How to repair cracks in walls for a smooth and secure finish

Person fixing crack in white wall with filler and filling knife
(Image credit: Getty Images)

If you’ve got unsightly, unwanted cracks in your home you need to know how to repair cracks in walls to stop them getting any worse. Hairline or small cracks in plaster, concrete or mortar are straightforward to fix for any DIYer, and typically not something to worry about.

But if you have larger cracks you might want to think about plastering walls after filling to get a smooth, good-looking finish. But larger cracks in plaster might be hiding an underlying problem that needs the professional eye of a surveyor to determine the issue.

Here we reveal how to remedy everyday cracks in walls along with expert insight on how to spot what might be structural issues.   

How to repair cracks in walls 

Ian Rock
Ian Rock

Chartered surveyor Ian Rock MRICS is a director is and the author of eight popular Haynes House Manuals, including the Home Extension Manual, the Self Build Manual and Period Property Manual.

Ian is also the founder of Zennor Consultants. In addition to providing house surveys, Zennor Consultants provide professional guidance on property refurbishment and maintenance as well as advising on the design and construction of home extensions and loft conversions, including planning and Building Regulations compliance.

Steve Jenkins

Steve Jenkins is a freelance content creator with over two decades of experience working in digital and print and was previously the DIY content editor for Homebuilding & Renovating. 

He is a keen DIYer with over 20 years of experience in transforming and renovating the many homes he has lived in. He specialises in painting and decorating, but has a wide range of skills gleaned from working in the building trade for around 10 years and spending time at night school learning how to plaster and plumb.

He has fitted kitchens, tiled bathrooms and kitchens, laid many floors, built partition walls, plastered walls, plumbed in bathrooms, worked on loft conversions and much more. And when he's not sure how to tackle a DIY project he has a wide network of friends – including plumbers, gas engineers, tilers, carpenters, painters and decorators, electricians and builders – in the trade to call upon.