This article is about how to dig a foundation for a house, deck or any other construction. Digging a foundation is essential for the rigidity and durability of your construction on the long run, so it is important to pay attention to our step by step diy guide. Remember that you have to hire a qualified engineer to determine the depth of your foundation, as well as the number and complexity of the reinforcing bars you are going to use. Nevertheless, in this article we show you several basic techniques, when talking about digging a foundation.
You have to understand that the soil structure influences to a great extent the depth and size of your foundation. For example, in most of the cases, you will have to build pillars if you have an infill site. On the other hand, for an average soil you have to dig 3-4′ deep and 2′ wide tranches. Therefore, it is better to evaluate the quality of the soil before purchasing it, or before deciding to build a construction. Before digging a foundation, you have to prepare the site thoroughly. Consequently, you have to remove the trees and most importantly their roots. Nevertheless, you have to comply with the local regulation regarding these issues, otherwise you risk a significant fine. If on your site there are a lot of old trees, it would be a good decision to search for another land, as it is very expensive and time-consuming to cut trees, transport them and remove their roots from the ground.
In order to dig the foundation, you have two main options: renting a hydraulic digger, or hire several people to dig the trenches by using shovels. Obviously, the first alternative will do the job quickly, but there are cases in which a hydraulic digger might not have access to narrow or isolated sites. In that case, the only solution is to hire 3-4 persons to dig the foundation by using shovels. From our experience, digging a foundation with shovels is better and cheaper than renting a digger. First of all, the trenches might collapse while using the machinery and secondly, you have more control when using the shovels. Nevertheless, if we speak of a large foundation, a digger is the best choice. See all my Premium Plans in the Shop.
Made from this plan
Materials
- 1×4 lumber to build the batter boards
- Nails, string
- Digging shovel, Shovel
Tools
- Safety gloves, glasses
- Hand saw/circular saw
- Hammer, spirit level
- Shovels, wheelbarrow
Tips
- Pound the natter boards into ground, for at least 16”/50 cm
- Clean thoroughly your tools after you have finished the project
Time
- Several days, according to the surface of the foundation
My best tips on how to dig a foundation:
Whether you’re building a small shed or an addition to your home, a solid foundation is key to the stability of any structure. Digging a foundation requires planning, precision, and some hard work, but with the right approach, you can ensure your project starts off on the right foot. Here are my best tips for digging a foundation.
1. Plan and Mark Your Foundation Area
Before you start digging, it’s crucial to plan and mark the area where your foundation will go. Use stakes and string to outline the perimeter of the foundation, making sure it’s square and level. For larger projects, consider using a builder’s level or laser level to ensure the foundation lines are accurate and straight.
2. Check for Permits and Utility Lines
Before digging, make sure to check local building codes and obtain any necessary permits. You should also contact your local utility company to ensure there are no underground utility lines (gas, water, electric) in the area. This step is essential for safety and to avoid costly mistakes.
3. Determine the Depth of Your Foundation
The depth of your foundation depends on the type of structure you’re building and the soil conditions in your area. Generally, most foundations are dug at least 12 inches below the frost line to prevent movement from freezing and thawing cycles. For larger buildings, you may need to dig deeper or consult with a professional to determine the required depth.
4. Choose the Right Tools
Digging a foundation can be hard work, so using the right tools will make the job easier. Here are some essential tools you’ll need:
- Shovels: A spade for cutting through the soil and a flat shovel for removing loose dirt.
- Pickaxe: For breaking through tough or rocky ground.
- Wheelbarrow: To transport removed soil away from the dig site.
- Post hole digger or auger: For digging deeper holes if you’re installing footings or posts.
- Excavator: For larger foundations, consider renting a small excavator to speed up the process.
5. Start Digging the Trenches
Once everything is marked and ready, start digging the trenches for the foundation. Use your shovel to remove soil along the marked lines, ensuring the trenches are straight and uniform in depth. Be sure to remove any rocks, roots, or debris that could interfere with the foundation. As you dig, periodically check the level and depth to ensure consistency.
6. Check for Drainage
Good drainage is crucial for a stable foundation. Make sure the bottom of your foundation trenches slopes slightly to allow water to flow away from the building. If water tends to pool in your area, consider installing a drainage system or gravel bed at the bottom of the foundation to help manage moisture.
7. Compact the Soil
After digging the trenches, you need to compact the soil at the bottom to create a solid base. Use a hand tamper or plate compactor to compress the soil and prevent future settling. This step ensures your foundation stays level and stable over time.
8. Install Footings or Forms (if needed)
For some projects, you’ll need to install concrete footings or wooden forms before pouring the foundation. Footings provide extra support, especially for larger buildings, while forms help shape and hold the concrete in place. Make sure the forms are properly aligned and level before proceeding.
9. Handle the Excavated Soil
As you dig, you’ll accumulate a lot of excess soil. Decide in advance where to store or dispose of it. If you need to keep the soil, pile it away from the dig site, ensuring it won’t fall back into the trenches. If not, consider renting a dumpster or hiring a removal service.
Bonus Tip: Allow for Extra Depth Around Footings If your project requires concrete footings, dig the trenches slightly wider than the actual foundation width to give yourself enough room to work and pour concrete.
By following these steps, you’ll be able to dig a solid and level foundation for your project. Whether you’re working on a small shed, a patio, or a larger structure, proper planning and digging are essential for long-lasting stability.
Laying out the house foundation
Batter boards
The first step is to lay the foundation of your house. In order to do a proper job, you need to construct two batter boards for each outside corner of the foundation. In order to build batter boards you need either 1×4 or 2×4 lumber, several nails and a hammer. Remember that the batter boards have to be rigid, otherwise while digging the foundation you might move them from the right position. In addition, you have to fasten squarely a crosspiece over the two stakes.
Laying out the foundation perimeter
Next, you have to lay out the perimeter of your house, but you must ensure it is exactly over the location written in your construction permits. Even the slightest error will make your life miserable, so pay attention when installing the batter boards and laying out the foundation perimeter.
corner footings
Next, you have to check if the corners are square by using the well-known 3-4-5 method. Starting with one corner, you have to measure along one side 3′ and make a mark on the string. Next, measure 4′ along the other side of the corner and make a mark again. Then, you have to measure the distance between the two marks. If the distance between the two marks is 5′, then your corner is perfectly square, if not you have to redo the previous steps until your layout is perfect. You have to apply the 3-4-5 technique for at least 3 corners of the layout. Check again if the diagonals are equal.
How to dig a foundation
Digging foundation
After you have made sure the layout of your house is perfect, you can start digging the foundation. As we have already said, there are cases in which you cannot rent a hydraulic digger, so you have to use the traditional method: digging the footings with shovels. Although it might seem a straight forward process, we can assure you it is complicated, but if you pay attention to our guidelines, you will pull it through easily.
First, you have to mark the footprint of your foundation on the ground. In this way you will make sure the footings will be straight. However, we have to emphasize that you must read carefully the foundation plans, as to dig the foundation properly. Another aspect you have to take into account is to prepare a site, near the foundation, where to deposit the soil you excavate from the trenches.
Digging foundation along house
If you have to dig a foundation near your house, you have to pay special attention to the operation, as it might affect the structural rigidity of your house. Consequently, you have to make sure you don’t dig under the foundation of the house , to ensure you don’t damage it.
Work attentively and with patience, as any mistake you make will amplify when building the actual house. Strange as it might seem, there are many persons who think that the foundation is not important, as it’s not visible. Nothing can be more wrong, so make sure you build the foundation according to the plans, as your safety is at stake.
Breaking concrete slab with a jackhammer
If there concrete stamps on the site of your foundation, you will have to break them with a jackhammer. This is the easiest and most efficient method to break concrete, but you can also use a sledge-hammer. It will do the same thing, but you have to put more effort and it is time consuming, that is why we kindly recommend you to rent a jack hammer for a day or so.
Foundation trenches
Continue digging the foundation according to the plans, and make sure you deposit the soil near the construction site, as you will be needing a significant amount to fill in the foundation.
Moving earth with wheelbarrow
You can transport the soil from the foundation, by using a wheelbarrow. The wheelbarrow is a great tool, as it allows to to deposit the soil near the construction site, without putting too much effort.
Installing wooden bridge over trenches
If you have to transport the soil or just walk over the foundation trenches it would be a good idea to make a bridge, by using two thick wooden boards (2×4 lumber) locked together at both ends with two pieces of 1×2 wooden boards.
Foundation depth
When digging a foundation, it important to make sure its bottom is perfectly level. There are cases in which the site is not level, so it is hard to tell by eye if the bottom of the foundation is perfectly level on the whole surface. Nevertheless, we will show you a techniques which works in any situation.
Just use a laser level or a water level to make visible marks on four posts installed at each corner of the foundation. Next, use a tape measurement to see the distance from the marks to the bottom of your foundation trenches. If the four depths are equal, it means the corners of your foundation are level. If the depths are different, you have to adjust them accordingly.
Read more about how to build the formwork for a foundation.
Thank you for reading our article on how to dig a foundation and we recommend you to check out the rest of our projects. Don’t forget to LIKE and SHARE our articles with your friends, by using the social media widgets.
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