Application, Coverage and Joint Design

Posted on 03th, Jul 19

Silicone needs to be installed in a dust free environment to avoid any debris to affect to final finish.


Apply at temperatures between 5°C to 40°C. Trim end of nozzle to obtain the correct bead width and place cartridge in applicator gun. Apply sealant in a steady continuous bead ensuring good contact with both sides of the joint to achieve the required adhesion. Tool off with a moistened spatula to finish the joint smoothly before a skin forms, approximately 10 minutes. While the silicone is still wet, clean off any excess. If joint edges have been masked, remove tape whilst the sealant is still wet. If the silicone has dried on the surface, clean with white spirit solvent to soften the silicone then scrape off with a blade. Do not paint over thesilicone.


Coverage will vary according to joint width and depth, as well as the type and method of application. The figures below can be used as a guide for flat joints.

Application, coverage and joint design
Joint Size (mm)width x depth

Linear Metres/

cartridge5mm x 5mm= 12lm

10mm x 10mm= 3lm

20mm x 10mm= 1.5lm

30mm x 15mm= 0.7lm


Where possible, the silicone should be at a 2:1 ratio (width:depth). For internal joints the width and the depth of the joint should be minimum 5mm, and for external joints 10mm. Maximum

joint width is 30mm and depth 15mm. For joints greater than 10mm deep a backing rod should be used. The silicone should only be fixed to two surfaces to allow movement. Hence on flat joints

use a polyethylene tape or release agent to prevent a 3 side adhesion of the silicone. Please observe the following depth of silicone in regard to the width of the joint:

Width Depth

5 – 10mm as width min. 5mm

10mm 8 – 10mm

15mm 8 – 12mm

20mm 10 – 14mm

25mm 12 – 18mm

Ardex st silicone

Pay attention to the following:

To support the antifungal agent, it is recommended to regularly clean the joint and surrounding surfaces with detergents and disinfectants. Dirt and soap that often remains on the joint is ideal grounds for mould growth. Do not use in continuous immersion applications e.g. swimming pools or with waterproofing membranes, use ARDEX ST.

ARDEX SE is water resistant; however rules of undertile waterproofing must still be maintained.

Not suitable for painting over or load bearing construction.

Fresh spills can be removed with a thinner, after curing it is only possible by mechanical means if the substrate is suitable. On painted surfaces and plastic substrates a trial application is recommended. In contact with bituminous substrates or if iodine developing cleaning agents are used, discolouration may occur.

ARDEX SE is not suitable for use with bitumen, marble, natural stone, certain metals (brass, copper) and tar due to discolouration or polyethylene, butyl, EPDM, rubber, neoprene and Teflon due to lack of adhesion.

Builders needs to coordinate the other trade to make sure that all the items internally and externally are complete and the cleaners are preparing all the joints prior to sealing. This will give us opportunity to seal with perfection!