Building expansion and movement joints

The work, step by step

General guidance based on the manufacturer data sheets. Site conditions differ: confirm the system with MCT before you start. Where we do not name a product, ask us and we will confirm the right one.

1. 1

   Step 1: Survey and size the joint

   The joint width must suit the movement and the sealant. All joints must be designed to the relevant standards. For Sikaflex Construction AP, joints are 10–40 mm wide with a 2:1 width-to-depth ratio. For example, joints at 6 m spacing need at least 20 mm width and 10 mm depth (Sikaflex Construction AP p.2).

2. 2

   Step 2: Repair edges and set the depth

   Joint faces must be clean, dry and sound. Cut back weak edges and fill them with repair mortar. Press a closed-cell polyethylene backer rod tightly into the joint to set the depth, and use bond-breaker tape over the backer. Mask the edges (Sika Polysulphide GG p.3).

3. 3

   Step 3: Prime porous joint faces

   Sika Primer PS is the primer for Sika Polysulphide GG on porous substrates such as concrete, brickwork and timber (Sika Primer PS p.1; Sika Polysulphide GG p.3). Brush it on the two joint sides only; wait at least 30 minutes and no more than 3 hours (Sika Polysulphide GG p.3). For Sikaflex sealants, use the primer named in that sealant's own data sheet; ask us, as that primer's data sheet is not on file.

   Sika Primer PS Sika

   It is used on porous substrates such as concrete, brick work and timber. (TDS p.1)

   Temperature stated in TDS

   +5 °C min. / +40 °C max (TDS p.1)

4. 4

   Step 4: Structural joints in walls, roofs and retaining walls

   Sika Polysulphide GG is a two-part sealant for vertical and horizontal expansion joints in high- and low-rise buildings, retaining walls, reservoirs and bridges (Sika Polysulphide GG p.1). Movement up to ±25 % at a 2:1 width-to-depth ratio, for joints 6–50 mm wide (Sika Polysulphide GG p.2).

   Sika Polysulphide GG Sika

   It is used in both vertical and horizontal expansion joints in many types of buildings and civil engineering constructions such as: Retaining walls, Underpasses and tunnels, Reservoirs, Precast concrete elements, Bridges, High and low rise buildings and. (TDS p.1)

   Temperature stated in TDS

   -20 °C min. / +80 °C max (TDS p.2)

5. 5

   Step 5: General building joints on porous substrates

   Sikaflex Construction AP is a one-part elastic sealant for movement and connection joints on porous substrates, indoors and outdoors, with ±25 % movement (Sikaflex Construction AP p.1). Sikaflex AT Facade is a low-modulus option, for joints up to 50 mm wide (Sikaflex AT Facade p.1, p.2).

   Sikaflex Construction AP Sika Request a quotation

   Sikaflex® Construction AP is designed for movement and connection joints on porous substrates as well as indoor and outdoor general sealing applications. (TDS p.1)

   Temperature stated in TDS

   −40 °C to +70 °C (TDS p.2)

   Sikaflex AT Facade Sika Request a quotation

   Sikaflex® AT Facade is designed for joint sealing of movement and connection joints, porous and nonporous substrates such as concrete, brick, steel metals. (TDS p.1)

   Temperature stated in TDS

   40 °C to +90 °C (TDS p.2)

6. 6

   Step 6: Wide or uneven movement, and below-ground joints

   Sikadur-Combiflex SG-20 P is a bonded tape for movement joints, cracks and building parts where settlement is expected, in basements and water-retaining structures (Sikadur-Combiflex SG-20 P p.1). For higher movement, loop the tape into the joint. Bond it with Sikadur-31 DW (Sikadur-Combiflex SG-20 P p.3), which is for experienced professionals only (Sikadur-31 DW p.1).

   Sikadur-Combiflex SG-20 P Sika Request a quotation

   Sikadur-Combiflex® SG-20 P is used for sealing: Movement joints, Construction joints, Pipe penetrations, Cracks, Building components where differential settlement is expected Sikadur-Combiflex® SG-20 P is used for the following areas:, Tunnels. (TDS p.1)

   Temperature stated in TDS

   +40 °C -30 °C (TDS p.2)

   Sikadur-31 DW Sika Professionals only Request a quotation

   Structural adhesive for bonding: Concrete elements, Hard natural stone, Ceramics, fibre cement, Mortar, Bricks, Masonry, Steel, Iron, Aluminium, Wood. (TDS p.1)

   Temperature stated in TDS

   +10 °C to +30 °C (TDS p.1)

7. 7

   Step 7: Tool and cure

   Tool the sealant firmly against the joint sides (Sikaflex Construction AP p.3). Polysulphide must be fully cured before it is kept under water (Sika Polysulphide GG p.2).

Steps and product facts are taken from the manufacturer data sheets (page cited). Products are named only where the data sheet confirms the use; quantities follow a site visit or photos. General guidance: check the data sheet or ask us before you start.