NSSCO Building Studies 6186 common mistakes
NSSCO Building Studies 6186 · Understand the traps and how to avoid them.
When asked to identify a hazard on a described site situation, candidates write only 'it is dangerous' or 'unsafe' instead of naming the specific hazard (e.g. open excavation, unguarded scaffold platform, live exposed conductor) and the control measure required.
Candidates learn safety as a general attitude rather than as a vocabulary of named hazards and controls; under time pressure they default to vague reassurance instead of the technical term the mark scheme rewards.
What to do instead
Build a two-column revision table: hazard name on the left (open trench, missing toe board, trailing lead, unshored excavation, no edge protection) and the specific control on the right (barrier and signage, guardrail and toe board, cable management, shoring/battering, harness and anchor point). Practise rewriting 'it is unsafe' answers into 'hazard + who is at risk + control' in one sentence.
On drawing questions, candidates produce a freehand sketch with no scale bar, no title block, no north point, and inconsistent line weights, so the drawing cannot be read as a construction document even when the shape is roughly right.
Candidates treat drawing tasks as art exercises and focus on making the building look recognisable rather than on the conventions that make a drawing communicable to a builder.
What to do instead
Before any drawing answer, allocate 60 seconds to set out the sheet: border, title block (project, drawing title, scale, date), north point, and scale bar. Use a sharp H pencil and light construction lines for setting out, then a darker grade for final outlines. Keep line-weight discipline: heavy for cut sections, medium for visible edges, light for dimension and projection lines.
Candidates confuse plan, elevation and section, drawing a section where an elevation is asked for, or showing roof pitch and window heights on a plan.
The three views are taught together and candidates memorise them as 'views of a house' rather than as distinct projections with defined information content: plan shows layout in horizontal cut, elevation shows external face, section shows a vertical cut through the building.
What to do instead
Learn one rule and apply it: a plan is a horizontal cut at about 1 m above floor level looking down; an elevation is the outside face seen straight on with no cut; a section is a vertical cut looking in one direction, with cut surfaces hatched. Practise by taking one simple building and drawing all three, labelling what each view can and cannot show (e.g. only the section reveals floor and roof construction thickness).
When asked to set out a rectangular building, candidates quote '3-4-5' without explaining that it is used to establish a right angle, and omit the diagonal check for squareness and the need to check both diagonals are equal.
The 3-4-5 rule is memorised as a phrase; candidates do not connect it to the actual site operation of establishing a corner and then verifying the whole rectangle.
What to do instead
Write the setting-out procedure as an ordered sequence: establish a baseline from the boundary or building line, set the first corner with the 3-4-5 (or Pythagoras) method to give a right angle, measure and mark the sides, then check squareness by confirming both diagonals are equal within tolerance. Learn the profile-board method for transferring corners and the purpose of a datum and sight rails for levels.
In foundation questions, candidates write 'dig a trench and pour concrete' without stating the depth and width criteria, the function of the foundation, or the difference between strip, pad and raft foundations and when each is used.
Foundations are studied as a construction sequence rather than as an engineering response to load and ground conditions, so candidates never link soil type and building load to foundation choice.
What to do instead
For each foundation type, learn three things: what it is, what load or ground condition it suits (strip for load-bearing walls on reasonable ground, pad for isolated columns, raft for weak or variable ground or high loads), and one construction detail (minimum depth below ground and below frost line, wider than the wall, stepped or reinforced as needed). Answer in the form 'because the ground is X and the load is Y, foundation Z is appropriate'.
Candidates mix up English bond and Flemish bond, or describe stretcher bond for a one-brick-thick wall, and cannot explain the purpose of bond at all.
Bond patterns are memorised from pictures without understanding that bond exists to distribute load and prevent continuous vertical joints (straight joints) through the wall thickness.
What to do instead
Learn the diagnostic feature of each bond rather than the picture: English bond alternates whole courses of stretchers and headers; Flemish bond alternates stretcher and header within every course; stretcher bond shows only stretchers and is only suitable for half-brick (cavity) walls because it has no headers tying the leaves. For each, state the purpose: no continuous vertical joint, load spread across the wall, and tying of the two leaves.
When specifying concrete, candidates give a single '1:2:4' mix with no mention of what the numbers represent (cement:sand:coarse aggregate by volume), no water-cement ratio discussion, and no curing requirement.
The mix ratio is learned as a label for 'strong concrete' rather than as a proportioning system, and curing is treated as an afterthought rather than the process that develops strength.
What to do instead
Learn to read a mix as cement : fine aggregate : coarse aggregate by volume, and know that a lower water-cement ratio gives higher strength and durability up to the point of workability. Always add the curing statement: keep concrete moist for a defined period after placing to allow strength gain and reduce cracking. Link mix choice to use (mass concrete, reinforced work, blinding).
On roofs and carpentry, candidates cannot distinguish a rafter from a joist or a purlin, or explain what a wall plate, ridge board and ceiling joist each do, so roof descriptions become a list of timber names with no structural role.
Roof members are learned as a labelled diagram rather than as a load path from roof covering down to the walls, so the names have no attached function.
What to do instead
Learn the roof as a load path: covering to battens to rafters to purlins to ridge board and wall plate to walls. For each member state its role in one line: wall plate distributes rafter loads onto the wall, ridge board aligns the tops of opposing rafters, purlins support rafters at mid-span, ceiling joists tie the feet of rafters and resist outward spread. Practise naming members on a described pitched roof, not just a drawn one.
In plumbing and drainage answers, candidates describe pipe routes without gradients, without trap or vent provision, and without distinguishing soil from waste or surface water drainage.
Services are learned as pipe layouts rather than as systems governed by fall, seal and ventilation, so the reasons behind the components are missing.
What to do instead
Learn the three governing principles and attach numbers where you can: drainage relies on gravity fall (typically around 1 in 40 to 1 in 80 for common sizes, steeper where solids dominate), every appliance needs a water seal trap to stop sewer gas, and the system needs ventilation to protect those seals. Label each pipe as soil, waste or surface water and state where it discharges. For water supply, distinguish mains pressure from tank-fed and know the purpose of a stop valve.
In costing questions, candidates add up material prices and present the total as the cost of the job, omitting labour, plant, overheads, profit, and wastage allowance.
Candidates equate cost with the visible purchase price of materials and have no mental model of a priced bill or estimate build-up, so the structure of a cost answer is missing.
What to do instead
Use a fixed build-up order for every estimate: take off quantities from the drawing, apply wastage allowance to materials, multiply labour hours by a labour rate, add plant and subcontract items, then add overheads and profit as a percentage. Show the build-up line by line rather than a single figure, and state any assumption you make about rates. This structure also earns method marks even when arithmetic slips.
On maintenance and repair questions, candidates recommend demolition and rebuilding for defects that have a targeted repair, and cannot name the defect precisely (e.g. rising damp versus penetrating damp versus condensation).
Defect diagnosis is not taught as a comparison of symptoms and causes, so the first plausible remedy is offered without identifying which mechanism is actually at work.
What to do instead
Learn a symptom-to-cause table for the common defects: rising damp (damp patch low on wall, tide mark, salts) needs a damp-proof course or its repair; penetrating damp (patch linked to external defect, worse in driving rain) needs external repair; condensation (surface mould, worse in cold weather and poor ventilation) needs ventilation and heating, not a new damp course. Always state the diagnosis before the remedy, and prefer the least invasive repair that addresses the cause.