Project Guides
Long-form guides that explain the measuring, sizing, and buying decisions behind the calculators — written from the same published sources the tools are built on.
The calculators on this site compute; these guides explain. Each one walks through the reasoning behind a common estimating or sizing decision — where the published numbers come from, which conventions are safe to lean on, and where the shortcuts break down — so you understand the answer a calculator gives you, not just receive it.
Every factual claim in a guide traces to the same published manufacturer data and standards the corresponding calculators are verified against, and each guide links the tools that do the arithmetic.
All Guides
Asphalt vs. Gravel vs. Concrete: Three Ways to Buy a Driveway
One driveway question, three units of purchase — gravel by the yard, asphalt by the ton, concrete by the pour — and the depths and allowances behind each.
Updated August 11, 2026
Drywall Estimation Basics: Sheets, Mud, and the Butt-Joint Problem
How board area really adds up, why sheet length matters more than price, what 10% waste covers, and how framing spacing quietly sets your screw count.
Updated August 11, 2026
Fence Planning Basics: Posts, Rails, and Pickets
How a run length becomes posts, rails, and pickets, what the 1/3-height bury rule means for post length, and why concrete is bought once, on the total pour.
Updated August 11, 2026
How Much Extra Flooring Do I Need? Waste Factors by Pattern
Why plank and tile waste runs 10% straight, 15% diagonal, and 20% herringbone — and why broadloom carpet follows roll geometry instead of a flat percentage.
Updated August 11, 2026
Framing Lumber Math: Studs, Headers, and Board Feet
How a wall length becomes a stud count, why header depth comes from a code table while the takeoff counts stock, and how board feet price the lumber list.
Updated August 11, 2026
Gravel Base and Paver Patios: What Goes Under Matters Most
How base depth follows traffic and soil, why compacted gravel needs a 1.15 over-order, what the 1-inch bedding layer is for, and how lay patterns set waste.
Updated August 11, 2026
How Much Concrete Do I Need? Slabs, Footings, and the Bag Math
How slab, footing, and step volumes are figured, when bagged premix stops making sense, what the waste allowance covers, and where mix design enters.
Updated August 11, 2026
How Much Paint Do I Need? A Room-by-Room Walkthrough
How to measure walls, subtract doors and windows, pick a realistic spread rate, and decide on primer and coats — so you buy the right number of gallons.
Updated August 11, 2026
How Much Mulch Do I Need? Depth Decides Everything
Why spread depth drives every mulch and topsoil order, how bags compare with bulk delivery, what a yard really weighs, and how new lawns change the math.
Updated August 11, 2026
Sod vs. Seed: What Starting a Lawn Really Takes
What sod really costs in rolls and pallets, how seed rates swing by species, and how planting windows, slopes, and budget decide which route your lawn takes.
Updated August 11, 2026
Stair Layout Basics: Rise, Run, and the Code Chain
How a floor-to-floor rise becomes a riser count, why the IRC’s 7¾-inch limit governs the whole flight, and how the guard’s 4-inch rule finishes the stair.
Updated August 11, 2026
Topping Up Attic Insulation: Buy the Shortfall, Not the Target
How to read the insulation already in your attic, pick a target R-value, and turn the shortfall into bags using manufacturer coverage charts.
Updated August 9, 2026
Cord vs. Face Cord: Buying Firewood Without Getting Shorted
What a legal cord of firewood is, why a face cord’s value hinges on piece length, how to measure a delivered stack, and how to compare wood by heat, not volume.
Updated August 9, 2026
Deck Framing Spans 101: How the Load Gets to the Ground
The load path from decking to soil, what the IRC R507 span tables assume, how species and spacing change spans, and where prescriptive deck design ends.
Updated August 9, 2026
Why Your Boat Won’t Go Faster: A Diagnosis in Three Numbers
Why displacement hulls hit a wall at 1.34·√LWL, what Crouch’s formula says planing speed costs, and how prop slip diagnoses a slow boat.
Updated August 9, 2026
Pool Water Balance Basics: Gallons, ppm, and Four Levers
Why every pool dose starts with your gallons, what ppm really means, which chemistry levers you can raise by the pound, and why lowering pH is different.
Updated August 9, 2026
Why Your Room Sounds Bad: One Room, Two Problems
Room modes and reverberation time in plain terms — why small rooms have lumpy bass, what RT60 targets mean, and where the Schroeder frequency splits the job.
Updated August 9, 2026
Window AC Sizing: The ENERGY STAR Method, Explained
How the ENERGY STAR room-AC table works, what the sun, occupancy, and kitchen adjustments really adjust, and why an oversized unit leaves a room clammy.
Updated August 9, 2026