Caulking Precast Panels: What, why and how?

Caulking: what, why and how?

Once installed, precast panels need to be “caulked”.

Why?
• To prevent air and water from getting in between.
• So what? If water gets in, it will cause damage: mould etc. – which is not pleasant for those occupying the building.

What is caulking?
• Basically putting a sealant in between the panels, to prevent air and water from getting in.
• Most caulking, when done well, can last up to 20 years, and perhaps much longer.
• Ideally, you should use fire resistant caulking.

How do you do it?
1. Wire brush the panel joints. This means to get a wire brush and scrape the edges of the panel. Why? This helps for the sealant (i.e. the caulk) to stick to the panel. Then get rid of any dust which accrued due to the wire brush. Why? To ensure maximum adhesion.

2. Add prime: where applicable. Why?
◦ Helps the caulk to stick.
◦ Fills in any porous areas, or shallow areas.
◦ Makes it easy to spot areas which need caulking and priming. But mostly, for precast panels, you might not need to prime if you choose the right sealant, and the circumstances do not require it.

Add Backing Rod
• This ensures the sealant will last.
• The rod is shaped in a particular way. Make sure the backing rode retains the hour glass shape. Do not push it in the center – because this will make it lose its concave shave – but push it in from the edges, to retain that shape.

Apply the sealant properly:
• You must have an hour glass shape (notice the red colour). The width must be x2 the depth. It is thin in the middle. If you don’t do this you will compromise the life of your sealant, quite severely.