Water leaking into the basement after heavy rain is a common occurrence. Water always finds a way by following the path of least resistance, so basement waterproofing and adequate drainage are especially needed in cases where groundwater is likely to build up in the soil and the water table to rise closer to the surface.
There are many ways water can enter a basement or below-grade structure. Water can intrude through the foundation slab, retaining walls, basement windows, cracks, and pipe penetrations.
In Singapore and Singapore areas, we often see that buildings that are cut into a hillside stand a greater risk of having the “hillside side” affected by hydrostatic pressure if adequate steps to redirect the water are not taken. Poor drainage can cause water to collect against the concrete foundation and retaining walls during heavy and persistent rain events, and when building up in volume it and can cause problems attributable to lateral and hydrostatic pressure (water pressure from the soil). Steps that are taken to direct water flow away from basements/foundations eliminate pooling and help reduce the chances of water building up around the building.
Water ingress in basements is commonly experienced during heavy rain due to the rising water table bringing the groundwater closer to the surface. This increases the hydrostatic pressure onto the slab of your building and can force water to pass through cracks in the concrete and/or the construction joint between the floor and the wall, otherwise known as the cove joint or floor to wall joint. This joint effectively begins working as a highway passage for water into your basement.
The floor to wall joint – especially when it is an infill slab where the slab is poured between existing walls – can be extremely vulnerable to water intrusion/seepage. Water can leak in through the floor to wall joint even with an intact positive side waterproofing where the waterproofing system has been installed to the soil facing side of the subsurface building components, as illustrated in the image below.
Please note that for a concrete slab to be impacted by hydrostatic pressure, it must be below the water table or intrude into a natural water pathway. Interestingly, the water table level can be altered by adjacent construction, so a basement that used to be dry can now be at risk of water intrusion.
How water gets into your basement.
Water seeping through concrete dissolves minerals like calcium hydroxide, which is extremely corrosive to galvanized steel. Below you can see the rusted air duct after the water that has been seeping through the concrete dripped onto it. Furthermore, high humidity and sodium chloride (salt) in the air or water can cause corrosion of galvanised steel and concrete reinforcement.
Carbonation and cracks cause concrete structures to move, which can lead to water infiltration, which can compromise the structure’s durability. To extend the lifespan of your assets, regular inspections and preventive maintenance are essential. Concrete cracks, water seepage, and spalling are issues that affect the integrity of the asset, so it is best to address them early to avoid costly remedial repairs later.
When water seeps through concrete, it dissolves minerals such as calcium hydroxide, which is extremely corrosive to galvanised steel, causing it to rust.
A wet basement can be treated by targeted high-pressure injection into the wall-floor joint and/or into vertical joints, such as between contiguous piles. The injected hydrophilic polyurethane liquid chases the water deep into cracks and forms a flexible watertight seal. This remedial waterproofing treatment can be followed by the application of a waterborne epoxy coating or a negative side waterproof membrane.
The waterproofing membrane systems we use create an effective barrier against waterborne salts. They are also resistant to atmospheric gases and comply with potable water safety standards.
The systems are supported by the manufacturer’s warranty for 10 years, which is extendable to a further 10 years with a maintenance application.
Our highly-skilled technicians frequently perform remedial high-pressure leak-sealing injections to stop water seeping into building structures. Whilst other remedial companies may average once a year (or at most once a month), our technicians perform quality high-pressure leak-sealing injection work several times per week.
Basement car park – vertical concrete joint injection of polyurethane to waterproof the leaking cracks in contiguous piles.
Waterproofing Repair. Installation of reverse side cementitious waterproof membrane. Below Ground Car Park in Singapore.
Are you interested in finding out more about the various remedial building services we are providing?
Good maintenance begins with a proactive approach to maintain, keep, preserve and protect a building.
Remember that seepage/water ingress into areas such as basements, concrete roofs, car parks and retaining walls, should not be ignored – call a remedial waterproofing professional today for an assessment to provide you with the best solution for your situation.
At Singapore Waterproofing, we carry out a wide range of remedial works to concrete structures post construction stage.
Equipped with major civil works experience, we can quickly determine the best approach to rectify all seepage and concrete deterioration issues.
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