The shallow foundation is the most commonly used type of foundation in building and structural engineering. It transfers loads into the ground close to the surface and is used as strip foundation, isolated footing or foundation slab (floor slab). Its planning and execution touch numerous adjacent disciplines—from geotechnical engineering, drainage and frost protection to deconstruction and refurbishment of existing foundations. In the context of concrete demolition and special deconstruction, the controlled treatment of foundations plays a central role: Tools such as concrete pulverizers as well as hydraulic rock and concrete splitters from Darda GmbH enable interventions with low vibration levels, for example when adapting, partially removing or selectively deconstructing foundation slabs and foundation beams—especially where neighboring buildings, sensitive installations or confined space conditions require special operations.
Definition: What is meant by shallow foundation
Shallow foundation refers to foundations whose base level lies at a shallow depth relative to the ground surface and whose load transfer occurs primarily via soil bearing pressure. Common forms are isolated footings for columns, strip foundations under walls and foundation slabs (floor slabs) for areal loads. In contrast to deep foundations (piles, caissons), the building loads in a shallow foundation are introduced into load-bearing soil layers near the surface. Decisive influencing factors are the load-bearing capacity and deformability of the subsoil, the frost penetration depth, the groundwater level, drainage, and the limitation of settlements and differential settlements. Frequent construction details include a capillary-breaking layer, blinding layer, reinforcement, frost skirts and, where appropriate, waterproofing. From a concrete technology perspective, these are usually reinforced cast-in-place concrete constructions with defined joints and support conditions.
Structure, types and execution of shallow foundations
The structure follows the principle of a load-bearing, drained and frost-protected subgrade beneath a foundation cross-section adapted to the loads. Typical layers are: prepared formation level (possibly ground improvement), capillary-breaking base layer of gravel/chippings, blinding layer, reinforcement and the actual concrete section. In strip foundations loads are transferred linearly; isolated footings concentrate point loads; foundation slabs distribute loads over an area and reduce differential settlements. Edge beams, upstands, frost skirts, thermal insulation and waterproofing complement the system depending on use. In practice, subsoil classes, loads (permanent, variable, seismic), groundwater, the drainage concept and detail points such as penetrations and joints influence execution. In conversions, change of use or deconstruction, foundation parts often have to be adapted, cut in or removed section by section. Here, concrete pulverizers for controlled nibbling and edge breaking as well as hydraulic splitters for rock and concrete for low-vibration widening of boreholes are proven methods to segment massive sections. Hydraulic power units for tools provide the power supply; hydraulic shears and Multi Cutters cut reinforcement, combination shears support switching between concrete and steel components. Where foundation works meet rocky subsoil, rock wedge splitters facilitate the adjustment of the subsoil without blasting—a benefit in inner-city locations and sensitive environments.
Planning, subsoil and design
A load-bearing and durable shallow foundation begins with a geotechnical investigation determining relative density, grain size distribution, consistency, water balance and possible settlement tendencies. Based on this, the dimensioning is carried out with respect to allowable bearing pressures, safety against soil failure (bearing failure) and estimation of total and differential settlements. Frost protection (foundation below frost penetration depth or insulation/drainage concepts), capillary-breaking layers and surface drainage prevent frost heave and moisture ingress. With a high groundwater level, buoyancy safety, sealing concepts and construction stages (excavation, pit shoring) must be considered. Normative requirements and local regulations must be checked for the specific project; statements here are general and not legally binding.
Type selection and load transfer
Isolated footings are suitable for point loads (columns, masts), strip foundations for load-bearing walls and frames. Foundation slabs are used where subsoil load-bearing capacity is low, where high service loads require distribution, or where differential settlements are to be minimized. Edge beams increase stiffness, reduce slab creep at the edges and facilitate load redistribution. In refurbishments, foundation strengthening is realized through overlays, underpinning or partial replacement; here, concrete pulverizers can be used for exposing, hydraulic shears for rebar cutting and hydraulic splitters for controlled opening of the component.
Construction sequence in practice
- Topsoil removal, preparation of the formation level, if necessary ground improvement and compaction.
- Install the capillary-breaking base layer, create slope and drainage routing.
- Place blinding layer, set formwork and spacers.
- Install reinforcement, plan penetrations and joints.
- Concreting, concrete curing, protection against early shrinkage and weather.
- Execute waterproofing, thermal insulation and connection details; release for loading only after sufficient strength has been reached.
Deconstruction and adjustment of shallow foundations
During the selective demolition of foundations, vibrations, noise, dust and component protection must be limited. In densely built situations, for special demolition or special operations a sequential approach has proven itself: pre-cutting of component edges, segmentation and then controlled removal. Concrete pulverizers allow defined nibbling of edges, reduction of cross-sections and opening of construction joints. Hydraulic splitters for rock and concrete generate a separating tensile stress in the component via inserted boreholes—advantageous for thick foundation beams and foundation slabs when impact energy is to be avoided. Hydraulic shears cut reinforcing steels, combination shears and Multi Cutters offer flexibility with changing material proportions. Hydraulic power packs supply the tools, supporting precise work with low emissions.
Low vibrations and component protection
Low-vibration methods reduce risks to neighboring buildings, utility lines and sensitive installations. Splitting technology avoids impact loads and is particularly suitable for massive foundation bodies, upstands, pocket foundations and slab bearings. In interior areas, near laboratories, hospitals or production facilities, this makes it easier to meet protective requirements for vibrations and airborne sound.
Segmentation and material separation
Clean segmentation facilitates material separation: concrete elements are brought to manageable sizes, reinforcement is separated and sorting for recycling is prepared. Concrete pulverizers create fractured rough edges with low crack propagation; hydraulic shears separate reinforcing steel efficiently. This improves the recyclability of the fractions and reduces disposal costs.
Shallow foundation in rock and on slopes
If the foundation meets rocky subsoil, irregularities and protruding rock ledges can impair bearing quality. rock wedge splitters enable targeted adjustment of the rock without blasting. Slopes require special attention to grade steps, hillside water pressure and surface drainage; stepped foundations, drains and roughening/interlocking of the contact surfaces improve shear transfer. During deconstruction near rock, splitting technology offers advantages through defined crack guidance and reduced edge spalling.
Refurbishment, underpinning and strengthening
In the event of settlements, change of use or vertical extensions, underpinning, foundation widenings and slab strengthening are used. The partial opening of foundation zones, the creation of construction joints and the exposure of reinforcement can be achieved in a controlled manner with concrete pulverizers. For creating separation joints and the controlled breaking of massive sections, hydraulic splitters for rock and concrete are appropriate. The intervention requires a structural concept, temporary shoring, construction stage verifications and monitoring of deformations. The statements here are general in nature and do not replace project-specific planning.
Occupational safety, environment and quality
Occupational safety has priority: excavation support/pit shoring, load exclusion zones, protection against undermining, protection from falling parts and safe hydraulics handling must be observed. Dust and noise reduction measures (e.g., through coordinated cutting and splitting sequences) as well as limiting vibrations protect personnel and surroundings. For environmental and resource protection, clean material separation, the recycling of concrete debris and reinforcement as well as short transport routes are sensible. Quality assurance includes documented subsoil and compaction tests, control of reinforcement and concreting sections and monitoring of joint and waterproofing details—particularly for foundation slabs with water-sensitive use.
Checklist for planning and execution
- Subsoil investigation including load-bearing capacity, settlement behavior, groundwater and frost penetration depth.
- Define drainage, capillary-breaking layers, frost protection and edge details.
- Select type (isolated footing, strip foundation, foundation slab) based on loads and subsoil.
- Coordinate joint and penetration planning, waterproofing and thermal protection.
- Deconstruction/adjustment concept: segmentation, concrete pulverizers, hydraulic splitters for rock and concrete, rebar cutting.
- Coordinate hydraulic power and tool combination (e.g., hydraulic power packs, hydraulic shears, combination shears, Multi Cutters).
- Vibration, noise and dust management, neighborhood protection and monitoring.
- Material separation and recycling routes; observe general legal requirements and permits.
- Quality assurance and documentation of construction stages; approvals before load application.
Typical damage patterns and prevention
Cracks due to uneven settlements, frost heave, moisture ingress or inadequate joint detailing are among the most frequent damages. Prevention is achieved through load-bearing, homogeneous foundation bases, functional drainage, sufficient slab or foundation stiffness and careful detailing. During deconstruction, low-vibration methods prevent unwanted cracking in adjacent components; well-planned segmentation, exposing the reinforcement and the controlled use of concrete pulverizers and hydraulic splitters for rock and concrete reduce consequential damage.