ANSWER - Per ANSI A108. 10 Installation of grout in Tilework, it says that all grout joints shall be uniformly finished. Cushion edge tile shall be finished evenly to the depth of the cushion. The grout should be installed at the bottom of the bevel so it is slightly concave.
You want it close to being flush with the tile edges; otherwise, you'll be able to both see and feel the corners of your tile when you walk over it. A higher-level of grout is also much easier to keep clean than grout lines that fall halfway down the tile.
SHOULD GROUT COLOR AND TILE COLOR BE THE SAME? You don't have to pick a grout that matches your tile. In fact, it can be tricky to get an exact match. If you use a grout that requires the addition of water, the color can be affected by how much water is added, how long the grout cures, and other factors.
The main cause for this variation in color is uneven drying of the Portland cement in the grout. There are jobsite conditions and factors which create the conditions for uneven drying and improper cement hydration.
If you really have excessive tile lippage, then normally you might have to remove the affected tiles to perfectly correct the problem. However, if most or all of the grout joints are low, it is possible to fill them but it may not be a practical solution after all.
Uneven tiles
It is also possible that the floor or wall itself is uneven causing the tiles to be uneven. Lippage is the most common uneven tile issue – this is when the edge of a tile is slightly higher or lower than the one next to it. This is often caused by the installer choosing the incorrect pattern or offset.
The short answer is, “no.” You cannot put new grout over old grout. With regard to filling in holes and cracks on the surfaces in our homes, we might compare grout repair to drywall repair. For holes in drywall, we would simply purchase spackle, and fill the hole in.
The common practice is a gap of 2mm or 3mm for wall tiles and between 3mm and 5mm for floor tiles, however it is important to follow the standards within the BS 5385-1 which outline the sizes required depending on the tiles being used and the substrate.
Sanded grout is more durable and stable for interior flooring. Unsanded grout can be prone to severe cracking when pressure is applied to it. Use unsanded grout for walls, countertops, and bathtub enclosures because it clings to fine surfaces and hairline grout lines better than sanded grout.
Look for undertones. Whether you are matching or contrasting, if you have a warm tile, you will want a warm grout color. Likewise, if you select a cool tile color, you want a grout that reads cool. You'll want to test the tile and grout in the same kind of light that will be shining on it in your house.
You can't just slather grout over any porous or uneven surfaces such as split-slate tiles or limestone or similar stone tile that has crevices, holes or open cracks. The grout will fill in those areas and even if you're able to clean them out, you'll never have enough time to clean everything before the grout sets up.
You can apply new grout right over the top of the old grout. To do this, all you need is a grout removal tool. Use the tool to strike out the old grout, making sure the depth is at least 2mm, which is about the thickness of two dimes stacked one on top of the other.
Sika® Grout Ultra
SikaGrout-Ultra is a blend of Portland cement, carefully selected and graded aggregates and Sika Admixtures, enabling it to be self levelling and achieve very high strengths in short times, making SikaGrout-Ultra suitable for critical grouting applications in the most demanding of circumstances.
Deterioration Of Grout Joints
When you look at your grout lines, it should be secure and look whole. However, if you see cracking, crumbling, and deteriorating grout lines, then something is amiss. This could be due to improper installation, or a sign of deeper problems.
The standard cement grout commonly found in most hardware stores and used in most residential homes takes around 48-72 hours to cure. But it is worth pointing out that you need to know how to mix grout the right way. If too much water is added it will obviously take longer to dry and won't do its job as well.
A good grouting job can often mask imperfections in a tile installation, while a poor job can mar an otherwise outstanding tile installation. To look good, the grout must be smoothed so it forms an even border around each tile.
Tiles that have been installed properly should not have any visible damage such as cracks, depressions, holes, specks, spots, and cavities, as they could lead to water damage over time.
When tiles are installed, the edge of one tile can sometimes be slightly higher or lower than the edge of the adjacent tile. This height difference is know as tile lippage and it's not particularly desirable, as you might expect. It doesn't look attractive and in the case of floor tiling, it can create a trip hazard.
Lippage is a situation referring to the difference in elevation between two adjacent tiles that are installed on the floor or wall¹. The larger the size of the tiles (length is more than 450mm), the higher possibility that they are not completely flat.
Benefits of Putting New Grout Over Old Grout
It can also strengthen the surface to increase water resistance and make it less susceptible to impurities. However, you must make sure you are re-grouting with the same type of grout you originally used.
Powdery grout is a common problem and it is caused by not using enough water when initially making the mixture. The only solution for this is to scrap the old and start anew. Dig out the old grout and replace it with properly mixed grout. Ironically, pinholes in grout is caused by too much water in the grout mix.
ANSWER. ANSWER - It is possible to grout over existing grout if there is enough depth to do so. 1/8 inch depth may or may not be adequate depending on the type of grout used. A latex modified grout may work, but you have to properly clean the existing grout to ensure the new grout adequately bonds.