5 Essential Foundation Types for Your ADU: How to Pick the Right One
The most important decision before building an Additional Residential Unit (ADU) is to choose its foundation. The foundation is the most important part of a building which provides strength to the entire structure. Choosing the right types of foundation will keep your ADU strong and secure in the long run. While choosing a foundation, many things must be taken into consideration such as ground conditions, weather conditions, and the size of the building.
1. Slab Foundation:
Slab foundation is the most common and simple type of foundation that is used for ADUs. It is a reinforced concrete sheet that is poured directly onto the ground. It takes less time to make a slab foundation and it is also economical.
In this foundation, a mesh of steel bars is laid which gives extra strength to the concrete. Slab foundation is best suited for flat land where soil conditions are good. This foundation protects against water and moisture and provides protection from insects.
In cold areas insulation is applied under the slab foundation which saves heat. The floor heating system can also be easily installed in the slab which remains comfortable in winter. Special coating is done to protect the edges of the foundation from frost.
Special waterproofing additives are added to the slab foundation that keep the foundation safe from water. Additional steel reinforcement is used to reinforce the edges of the foundation. Expansion joints are built into the slab that control the expansion caused by temperature.
2. Crawl Space Foundation:
In the Crawl Space Foundation, a hollow space is created just above the ground. This place is used to keep pipes and wiring. The height of the crawl space is so that a person can crawl into it.
Vents are installed in this foundation for the movement of air which controls moisture. Waterproofing is done in the crawl space which protects against water. This foundation is also suitable for ADUs on sloping ground.
Insulation is applied to the crawl space that keeps the floor warm. The crawl space is easily accessible for repairs and maintenance. The vents are covered with mesh covers so that insects cannot get in.
Sensors can be installed to monitor air quality in crawl spaces. Vapor barriers are used to protect against moisture which prevents vapour. Emergency lighting is provided in the crawl space which comes in handy at the time of repair.
3. Basement Foundation:
The basement foundation provides a complete underground room that creates additional living space. This foundation is the deepest and is surrounded by concrete walls. The basement doubles the livable area of your ADU.
Waterproofing is done in the basement walls and drainage system is installed outside. Windows and emergency exits are made in the basement, which is also a legal requirement. This foundation is the strongest and lasts the longest.
Special barriers are installed in the basement walls to protect against radon gas. A sump pump is arranged in the basement which drains out the accumulated water. Thermal insulation is installed in the walls of the basement which saves energy.
4. Pier and Beam Foundation:
In pier and beam foundations, concrete piers (piers) are buried in the ground. Wooden or steel beams are placed on these pillars that support the DU. This foundation is excellent for sloping and uneven ground.
This foundation minimally affects the ground and maintains natural drainage. The piers are mounted in such a way that they can withstand earthquakes and strong winds. The beams are treated with special chemicals that protect against termites.
Epoxy coating is done to protect the piers from corrosion. Special metal connectors are used at the joints of the beams. Cross bracing is installed to protect against air pressure which provides strength to the structure.
5. Screw Pile Foundation:
The screw pile foundation consists of metal screw-like poles mounted by rotating them into the ground. This foundation can be applied very quickly and can also be easily removed. This foundation is environmentally friendly as it does not use concrete.
The screw piles are planted in the ground with the help of a machine that works exactly. This foundation is also suitable for places with marshy and weak soil. The piles are coated with an anti-corrosion coating which makes them long-lasting.
Load testing is done to check the capacity of the piles. GPS guidance is used to place the piles to the exact depth. Metal poles are made from galvanized steel that resists corrosion.
Choosing the right foundation types for ADU is very important as it decides the strength and durability of your building. Choose the most suitable foundation from these five options, keeping in mind your ground conditions, weather and building needs. Get the foundation built by consulting an expert and following all the rules. A good foundation will not only strengthen your ADU but will also increase its cost and reduce maintenance costs.
