Q: Tried to gap fill then varnish my 50 year-old ash floor, but timber movement resulted in the gap fill cracking out, and varnish not lasting two years. Is there an alternative, with a lasting gloss finish?
The world is still waiting for the ideal gap filler for floors. Soft, flexible fillers that accommodate movement will smear when the floor is sanded. Hard-setting fillers that can be sanded don’t ‘give’ when the boards move, and will work loose. So we can only suggest that you accept gaps as part of the character of an old timber floor. Polyurethane varnishes specially formulated for floors generally give good service. Ordinary varnishes won’t wear too well, but flooring grade polyurethanes (solvent-based or water-based) stand up well to wear. If your varnish has lasted less than two years, and it was a flooring grade product not exposed to exceptionally harsh conditions, you might like to discuss it with the manufacturer.