Canadian Roofing Reference Manual

There are many materials that can be used for waterproofing including:

• Asphalt built-up membranes
• Hot liquid-applied modified asphalt membrane
• Modified bitumen sheet membranes
• Thermoset (Butyl or EPDM) membranes
• Thermoplastic (PVC) membranes
• Fluid-applied elastomeric materials
• Bentonite
• Metallic waterproofing
• Cementitious waterproofing
• Crystalline waterproofing

Of these materials, several materials are commonly used in both roofing and waterproofing.

12.1.5.1 Asphalt built-up membranes

Asphalt built-up waterproofing membranes are composed of alternating layers of asphalt and reinforcing ply sheets. Ply sheets may be either glass fibre or organic felts installed in phased applications. The number of plies of membrane depends on the hydrostatic pressure head that needs to be resisted.

Asphalt built-up waterproofing membranes are composed of alternating layers of asphalt and reinforcing ply sheets. Ply sheets may be either glass fibre or organic felts installed in phased applications. The number of plies of membrane depends on the hydrostatic pressure head that needs to be resisted.

Asphalt built-up waterproofing membranes are used to resist water penetration on those areas of structures that are exposed to hydrostatic pressure. These include walls below grade, promenades, shower pans, bridges and roadbeds, and other sub-grade construction.

Asphalt built-up waterproofing membranes generally should not be installed when ambient temperatures are below 0°C (32ºF). Installation should not proceed when moisture is present.

The completed membrane should not be exposed to prolonged periods of sunlight before covering or backfilling to prevent slipping and softening of the bitumen.

Surface Preparation

The substrate must be structurally sound. Surfaces to receive asphalt built-up membrane waterproofing must be broom clean, adequately dry, reasonably smooth and free of dust, dirt, voids, and sharp projections. Cracks in the substrate that are 1.6 mm (1/16 in) or wider should be reinforced with an additional ply of reinforcing felt, mat, or fabric applied with hot asphalt prior to the application of the primary membrane system.

Application

• Prime the surface with asphalt primer as recommended by the manufacturer of the waterproofing materials.
• Reinforce all inside and outside corners with two 300 mm (12 in) wide plies of reinforcing material centered on the corner.
• Apply the required number of plies of reinforcing felt or mat using the phased method of application.

Under no circumstances should all plies be installed in shingle fashion in one complete operation.

• Apply asphalt in a continuous, firmly bonding film, and with sufficient pressure to assure good adhesion.
• For horizontal applications, consideration should be given to installing one-half of the total number of plies shingle fashion in one direction, then installing the remaining plies shingle fashion in a direction across the underlying plies.
• For vertical applications, orient the reinforcing felt or mat vertically in conveniently workable height lifts, fastening the reinforcing felt or mat at the top of each course. Generally, vertical applications require double mopping of asphalt to achieve complete coverage and a continuous film.

Flashing

• Flash all penetrations with two plies of reinforcing material. Use the base flashing material as recommended by the membrane manufacturer at the intersection of vertical and horizontal surfaces.

Protection Course

• Cover the membrane with a protection course as recommended by the membrane manufacturer.
• Install the wearing surface or backfill within 24 to 72 hours after completion of the waterproofing membrane. If surfaces are exposed to the sun or if the waterproofing is being installed during extremely hot weather; the installation of the protection course and backfilling should occur within 24 hours.

12.1.5.2 Hot Liquid-Applied Modified Asphalt Membrane

Hot liquid-applied polymer modified asphalt consists of refined asphalt modified with synthetic rubbers. The material is typically supplied in 22.7 kg (50 lb) cakes wrapped in polyethylene film, shipped in containers that weight 181 kg to 272 kg (400 lb to 600 lb). The cakes are melted in a double jacketed oil bath kettle and applied as a liquid that quickly cools to form a solid membrane material.

Hot liquid-applied modified asphalt membrane waterproofing is used to waterproof basement slabs, plaza decks, parking decks and ramps, pools, reservoirs, mechanical equipment rooms, walls below grade, planters, and other below grade construction.

Hot liquid-applied polymer modified asphalt membrane waterproofing should generally not be installed when temperatures are below manufacturer specifications. Installation should not proceed when moisture is present.

Hot liquid-applied polymer modified asphalt membrane waterproofing cannot be left exposed to prolonged periods of sunlight and must be covered to protect it from ultraviolet light.

Surface Preparation

• The substrate must be structurally sound. Surfaces to receive hot liquid applied modified asphalt membrane waterproofing must be broom clean, adequately dry, reasonably smooth and free of dust, dirt, voids, cracks, sharp projections, oil, and grease.
• Cracks 1.6 mm (1/16 in) or wider should be reinforced with an additional ply of reinforced membrane prior to the application of the primary membrane. The reinforcement may consist of polyester, butyl, fibreglass or other compatible fabrics.

Application

• Prime the surface with asphalt primer as recommended by the manufacturer of the waterproofing materials.
• Reinforce inside and outside corners, cracks, and construction joints with a 150 mm (6 in) wide piece of reinforcing sheet embedded in hot liquid-applied modified asphalt.
• Fillet cant strips are required by some manufacturers at the base of some vertical flashing conditions.

12.1.5.3 Modified Bitumen Membranes

Modified bitumen membranes are composed of modified asphalt and one or more layers of reinforcing material. They can be installed by torching on to the substrate or by mopping with hot asphalt. Some membranes are self-adhering.

Modified bitumen membranes waterproofing should generally not be installed when the temperatures are below 4.4°C (40ºF). Installation should not proceed when moisture is present.

Unsurfaced SBS modified membranes cannot be left exposed to prolonged periods of sunlight and must be covered to protect it from ultraviolet light.

Surface Preparation

• The substrate must be structurally sound. Surfaces to receive modified asphalt membranes must be broom clean, adequately dry, reasonably smooth and free of dust, dirt, voids, cracks, sharp projections, oil, and grease.
• Cracks 1.6 mm (1/16 in) or wider should be reinforced with an additional ply of reinforced membrane prior to the application of the primary membrane. The reinforcement usually consists of a reinforced modified base sheet.

Application

• Prime the surface with asphalt primer as recommended by the manufacturer.
• For torch-applied sheets, heat the underside of the sheet exercising care not to overheat the sheet.
• Roll the membrane into the softened bitumen in a manner that minimizes voids and wrinkles, exercising care to ensure proper lap alignment.
• Seal membrane laps together as the sheet is being applied.
• For self-adhered applications, remove the release paper from the underside of the sheet, and roll the sheet directly onto the primed substrate in a manner that minimizes voids and wrinkles.
• Exercise care to ensure proper lap alignment.
• Seal membrane laps together as the sheet is being applied and apply pressure to both the sheet and lap area to assure an adequate bond.

Flashing

• Use the base flashing material as recommended by the membrane manufacturer at the intersection of vertical and horizontal surfaces (in many instances, the same membrane material used in the field of the roof is also used as the base flashing material).

Protection Course

• Cover the membrane with a protection course as recommended by the membrane manufacturer. Install the wearing surface or backfill within 24 to 72 hours after completion of the waterproofing membrane.

12.1.5.4 Thermoset membranes

Thermoset waterproofing membranes consist of factory fabricated sheets that are 1.1 to 1.5 mm (45 to 60 mils) thick. Sheets are normally available in sizes up to 15 m (50 ft) wide and up to 46 m (150 ft) long. Sheet sizes should be limited to the sizes which can be handled easily for the project.

Thermoset membranes are used to resist water penetration on areas exposed to hydrostatic pressure, including walls below grade, promenades, bridges, roadbeds, reservoirs, pools and other below grade construction.

Thermoset waterproofing membranes should not be used in contact with bituminous cements and mastics. Thermoset membrane sheets cannot be used in contact with certain acids, oils, and solvents. Contact the membrane manufacturer for specific details concerning these contaminants.

Surface Preparation

• The substrate must be structurally sound. Surfaces to receive a thermoset membrane waterproofing must be broom clean, adequately dry, reasonably smooth and free of dust, dirt, voids, cracks, and sharp projections.
• Cracks 1.6 mm (1/16 in) or wider should be reinforced with an additional layer of membrane prior to the application of the primary membrane.

Application

• Lay the membrane on the substrate or a flat surface and allow it to relax for a minimum of one-half hour before use.
• Clean membrane surfaces to be bonded of any dust, dirt, and release agents as recommended by the manufacturer.
• Apply adhesive to both the sheet and the substrate at a rate as recommended by the manufacturer; and allow it to dry until it does not stick to a dry finger.
• Position the membrane on the substrate without stretching, in a manner that minimizes voids, wrinkles, and entrapped air.
• Clean overlapping areas between sheets and join the sheets with recommended adhesives.

Flashing

• Flash the intersection of vertical and horizontal surfaces, and all penetrations with the base flashing material recommended by the membrane manufacturer.

Protection Course

• Avoid all unnecessary traffic on the completed membrane. Cover the membrane with a protection course as recommended by the membrane manufacturer.
• Install the wearing surface or backfill within 24 to 72 hours after completion of the waterproofing membrane.

12.1.5.5 Thermoplastic Membranes

Thermoplastic waterproofing membranes consist of factory-fabricated sheets of reinforced polyvinyl chloride. Sheets are normally 0.5 to 1.6 mm (20 to 60 mils) thick, 1.8 m (6 ft) wide and up to 30 m (100 ft) long. Large sheets may contain factory splices. The sheets are normally black or grey in colour.

Thermoplastic waterproofing membranes are used to resist water penetration on those areas of structures that are exposed to hydrostatic pressure. These include walls below grade, promenades, shower pans, and other below grade construction.

Thermoplastic membranes should generally not be installed when ambient temperatures are below 4.4°C (40ºF). If installation at lower temperatures is necessary due to project conditions, consult the manufacturer for specific cold weather application recommendations.

Installation should not proceed when moisture is present.

The completed membrane should not be exposed to prolonged periods of sunlight before covering or backfilling to prevent slipping. Thermoplastic materials are not compatible with polystyrene insulation products and certain asphalt-based products.

Surface Preparation

• The substrate must be structurally sound. Surfaces to receive thermoplastic membrane waterproofing must be broom clean, dry, smooth, free of dust, dirt, voids and sharp projections.
• Cracks 1.6 mm (1/16 in) or wider should be reinforced with an additional ply of the membrane prior to the installation of the membrane system.

Application

• Lay the membrane on the substrate and allow it to relax before use.
• Install the sheets in an adhesive recommended by the manufacturer.
• Keep the adhesive away from the lap or splice areas.
• Position the membrane on the substrate so that it minimizes voids and wrinkles that can trap air.
• Heat weld all laps.

Flashing

• Flash the intersection of vertical and horizontal surfaces, and all penetrations with the base flashing material recommended by the membrane manufacturer.

Protection Course

• Avoid all unnecessary traffic on the completed membrane. Cover the membrane with a protection course as recommended by the membrane manufacturer.
• Install the wearing surface or backfill within 24 to 72 hours after completion of the waterproofing membrane.

12.1.5.6 Hot Rubberized Asphalt

Hot rubberized material is applied to wall surfaces or bridge decks in order to waterproof them.

There are basically 2 major steps in the procedure for applying hot rubberized material. These steps are:

1. Estimate materials required.
2. Apply the surface waterproofing.

Estimating Materials

The types and amounts of materials required for a particular job will depend upon two factors:

1. Manufacturer’s specifications
2. Job specifications

The first step in estimating material requirements is to determine the area which needs to be covered with hot rubberized material. Take all expansion joints and other details into consideration.

Material requirements will vary from application to application, depending on both manufacturer and job specifications. Always consult both sets of specifications before beginning a job.

Generally, the materials required for all hot rubber applications include:

• Primer
• Reinforcing sheets
• Membrane
• Protection boards

Therefore, there are 4 major steps in the procedure for estimating materials. These steps are:

1. Estimate the amount of primer required.
2. Estimate the number of reinforcing sheets required.
3. Estimate the amount of membrane required.
4. Estimate the number of protection board required.

Estimating the Amount of Primer Required

All surfaces requiring coverage with a membrane must be primed. One litre of primer will cover an area of approximately 5 to 10 m². (One gallon of primer will cover an area of approximately 300 to 600 ft2). Note, however, that the amount of primer required will depend upon the porousness of the surface being covered, and manufacturers specifications.

Estimating the Reinforcing Sheets

Reinforcing sheets are needed to cover all cracks, expansion joints, and direction changes on the surface. Surface cracks must be covered with a spun polyester reinforcing fabric. This type of fabric is available in rolls of 183 m (200 yard) lengths and widths of 150 mm, 300 mm or 1000 mm (6 in, 12 in, or 39 in).

Construction joints and cracks which are between 1.6 mm to 6 mm (1/16 in to ¼ in) in size must be covered with a 47-mil elastomeric reinforcing sheet. This type of sheet is also used to cover areas where the surface changes direction and no movement occurs.

Elastomeric sheets are a synthetic rubber blend of butyl and EPDM. Rolls of elastomeric sheets are available in 23 m (75 ft) lengths and widths of 150 mm (6 in), 225 mm (9 in), 300 mm (12 in), 450 mm (18 in), 600 mm (24 in), 900 mm (36 in), and 1220 mm (48 in).

Applying the Membrane Waterproofing

The application of hot rubberized material to a surface is similar to the installation of a rubber roof covering. There are basically 4 steps in the procedure for applying the surface covering. These are:

1. Apply the primer
2. Heat the membrane
3. Apply the reinforcement
4. Apply the membrane

Applying the Primer

Primer must be applied to all surfaces which will be receiving the membrane. Before applying the primer, ensure that all of the following conditions are met:

• Other trades are finished with their installations.
• The work done so far is of an acceptable quality.
• The surface is clean and dry.
• The concrete is fully cured.
• The temperature is not below manufacturers recommended.

Priming is necessary to ensure good adhesion between the rubberized membrane and the surface. Primer can either be sprayed on or applied with a brush or roller. Primer is applied at a rate recommended by the manufacturer. Allow the primer to dry before applying the reinforcement.

Heating the Membrane

The membrane must be heated and melted in a double walled, indirectly fired kettle.

The kettle must be equipped with a mechanical agitator to stir the membrane during melting. Heat the membrane to a temperature of 204°C (400°F). Do not overheat.

Heat only the amount of membrane that will be used that day. Drain the excess membrane from the kettle at the end of the day.

Applying the Reinforcement

All details must be reinforced with a continuous layer of liquid membrane before the reinforcing sheet is applied. This reinforcing membrane must be 300 mm (12 in) wide and 3 mm (1/8 in) thick. Apply reinforcement to all cracks, construction joints, expansion joints, and locations where the surface changes direction.

Procedures for applying the reinforcing sheet are as follows:

1. Estimate the amount of membrane required.
2. Apply the membrane with a trowel, squeegee, or sprayer. Wear protective clothing as the membrane is HOT.
3. While it is warm, embed the reinforcing sheet.
4. Center a 150 mm (6 in) wide layer of spun polyester fabric on surface cracks. Embed the entire length of the crack on the membrane.
5. Center and embed a 225 mm (9 in) wide layer of 47 mil elastomeric sheets on:
   1. Construction joints with cracks between 1.6 mm – 6 mm (1/16 in – ¼ in) wide.
   2. Locations where the surface changes direction with no possible movement. When laying elastomeric sheets, ensure that they are smooth and free from wrinkles or air pockets.
6. Press the membrane firmly in place.
7. Reinforce cracks or joints, which are 6 mm – 12.7 mm (1/4 – ½ in) wide, in the manner as explained above. However, use 63 mil elastomeric sheets instead of 43 mil elastomeric sheets.

Use 63 mil elastomeric sheets to reinforce expansion joints which are 12.7 mm – 50 mm (1/2 in to 2 in) wide and to reinforce areas where the surface changes direction with possible movement. Apply reinforcement sheets so that they lap down into the crack at a distance equal to the width of the crack.

Example:

On a 50 mm (2 in) wide crack or joint, the reinforcing sheet must extend 50 mm (2 in) down into the crack. Press the reinforcement firmly into the membrane on the top flat surface.

Applying the Membrane

After the reinforcement, has been applied, the entire surface is covered with the hot rubberized membrane.

1. Apply the membrane with a trowel, squeegee, or spray.
2. Coat the entire surface with the membrane until an average thickness of 4.8 mm (3/16 in) is obtained.

Note: The membrane must not be less than 3 mm (1/8 in) thick.

Remember to wear protective clothing when installing the hot membrane.

If job specifications demand a complete covering of reinforcement, the membrane must be applied in two coats. First, coat the surface with a 2 mm (1/12 in) thick layer of membrane. While the membrane is warm, embed spun polyester reinforcing fabric. The rolls of fabric should be 1 m (39 in) wide and all laps must be a minimum of 50 mm (2 in).

1. Next, apply a second coat of membrane over the fabric. The second coat must be a minimum 2 mm (1/12 in) thick and be applied in a continuous manner. This process will sandwich the reinforcement.
2. Upon completion of the process, cover the membrane with a protective board. The protective board will protect the membrane from damage due to backfilling or construction traffic. When laying protective boards, ensure that all joints are tight. This precaution will ensure continuous protection of the membrane.

12.1.5.7 Self-Adhering Modified Bitumen Membrane

The procedures for installing modified bitumen membranes on foundation walls or parking garages are very similar to the procedures for installing the product on a roof deck. The main difference is that the membrane is applied vertically as well as horizontally. The steps for installing self-adhering modified bitumen membrane waterproofing are:

1. Estimate material.
2. Prepare the surface.
3. Install the membrane.

The different manufacturers of modified bitumen membranes have varying specifications for their product, but the basic steps remain the same. It is recommended to always consult manufacturers for specific job applications.

Estimating Materials

The procedure for estimating the material requirements to install a self-adhering Modified Bitumen waterproofing system can be divided into 2 basic steps. These are:

1. Calculating quantities.
2. Estimating materials required.

Calculating Quantities

The dimensions of the walls, footings or deck surfaces are either physically measured or taken from blueprints. The dimensions that are required may include:

• Wall area (length x height)
• Footing perimeter (length x width)
• Expansion joint lengths
• Area of the deck surface

Be sure that all calculations are accurate.

Estimating Materials Required

All surfaces that are to be covered with waterproofing membrane must be primed. The manufacturer will recommend the amount of primer that will be required.

Rolls of self-adhering modified bitumen are packaged in rolls, 30 m (98 ft) long and 300 mm or 1000 mm (12 in or 39 in) wide. Torch on membranes are available in rolls 1 m (39 in) wide and lengths of 4.9 m, 7.9 m, 9.8 m (16 ft, 26 ft or 32 ft). Allow for 75 mm (3 in) side laps and 150 mm (6 in) end laps.

All expansion joints or cracks over 6 mm (1/4 in) wide must be reinforced. The reinforcement is a combination of elastomeric modified bitumen polyester tissue and root repelling agent. Rolls are available in 9.8 m (32 ft) lengths and widths of 450 mm (18 in).

Mechanical fasteners must be placed every 300 mm (12 in) o.c. around the top of the walls. They must also be of sufficient length to penetrate the surface at least 19 mm (3/4 in).

Preparing the Surface

There are 2 steps to follow before the installation of a self-adhering Modified Bitumen waterproofing membrane can begin. These are:

1. Inspecting the substrate.
2. Priming the surface.

Inspecting the Substrate

All surfaces to be covered with a membrane must be inspected to ensure that they are smooth, clean and dry. Concrete surfaces must be allowed to cure anywhere from 8 days to 3 weeks. Foundation walls must be brushed clean.

At the base of the foundation wall, where it joins the footing, a concrete tapered cant strip must be in place for drainage.

Ensure the surface temperature is at least 10°C (50°F). If not, warm with a torch. The material must be stored at the same temperature, with the rolls carefully resting on end.

Priming the Substrate

Primer is applied to all surfaces to which the membrane is being applied. Priming ensures good adhesion. Only prime as much area as can be covered with the membrane the same day. The primer must be a combination of asphalts and selected oils to provide fungicidal properties. Use only primers recommended by the membrane manufacturer.

Apply the primer with a brush or roller at a rate of 0.4 l/m² (one gallon/square). Allow to dry completely.

Installing the Membrane

The procedures for installing self-adhering modified bitumen membranes for waterproofing are very similar to the procedures for installing them on roof decks. Installation must only be done in dry weather conditions and when the surface temperature is above 10°C (50°F). The procedures for installing the membrane can be divided into 3 steps. These are:

1. Installing the reinforcement.
2. Installing the self-adhered membrane.
3. Installing the drainage device (weeping/drainage tiles).

Installing the Reinforcement

Center a layer of self-adhering reinforcement membrane over all expansion joints and cracks over 6 mm (1/4 in) wide. The membrane should be at least 150 mm (6 in) wide. Peel off the backing, in the same way that you might remove the backing on a bandage. Wrap the backing around a broom handle. As you turn the broom handle, pull the backing off of the membrane.

Continue to turn the broom and pull the roll over the center of the crack. Using a hand roller, roll the top surface of the membrane with moderate pressure to bond the membrane to the surface.

Installing the Self- Adhering Membrane

Self-adhered membranes are applied in 2 – 3 m (6 1/2 – 10 ft) lengths. Peel back approximately 50 mm (2 in) of the release paper. Starting at the bottom, position the membrane in place. Using a broom handle as previously mentioned, turn and peel off the backing paper while simultaneously rolling the membrane roll up the surface.

Ensure that the membrane is pressed firmly in place with a hand roller. Pay special attention to rolling the joints. Continue to apply the next rows in a similar vertical manner, ensuring a minimum 75 mm (3 in) side lap. The membrane must extend above the grade level of the ground. Fasten the membrane to the surface above grade level 300 mm (12 in) o.c.

On flat surfaces, the membrane must be lapped a minimum of 75 mm (3 in) on the sides and 150 mm (6 in) on the head. The main membranes should be cut off to extend 100 mm (4 in) up the wall.

Apply self-adhered membrane up the wall, lapping to the deck surface at least 100 mm (4 in). The self-adhered membrane should extend up the wall to the required height. As an example, for shower rooms, the membrane should extend up the wall at least 1600 mm (63 in). After installing the membrane, lay a layer of suitable protection board over the membrane before the concrete floor is poured.

Installing the Drainage Device

A drainage pipe (weeping tile) must be laid around the entire perimeter, along the base of foundation walls at the footing. The pipe must be laid with a positive slope to ensure all water will free flow to the city storm sewer system. The excavation should then be backfilled with washed gravel to provide a drainage bed. Effective drainage will prevent hydrostatic pressure from developing. Hydrostatic pressure is a force exerted by liquids at rest.