Structural Cracking

If you notice cracking in your home, wherever and however big it can cause concerns. However, just because a crack has shown it doesn’t necessarily mean your property is falling down. Although, that is the case it is important that a professional takes a look and reviews the issue so they can confirm whether or not a structural engineer is required.

BRE groups have a number of useful documents one of which is called ‘Assesing Cracks in Houses’ the link can be found here: https://www.bre.co.uk/page.jsp?id=3356

Cracking categories described within the article are referred to below:

0 – Hairline cracks of less than about 0.1 mm which are classed as negligible. No action required.

1 – Fine cracks that can be treated easily using normal decoration. Damage generally restricted to internal wall finishes; cracks rarely visible in external brickwork. Typical crack widths up to 1 mm.

2 – Cracks easily filledRecurrent cracks can be masked by suitable linings. Cracks not necessarily visible externally; some external repointing may be required to ensure weather-tightness. Doors and windows may stick slightly and require easing and adjusting. Typical crack widths up to 5 mm.

3 – Cracks that require some opening up and can be patched by a masonRepointing of external brickwork and possibly a small amount of brickwork to be replaced. Doors and windows sticking. Service pipes may fracture. Weather-tightness often impaired. Typical crack widths are 5 to 15 mm, or several of, say, 3 mm.

4 – Extensive damage which requires breaking-out and replacing sections of walls, especially over doors and windows. Windows and door frames distorted, floor sloping noticeably. Walls leaning or bulging noticeably, some loss of bearing in beams. Service pipes disrupted. Typical crack widths are 15 to 25 mm, but also depends on number of cracks.

5 – Structural damage that requires a major repair job, involving partial or complete rebuilding. Beams lose bearing, walls lean badly and require shoring. Windows broken with distortion. Danger of instability. Typical crack widths are greater than 25 mm, but depends on number of cracks.

In general, categories 0, 1 and 2 with crack widths up to 5 mm can be regarded as ‘aesthetic’ issues that require only redecoration. Categories 3 and 4 can generally be regarded as ‘serviceability’ issues, that is, they affect the weathertightness of the building and the operation of doors and windows. Category 5 presents ‘stability’ issues and is likely to require structural intervention.

The Causes Structural Cracking

During our experience we note the most common causes of structural cracking are drainage issues and trees.

Although it may sound odd that trees are a major cause of structural cracking the reason is due to the what substance the property is built on. Clay is a common subsoil in the UK and it’s issues lie with the fact that it changes with moisture content; it expands when subject to increased levels of moisture and shrinks when subject to times of drought.

So with this in mind, trees in close proximity of a property can cause additional issues. A tree in close proximity will draw up any moisture it can through the roots making the clay shrink further, this as a result can be a major factor causing subsidence.

In the UK the main trees known to cause issues are Oak, Eucalyptus, Rowan and Poplar. It is recommended that these trees are planted a minimum recommended distance of 30m from the property. We will comment on the proximity of trees to a property within our reports.

The other main cause of subsidence and structural cracking in a property is due to drainage issues. This is because if a drain becomes damaged under or within close proximity of a property it releases water in to the ground causing issues for the sub soils whether they be clay based or of a sandy substance. If a clay based subsoil it causes swelling due to increased moisture content whereas a sandy substance subsoil can be washed away causing a downward movement.

Should you be concerned about cracking within a property please give us a call or an email so we can discuss the issues.

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