While building a container home, the foremost thing you need to consider is its foundation. These foundations decide the strength of your house. Choosing the right type of foundation is, therefore, very important.
Choosing the right type of container foundation
Primary considerations while designing the foundation include:
Calculating the cost involved in laying a specific type of foundation will help you plan your budget well in advance. Ask about the material cost from your local stores and compare them for the best price offered.
Selecting a foundation also depends on the container structure you are planning to build. Consulting a qualified builder or engineer will be helpful here.
Secondary considerations while designing the foundation include:
- Type of soil
- Number of containers
Type of soil
The type of soil you are laying your foundation upon plays an important role in selecting the right foundation type. Soft soil requires deep foundations whereas minimal foundations are sufficient for the hard soil. It is because the hard soil can carry the weight of your container to a large extent.
Number of containers
The number of containers you are planning to use in constructing your home shall also be considered. Using more containers will add to the weight of your container home. You will have to decide the strength of your foundation accordingly.
Some people prefer to make their foundation stronger than necessary because of a preferred style of foundation. It is up to you to decide the best foundation type for your home considering the factors discussed above. Just remember that choosing the wrong foundation type can have a disastrous impact on the whole of your project.
Let us discuss all the aspects related to three major types of foundations for helping you make the right decision.
Types of foundations
All the traditional home foundations can be used for shipping container homes as well. You can classify them into:
Shallow ones are laid very near to the ground level. Whereas deep foundations can be laid at depths of up to 10 meters. Within this broad classification lies several types of foundations. The three most common popular foundations out of them include concrete piers, slab on grade, and piles.
Concrete piers are the cheapest and simplest foundations. They are a type of shallow foundation recommended for most of the container homes. They are concrete cubes containing reinforced steel bars within them. These reinforced steel bars provide strength to the concrete. They can be in the form of a mesh of steel wires or a steel bar. Six piers are required for a single container. Four of these are used for giving support at the container corners. The remaining two are laid in the center of the container for adding support in the middle part.
The simplicity of this method makes it completely DIY friendly. The concrete piers don’t let the containers touch the ground directly. This, in turn, helps in proper ventilation and prevents the formation of condensation underneath.
Concrete piers foundation
Slab on grade
A slab on grade or raft foundation is more expensive than a pier foundation. It also takes more time to construct as you need to dig a lot for raft foundations. For soft soils, this foundation type works exceptionally well. A raft foundation can usually be found in warmer climates.
This foundation type is less vulnerable to termite infestation as there are no hollow spaces in the foundation. On the flip side, it becomes difficult to access the utility lines after the concrete hardens. You might also face heat loss issues if the ground temperature falls below your home’s.
Pile foundations are used in case of weak or soft soil. In other words, when the soil cannot provide adequate support, pile foundations will be helpful. This very feature makes them the most expensive ones among the three discussed here. Cylindrical solid steel tubes are called piles. These tubes are hammered deep into the soft soil until a harder surface is reached. After securing the piles firmly to the load-bearing ground, a block of concrete is spread over them. This concrete capping takes the form of a grid system.
Since there is a lot of digging involved, a DIY installation is not a good idea. A contractor can lay the pile foundations better as special building equipment is required for the process.
Strength of concrete foundation
After choosing the type of foundation, you need to decide the strength of concrete to be used. The geotechnical engineer’s report will reveal you the concrete strength required for building your foundation. It is technically called the ‘AC value’. As a general rule, with an increased cement content, the concrete becomes stronger. For eg. c30 is a very strong concrete with a higher proportion of cement used.
You can either choose the DIY way for your concrete requirements or get it in a ready to use form. You can use your hand for mixing the small quantities or use the power of a cement mixer. Ensure to mix it properly as an improper mixing will greatly reduce the strength of the concrete. For large requirements, it is better to get ready-made concrete delivered to your site.
Estimating the concrete requirements
For estimating your concrete requirement, you must know the volume of your foundation. To calculate this, you need to multiply the three dimensions of your foundation. For example, To calculate the concrete requirement for a foundation with dimensions 22 by 10 by 2, multiply these three numbers. That will reveal to you the amount of concrete needed.
The cement will start to cure once it is mixed with water. A properly cured concrete carries a good strength and durability. You need to keep its temperature within a suitable range for proper curing. For the correct temperature range, consider the manufacturer’s instructions. Normally a period of 5 to 7 days is required for curing the concrete. You must keep it moist during this time.
Pouring concrete for your foundation involves the use of special care and attention to the temperature in your area. If you live in an area with moderate temperatures, you don’t need to take any special steps. But in case you live in an area having extreme temperatures, follow these tips for curing the concrete properly.
Pouring concrete in hot weather
It is important to prepare your site properly while laying concrete in hot weather. Placing temporary shades before pouring the concrete will help to block any direct sunlight. Spraying cold water over the ground and mixing concrete with cold water is also helpful. Alternatively, pouring concrete in the early morning or late evening will help in avoiding the peak temperatures.
Pouring concrete in cold weather
Pouring concrete in the cold weather also need some site preparation. Clean all the ice or snow and clear any standing water from the surface before pouring concrete. Covering the concrete with insulating blankets after laying is also helpful in proper curing. Consider using them for three to seven days and removing them gradually afterward. It will prevent the concrete from cracking due to quick temperature change.
Selecting the type of foundation is easy when you know the basics. Don’t forget to follow the tips given above for laying concrete in the extreme temperatures.