Unit 3: Standard Field Execution Procedures

Why write standard procedures and hold points?

Most insulation failures found after handover are not caused by the material itself but by a step that was skipped or rushed: a surface that was never cleaned of cement laitance, a crystalline coat that dried under the midday sun, or a membrane lap whose underside never melted. A standard operating procedure (SOP) turns a good technician's experience into a repeatable list, and it defines inspection hold points: moments after which work may not proceed to the next step until a supervisor or consultant has inspected and signed off.

This unit covers four systems common in rehabilitation projects and new insulation work. Before you start, review Unit 1 on equipment and Unit 2 on safety, because every procedure here assumes the equipment is calibrated and the work permit and protective gear are in place.

Procedure 1: Crack injection with polyurethane or epoxy resins

Injection treats a crack from the inside instead of covering it from the surface. The first decision is not how to inject but what to inject and why. The European standard EN 1504-5 (external source via the Consumer Safety Center) classifies concrete injection products into three categories: F for force-transmitting filling, D for ductile filling, and S for swelling-fitted filling. That classification summarises the difference between epoxy and polyurethane.

There are two types of polyurethane. A hydrophobic resin needs only a little water to trigger the reaction and water does not become part of the cured material, so it does not shrink or swell with drying and wetting. A hydrophilic resin absorbs water and forms a highly flexible foam or gel, but it may shrink if its surroundings dry out, as the SealBoss comparison (external source via the Consumer Safety Center) explains. In buried tanks and basements that stay damp, hydrophilic may suit; for elements exposed to wet-dry cycles, hydrophobic is usually preferred. The final call belongs to the data sheet.

RAP-1 states that epoxy injection addresses cracks from about 0.05 mm wide, and that fine cracks (about 0.25 mm and below) need low-viscosity epoxy (500 cps maximum). The Sika method statement (external source via the Consumer Safety Center) notes that slow, low-pressure injection is more effective than rapid, high-pressure injection.

Drilling geometry: angle and spacing

The common method is injection through angled drill-in packers rather than surface ports alone. The Sika method statement and the De Neef TB-0055 bulletin (external source via the Consumer Safety Center) call for drilling at 45 degrees, alternating sides of the crack, so that each hole intersects the crack near mid-depth of the element. Packer spacing is about half the element thickness (d/2), and holes are offset from the crack by about half the thickness as well; a 30 cm wall is drilled about 15 cm from the crack. The narrower the crack, the closer the packers.

1. 1

   Diagnose and select the material

   Identify the crack type (hairline, shrinkage, movement, structural) and the water condition (dry, damp, active leak). Choose PU or epoxy using the table above and record the decision. Hold point H1: consultant approval of the material, plus the structural engineer's approval if the crack is in a load-bearing element.

2. 2

   Clean and mark the crack

   Clean the surface on both sides of the crack and mark its path and alternating packer positions. For epoxy, seal the crack face with a temporary surface seal after fitting the ports so resin does not escape.

3. 3

   Drill and fit packers

   Drill about 1 mm larger than the packer diameter, as Sika specifies, at 45 degrees to roughly mid-depth. Blow the dust out of the hole, insert the packer and tighten it.

4. 4

   Flush with water (for polyurethane)

   Flush the crack with water through the packers until the water runs clean; this removes dust and confirms each hole connects to the crack. Epoxy work is generally not water-flushed, and Sika notes that oil contamination needs appropriate pre-flushing. Witness point W1: confirm every packer connects to the crack.

5. 5

   Inject from the bottom up

   On a vertical crack start at the lowest packer; on a horizontal crack start at the narrowest point or one end. Continue until resin appears at the adjacent packer, then move to it. The De Neef bulletin notes injection pressure may range from about 200 to 2,500 psi depending on crack width, concrete thickness and condition, so start low and increase gradually.

6. 6

   Monitor pressure and consumption

   Record for each packer: pressure, quantity, injection time, and resin emerging at the next packer. A sudden pressure rise with no flow may mean a blockage; a sudden drop may mean resin escaping into a void or out of the element. Carry out secondary injection within pot life if needed.

7. 7

   Remove packers and patch

   After full cure per the data sheet, remove the packers or cut them flush, fill the holes with a suitable repair mortar, and grind off the surface seal. Hold point H2: visual check for absence of seepage and, where the engineer requires, a core or non-destructive test as RAP-1 suggests.

Procedure 2: Crystalline slurry system

Crystalline materials react chemically with moisture in the concrete and cement hydration by-products to form crystals that block pores and hairline cracks. Water is therefore not the enemy here but a condition for success. The chemistry is covered on the crystalline waterproofing page; the figures below come from the Xypex Concentrate data sheet (external source via the Consumer Safety Center) and the Xypex coating installation guide (external source via the Consumer Safety Center) as an example of one well-known product, and may differ for others.

1. 1

   Surface preparation

   Remove laitance, paint and oil, and open the pores to the required profile. Treat honeycombing and cracks wider than hairline by chasing them to a U-shaped groove and filling with the dedicated product (Dry-Pac or equivalent). Hold point H1: acceptance of surface profile and cleanliness.

2. 2

   Saturate to SSD

   Spray the surface with clean water until saturated (preferably from the previous night for old, dry concrete), then remove free water immediately before application. The surface should look dark and damp with no sheen.

3. 3

   Mix

   Mix powder and water at the ratio in the data sheet with a low-speed mixer, and never add water later to re-temper a mix that has started to stiffen.

4. 4

   Apply by brush or spray

   Use a semi-stiff nylon brush, a push broom for large horizontal areas, or dedicated spray equipment. Work the material into the pores and keep the thickness even. Check consumption by dividing the quantity used by the area covered.

5. 5

   Second coat

   Where the specification calls for two coats, apply the second after the initial set of the first while it is still green, with light misting in between. Witness point W1: review the consumption log against the required rate.

6. 6

   Moist curing and protection

   Start mist spraying as soon as the coat can take it without washing off, and repeat as the data sheet requires. Protect the surface from direct sun and drying wind with wet hessian or shading, and do not cover it with a fully impermeable material without the manufacturer's approval. Hold point H2: sign the daily curing log before any backfilling, covering or filling.

Procedure 3: Torch-applied bituminous membranes

A modified bituminous membrane (SBS or APP) is bonded by melting its bitumen underside with a torch onto a primed surface. Success depends on three things: a dry, clean substrate, lap width, and melt quality. The material itself is covered in the bituminous membrane guide, and hot-works safety requirements in the safety unit.

1. 1

   Substrate acceptance

   A dry, clean surface free of grease, dust and loose particles, with correct falls to drains. Form a cant fillet where the deck meets the wall so the membrane does not bend at a sharp angle. Hold point H1: acceptance of substrate, falls and details.

2. 2

   Primer

   Apply bituminous primer by brush, roller or spray at the data sheet rate (Insuflex example: 0.2–0.3 L/m²) and let it dry fully before torching; wet primer is flammable and weakens adhesion. Witness point W1: check primer dryness.

3. 3

   Alignment and dry lay

   Lay the rolls out dry first and align them with a chalk line, starting at the lowest point (the drain) and working upward so each roll overlaps the one below in the direction of water flow. Then re-roll them ready for torching.

4. 4

   Torching technique

   Direct the flame at the junction between the substrate and the underside of the roll, melting the backing film until it starts to flow, then push the roll forward. A continuous bead of molten bitumen should appear at the lap edge; the Sika guide mentions about 1 cm, while the CRCA manual limits bleed-out at cap sheet side laps to about 6 mm. No bead means under-melting; heavy bleed-out means excessive heat that can damage the reinforcement.

5. 5

   End laps

   Cut the membrane corner at the end lap at 45 degrees (the Sika guide describes a triangle of 10 cm per side), and heat the mineral surface of the underlying roll thoroughly until the granules sink in. Stagger end laps as shown in the table.

6. 6

   Sealing the laps

   Press the lap while hot with a seam roller. The Sika guide warns against filling or scraping laps with a trowel or spatula because it can damage the membrane reinforcement, so use a hot trowel only where your product data sheet calls for it to finish the edge. Hold point H2: probe every lap with the tip of a cold trowel under light pull to find unbonded areas.

7. 7

   Upstands and details

   Install reinforcing strips at corners, drains and pipes before the main layer, turn the membrane up walls to the height in the specification, and secure the top edge with a metal termination bar and sealant or in a wall chase.

8. 8

   Water test and protection

   Once complete, carry out the water test per the checklist below, then install the protection layer or thermal insulation on top according to the roof design. For the full layer sequence see the roof insulation guide.

Procedure 4: Spray foam with topcoat, and polyurea

Both systems rely on heated plural-component spray equipment (proportioners), whose setup we covered in the equipment unit. Here we give the short field sequence; for more on the materials see the spray polyurethane foam guide and the polyurea guide for Saudi Arabia.

1. 1

   Measure conditions

   Record air and surface temperature, relative humidity and dew point before starting and every two hours. Many data sheets require the surface to be at least about 3°C (5°F) above the dew point. Hold point H1: sign the weather log and confirm the surface is dry.

2. 2

   Test spray

   Spray a sample on a board off the roof to check reactivity, density, colour and cell structure of the foam, or cure time and appearance for polyurea, before spraying the work.

3. 3

   Primer where required

   Apply the approved primer to concrete or metal within its recoat window. On concrete the primer also helps reduce bubbles from gases escaping the pores.

4. 4

   Spray foam in passes

   The SPFA technical bulletin states a minimum single pass on roofs of about 13 mm (half an inch) to reduce blistering, that the maximum is set by the manufacturer, and that 15–30 minutes should be allowed between passes to dissipate heat. Witness point W1: measure thickness with a probe at an agreed frequency.

5. 5

   Topcoat the foam

   Exposed foam degrades under ultraviolet light, so it is covered with a topcoat (acrylic, polyurethane or polyurea) within the time the manufacturer allows and at the required dry film thickness. Hold point H2: measure the topcoat dry film thickness before acceptance.

6. 6

   Spray polyurea

   Spray in cross-hatched passes to reach the specified thickness, respecting the recoat window; in a case documented by KTA the window was 16 hours and the data sheet required sanding beyond it. Aromatic polyurea needs a UV-resistant topcoat if exposed. Hold point H3: visual check for pinholes, and an adhesion test where the specification requires.

Water testing and final acceptance

Water testing of horizontal surfaces usually follows ASTM D5957, a guide that leaves water depth and duration to the project specification. One published example is an American Hydrotech technical bulletin requiring flooding the membrane with at least two inches (about 50 mm) of water for 24 to 48 hours (external source via the Consumer Safety Center), followed by inspection of the slab underside. Confirm structurally that the slab can carry the water load before testing (every 10 cm of water weighs about 100 kg/m²).

A complete acceptance file is the basis of any warranty: at Azl a written warranty is issued whose duration depends on the insulation type and surface condition, detailed in the warranty policy. If seepage appears during the test, go to Unit 4: the troubleshooting guide to diagnose the cause before patching.