Construction Guides & Tips
Expert advice and step-by-step mathematical guides for your construction projects.
Concrete3
Concrete Mix Ratios: M10, M15, M20, M25 — and the C Grades
What each concrete mix ratio means, which one your footing or slab actually needs, why C20 is not the same as M20, and why you order 1.54 cubic metres of dry material per cubic metre of concrete.
The 10% Waste Factor: When It's Enough, When It Isn't
What a waste factor actually pays for, the jobs where 10% falls short, and how it differs from bulking, settlement and compaction.
Concrete Curing Times: How Strength Builds Over 28 Days
Why concrete hardens by reacting rather than drying, what strength it has reached at 1, 3, 7 and 28 days, and how to cure a pour in hot or freezing weather.
Masonry3
Masonry Joint Thickness: Why 10 mm Is the Standard
Why a brick occupies its size plus one joint, how 2 mm of joint changes the brick count by 4%, and which joint profile survives an exposed wall.
Brick Types: Facing, Common and Engineering Compared
What separates a facing brick from an engineering brick, which one belongs below the damp course, and how brick size changes the count per square metre.
How Much Mortar a Brick Wall Actually Needs
Work mortar out by subtraction rather than a rule of thumb, convert it to bags of cement and tonnes of sand, and pick a mix weaker than the brick.
Rebar4
Rebar Grids: Counting Bars, Spacing and Laps
Why a 4 m width at 200 mm centres takes 21 bars and not 20, how one-way and two-way mats differ, and how much extra steel the laps add.
Rebar vs Mesh: Which One Your Slab Actually Needs
Mesh controls shrinkage cracking; bar carries designed load. Where each belongs, how to lap mesh, and the spacer mistake that defeats both.
Rebar Grades: What Grade 40 and Grade 60 Actually Mean
The yield strength behind each grade number, when a higher grade lets you use less steel, and why you cannot substitute one for another on site.
Rebar Sizes: Metric, US and Canadian, and What Each Weighs
How imperial bar numbers convert to millimetres, what each size weighs per metre, and why a size up adds far more weight than the number suggests.
Tiling3
Tile Waste Factors: How Many Spare Tiles to Order
Why a straight grid needs 10% and herringbone needs 20%, how tile size and room shape change it, and why you should keep a box back after the job.
Tile Grout and Adhesive: How Much You Actually Need
Why grout is a volume rather than a rate per tile, when to use sanded or unsanded, and how the trowel notch decides your adhesive coverage.
Tile Pattern Layouts: Straight, Offset and Herringbone
How each layout looks, sets out and cuts — including the lippage trap that makes offset bond fail with long plank tiles.
Finishing3
Paint Coverage by Texture: 10 to 5.5 m² per Litre
Smooth plaster gives about 10 m² per litre and bare block barely 5.5. How to measure a room, subtract the openings, and land the right number of tins.
Paint Sheen Guide: Matte, Eggshell, Satin and Gloss
What sheen actually changes — how well the paint washes, and how much it shows up a bad wall. Which level belongs in a hallway, a bathroom and on woodwork.
Do You Need Primer? When to Skip It and When Not To
Primer is not a rule, it is an answer to a specific problem. The surfaces that genuinely need it, the ones that do not, and how much to order.
Ceilings3
Suspended Ceiling Take-Off: Tiles, Tees and Wall Angle
What a drop ceiling is made of and how to count each part — mains at 1200 mm, cross tees per cell, wall angle round the perimeter, and what the module changes.
NRC vs CAC: Which Ceiling Tile Rating You Need
One rating measures noise inside the room, the other measures sound leaking to the room next door. Why a tile that is good at one is often poor at the other.
Hanging Lights From a Suspended Ceiling, Safely
A ceiling grid is designed to carry tiles and nothing else. Which fixtures need their own hangers back to the structure, and how sagging starts.
Timber3
Board Feet: The Formula, and Why It Uses Nominal Size
Board feet are nominal width × nominal height × total linear feet ÷ 12. Why timber is billed at a size it does not have, and when the real size matters.
Lumber Grade Stamps: What the Marks Actually Mean
Visual versus machine grading, the five things printed on a grade stamp, and why the species group beside the grade matters as much as the grade itself.
Stud Spacing: 16 or 24 Inch Centres, and Counting Studs
Where 16 and 24 inch centres come from, why a 12 foot wall takes 10 studs and not 9, and the extra pieces corners and openings add on top of the arithmetic.
Groundwork6
Asphalt Driveway Estimate: Area to Tonnes to Truckloads
The full take-off for a driveway — measuring the area, choosing a thickness, converting to tonnes, and working out how many truckloads that actually books.
Why Ordered Topsoil Settles, and the 15% Allowance
Soil and mulch are sold loose and settle once watered in. Why ordering to the finished depth leaves you short, and why settlement is separate from waste.
How Deep Should a Garden Bed Be? Depth by Planting
Rooting depths for lawns, vegetables, shrubs and trees, why depth is the one dimension that doubles your delivery, and how to fill a deep bed without wasting soil.
Mulch vs Compost vs Stone: Weight, Depth and Cost
The same hole filled with bark weighs a third of what topsoil does. What each material is for, how deep to lay it, and which one your delivery can carry.
Asphalt Sub-Base: Why Paving Fails From Underneath
The layers under a driveway, how the load spreads through them, and why the sub-base decides whether the surface lasts twenty years or cracks in two.
Compacted vs Loose Asphalt: The Depth That Counts
Why asphalt is specified at its compacted depth, what roll-down does to loose material, and why adding a compaction allowance to your tonnage double-counts.