Beta Structural Engineers can offer Clients advice when creating an opening in an external wall.
Homeowners sometimes need to make openings in external walls. These openings range from creating a new window in an external wall to let in more light to the case where the homeowner wants to knock down as much of the wall as possible to create a large open plan space when building side extensions or rear extensions. Examples also include making an opening to create a new door for access to the outside, or to a garage, or to a lean-to structure. Another example is when a homeowner wants to enlarge an existing door or window.
Making an opening in an external wall requires the installation of beam or a frame to ensure the loads being previously carried out by the wall are safely re-distributed. External walls often act as “buttressing” walls for party walls. This means that the rigidity offered by an external wall is required to prop the party walls and preventing them from moving sideways. Creating an opening in an external wall would therefore impact on the rigidity that an external wall has. If the opening in the external wall is not properly designed or not properly executed, the stability of the building may be affected. Building Regulations Document A Clause 2C28 states that “the number, size and position of openings and recesses should not impair the stability of a wall of the lateral restraint afforded by a buttressing wall to a supported wall. Construction over openings and recesses should be adequately supported”. To comply with this requirement the minimum length for external wall corner return dimension back to an opening should be 665mm. For a typical period property party wall of 9”, this means that the minimum length of return required to ensure lateral stability is 550mm if measured from the internal edge of the wall to the edge of the opening (excluding any finishes). If this condition is not met, and the client wants to the opening to be larger, the only way to meet the requirement would be to provide a steel frame that is tied to the party wall. The steel frame would be designed to replicate the rigidity of the removed wall. This has been a very popular way of creating large through kitchen-diner extension keeping as little of the original external wall as possible.
Beta Structural Engineers have the expertise to provide you with a design that meets the Building Regulations and ensure that your builder has a practical and safe design to work with. We provide the following:
- Sizes of beam and pad-stones or steel frame and bottom ground beam – depending on the size of opening and loads in question.
- Drawings and specifications for the builder to execute the works safely.
- A structural calculation report to be submitted to the Building Control department of the local authority to satisfy them that works are compliant with the Building Regulations. If the dwelling is in a flat or a leasehold property, a copy of the report may be needed by the Management Company.
Beta Structural Engineers have worked on scores of West London properties where we have advised on how to safely create openings in external walls. Please contact us to enquire about our case studies for the following projects:
Removal of external structural wall in Kingston.
Removal of external structural wall in Richmond.
Removal of external structural wall in Hounslow.
Removal of external structural wall in Ealing.
Removal of external structural wall in Hammersmith and Fulham.