Can I place a storage
building on an existing
concrete foundation?

30 October 24
E509-27loodsen-PaulNiehaus (7)

If you already have a concrete foundation in place and want to install a self-build storage building on this site, we've seen this situation with our customers quite often in Kroftman's 15-year history. It can be cost-effective if you don't have to lay down a (new) foundation. Kroftman does not lay foundations ourselves, and this is not our expertise. For very specific questions about a concrete foundation, we advise you to consult a structural engineer. However, we can provide you with four points to consider if you want to place a storage building on an existing concrete foundation.

 

1. Strength of the foundation for your storage building

If you want to use the existing concrete foundation on your site, it's important to check if it's strong enough. The snow and wind loads of the storage building must be supported by the foundation. The requirements for the foundation are described in the static calculations of the storage building. We recommend having a structural engineer assess whether your foundation is strong enough. If not, consult with your structural engineer about what you can do. The same applies to the condition of the foundation. Is it still good and usable, or are the reinforcements sticking out of the concrete in some places and/or do you see rust stains? Your structural engineer can best advise you on the condition of your foundation and how you can improve it.

 

2. Irregularities in the foundation of your storage building

It's important that there are no conduit pipes, drainage pipes, and/or lightning rods in a place where the profiles of the storage building are mounted or where the doors are installed. The concrete surface must be horizontal and flat before the storage building can be installed. Unevenness higher and/or deeper than 5 millimeters prevents a good connection of the storage building to the foundation. The infographic below clearly shows the requirements for the substrate.

3. Drainage of the foundation for your storage building

The exact surface dimensions of your foundation are important for installing the frame or water barrier. This must fit precisely around the foundation to divert rainwater over the edge of the foundation. This means that the concrete foundation should protrude approximately 6 centimeters on all sides of the planned storage building. The image below shows a picture of this water barrier.

Water can also come onto the foundation from the surrounding ground level. To prevent this, the foundation must be a few centimeters higher than the ground level. If your existing concrete foundation does not exactly meet the surface dimensions as stated in our construction drawings, you will not be able to connect the above water barrier to your foundation. In that case, you will need to use the simple water barrier (see image below).

Water cannot be adequately diverted from the storage building with the simple water barrier and remains on the edges of the foundation. If your foundation is too large for the storage building, our advice is to make the foundation smaller for the best possible drainage.

 

4. Surroundings of the foundation for your storage building

When reusing an existing concrete foundation, it's important to check if there are no trees, power poles, etc., in the way. The ridge height of a storage building is almost always more than 4 meters. To be able to assemble the storage building, there is working height needed for the crane. At Kroftman, we assume a working height of twice the ridge height. If the ridge height is 4.25 meters, you will need 8.5 meters of working height. This height is needed to be able to set up the rafters. If you have to cut down a tree for this, you may need a environmental permit (the old felling permit).

In summary, you can use your existing concrete foundation to place a self-build storage building. Please consider the above four points carefully. Kroftman does not lay foundations and does not have the expertise for this. For specific questions, we always advise consulting a structural engineer. They can also assess the situation on-site.

If you want to know if the storage building you want fits on the existing foundation and if there is sufficient working height, fill in our tool 'Discover if the storage building fits at your location' now. In five simple steps, you'll see if there are trees, buildings, or fences in the way.

 

We hope the above information helps you make an informed decision. If you want to know exactly what the storage building of your choice costs, fill in our quotation tool without obligation. We ask you to enter your postcode to calculate the transport costs of your storage building. After requesting the quote, you will receive your login details for your personal Kroftman page within a few minutes. Here you will find the quote with the total price including any transport costs.

You can create multiple quotes and check different options. This allows you to compare them effectively.

Do you still have questions? We are happy to assist you.