Loft conversion structural package
Everything structural for a loft conversion, from survey to Building Control approval.
About this package
The loft conversion structural package covers everything structural for turning a roof space into a habitable room. It starts with a site inspection, moves through the full structural design for floors, steels and roof alterations, and finishes with Building Control's questions answered. It works for rear dormers, hip-to-gable conversions, mansards and roof-light conversions, on terraced, semi-detached and detached houses across London.
It suits homeowners who have an architect's or designer's layout and need the engineering, and loft builders who want one engineer to take a project from survey to approval. It also suits people still weighing up options, because the site inspection often shows early whether the existing walls and roof suit a particular type of conversion, before money is spent on detailed drawings.
Loft structures interact with everything below them. New steel beams bear on party walls and internal walls, which bear on foundations never designed for extra load. Handling inspection, design and Building Control together means the engineer who saw the house answers the inspector's questions. Your calculations are checked through our three-step quality control process and signed off by our Head of Engineering before they reach Building Control.
What the package brings together
- Site inspection
- Loft conversion structural package
- Building Control queries
Stages
- Site inspectionWe inspect the roof structure, ceiling joists, party walls and the walls below that will carry new loads. We check for purlin struts, chimney stacks and any past alterations that affect where steel beams can go.
- Loft conversion structural designFull calculations and drawings for new floor joists, steel beams and padstones, dormer framing, ridge and purlin supports, and any hip-to-gable masonry. The drawings give your builder what is needed to order steel and set out the structure.
- Building Control queriesWe send our design to Building Control and respond to their comments on bearings, connections, fire protection to steel and related structural points, keeping your approval moving while the builder gets on with the work.
Who it suits
- Rear dormer on a Victorian or Edwardian terrace
- Hip-to-gable conversion on a semi-detached house
- Mansard roof extension in a conservation area
- Adding a bedroom and bathroom under the roof
- Loft builders who need an engineer from start to finish
How it works
Frequently asked questions
Will my loft need steel beams?
Most do. Steel beams usually carry the new floor where ceiling joists are too small, support the roof where purlins or struts are removed, and frame the opening for a dormer. In some smaller conversions, timber or engineered joists spanning between walls may be enough. The site inspection shows which approach suits your roof. Our guide to steel beams and padstones explains how they bear.
Do loft conversions need party wall notices?
In terraced and semi-detached houses, almost always. Bearing steel beams into the party wall, raising it for a hip-to-gable or mansard, or cutting in flashings are notifiable works. Our drawings show exactly what affects the party wall, which helps the notices describe the works accurately. A party wall notices and schedule of condition service can be added if you need it.
Can the existing foundations take the extra load?
In most two-storey houses a loft conversion adds modest load, and the existing foundations cope. The question matters more for older houses with shallow footings, where there is evidence of past movement, or where steel beams concentrate load at a few points. We check the load path down to the ground and flag any concern at the inspection stage.
Does the package include the architectural drawings?
No. The package covers the structural engineering: inspection, calculations, structural drawings and Building Control liaison on structural matters. Layouts, planning drawings and non-structural details such as insulation, stairs and escape routes are usually prepared by your architect or designer. We coordinate with them so the structural and architectural drawings match.