Buildings are most vulnerable to leakage at the joint. The purpose of joint sealing is to create a secure barrier to protect against water ingress, an ever-present and potentially damaging threat on any areas where structural integrity could be compromised.
Joint sealing must always be capable of accommodating any anticipated movement, expansion and contraction caused by any load, moisture or thermal changes.
When it comes to watertight concrete systems, consideration must be made to both types of joints; construction joints (static) and movement joints (flexible).
Construction joints, or day joints, are created either to divide areas of the structure into separate concrete sections for work/pour scheduling, or as a structural measure to transfer load. Movement joints are included to accommodate any expected lateral movement between adjacent parts of a structure. These two different types of joint must be handled differently.
Water will always find a way somewhere, whether it’s in, over, around, under or through, so preventative measures need to be implemented to provide long-lasting protection.
Prevention is better than cure
Because water is generally unable to penetrate a building’s main structure, its joints between these that are its weak spots.
If joints aren’t sealed at all or sealed inadequately, water will find a way in and any water ingress can cause both immediate and long-term issues, from damp to full flooding of below ground areas, including damage to anything that is in the area at the time – documents, electronics, furnishings, finishes and art.
Only correctly-specified and professionally-applied, high–quality materials will keep a building or structure protected during its lifespan and with so many materials on the market, it’s important to correctly design the correct system and specify the correct ones.
With a range of materials and systems for different requirements and applications, the five most common are explored below:
- Hydrophilic Strip (SikaSwell®) – a flexible water–stop for use at construction joints and penetrations in underground reinforced waterproof concrete structures which expands when exposed to water
- Metal waterbar (Sika® Metalsheet-FBV Set) – a galvanised metal sheet water-stop coated on one side to increase its adhesion to fresh concrete and prevent water ingress at construction joints
- Post–applied flexible strip (Sikadur® Combiflex® SG System) – a high performance system for construction, expansion and connection joints, as well as cracks which allow irregular and high movement in multiple directions
- PVC/Elastomer/Special waterbars – available in a range of materials, types, shapes and profiles, they are suitable for different structures and joint-sealing applications. Use in both construction and movement joints
- Reinjectable Hose (SikaFuko VT-1) – an injectable hose system with integral ‘valves’ for sealing and possibly resealing construction joints. Used with a range of injectable liquids to retrospectively seal joints through the life of a structure.
By seeking expert advice at the design phase, the correct solution will be specified in order to protect the long-term structural integrity of building. The costs of rectifying a leak if the joints have not been correctly specified and sealed can be many times (add a couple of zeros) the cost of incorporating them early on.