Estimating guides & standards references
Practical guides on Philippine construction estimating — PNS/DPWH standards, BOQ structure, and the formulas behind ConstructPro's calculators, written for estimators and contractors.
Doors & Windows: Why Jamb Perimeter Isn't 2(H+W)
The frame perimeter formula for door and window openings deliberately leaves out one edge — here's which one, and why.
4 min read · Doors & Windows EarthworkTemporary Shoring: Excavation Depth vs Embedment Depth
Shoring piles run deeper than the excavation itself — the extra length below the cut line is what actually holds the wall up.
4 min read · Earthwork Cold-Formed SteelCold-Formed Steel Framing: How Stud and Joist Counts Actually Work
Why framing member count depends on run length divided by spacing, not just square footage — and what the track members add on top.
4 min read · Cold-Formed Steel Structural SteelWhy Structural Steel Weight Comes From a Catalog, Not a Formula
Unlike concrete or rebar, a steel member's weight per meter isn't calculated on site — it's looked up, and getting the section name right matters more than any formula.
4 min read · Structural Steel PlumbingSwimming Pool & Fountain Plumbing: What "Average Depth" Really Means
A pool's volume calculation depends on a depth figure that isn't the shallow end, the deep end, or a guess — here's how it's actually defined.
4 min read · Plumbing PrecastPrecast Concrete: Why Erection & Cranage Is Priced Separately From Supply
Precast panels and elements are quoted two ways — cost to supply the piece, and cost to lift and set it — and conflating the two under-prices the crane time.
4 min read · Precast Solar PowerSolar Power Systems: How Array Capacity (kWp) Is Actually Calculated
Array capacity is a straight multiplication once you know panel count and panel rating — the estimating risk is in the inputs, not the math.
4 min read · Solar Power WaterproofingWaterproofing Membranes: Why Coverage Rate Isn't the Same as Roof Area
Membrane material needed is roof area plus overlaps, upturns, and detailing allowances — treating coverage as a 1:1 match with plan area under-orders every time.
4 min read · Waterproofing ElectricalElectrical: Why Wire Length Isn't the Same as Conduit Run Length
Wire measured for a circuit needs more length than the conduit it runs through — service loops, box connections, and vertical drops all add up.
4 min read · Electrical