage for thickness.
    • Read all instructions on the label before beginning.
    • Always run a test patch first in an inconspicuous area to ensure that proper adhesion and drying occurs with your product and that the product works to your satisfaction before proceeding.
    • Do not proceed unless you are satisfied.
      For product information or technical assistance, call 1-888-345-0809 or contact us via email.
Weather & Drying Guidelines
    • As with all roof coatings, coordinate a schedule to apply materials prior to high heat of the day. Best temperature range for application is 50º to 90ºF (10º to 32ºC) When working in hotter temperatures apply in smaller areas to maintain control of the wet material during application. • Recommended minimum temperature of 40 ºF (5 ºC) and rising before applying.
    • Plan application to avoid inclement weather for 24 hours after application in cooler climates or if rain is predicted.
    • Dry times are dependent upon the thickness of application, humidity, and weather. Product should be dried and cured after 24 hours. Low temperature, high humidity, and morning dew (condensation) can delay start times and increase drying and curing times. Always test the roof after initial cure to determine if cooler temperatures and high humidity may have slowed down the drying time before walking on the roof or beginning a second coat.
Application Techniques

Spray Application

  • When spraying, airless equipment sizing should be a flow rate of 1.0 to 3 GPM, 2500 to 3000psi, heavy duty reversal-clean tip (without diffuser pin) sizes 629 (12” fan .029 orifice size) to 633 (12” fan -033 orifice size). For long hose runs, hose sizes that are 5/8” should be reduced to ½” before connection to gun swivel.
  • Alternately, you can size your hose for shorter runs at ½” and a whip line of 3/8” or ¼” at the gun for improved gun control.
  • Consult AMES tech services for assistance in determining if your specific airless sprayer is suitable for the project.
  • If the airless sprayer has a machine filter in addition to the intake rock screen, we recommend either a 40 mesh filter or temporarily removing the machine filter cartridge altogether.
  • Airless equipment should be cleaned after use without delay.

Squeegee and/or Roller Application

  • Pour out a ribbon of material in a line across the surface of the roof.
  • Squeegee or roller spread the material out to the recommended wet mil application rate.
  • Pour out successive ribbons of material adjacent to the first area applied and follow the same procedure to the recommended wet mil application rate.
  • Back roll through the squeegeed material to even up the coating thickness as you move across the roof applying coatings.
  • 24” to 36” roof squeegees with broom style handles are recommended.
  • 18” by 1” to 1 & 1/2” nap rollers/frames are recommended.
  • 9” roller covers can be used for small jobs and embedding fabric.
  • 4” mini roller frames and covers work great for embedding flashing around small detail areas.
  • If roller covers dry in the sun, replace them promptly with useable roller covers.
  • Clean squeegees as needed to avoid excessive material buildup.
  • Rollers can be rolled up into plastic sheeting to keep the roller covers moist and to extend the useful life of the roller covers.

Good Better Best System

A waterproofing guideline system designed to give you the best for what you actually need. Each application guide will have a level of application needed for the system and conditions you are applying it to.
For all DIY'ers we recommend the "Better" system.
Click on each box to find out more...


Great for mild climates, areas that would most likely not see large swings in weather. Mild to moderate rain a few times a year while also not being overly humid or hot. When you need great protection but not expecting hurricanes and snow blizzards.

Good Roof Application Visual


For climates that experience all four seasons and need to be well protected all year round. We recommend this system for our DIY and Professional Contractors. This system makes sure you and your clients are well protected when the weather can fluctuate dramatically.

Better Application Diagram


A system designed for our Facility Management buildings and large warehouses/schools. This system is designed to stand the test of time and be moderately monitored and maintained, saving costs and staff overhead.

Best Application diagram visual

Application Process

Step One Surface Preparation
  • Power wash the surface area of the roof to remove most of the loose material.
    • Use caution so you don't damage any interior areas of the building due to roof leakage.
    • You may need to roughen the surface.
  • Fill any large cracks and crevices with Blue Max Trowel Grade and seam tape.
  • Do not use any soaps or detergents.
Step Two 1st Base Coat of Blue Max (optional)

(This bonding coat is necessary if the metal roof has begun to rust or retains a chalky finish after pressure washing) - If the metal roof has no rust or remaining chalky, finish present this bonding coat can be omitted. 

  • Blue Max can be applied with roller or spray application. 
  • Mask and protect adjacent surfaces not intended to be coated.
  • Do not block vents. 
  • When applying Blue Max, apply 1st coat at a rate of 75 sq. ft./gal (22 mils wet) and allow to cure a minimum of 8 hours - 24 hours in cooler climates or when humidity is high. 
Step Three Detail Work
    • Application detail work can begin after roof repairs. Apply a bonding coat of Blue Max when roof is rusty or excessively chalky. 
    • Irregular, sunken, and rough transitions exist between mechanical supports, around roof jacks, and at vent penetrations. These irregular areas can be pre-leveled or pre-smoothed out by applying Blue Max Trowel Grade Roof Transition material with a trowel, bondo squeegee, or chip brush. If applying multiple layers of trowel grade, apply in maximum lifts of ¼ inch. Material can be bulked up with the addition of rubber granules. The smoother transitions created by using Blue Max Trowel will make the flashing work apply more evenly and will trap less water.  Blue Max Trowel needs to cure 24 hours before continuing with further flashing detail work.
    • Loose fasteners need to be tightened down and replaced if stripped out. If fasteners spin when attempting to tighten, this indicates the fasteners are stripped. Removing and replacing with screws one size larger will result in tightly adhering screws in most cases. Missing fasteners also need to be replaced. The fastener tightening and replacement should take place before reinforcing any of the overlapping panel joints on the roof as the process of tightening the screws will frequently pull down tightly the panel edges and slightly reposition the panels in the process. 
    • Fasteners should all be spot coated with Blue Max after tightening. Old holes where fasteners were moved should be filled with Blue Max Trowel Grade sealant or covered with embedded fabric. 
    • On all roof types, overlapped seams between roof sheeting, flashing details, mechanical equipment curbs, pitch pockets, cable mounts and drain transitions need to be counter flashed with polyester fabric and installed into a wet bed of Blue Max. 
    • To achieve this, apply Blue Max at a wet mil rate of 15 mils wet in a path at least 1” wider than the fabric being used. Follow by laying the fabric being used into the wet base material. This is achieved by unrolling the fabric into the wet base material. Smooth out any wrinkles or air pockets with a mini roller or a chip brush sufficient to fully saturate the fabric into the wet underlying material. If necessary due to windy or hot sunny conditions, apply up to an additional 7 mils wet of Blue Max material over the embedded fabric. This is so the fabric is fully saturated with wet material without air pockets or dry edges.
    • Do not forget to use your mil comb to check coating application rate. 
    • Before beginning the first coat of Maximum Stretch, allow embedded flashing details to dry 8 hours minimum and 24 hours in cooler climates or when humidity is high.
    • Alternatively, you can use AMES Self Adhesive Seam Tape to pre-flash seams and details. Care must be taken to seal the fabric face of the seam tape if it is over-lapping onto another piece of seam tape. Allow this area to cure before placing the next piece of overlapping material. Once the self-adhesive seam tape has been installed, it needs to have the fabric face of the self-adhesive tape fully coated with a coat of Blue Max. 
    • If other details not mentioned here exist on your project, contact our Technical Services Dept. for our recommendations in proceeding. 
Step Four Reinforcing Details for Metal Roofs at
    • Interlocking or overlapping seams
    • Exposed and concealed fasteners – screwed and riveted. 
    • Penetration Flashings 
    • Ridge Caps 
    • Valley Flashings 
    • Changes in Slope 
    • Edge Flashings 
    • Adjacent Guttering 
    • Rooftop Mounted Equipment 
Step Five 1st Finish Coat Maximum Stretch
    • Maximum Stretch can be applied with a roller, squeegee or spray application. 
    • Apply Maximum Stretch at a rate of 50 sq. ft./gal (30 mils wet) 
    • Don’t forget to use your wet film thickness gauge to check coating application rate. 
    • Allow to cure a minimum of 8 hours - 24 hours in cooler climates or when humidity is high. 
Step Six 2nd Finish Coat Maximum Stretch
    • Maximum Stretch can be applied with a roller, squeegee or spray application. 
    • Apply Maximum Stretch at a rate of 50 sq. ft./gal (30 mils wet) 
    • Don’t forget to use your wet film thickness gauge to check coating application rate. 
    • Allow to cure a minimum of 8 hours - 24 hours in cooler climates or when humidity is high. 
    • Take an inventory of the remaining materials of Maximum Stretch to determine if excessive materials remain. If excessive materials remain this indicates insufficient wet milage of the product being applied.
    • Continue to apply the balance of the materials to the roof surface until the materials are depleted and the materials calculated for the roof project are all applied. 
Step Seven 3rd Finish Coat Maximum Stretch (optional for Extreme Climates)
    • Recommended for Extreme Climates.
    • Repeat Step Six
Metal Roof Diagram
Pipe and Flashing diagram
Inspection of Seams on metal roof
Maximum Stretch tinted to match roof and customer needs

Post Application

Weather & Drying

AMES® products are best applied between 50° to 90° F (10° to 32° C) on warm dry surfaces. Products start to dry in 2-8 hours. If possible, wait a minimum of 24 hours between coats for best results. Depending on thickness of application and weather the products cure in 24 hours. Low temperatures, high humidity and evening and morning dew will require increased drying/curing time.

Clean Up & Storage

Clean tools and small spills with pure water, no soaps or detergents needed. Store unused product in its original container, tightly sealed and protect from freezing. If unopened, most AMES products will last on the shelf for two (2) years. Dispose of this product in accordance with local, state, or federal requirements.

Health & Safety
      • Use hand and eye protection when using this product
      • Wash with soap and water after contact with skin
      • If eye contact occurs rinse with clean water and seek medical advice if symptoms continue
      • Keep out of reach of Children.
      • CA Prop 65 This product may contain chemical(s) known to the state of California to cause cancer and/or birth defects or other reproductive harm.
Inspection, Testing & Repair
  • Inspect after final coat is dry and repair any obvious deficiencies.
  • Document the substrate conditions before, during and after completion of an AMES Liquid Membrane project. (professional application only)
  • If excessive materials remain this indicates insufficient dry millage of the product was applied.
  • Continue to apply all unused materials to the surfaces until materials are depleted and the calculated dry millage for the project is reached and to recommend product specifications.
  • Follow all warranty guidelines and requirements.

Featured Products

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Maximum Stretch
Blue Max Regular Grade

AMES Technical & Sales Support Staff

AMES trained support team has over 80 years of combined knowledge and experience in the paint and coatings industry. They are available Monday through Friday from 7:30am to 4:30pm PST to answer any questions you have about AMES waterproofing roof coating and sealant products, the application process, becoming a Retailer/Distributor or reaching out to locate contractors and much more.