Preparing the Best Base For a Shipping Container
Getting the foundations and ground preparations for shipping containers right will help ensure your investment lasts for years to come. Whether itâs as storage, an office or a home, we explain how to prepare your site, and offer container foundations ideas for both temporary and permanent installations.
Why You Need to Prepare the Ground for a Container
Shipping containers are extremely sturdy, but they were made to cross the seas. Some features that make containers excellent for shipping can cause problems when they are left sitting in the same place for years on end.
Level, Sturdy Surfaces
Placing your heavy container on a soft surface will cause it to subside over time. Having a container that isnât level can cause issues with alignment, power and wiring, safety and container security.
The steel that containers are made from is very strong, but slightly flexible. This is great for rocky conditions on the back of a boat. However, if your site isnât completely level then the frame of the shipping container can twist and warp.
Among other things, this can affect the doorâs locking mechanisms, throwing them out of alignment. Known as âracking outâ, it means you wonât be able to use your containerâs doors properly. It can also become a security risk for your container. Making sure you have sturdy and durable foundations will prevent this.
Corrosion
Rust from moisture can begin to corrode a shipping container if left untreated. This can cause weaknesses in the structure of the container. It can also cause cracks or holes to form in the exterior walls of the container. This allows the moisture to get further into your interior, potentially damaging your belongings.
Several site issues can lead to moisture issues that will impact your container.
Site Drainage
Choosing the right drainage options for your site is vital. Poor drainage can cause water pooling around and underneath your container. Leaving this moisture to pool will increase the risk of rust and corrosion over time. Youâll need to consider the area around your container, the weather conditions, and your foundation choice.
Lack of Airflow
Having little to no airflow underneath your container can also allow moisture to build up. By choosing a base that lifts the container slightly off the ground, air can circulate underneath. Taking away this moisture will help to prevent rust or mold.
Safe Stacking
Extra precautions should be considered when stacking multiple containers. Their weight will be supported by a smaller surface area, so your foundations will need to be strong, durable, and distribute weight evenly.
Reduced Lifespan
The issues above can be a pain to live with and/or a costly fix. However, the most important reason to safeguard against these issues is that they will reduce the lifespan of your container. The costs of prepping, delivering, converting, and using your container can be high. Making sure your container lasts as long as possible will help you get your moneyâs worth long-term, whether you keep your container or sell it on.
Planning Your Shipping Container Base & Foundations: Key Things To Consider
You can reduce future issues by taking the time to plan out your container project from the start, including preparation time. This can be time consuming and create additional expenses upfront, but itâs always more economical to avoid problems rather than fix them later.
Shipping container use
Your preparations and foundations will be affected by how you plan to use your container. Storage containers will need to be treated very differently to containers that will be converted into a home. Moving a container or replacing a foundation when the container is in use will be significantly more difficult compared to getting it right in the first place.
Temporary or permanent structure
Will your container be placed here temporarily or permanently? There are some cheaper options for shipping container foundations, but they arenât recommended for long term use. This makes them more suitable for temporary containers. Youâll need to consider more durable foundation systems if your shipping container installation is permanent.
At this stage, you should also check whether your shipping container will need planning permission.
Container weight
Empty container weights can be anywhere from 2.2 tonnes to 4.2 tonnes and your foundations will need to be able to support this.
If youâre using your container to store heavy machinery or stacking multiple containers, you will need to consider foundation load weights. This will help to make sure the foundation doesnât sink or crack under the weight of the shipping container.
Positioning and access
Choosing a good position for your shipping container can reduce a lot of future stress. You should consider the environment that youâll be putting the container in but also how youâll be using it. Do vehicles need access to the container? Will you need to move the container in the future? Will you be adding electrics or plumbing to the site?
Avoid covering any drain covers, access points, or buried cables with your shipping container. If you ever need access, then it will be a costly and complicated process to get at them.
Site weather and environment
The weather in the UK can be a struggle to work with. You should take the time to think about the weather conditions in your chosen position. Is the area exposed to the elements or is there some shelter? Is your site at risk of flooding?
- High rainfall
- UK rainfall can vary throughout the country. You should consider whether youâre in an area that has a high rainfall or is prone to flooding. Positioning your container away from waterlogged areas can stop it from sitting in water.
- Soil type
- The type of soil in your area could affect your foundations in different ways. For example, soil that is full of sand or gravel may shift under heavy weights. Clay expands when wet and shrinks when dry, which causes significant shifting. Peaty soil is usually waterlogged and can compress under heavy weight.
- Frost expansion
- When water in the ground freezes, it expands. This adds pressure to foundations and can lead to cracking or shifting. If youâre in an area where frost is common then you could use foundations that are installed below the frost line.
- Surface water pooling
- The environment that youâre placing your container in may be prone to surface water pooling. This can be because of the soil type, the elevation, or even the foundations themselves. By taking note of any water pooling you can try to reduce any risk of rust or corrosion.
How to Prepare the Ground For a Shipping Container
Preparing the ground before your container arrives can help you to plan the next steps in your project. Groundworking can be a time consuming task but it's best to uncover any problems while you still have the time and budget to update your plans.
Clear the Container Site
Remove any obstructions like rocks, trees, roots or rubbish. This will give you a better idea of the land. Map out the area you want the shipping container to sit with chalk or string.
Remove Overhead Obstructions
Clearing any overhead obstructions can make it easier to have your container delivered. If youâre doing construction work around your container then having the vertical clearance can be helpful.
Level the Ground
Itâs important to make sure that your site is level to stop your container from shifting or warping over time. Levelling the ground first can make it easier when installing any foundations.
Install Drainage
Adding a comprehensive draining system should be done before your container arrives. Draining water away before it can pool underneath or around your container should be a priority.
Use Foundation Membranes
Foundation membranes are moisture barriers that can help to stop water rising from the soil. This moisture could damage your foundations. The most common damp proof membranes are heavy-duty plastic sheets that can be laid underneath slabs or sleepers.
Choosing Your Shipping Container Foundations
Deciding what type of foundations you need for your shipping container can be a daunting task. Each foundation type has different benefits and drawbacks. Your container base and foundations should be based on your site, the size of your container, and what it will be used for. What works best for one project might not necessarily be the best for another container.
Temporary Container Foundations Ideas
If youâre not planning on having your shipping container on site long term, then you can look at temporary foundations. These are generally cheaper options that can be removed when they are no longer needed. However, you will still need to consider your project as a whole. Some containers or sites will require hardwearing foundations, no matter how long you have the container.
Concrete Slabs
Using concrete blocks or paving slabs to base your container can be a good choice for short to medium term solutions. They are also relatively cheap, so good for those on a budget. However, they are less stable than full foundations and require solid and level ground underneath to be effective.
Gravel Bed Foundations
Compacted gravel is usually used in combination with other foundation options such as railway sleepers or concrete slabs. The gravel offers good drainage, so will help to stop water from pooling around your container. It is also relatively cheap so an excellent choice for those on a budget.
Railway Sleepers
Traditionally the term railway sleeper referred to a heavy support beam that was laid directly underneath train tracks. They are still referred to as ârailway sleepersâ but are used in all sorts of construction projects including as a foundational support.
Timber
Timber railway sleepers can be used as a base for shipping containers, but untreated wood can rot over time. Using wood or other organic materials as a base should only be used for a shipping container that will be in place temporarily. They should be combined with a gravel bed so that they are raised up for increased airflow and to stay out of pooling water.
Concrete
Concrete railway sleepers are much more durable than their timber counterparts. They still allow airflow to circulate underneath the container but are much more moisture resistant. However, using railway sleepers as a foundation is usually not best for permanent structures.
Gravel beds or softer soil may subside under the weight of a shipping container. This will mean that your sleepers are no longer level and your container frame might start to twist and become inaccessible.
Permanent Container Foundations Ideas
You will need to add more durable and hardwearing foundations for a permanent shipping container. These types of foundations provide a higher level of stability, durability, and longevity. Permanent foundations can also be a necessary safety precaution if youâre planning on stacking containers.
Poured Concrete Slab
A concrete slab is a durable choice that can be inexpensive when compared with other permanent foundation systems. It consists of pouring concrete into a temporary wooden frame over a compacted gravel sub-base. This slab should be between 100mm-150mm thick.
Concrete Footings
These shipping container foundations involve filling a hole or trench with concrete. This distributes the weight of the container across a wider area, stopping it from sinking or slumping. Using concrete footings is a good choice for areas with soft soil that wouldnât otherwise support the weight of a container.
Concrete Piers
Concrete piers are vertical columns of concrete that are poured into bored holes in the ground. These piers concentrate the weight of the container at strategic points on the frame. They are generally used in areas with sloping terrain or flood prone areas. This type of foundation can support elevating the container off of the ground.
Concrete Pile Foundations
A piles foundation system is very similar to a piers system. However, while piers are poured concrete in bored holes, piles are driven or hammered into the soil. Choosing between piles and piers usually comes down to the soil environment. Piles are used on sites with unstable soils or where digging is risky.
Making sure you have a solid and level base can go a long way for most containers. Adding foundations can stop common container issues such as âracking outâ and subsidence, but youâll choose your siteâs shipping container foundations based on your specific needs. By taking the time to plan what your container and site need, you can ensure your container will last well.