A basement is a part of a building structure that is either entirely or partially below ground and can be a blessing for a house owner if designed, planned, and appropriately maintained. It was typically referred to as a ‘cellar’ in its earlier days when it was mostly used to store crops and food products. Before refrigerators, these root cellars, cooler than most parts of the house, were the best places to store items at lower temperatures.
As cellars evolved into basements with concrete walls and floors, their functions were still a part of building necessity. Today, basement construction not only provides valuable space for both residential and commercial use but also provides sustainable benefits of improved energy efficiency, by saving on space heating when compared to similar on-ground buildings. From a structural point of view, every basement is different and has its strengths, weaknesses, and nuances. They are common in high-rise buildings as car parks, storage of services, and underground shopping centers.
The term ‘basement’ is synonymous with the term ‘deep pit’ which applies to excavations over 4.5m deep. Technically speaking, it is always favorable to give a provision of a basement, especially if the house plot is low-lying. It is the best solution instead of filling up the low-lying area with earth, which, if not compacted well, can lead to settlement of floors. Another instance where building a basement is beneficial is shrunken plots. In small-sized plots, extra storage space can be created underground while benefiting from more livable space on the upper floors.
Advantages of Basements
Basement construction is advantageous in building energy-saving as the thick basement walls are insulated by the ground making it easy to heat them and simultaneously the above rooms quickly. While building a house on a hill, the basement provides an opportunity for an additional door to the outside. It also provides repair access for the services of the above floor as all the pipes are under the floor slab, making it easy for maintenance and general upkeep.
There are two major concerns for basement construction: the cost factor and the possibility of flooding in unforeseen events. When building a dream house, it is advisable to get it done once without any regrets. The construction costs are calculated per square foot area and completely depend on the size and requirements of the owner. The other snag point is the risk of moisture and water seepage which is very important to take care of during the construction stage itself. It is important to make sure the contractor does appropriate basement waterproofing along with proper drainage systems to mitigate excess seeping water into the basement. The basement is essentially a part of the foundation and helps keep the structure stable and safe to live in. Therefore, it is of utmost importance to safeguard it from water seepage which can develop major foundational problems including building settlements and cracks.
The above points indicate that there is no guaranteed unison on whether a basement construction is necessarily a good or bad idea. It ultimately depends on the owner’s perspective, needs, and tastes and thus has to weigh the various pros and cons before making the decision. An architect or a civil engineer can help you with everything you ought to know while planning to build or purchase a property; but it’s best to have a basic knowledge of basic basement construction.
Materiality and Framing
When choosing the materiality and framing, it is always advisable to go for the RCC (Reinforced Cement Concrete) structure where the foundation, walls, floor, and roof slab are all in RCC as it keeps the dampness away. A qualified structural engineer with an architect should design the basement with proper steel reinforcement in footings, floor, walls, and roof slab. The structural engineer does proper analyses of the earth pressure on the basement walls and provides appropriate reinforcements to them. It is also important to embed the electric conduits and switch boxes in designated locations before laying concrete as it is not possible to cut RCC for chasing.
The outer surface of the basement RCC walls should be painted with waterproofing black epoxy paint before filling the earth around them. All grass and weed should be removed with proper compacting of the soil before laying the basement flooring. A 4-inch-thick layer of fine sand followed by a double layer of polythene sheet and RCC layer should be laid on compacted soil. The RCC floor should be at least an inch thick with waterproofing compound added to the concrete compound and with 8mm diameter steel bars in both directions. The finishing material can be vitrified tiles.
Necessities of a good basement
Having daylight and fresh air in the basement is a part of building regulations and it is necessary to incorporate ventilators (natural or mechanical) in the design to avail adequate lighting and ventilation. Good ventilation systems help in removing odors, moisture, and contaminated air while creating a healthy environment that will circulate throughout the entire room. Poor ventilation can cause respiratory issues, sinus problems, allergic reactions, etc., to the inhabitants. There should be one light switch on the entrance side wall that should switch on all its lights and flood the basement with light. The basement ceiling level can be offset from ground level to provide for ventilators sealed well against entry of water and fitted with exhaust fans or a light well that can allow the influx of light and air to the basement naturally.