‘Settlement’ and ‘Shrinkage’? What is the difference?

‘Settlement’ from a building surveying point of view technically lasts for 10 years, although on a practical basis, you should only really notice the signs within the first 12 months after completion.

These signs include:

• Doors not closing
• Cracks around the window sills, stairs and door frames
• Cracking floor tiles upstairs
• Cracking to brickwork outside

The severity of it will depend upon the foundation type and construction method to build the house, ie. timber framed vs traditional build. In either case, it is the house settling into its new foundations.
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The reason that settlement cracks occur particularly around door frames, windows and staircases is not because it’s where timber and plaster adjoin (a common misunderstanding that Site Managers will tell customers). The truth is that from a structural point of view, the windows, stairs and doors are the weak areas of the house since they are openings. This is why you will find the most common settlement cracks occur around these openings vs shrinkage cracks which occur elsewhere.

​Shrinkage can however show signs in other places such as cracks in your brickwork/mortar outside. It can also cause floor tiles to crack (mainly upstairs). This is often why the Sales or Site team will suggest against laying tiles upstairs, as they are less durable to cope with the movement of the house.

We would therefore recommend laying a temporary floor surface material in your bathroom such as lino down and then waiting a year before changing to tiles.

Shrinkage is due to the construction materials drying out. As shown in this video, shrinkage cracks often run along the top of walls rather than at openings, at a constant width no less than 2mm. As these ‘wet’ construction materials (plaster, mortar and concrete) contain a lot of water, it usually takes several months for the shrinkage cracks to occur.  Allowing for ventilation (trickle vents) in the property helps during this drying-out period.

So, with this being said, what does the builder have to do? The answer is that it depends on what severity the crack is. According to the BRE, anything less than 5mm is considered minor (cosmetic). The NHBC have a similar stance on this and advises that anything less than 2mm is not of concern. To check this during our snagging survey we use a crack gauge ruler and our photographs are date-stamped to monitor if the crack grows.

For more information about cracking, a useful document provided by the NHBC is here. Also, feel free to get in touch with us if you have any concerns over cracks appearing in your home that may be beyond settlement.