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How to Repair Cracks in Concrete Floor in Basement

Crack in a Concrete Floor

In the UK, it’s thought that only around 2% of homes have basements (rooms at least 1m below ground with a permanent staircase, concrete floor and natural lighting). In instances where basements do exist, they are typically part of large, old houses located in cities and are commonly divided into flats or sub-dwellings.

You could speculate for days about why basements are not common in the UK. With some people citing cost, others blaming the water table, and a further proportion saying the lack of extreme weather is the reason why there are so few basements here.

Whatever the cause, most people won’t have to think too much about basement waterproofing because they don’t have one. In the case of older properties or self-build properties, maintaining a basement is an essential part of looking after the condition of their house.

If a basement is not properly maintained, it can compromise the structural integrity of the rest of the property. For the 300,000+ homeowners who do have an underground level to maintain, one of the biggest issues that can arise is in the form of cracks in the concrete floor, and it is this issue that can cause severe and expensive problems in the rest of the house.

Types of Basement Floor Cracks 

There are several types of basement floor cracks, and the type your property is suffering from will dictate whether or not you need to go about repairing them.

Hairline Cracks 

Hairline cracks are small, spiderweb looking cracks that are less than 1/8-inch wide. They are purely superficial and may not require any treatment because they’re often not indicative of a deeper issue. Hairline cracks occur when the concrete shrinks as it dries. They can appear up to 12 months after the initial build and are nothing to worry about.

Settlement Cracks 

When houses are built, they can take a number of years to completely settle. Sinkage as a consequence is a common issue, with the tell-tale signs being large cracks and uneven floors creating a trip hazard. To treat settlement cracks, the floor may need to be lifted and re-levelled.

Heaving Cracks 

If you notice large cracks in the floor accompanied by a bulging effect, there is a high chance your basement has fallen victim to heaving. This is a serious issue that can affect other aspects of your home, including cracks in walls above ground and trouble opening and closing doors. Heaving occurs when the soil beneath your home (usually clay soil) expands with moisture. This is due to the head of the water applying sufficient hydrostatic pressure to a concrete slab of insufficient thickness and strength.

The pressure of it can cause concrete slab floors to crack and move. When the floor starts to move beneath supporting walls, the entirety of your home’s structure can be compromised. Typically, heaving is solved by removing the basement floor, digging down further and relaying the floor with additional structural collateral.

Spalling Cracks 

Similar to hairline cracks, spalling cracks and flaking are not a serious issue and are nothing more than surface-level discrepancies. Spalling occurs when the mix of the concrete is too wet, or when it hasn’t been cured properly and begins to loosen and evaporate as it dries. Whilst it looks unsightly, it isn’t anything to worry about and can be rectified simply by resurfacing the concrete or installing a waterproof floor over the top.

Basement Damp

Nearly all basement floor cracks can herald in water damage, causing further problems for your property. Damp in basements is a common issue that is only exemplified by floor cracks, but there is a solution that can potentially stop your basement from falling victim to both floor cracks and dampness: basement waterproofing systems.

Basement tanking is a process that essentially waterproofs the entirety of your underground level, but there are two different methods to basement tanking.

Type A Waterproofing (BS8102:2009)

Type A waterproofing uses cement and other directly applied membranes to form a barrier between your basement and the surrounding groundwater. First, the walls are stripped back to their base, then, a splatter render made up of sand and cement is applied. After this, multiple coats of another waterproof render are applied. As basement waterproofing specialists, the waterproof agents we use in this process vary depending on the job at hand.

Type A essentially stops water from entering your basement.

Type C Waterproofing (BS8102:2009)

Type C waterproofing is often more complex than Type A, and it is usually recommended in areas where there are high levels of unpredictable water. To install it, walls and floors are stripped right back and a membrane is applied using plugs. Pipes and plumbing are integrated into the membrane. Next, a sump and pump system is installed via perimeter channels. It is this system that will carry excess water away from your house but at no additional structural pressure.

Type C basically removes water from within your property and directs it to the appropriate pre-existing external drainage. Essentially, the system allows water in and then ships it out, and this reduces structural stress than can result from Type A waterproofing.

If you have a basement, it’s essential that you ensure it is waterproof if you are going to prevent things like heaving cracks in your cement basement floor. If you want to avoid the hassle of having to learn how to repair cracks in concrete floors in your basement and dealing with issues elsewhere in your home later down the line, we would recommend basement tanking of any description.

Get in Touch

To talk more about basement tanking and dealing with damp caused by cracks in your basement floor, please contact us to arrange a site survey and no-obligation quote.

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