With a shortage of space for development and high land values, basement construction is becoming increasingly popular as a way of gaining additional space in both homes and commercial properties.
At Croft Structural Engineers we have extensive specialist knowledge in basement construction. Our comprehensive technical expertise ensures that all projects meet our client’s aspirations, comply with the relevant planning requirements and are delivered on time and within budget.
Croft are an Associate Member of ASUC confirming its position as a skilled underpinning and basement structural design consultancy.
Our Design Process
We play an integral part in providing solutions for day-to-day temporary works activities and a sensible approach is always provided in our design. Our knowledge of structural engineering and construction methodology has provided our clients with alternative design and construction processes. These have resulted in both cost and time savings on contracts: Shot Crete walls, integration of permanent and temporary support are some techniques used.
It is essential that the stability of a structure is maintained throughout the construction process and this is reflected in our designs. We are totally committed to creating a safe working environment on all our projects.
The majority of basement construction requires issuing a Party Wall Notices to adjoining owners. Our expert knowledge of the Party Wall Act ensures we are the first point of contact for Party Wall Surveyors in providing reliable, specialist design reviews.
Croft’s professional and friendly approach, combined with our cost effectiveness, gives us the enviable reputation for repeat work. Contractors often approach us at tender stage to look at redesigning basements to reduce the costs and win them the project. You will be getting the best possible value for money when you choose Croft Structural Engineers for your basement conversion.
Croft Structural Engineers leads with the latest technological innovations. We have invested heavily in design software to help support our engineers in providing the appropriate design outcomes. These technologies allow us to determine the loads of adjacent buildings more accurately, resulting in using lighter reinforcement.
Loose bar schedules require rebar fixers. It is much more cost effective to use special prefabricated meshes which are predominant on our drawings.
These are just a couple of examples where we drive down material costs and reduce the spending required by our clients.
Basement formation process involves gradual excavation and propping of the house. Cantilevered retaining walls are cast to support the weight of the house above and to resist the lateral earth pressures.
A complete basement acts as one unit resisting the soil forces. In the excavation phase the stability of the area worked in is of upmost importance. Temporary propping is required until cantilevered retaining walls can be inserted. These are inherently stable and individually resist the ground forces.
Ground Movement Assessments
Croft can undertake ground movement assessments on the soils. These provide predictions on the level of movement that may occur to the property and also the surround areas. Over time these have become more complex, Croft uses the skills of specialist Chartered Geologist to provide this level of information. The level of movement is related back to strains within the building and these are equated to damage categories under the Burland Scale. Typically, movements between slight to very slight are predicted. However in our experience, which is back up by site monitoring, the level of movement has been less that the predicted movement.
The staff at Croft are a clever bunch and have worked out how the Geologist undertake their assessments and for simple conditions can undertake movement assessments. We consider movement in line with the guidance of CIRIA’s C720 and also included the heave if the clay that occurs when the soil is excavated. Most Structural Engineers will pass the ground movement assessment solely over to Geologist, on small projects this can be an expensive option. Croft has written software to allow for initial Ground Movement Assessments to be undertaken without the need for specialist Geotechnical Engineers.
What are GMAs?
GMA = Ground Movement Assessment
Give theoretical prediction on how ground near excavations will move
Party wall responses, especially near listed buildings
Carried out on excavations near properties that might be affected