Adhesives, Sealants, Grouts & Fillers Guides

What Adhesives, Sealants, Grouts & Fillers covers

This section covers products that stick, seal and fill: tile adhesives, grouts including epoxy grout, silicone and other sealants, and fillers.

The distinction that matters most is between a grout and a sealant, because using one where the other belongs is the most common tiling failure in bathrooms. Grout is a cement-based filler for the joints between tiles. It is rigid and does not accommodate movement. Sealant — usually silicone — is flexible and belongs wherever two different surfaces meet or where movement occurs: the joint between wall and bath, around a shower tray, at internal corners.

Grout those junctions instead and it cracks out within months, because the bath moves slightly when it fills and the wall does not. Water then gets behind the tiles, which is a considerably more expensive problem than the original joint.

Silicone itself divides further. Sanitary grade contains a fungicide and is intended for wet areas. General purpose does not, and grows mould in a shower. Neither is paintable, which surprises people who apply it before painting a skirting or window reveal — for that, a paintable acrylic sealant is the right product.

Browse individual used-for guides

Most searched questions in this topic

How the guides in this section differ

Rigid or flexible. Grout and most fillers are rigid. Sealants flex. Anything that moves needs the flexible option.

Cement grout or epoxy grout. Cement grout is standard, easy to work and porous — it stains and needs sealing in some settings. Epoxy grout is chemically resistant, effectively non-porous and much harder to apply, with a short working time. It earns its place in commercial kitchens, laboratories and heavily used showers.

Adhesive type by substrate and location. Tile adhesives differ for walls and floors, for porcelain versus ceramic, and for interior versus exterior. A standard adhesive on a wet-area floor or a large-format porcelain tile is a common cause of tiles lifting.

Paintable or not. Silicone is not paintable. Acrylic sealants are. Applying silicone where paint has to follow means removing it again.

Product	Use it for	Do not use it for
Cement grout	Joints between tiles	Wall-to-bath and corner junctions
Epoxy grout	Chemical resistance, heavy wet use	Jobs where a long working time is needed
Sanitary silicone	Wet-area junctions, baths, showers	Anywhere it must be painted
General-purpose silicone	Dry-area sealing	Showers and baths — mould risk
Acrylic sealant	Gaps that will be painted	Wet areas and moving joints
Tile adhesive	Fixing tiles, matched to substrate	Structural bonding

Safety, accuracy and next-step checks

These guides follow manufacturer technical data. Where a product’s own specification differs from a general rule, the specification wins.

Points worth carrying:

Ventilate when using solvent-based adhesives and sealants. Curing silicone releases vapours; enclosed bathrooms concentrate them quickly.
Epoxy products can sensitise skin. Epoxy grouts and adhesives cause dermatitis and allergic sensitisation with repeated exposure. Wear suitable gloves and avoid skin contact — once sensitised, it is generally permanent.
Surfaces must be clean, dry and sound. Adhesives and sealants fail on dust, grease and loose material far more often than through product defects.
Respect the movement joint. Wall-to-floor and wall-to-bath junctions, and large tiled areas, need flexible joints. Filling them rigidly guarantees cracking.
Mind the working time. Epoxy grouts and rapid-set adhesives have short pot lives. Mix what you can use.
Cure before wetting. Sealants and grouts need their stated curing period before a shower is used, and rushing it causes early failure.
Cement-based products are alkaline and burn skin with prolonged contact. Gloves, and wash off promptly.
Do not use a bathroom filler as a waterproofing system. Sealant is a joint detail, not a tanking membrane. Wet rooms need proper waterproofing beneath the tiles.

Frequently asked questions

Should I grout or silicone the joint between the bath and the wall? Silicone, in a sanitary grade. That junction moves when the bath fills, and rigid grout cracks out and lets water behind the tiles.

What is epoxy grout used for? Situations needing chemical resistance and a non-porous joint — commercial kitchens, laboratories, heavily used showers. It is harder to apply and has a short working time.

Can I paint over silicone? No. Paint does not adhere to it. Where a joint must be painted, use a paintable acrylic sealant instead.

Why is my shower silicone going mouldy? Usually general-purpose silicone used instead of a sanitary grade containing fungicide, or poor ventilation. Remove it fully and replace with the correct product.

Do I need a special tile adhesive? Often yes. Requirements differ for floors, wet areas, exterior work, porcelain and large-format tiles. Check the adhesive against both the tile and the substrate.

Adhesives, Sealants, Grouts & Fillers Used-For Guides