If you are seeing cracks in your grout or white chalk lines through the grout lines on your balcony, these white marks are also known as efflorescence. It’s fair to assume that water penetration is getting through your grout and pooling under your tiles.
The polyurethane seals also known as silicon seals around the balcony perimeter are also a common area for water to penetrate through if they are split and worn away. Both grout and silicon /polyurethane seals are a maintenance requirement and they should both be inspected annually as they tend to be the main reasons your balcony breaks down from being water tight.
Perimeter Seals Removal
To remove silicon / Polyurethane seals you should be wearing safety gloves and glasses.
Carefully remove the seals using a Stanley Blade with a sturdy handle. Be sure NOT to extend the blade out from the main housing more than 20mm to avoid the blade snapping off. Throughly clean back the area and ensure No Loose threads of seals remain. Apply New Seals cutting the Plastic has application nossel at a 45* angle and then lightly & evenly apply pressure squeezing out the product to replace the seals. You can buy spatulas to remove any excess silicon from most hard ware stores.
Grout Removal, 4-5’ Angal Grinder. Please do not attempt this repair job if you have prior experience using an angle grinder. Please get a professional company in if you are not confident using an angle grinder. (Diamond Blade).
When removing Grout be careful not to grind deeper than the thickness of the tile approx 10mm for most common tiles. We personally would recommend grinding out between 5-8mm deep as deeper can compromise the waterproof membrane below your tiles (if a membrane was applied)!
After grinding out your balcony use a vacuum to suck up all dust particles.
Following the instructions on the bag of the grout you choose be sure to clean off any grout excess or residue thoroughly as this becomes extremely difficult once dry.