Interior Filler

Fillers repair holes, cracks and gaps in walls, ceilings, woodwork and masonry so the surface can be smoothed and painted. This category covers ready-mixed and powder fillers, lightweight and deep gap fillers, wood fillers, exterior and masonry fillers, flexible gap fillers and expanding foam.

Choosing a filler

• Interior fillers: for holes and cracks in plaster and plasterboard. Ready-mixed fillers are used straight from the tub, while powder fillers are mixed with water first.
• Depth of fill: check the maximum depth on the pack. Some fillers are for shallow holes of around 5mm, deep gap fillers take around 20mm, and lightweight fillers can fill up to 50mm in one go without sagging.
• Wood fillers: repair dents, splits and nail holes in timber, and come in white or wood shades such as oak and pine. Two-part wood fillers are made for larger interior and exterior repairs.
• Exterior and masonry fillers: made to stand up to the weather on outside walls, render and woodwork.
• Flexible gap fillers: stay flexible to move with joints that open and close.
• Expanding foam: swells to fill larger gaps and voids.

Using fillers

Clean out loose material and dust before filling. Let the filler dry fully, then sand it smooth, and follow the pack for the time to wait before painting. Expanding foam contains isocyanates and an extremely flammable propellant, and may cause allergy or asthma symptoms if breathed in. Wear gloves and eye protection, use it only in a well-ventilated area, and do not use it if you have asthma or allergies. Follow the manufacturer's instructions and safety data for every filler.

For joints that need a seal, see sealants; for sandpaper, browse abrasives.