The best grout for large gaps (over 18 18" up to 34 34") is sanded cement-based grout. The added sand acts as an aggregate that prevents the grout from shrinking and cracking as it cures. For the ultimate in durability, stain resistance, and zero shrinkage, 100%-solids epoxy grout is the premium choice.
Sanded & Unsanded Grout
Generally, unsanded grout is used for tile applications with narrower grout joints, from 1/16” to 1/8”. The additional structure of sanded grout is needed for wider grout joints from 1/8” to 5/8” and some even can go as wide as 1”.
Grouting isn't a one-size-fits-all solution. Here are some additional factors to consider: – Large Gaps: Gaps exceeding ½ inch might require backfilling with a suitable material like concrete or specialized filler before grouting.
The short answer is no; you cannot simply smear new grout directly over old grout. Because grout is a porous mixture that needs a certain depth to bond, new grout will not stick to the old surface and will crack, flake, and fall out within a few weeks.
Depending on the grout type, grout can generally fill gaps ranging from 1161 over 16 end-fraction𝟏𝟏𝟔 of an inch up to 58five-eighths𝟓𝟖 of an inch. For gaps wider than 18one-eighth18 of an inch, sanded or epoxy grout is strictly required. Gaps exceeding 12one-half12 inch are too large for structural integrity and will crack; they require backer rod or mortar to fill the bulk of the void.
If you are grouting a large area, start by mixing only a small portion of grout. This will ensure your supply of grout stays moist and usable and does not dry out and become crumbly.
Builders often skip sealing grout to cut costs, save time, and avoid returning to the job site. Additionally, many modern polymer-modified grouts are stain-resistant, and sealing un-cured grout can trap moisture. Some installers even use it as an upsell or exclude it because sealing can leave a hazy film on certain tiles.
Grouting mistakes make your tile project look less than perfect—despite all of your hard work. Common errors include adding too much water to the grout mix, holding the grout tools wrong, and neglecting timing.
The new grout can be applied right over the top of the existing grout. You will need a grout removal tool, which is a small tool with a sharp blade capable of chipping away the grout. To remove the top layer of grout, simply chip out the old grout to a depth of at least 2mm (about the thickness of two dimes together).
Neither sanded nor unsanded grout is inherently better; the right choice depends entirely on your tile spacing and the type of material you are installing.
Sanded grout is best for joints of 1/8 in. or larger. The sand gives sanded grout a grittiness that can help improve traction when used on floors and gives extra stability when installing heavier tiles on walls. This exceptional strength also means sanded grout offers superior resistance to shrinking and cracking.
One very common regrouting mistake is spreading the grout unevenly between the tiles, forming “peaks and valleys.” This makes for a noticeably messy, uneven grouting job, and it can ruin the look of a tile wall or floor. The fact that grout shrinks as it dries makes this problem even harder to avoid.
Caulk alone is only reliable for gaps up to 14one-fourth𝟏𝟒 inch (6 mm) wide. For anything larger, the caulk will sag, shrink, or crack. To fill wider gaps properly, you must use a backing material first so the caulk only needs to bridge a 14one-fourth14-inch depth.
Spread grout over the tiled area
Make sure you completely fill the gaps between the tiles as you go. Work with a smooth and consistent action. You should press hard enough to fill the gaps with grout, but don't press so hard you make the grout bulge up between the tiles.
For 12x24 inch tiles, a 1/8-inch grout joint is generally considered the best, most versatile, and standard choice, particularly for floors to handle minor irregularities. If using rectified (precisely cut) tile, a narrower 1/16-inch joint is acceptable for a modern, sleek look, while non-rectified tiles may require 3/16-inch for a better finish.
SPECTRALOCK® 1 Pre-Mixed Grout
A professional-grade, pre-mixed grout offers the superior strength and performance of an epoxy grout without the hassle of mixing.
No, you cannot simply apply a new layer of grout directly over existing grout. Because grout is porous and thin layers cannot bond to a cured, dirty surface, the new grout will crack, crumble, and flake out almost immediately.
Yes, applying a second coat of grout is entirely possible, but you must take proper precautions to prevent the new layer from chipping or flaking off.
Yes, you generally must remove old grout before regrouting. New cement-based grout cannot bond to old, dirty, or crumbling grout and will flake off very quickly. You need to remove about 12one-half12 to 23two-thirds23 of the tile's depth to give the new grout a solid layer to anchor into.
Achieving a flawless grout job comes down to proper preparation, exact mixing ratios, and impeccable timing. The most critical mistakes to avoid include: using the wrong grout type for your joint size, over-watering the mixture, and wiping the tiles down too early.
Builders often skip sealing grout to cut costs, save time, and avoid returning to the job site. Additionally, many modern polymer-modified grouts are stain-resistant, and sealing un-cured grout can trap moisture. Some installers even use it as an upsell or exclude it because sealing can leave a hazy film on certain tiles.
Bleach can also weaken grout and damage any sealer that's been applied. Over time, bleach makes grout more porous, which means it gets dirty even faster. Why to avoid: Like bleach, ammonia strips away protective sealers. It can also discolor grout and weaken the integrity of the grout over time.
For standard cement-based grout, you should wait at least 48 to 72 hours before applying a sealer. This allows the grout to cure completely so that trapped moisture can evaporate.
The best grout sealers are Miracle Sealants 511 Impregnator and Aqua Mix Sealer's Choice Gold. Both are penetrating sealers that absorb deeply into porous cement grout, forming an invisible, breathable barrier against water and oil-based stains without altering the grout's natural color.
If you don't seal standard cement-based grout, it acts like a sponge. The porous material absorbs water, soap scum, and everyday spills, which leads to permanent discoloration, foul odors, and accelerated degradation. Over time, trapped moisture can spawn mold and mildew beneath the surface, potentially loosening the tiles.