01 · THE WHOLE SYSTEM CARRIES
A structure is more than the wall you can see
A building transfers actions through roofs, floors, beams, walls, columns, connections and foundations into the ground. This connected route is the load path, and it can cross several rooms and storeys.
An element may carry a floor, restrain a façade, stabilise the building against wind or anchor another component. A small connection or a short length of wall may therefore be more important than its size suggests.
Timber, steel, concrete and masonry can all form structural or non-structural elements. The system, its connections and the actions determine the role.
02 · VERTICAL LOADS AND HORIZONTAL STABILITY
The building must carry weight and remain stable
Gravity and use
Self-weight, people, contents, storage and snow are usually transferred through floors, beams, walls and columns to the foundations.
Wind and stability
Diaphragms, walls, frames, bracing, connections and anchors resist wind and other horizontal actions.
Connections and bearings
Forces concentrate at supports, holes and joints. Compression, tension, shear and movement can be decisive here.
03 · WHAT YOU CAN RECORD YOURSELF
Observation is useful. The conclusion needs expertise.
You can collect facts without opening the structure: building age, storeys, materials, wall positions, apparent span directions, visible beams, cracks, previous alterations and the proposed work.
Clues and history
- Existing drawings and permit records
- Photos of rooms, roof space and basement
- Wall positions on each storey
- Visible beams, columns and cracks
- The proposed change and new loads
Role and capacity
- Whether a wall carries or stabilises
- How much an element can carry
- Where a hole can safely be made
- How temporary support should be arranged
- Whether existing damage is stable
They provide limited clues and may hit services or weaken the structure. Intrusive investigation needs to be planned.
04 · WHEN STRUCTURAL BEHAVIOUR CHANGES
Demolition is not the only way to change a structure
Openings or removal
A wall opening, removed column, altered chimney, stair opening or cut floor.
More load
Heavy floor build-up, bath, tank, plant, solar array, green roof or storage.
Less beneficial weight
Removing heavy layers can also change stability or anchorage.
New penetrations
Holes in beams, slabs, walls or foundations can hit critical zones.
Changed use
A loft, room or building receives different loads or safety assumptions.
Roof or façade changes
Dormers, roof changes, large glazing, balconies and openings can affect load and stability.
Work near foundations
Excavation, drainage, lowering floors, services or extensions close to existing foundations.
Damage or deterioration
Rot, corrosion, fire, impact, storm, settlement, cracking or undocumented earlier work.
A local alteration can redistribute forces, change movement and affect adjoining structural zones. The final condition and every temporary condition both need assessment.
AIDOIT.AI · ORIGINAL PRINCIPLE DIAGRAM
A structural alteration also has a dangerous temporary state
The sequence is a decision principle for non-specialists, not a method statement.
- 01BEFORE
Investigate the existing structure
Build-up, load path, stability, materials, damage and previous alterations need to be understood.
→ - 02DESIGN
Document the alteration
The engineer defines the structural concept, calculations, details, sequence and checks.
→ - 03DURING
Secure the temporary state
Loads need a safe path throughout the work, including before the new solution is effective.
→ - 04AFTER
Check the completed load path
Materials, connections, bearings, anchorage and workmanship are checked against the design.
05 · EXISTING BUILDINGS
The real building takes priority over assumptions
Old drawings are valuable but may not show later alterations or the work as built. A structural engineer may need to investigate materials, dimensions, connections, foundations, condition and concealed construction before design can begin.
Define the scope
Which rooms, levels and elements could be affected directly or indirectly?
Reconstruct the history
What was altered, what records exist, and where is the evidence uncertain?
Establish behaviour
How do vertical and horizontal forces pass through the existing structure?
Assess condition
Are there cracks, movement, moisture, rot, corrosion, fire or impact damage?
Investigate with purpose
Open, measure or test only where the result is needed for a decision.
State the conclusion
Record assumptions, uncertainty, further analysis and consequences of the alteration.
06 · TEMPORARY STATES
The building must be safe at every stage, not only at the end
When a structural element is opened, removed or released, the original load path may disappear before the new one exists. Temporary props may also create large point loads on the floor or structure below.
Support, foundations for props, bracing, sequence and acceptable movement must be designed for the specific work. This is not an area for rules of thumb.
07 · DOCUMENTATION AND CHECKING
A safe solution can be explained, calculated, drawn and checked
Records should cover assumptions, actions, materials, structural model, calculations, details, changes and the work as built to the level required by the project.
Checking and professional roles depend on risk, complexity, consequence of failure, local law and the project’s approval route. A small-looking alteration is not automatically a low-risk alteration.
AIDOIT.AI · ORIGINAL PRINCIPLE DIAGRAM
From the existing building to a documented result
Good records follow the decision from the start; they are not reconstructed after the work.
- 01EXISTING
Record
Drawings, age, use, materials, previous alterations and visible condition.
→ - 02EXISTING
Investigate
Structural system, load paths, connections, foundations and concealed conditions.
→ - 03EXISTING
Assess
Existing safety, the proposed alteration and consequences for the affected system.
→ - 04DESIGN AND WORK
Design
Basis, calculations, drawings, details, sequence and temporary states.
→ - 05DESIGN AND WORK
Check
Design and execution are checked to the level required by risk, local rules and project arrangements.
→ - 06AS BUILT
Compile
Deviations, changes and the actual work are recorded so the next owner does not have to guess.
Updated drawings, calculations, checks and recorded changes matter for maintenance, sale and the next alteration.
08 · LOCAL RULES AND RESPONSIBILITY
Permission, professional registration and checking vary by jurisdiction
Structural alterations may require permission, a defined design-and-checking route or work by locally qualified professionals. Check the current rules where the building is located before design or work starts.
Agree in writing who investigates, designs, calculates, approves changes, checks the work and compiles the final records. Approval by an authority does not replace structural design.
09 · WARNING SIGNS
React to change — especially when several signs appear together
- A new crack or one that is widening
- Diagonal cracking near openings or beam ends
- Sudden deflection, lean or change in floor slope
- Doors or windows that begin sticking over a short period
- New cracking, popping or repeated structural noises
- Visible movement of wall, roof, beam, column or foundation
- Rot, insect damage or soft timber in a structural element
- Corrosion or section loss in steel
- Spalled concrete or exposed reinforcement
- Bulging, loose or separating masonry
- Settlement or washout near foundations
- Temporary support that moves, sinks or leans
Leave and isolate the area. Do not add load, strike the structure or attempt your own support. Contact emergency services where people face immediate danger; otherwise contact a structural professional and the person responsible for the building without delay.
10 · GET PROFESSIONAL HELP EARLY
When in doubt, the next step is a professional — not a test cut
Involve a structural engineer before altering walls, beams, columns, floors, roofs, balconies, foundations or stabilising elements. Do the same for heavy new loads, unknown construction, missing records, visible damage or disagreement between drawings and reality.
You do not need to prove that something is dangerous. If load-bearing and stability cannot be demonstrated, stop the work until a competent professional has resolved it.
11 · FREQUENTLY ASKED
Short answers with a clear safety boundary
Can I tell whether a wall is load-bearing?
Not reliably. Wall thickness, material, position and joist direction are clues, but hidden beams, stabilising functions, connections and previous alterations can change the answer. Obtain a documented assessment before opening or altering it.
Is a lightweight wall always non-load-bearing?
No. It may stabilise, brace or restrain another element, and it may have acquired load through movement or alteration.
Can I make a small hole for a pipe or duct?
Size alone does not make a hole safe. Position near bearings, reinforcement, connections and concealed services can be critical. Have it assessed before drilling or cutting.
Are old drawings enough?
Not necessarily. They may be incomplete, differ from the work as built or omit later alterations. Compare them with the actual building.
When is a structural engineer needed?
Whenever structural role, capacity, damage, temporary support or the effect of an alteration is uncertain. Local rules may also require registered or independently checking professionals.
What should I do if failure may be imminent?
Leave and isolate the area without returning to investigate. Avoid vibration and extra load. Contact emergency services for immediate danger to people and a structural professional without delay.
TECHNICAL DIALOGUE
A question about the guide?
Describe the building type, age, level, affected element, visible signs, existing records and the change being considered. Do not include sensitive personal information. Do not wait for a comment response if there may be immediate danger.