Setting out the first townhouse with the boundary pegs gone and diagonals that disagree

The box is a parallelogram, not a rectangle. For an 8.6 x 12.4 m rectangle the diagonal should be the square root of (8.6² + 12.4²) = 15.090 m. The two readings average 15.090 m, which confirms the side lengths are right - but an 80 mm difference between diagonals means the corners are roughly 40 mm out of square. 'Close enough for a slab' is wrong: concrete locks the error in, and every wall, truss, cladding line and joinery opening inherits it. You get tapered rooms, out-of-square doors, and a slab edge that wanders against the boundary.

Before boxing is fixed:

1. Get the surveyor back to re-establish the boundary and to mark building corners or give measured offsets from two boundary points. You need two references, not one, to fix position and orientation.
2. Stop using the fence as a boundary line. Fences are routinely 100 mm or more off the true boundary and sometimes are not on it at all. At 2.85 m from the fence you may already be further inside the required setback, or outside it.
3. Resolve the 200 mm slab step discrepancy by RFI to the designer before the pour. Do not choose a dimension yourself - the structural sheet normally governs, but you need that in writing.
4. Re-set out using the 3-4-5 method or a total station off the confirmed points, then check both diagonals (they must match within a few millimetres), the overall dimensions, and the setback to the surveyed boundary.
5. Record the check in the site diary with photographs of the tape readings, and notify the pour being at risk.

This is a planning problem, not just a tape-measure problem, and the building consent will not catch it.

Yard setbacks come from the district plan under the Resource Management Act, so a building consent can be granted for a building that infringes a yard. At 2.85 m you are 150 mm inside the 3.0 m yard, and a neighbour complaint or a council compliance check can result in an abatement notice, an enforcement order, or a requirement to apply retrospectively for resource consent.

Resolve it in this order:

1. Confirm the true boundary with the surveyor before deciding anything. If the true boundary is further out than the fence, the encroachment might already be different from what the tape says.
2. Check whether the 3.0 m figure applies to this boundary and this building type, and whether the site has an approved resource consent or existing use rights that cover a reduced setback. Ask the council's duty planner rather than guessing.
3. If the setback really is 3.0 m, the options are: shift the terrace row (which then affects every subsequent unit and the services trench), or lodge a resource consent for a setback infringement, with the neighbour notified. Shifting the row without checking the other units and the site coverage is a trap.
4. Look at the services trench too: it is inside the yard and close to the boundary, so check excavation depths against the neighbouring ground and whether any pipe crossing requires an easement.
5. Do not pour. Send a written RFI, record the answer, and issue a variation or delay notice to the client. Building to a known infringement and arguing later is the expensive path.

Treat the drawing set as a controlled document, because the dispute later will be about which sheet was current.

• Collect the full current set on site (architectural, structural, drainage, bracing and any specification) and mark clearly which revision you are building to. Remove or stamp 'superseded' any older sheets so nobody builds off them.
• Raise a written RFI for each discrepancy: the 200 mm slab step, the setback, and the missing boundary pegs. One item per RFI, with a sketch or photo, the drawing numbers and the date you need an answer by.
• Accept instructions only in writing. If a designer or the client gives a verbal answer, confirm it back by email the same day: 'as discussed, the step is 200 mm at grid B, please confirm'.
• When the answer changes the contract sum or the programme, issue a variation with the cost and time impact before doing the work, not after.
• Keep a site diary with weather, labour, visitors, deliveries and every instruction received, plus dated photos of the set-out and the benchmarks.
• On receipt of a revised drawing, check what else it changes - a moved slab edge will move the drainage, the cladding set-out and possibly the bracing - and re-issue the relevant information to the crew and subtrades.
• At handover, keep the as-built set showing the final set-out and any approved changes for the CCC application.