DIY cellar or basement in a house with a strip foundation

In a home with a strip foundation, finishing a cellar or basement can add useful living space or storage, making it a rewarding do-it-yourself project. Houses with a strip foundation, as opposed to those with a full basement, usually have a shallow footing that extends slightly below the frost line, making them appropriate for smaller-scale excavations.

It’s important to review local building codes and regulations before starting. These specifications will specify the maximum depth and size that your cellar or basement may have, guaranteeing both structural soundness and adherence to safety regulations. Speaking with a certified builder or a local building inspector can give you important information about what is required in your area.

Thorough planning and preparation are required for the initial stage of the process. You’ll need to decide where in your house the excavation won’t jeopardize the current foundation. This usually entails choosing a location close to the house’s perimeter where utilities like electricity and water are accessible.

Excavation is a labor-intensive process that requires accuracy. You will carefully excavate the specified area to the necessary depth using the proper equipment, such as a mini-excavator or even hand tools, being careful to preserve the integrity of the surrounding soil and foundation. Ensuring safety during the excavation process and preventing collapses require proper shoring up of the excavation site.

After the excavation is finished, walls must be formed and an appropriate foundation must be installed before the cellar or basement can be built. Concrete blocks or poured concrete can be used for this, based on your desired style and the needs of the structure. Maintaining the longevity and integrity of your new space can be achieved by installing appropriate drainage systems and adding rebar reinforcement to these walls.

The project is finally completed with finishing touches like flooring, insulation, and access points like hatches or stairs. These components improve your cellar’s or basement’s year-round comfort and use in addition to improving its functionality. Your DIY cellar or basement will last for many years as a valuable and secure addition to your house with regular upkeep and recurring inspections.

Cellar or basement?

There are two main differences between a cellar and a basement:

• Location. If the basement is an element of the foundation of the house and cannot be separated from it, then the cellar can be built either directly under the house or at a distance from the building, in any convenient place.
• Purpose. The cellar was traditionally intended for storing food products stored for the winter. The basement has a wider list of functions, from storing supplies for the winter to creating a workshop, warehouse, gym or other needs.

The temperature regime can be thought of as the most fundamental distinction between these structures. If a lower temperature is needed for product storage to ensure the safety of vegetables, blanks, etc., then a higher temperature is needed for the basement to function and be comfortable for carrying out different tasks.

Furthermore, if a cellar is able to be constructed on a completed building, the subterranean space is sizable and is only constructed during the building’s original construction.

Depending on the use, the strip foundation enables you to set practically any temperature in the basement. With this kind of base, you can get a maximum basement area that matches the size of the floors above ground.

Though less cozy than the typical premises on the upper floors, it can be furnished as housing if needed.

Conditions for building a basement

The primary prerequisite for basement construction is a low groundwater table. The basement will be wet and the concrete floor may heave if they are situated too near to the surface.

Their value can be crucial and cause the base and a concrete slab to deform due to their larger area. Seasonal variations may cause a sudden spike in loads if the groundwater table is too near to the basement floor, with potentially disastrous results.

Under these circumstances, the pit needs to have excellent drainage.

What should be the depth of the strip foundation?

In order to construct a basement, the tape must be submerged in the ground below freezing point. This is the lowest value; in actuality, they are primarily determined by the basement’s height, the sand preparation layer’s thickness, and the concrete floor.

The tape can be laid more than two meters deep overall. It is important to remember that in these circumstances, the belt’s side surface has a lot of area, which increases the horizontal loads acting on it from the outside.

Only by enlarging the foundation pit and raising the sinus backfill layer—which balances pressure and facilitates drainage—is it feasible to lessen their value. Both the quantity of waterproofing work and the total amount of building materials used rise, particularly in the case of a concrete floor.

It is necessary for a qualified specialist to calculate the basement structure because it would be too dangerous to act in this situation "like a neighbor."

Construction over part of the house and over the entire area

With a strip foundation, you can build a basement beneath a portion of the house or under the entire exterior wall perimeter.

Because of the intricacy of the construction and calculations involved, there are instances where the size of the subterranean space exceeds that of the portion of the house above ground. Nevertheless, these situations call for special consideration.

The depth of the tape is typically measured in accordance with the building parameters when the basement’s size is less than the base’s overall area. A different pit with a deeper foundation is dug for the basement, providing enough height for the space.

The entire perimeter of the tape bears an inscribed image of the pit. When using the shallow tape option is feasible, this option is chosen.

Soil is removed in the desired section of the tape to form the basement, if a full-fledged buried foundation needs to be built.

Waterproofing

Preserving the material’s functionality and extending the base’s service life require cutting off the tape when it comes into contact with water. Applying a layer of heated, molten tar to the side surfaces is the traditional method of waterproofing that has been practiced for many years.

Bitumen mastic is used to adhere a double layer of roofing material inside in order to trim off horizontal surfaces. The top layer is applied after the material has had time to cure and harden, and the bottom layer is laid before the armored belt is installed.

With today’s waterproofing materials, you can create excellent moisture-resistant concrete. The best results come from impregnations that completely remove the chance of water seeping into the material through its surface layer.

The majority of builders prefer tried-and-true techniques like applying a layer of hot tar or bitumen mastic rather than relying on novel and unproven methods.

General installation diagram

Basement construction happens concurrently with the general foundation construction. By doing this, you can create a solid, monolithic base that is resistant to outside loads and has the maximum load-bearing capacity.

While foundation block system (FBS) construction is one way to build prefabricated belts with basements, FBS technology is primarily employed in the construction of large multistory buildings.

Now let’s look at how a monolithic concrete strip is poured:

• Preparation of the site, marking, digging a pit.
• Preparing a trench for tape at the bottom of the pit.
• Creating a Sand Backfill Layer.
• Laying a layer of waterproofing.
• Installation of formwork.
• Creating a Reinforcement Frame.
• Pouring concrete.
• Holding the concrete strip until the material hardens completely.
• Stripping, applying waterproofing.
• Further work.

The process is shown in schematic form, lacking specifics. Specifics are dependent on the soil’s composition, hydrogeological conditions, and other factors.

Drainage, insulation, and other operations that are applied as needed and in accordance with design data are among the several other steps that might be required.

Installation of formwork

Usually, the formwork is built right there on the job site. Plywood or wood (edged board 25–40 mm thick) are the materials. With some technological leeway, shields are assembled such that their width and tape height match.

The assembled panels are placed in their designated locations, aligned with the tape’s axes, and secured with stops every 0.7–1.2 meters. Crossbars hold them in place and control the tape’s thickness based on their distance from one another. Ensuring maximum density is required during assembly.

Gaps or cracks bigger than 3 mm are not permitted. If there are noticeable fissures, wood slats are used to fill the spaces or tow is employed. Installing formwork requires caution and firmness in order for it to support the weight and loads of concrete as it is being poured.

You can achieve the highest quality of tape with plywood formwork, which also has a more straightforward and hermetic design.

Choosing reinforcement and its diameter

The width of the concrete strip determines the diameter of the reinforcing bars used in strip foundations. Typically, 6-8 mm smooth, auxiliary rods and 10-14 mm working rods are used.

A 10 mm rod is typically used for tape widths up to 20 cm, and 12 mm diameter rods are used for strip thicknesses up to 30 cm.

Reinforcement with a diameter of 14 mm is used for strips thicker than 30 cm, but the construction of private homes rarely uses such specifications. The most popular are 12 mm rods, which can guarantee the stability of nearly any type of tape structure in low-rise building.

Reinforcement

Inside the tape is a spatial grid that serves as the reinforcement frame. The rods’ depth within the concrete, which is between two and five centimeters, determines the armored belt’s specifications. The belt typically consists of two gratings made up of three to four rows of horizontal (working) ribbed rods, with a basement height of around two meters.

They stabilize and fortify the tape by absorbing axial tensile loads in all directions.

The working rods will compensate for all loads, both vertical and horizontal (directed towards the tape’s side walls), and smooth reinforcement will only be used to secure the rods in place while the concrete is being poured.

Reinforcement tying

The armored belt is typically put together by knitting soft, annealed wire. You can achieve a reasonably strong connection between the elements using this connection method, which does not require connecting to the power supply network.

Twisting two rods in a cross or longitudinal direction is how knitting is done. A special hook hooks the loop and creates a tight twist with a rotational motion after a piece of wire that has been folded in half covers the joint.

No particular skill is needed for this; it can be learned very quickly.

Fill

To guarantee the tape’s consistency and uniformity, concrete is poured from multiple locations. To create a high-quality, load-resistant concrete monolith, it is advised to use concrete grades no lower than M200 or M250.

To ensure that everything is finished in one sitting, make all the necessary preparations and schedule the concrete delivery before you begin working. The tape’s quality is drastically diminished by the existence of cold seams, endangering the structure as a whole.

Small air bubbles are removed after pouring by bayoneting or vibrating the container. Curing concrete takes 28 days. The tape is covered with polyethylene after three days of being watered every four hours.

Final stages of work

Following curing, a layer of waterproofing is applied to the tape’s surface, the sinuses are filled, and insulation is applied if needed. A concrete blind area is poured after the backfill layer has been compacted, preventing the sinuses from coming into contact with rainwater that is coming from the gutters or walls.

This relieves pressure on the drainage system and greatly lowers the likelihood of moisture seeping into the backfill layer.

Ventilation

The upper portion of the tape has vents created in it along the short sides of the perimeter. They are arranged in pairs, across from one another in the corners and uniformly every 1.5–2 m along the whole length.

By removing extra moisture and aiding in the drying of the walls, these holes manage air circulation in the basement and get rid of mold, mildew, and other undesirable growths.

While drilling holes in the tape’s side walls can be done later, it is advisable to install vents while the formwork is still being constructed.

Useful video

This video will teach you how to construct a basement-equipped monolithic strip foundation:

In a home with a strip foundation, creating a DIY cellar or basement can be a fulfilling project that provides useful additional space for living areas or even storage. It’s important to begin any planning for this kind of project with a careful evaluation of your foundation’s state and suitability for excavation. Although a solid strip foundation offers a stable base, maintaining its integrity during construction calls for careful planning.

Make sure you have all the required permissions and approvals from the relevant local authorities before you start digging. This step is essential to ensure your cellar or basement satisfies safety standards and complies with building codes and regulations. A structural engineer or architect can also help you determine whether your plans are feasible and advise you on any foundation modifications or reinforcements that may be required.

Prioritize safety precautions during excavation, such as securing the excavation site and supplying enough airflow. In order to shield your cellar or basement from moisture and temperature swings, which could eventually cause mold growth and structural damage, proper waterproofing and insulation are also crucial.

After construction is finished, give the cellar or basement a thorough inspection and testing. Look for any indications of water intrusion or potential structural issues that need to be fixed. A useful and valuable addition to your home for many years to come, your DIY cellar or basement will last with proper maintenance, which includes routine inspections and repairs as needed.

In a home with a strip foundation, constructing a DIY cellar or basement requires doable actions and considerations from the homeowners. Important topics like excavation depth, waterproofing techniques, ventilation needs, and materials appropriate for building subterranean spaces are covered in this article. DIY enthusiasts can confidently plan and carry out a cellar or basement project that improves the functionality and value of their home while making sure it complies with safety and regulatory requirements if they have a thorough understanding of these elements.

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