Developer

TBC

Architect

TBC

Main Contractor

YBC

Project Overview

ADS Structural was appointed to provide structural engineering design services for a typical domestic rear extension involving the complete removal of the existing ground floor rear elevation. The works required the design and installation of a steel goal post frame to provide vertical support and lateral stability to the rear of the original house following removal of the existing masonry wall.

The structural solution needed to create a wide open-plan connection between the existing house and the new extension while ensuring that the remaining structure of the original property remained stable, adequately supported and suitable for Building Control approval.

Scope of Services

ADS Structural provided structural design input for the key load-bearing elements associated with the rear extension, including:

• Structural appraisal of the existing rear elevation and supporting walls.
• Assessment of load paths following removal of the ground floor rear wall.
• Design of a steel goal post frame comprising a primary beam and supporting steel columns.
• Design of column base plates, holding down requirements and local support details.
• Assessment of lateral stability to the rear of the original house.
• Specification of padstones, bearings and connection details where required.
• Preparation of structural calculations and details for Building Control approval.

Project Challenges

Removal of the Existing Rear Elevation

The complete removal of the existing ground floor rear elevation significantly altered the original load-bearing arrangement of the house. The design needed to support masonry, floor and roof loads above the opening while providing a stable frame to replace the restraint previously offered by the removed wall.

Maintaining Stability of the Original House

Once the rear wall was removed, the remaining structure required a clearly defined stability system. The steel goal post frame was designed to resist vertical loads and provide lateral restraint to the rear of the original house, helping to maintain overall structural integrity.

Integration With the New Extension

The structural frame had to be coordinated with the proposed extension layout, finished floor levels, wall lines and architectural opening requirements. This ensured the steelwork could be concealed or integrated neatly within the completed building fabric wherever possible.

Construction Sequencing and Temporary Support

The works required careful sequencing, including temporary support to the existing structure during removal of the rear wall and installation of the steel frame. The design information therefore needed to support a buildable and safe construction approach.

Engineering Solution

ADS Structural developed a robust steel goal post frame solution to support the remaining structure above the new rear opening and provide stability to the back of the original house. The frame typically comprised a horizontal steel beam supported by vertical steel columns at each end, with suitable base fixings and foundation or slab support designed to resist the applied reactions.

Key elements of the structural solution included:

• Design of a primary steel beam to support the masonry, floor and roof loads above the removed rear elevation.
• Design of steel columns to form the goal post frame and transfer loads safely down to suitable supports.
• Consideration of frame action and lateral stability where the rear wall had been removed.
• Specification of base plates, holding down bolts and local bearing details.
• Assessment of padstones, foundations and supporting masonry to confirm load transfer capacity.
• Preparation of structural calculations and drawings suitable for Building Control and contractor use.

The goal post frame provided a clear and reliable load path, allowing the rear elevation to be opened up while maintaining support and stability to the existing house.

Project Outcomes

The structural design enabled the creation of a modern open-plan connection between the existing dwelling and the new rear extension while maintaining the safety and stability of the original house.

Key outcomes included:

• Safe removal of the ground floor rear elevation.
• A robust steel goal post frame providing support and lateral restraint.
• Clear load transfer from the original house into new structural supports.
• Improved open-plan living space between the existing property and extension.
• Structural calculations and details suitable for Building Control approval.
• A buildable solution suited to typical domestic extension works.

Key Achievements

• Efficient structural design for a typical domestic rear extension.
• Design of a steel goal post frame to replace the support and restraint provided by the removed rear wall.
• Successful coordination of vertical load support and lateral stability requirements.
• Practical detailing of bearings, base plates, padstones and connections.
• Clear Building Control-ready design information for homeowners, architects and contractors.

Conclusion

This typical rear extension case study demonstrates ADS Structural’s experience in providing practical structural engineering designs for domestic alterations where major load-bearing walls are removed. Through the design of a steel goal post frame, ADS Structural provided a clear and robust solution that enabled the complete removal of the ground floor rear elevation while maintaining support and stability to the original house. The result was a safe, buildable and Building Control-ready structural design suitable for residential rear extension projects.