--- title: "Structural Calculations" description: "Load bearing walls taken out, openings, attics and extensions calculated by a chartered engineer, with a site visit and a fixed fee quoted first." updated: "2026-10-12" url: "https://www.petruf.ie/services/structural-engineering/structural-calculations" --- # Structural Calculations > Load bearing walls taken out, openings, attics and extensions calculated by a chartered engineer, with a site visit and a fixed fee quoted first. Taking out a wall, opening up the back of a house or converting an attic changes how the house carries its weight. The calculation is what shows that the new beam, its bearings and what is under them can take it. In Ireland nobody approves those calculations for you: there is no building control approval for a beam. The owner has to comply with Part A of the Building Regulations whether or not the work needs a commencement notice, and the calculations are the record that it does. An engineer visits first, because the load on a wall is read off the house rather than off a photograph. The fee is fixed and quoted before we travel, and every set comes with a note on the temporary propping the builder needs before anything is cut. ## What we calculate ### Load bearing wall removal The beam, the bearings at each end and the load path down to the foundation, for one opening or a whole ground floor opened up. ### Steel beams and columns Beams, posts and connections sized against the sections a fabricator holds, with the padstones that spread the load into the wall. ### Rear and side extensions Foundations, walls, roof and the opening into the existing house, tied together so the new work and the old move as one. ### Attic conversions New floor joists, trimming around the stair, and the purlins, ties or walls a roof needs once its timbers are cut. ### Openings and lintels Widened doors and windows, new openings in external walls, and lintels checked against what is built over them. ### Timber floors and roofs Joists, rafters and binders checked for a new span, a heavier load or a change of use. ### Foundations Strip, trench fill and pad foundations sized from what the ground turns out to be, and checked where an old wall takes new load. ## Which route your job is on The Building Regulations apply to all of these. What changes with the size of the work is the paperwork with the council and the certificate at the end. ### Internal alteration: No commencement notice where neither planning permission nor a fire safety certificate is needed No statutory certificate. The calculations are the record, with an Opinion on Compliance if a buyer's solicitor asks for one. ### Extension of 45 m² or less: A commencement notice where planning permission is needed; none where the extension is exempt No statutory certificate. The calculations and an Opinion on Compliance are the record. ### Extension over 45 m², or a new house: A commencement notice under BCAR, with a design certifier, an assigned certifier, plans and calculations A Certificate of Compliance on Completion, backed by the engineer's ancillary certificates, before it is occupied. **We sign the structural certificates.** ### Opted out: For one house or an extension over 45 m²: a commencement notice with plans, calculations and a declaration of intention to opt out No Certificate of Compliance on Completion, but the calculations are still lodged with the notice. ## What you receive A fixed fee, quoted before we travel, covers all of it. - A site visit before anything is calculated - The calculation set, to the Eurocodes with their Irish National Annexes - The beam size and grade, and the bearing and padstone detail at each end - A check down to the foundation under each bearing - A note on the temporary propping the builder needs before anything is cut - Sketches or drawings the builder can work from - The ancillary certificate for the structure, where the work is under BCAR ## The questions that come first ### Do I need structural calculations to remove a load bearing wall? Yes. Part A of the Building Regulations applies even where the work needs no planning permission and no commencement notice. The new beam has to be sized for what it carries, and its bearings and padstones checked down to what is underneath them, and the calculations are the only record that they were. ### How do I know if a wall is load bearing? Not from its thickness: a 100mm block wall can be structural and a 150mm stud wall can carry nothing. What tells you is what sits on it. Joists running into the wall rather than alongside it, a wall directly above it upstairs, or a purlin in a cut roof propped off it all mean it is carrying load. The visit settles it before anything is priced. ### Does the floor above need propping while the wall comes out? Where the wall carries anything, yes. The floor, roof or wall above is held on temporary props, or on needles through the wall, while the opening is cut and the beam is set, and the props stay until the beam is bearing fully on its padstones. Every calculation set we issue comes with a note on the propping the builder needs. ### Do I need building control approval for a steel beam? There is no such approval in Ireland. The owner is responsible for complying with the Building Regulations, and a building control authority does not check or approve calculations before the work. What you need is the calculations, kept for the day the house is sold. ### Does my extension need a Certificate of Compliance on Completion? Only if it is over 45 m² and the owner has not opted out of statutory certification. An extension of 45 m² or less is outside BCAR, but it still has to comply with the Building Regulations, so the calculations and an Opinion on Compliance are what a buyer's solicitor will ask for. ### Who can sign structural calculations in Ireland? Any competent designer can prepare them, but the certificates under BCAR are signed by a chartered engineer, a registered architect or a registered building surveyor, and those are the signatures a lender and a buyer's solicitor look for. Our calculations are signed by chartered engineers. ### What if the work was done without calculations? An engineer can inspect it, opening up the structure where that is the only way to see the beam and its bearings, and give an Opinion on Compliance if it is adequate. Where it is not, the same visit says what has to be done to make it so. ### What do you need from me before the visit? Photographs of both sides of the wall, the ceiling over it and the attic above it, the size of the opening you want, and any drawings you have, by email or on WhatsApp to the office number. That is enough to quote a fixed fee and to know what to look at on the day. ### Which standards are the calculations done to? The Eurocodes, published in Ireland by NSAI with Irish National Annexes, which is what Technical Guidance Document A points to for showing that a structure complies with Part A.