CRC Builders Fill is a permanent repair or filler that can be used on a variety of surfaces. It is ideal to repair gaps, cracks, holes, dents or replacing rotten or missing wood sections. CRC Builders Fill is smooth and easily applied, with exceptional adhesion. It can be moulded to shape and trimmed while still semi hard. The unique ceramic additive makes CRC Builders Fill a superior filler. It cures by a chemical reaction so it will not shrink like common air drying fillers, will not rot and is waterproof. Once set it can be cut, sawn, drilled, chiselled, nailed, filed, sanded painted and screwed into.