Beginner: identify the parts
No prior knowledge needed. Start with anatomy, then use its links to pitch and flashing. Outcome: name the layers and explain their jobs. Allow about 30 minutes for a first pass.
Roofing 101
A roof is a stack of layers doing different jobs.
Sixteen guides to the layers, geometry, drainage, structure, and building science that make a roof work. Start with anatomy, then follow the question you are trying to answer.
30-second answer
What do I need to understand before I make any roofing decision?
Start with the layers and their jobs, then learn how pitch changes roof area. Use that vocabulary to ask about flashing, drainage, and the condition of concealed materials. A quote naming a shingle alone does not describe the complete roofing work.
Start here
Build the model, one question at a time.
Anatomy gives you the overview. Use the geometry guides for quantities, the layer guides for scope, and the building-science guides to understand how the parts interact.
Roof anatomy
Every layer from structure to covering, what each one does, and what happens when one is missing. The page the rest of the library links back to.
Roof pitch
Rise over run, the pitch factor that converts footprint to actual surface, and why slope rules some materials out entirely.
Roofing squares
The 100 sq ft unit contractors quote in, and why your number and theirs keep disagreeing.
How to measure a roof
Ground-based, satellite, and plan-based methods with their real accuracy limits. Nobody needs to climb anything.
Roof flashing
The metal at every interruption — walls, chimneys, valleys, penetrations — and why it leaks long before the field does.
Roof and attic ventilation
Intake and exhaust balance, net free area, the mixed-exhaust mistake, and why a correctly designed unvented attic is not a compromise.
How long a roof actually lasts
Why a “30-year shingle” names a warranty structure rather than a lifespan, and what actually moves a roof within its range.
What happens during a replacement
Stage by stage, with what normal looks like at each one — and what should prompt a question before the work is covered up.
Roof inspections
Four kinds of inspection with four different incentives, what each actually examines, and how to read the report you get.
Roof decking
Plywood, OSB, and boards; panel ratings, condition evidence, and how to define a concealed-damage allowance.
Roof underlayment
Felt, synthetic, and self-adhered products, their water-management role, and the coverage details a quote should identify.
Drainage, gutters, and downspouts
Follow water from the roof to its discharge point, with a worked example showing why rainfall intensity matters.
Insulation, air sealing, and vapor control
Three distinct control jobs, where the building boundary belongs, and how to write a coherent insulation scope.
Building science basics
Heat, air movement, condensation, and drying explained through ordinary roof examples and an investigation exercise.
Roof loads and structure
Dead, live, snow, water, and wind loads; the load path; and when a proposed roof change needs structural evaluation.
Fire, wind, and hail ratings
Read the test number with the classification, check the specified assembly, and keep warranty promises separate.
Learning paths
Choose the next lesson for your question.
Start with the layers if you are new to roofing. Each path below uses guides you can read now, without an account.
Intermediate: check a quantity
Begin after anatomy and pitch. Follow measurement with roofing squares. Outcome: distinguish footprint, sloped surface, and ordered material. Allow about 25 minutes.
Assess an existing roof
Begin with the basic layer vocabulary. Read inspection, then service life and repair-or-replace. Outcome: separate observations from conclusions and prepare inspection questions. Allow about 30 minutes.
Prepare for replacement
Begin once inspection has established the scope. Read the replacement process, then compare quotes. Outcome: recognize project stages and document questions before work is concealed. Allow about 25 minutes.
Next step
Put the vocabulary to work on a real quote.
The buying kit turns these roof layers into written scope questions, with worksheets for comparing materials, contractors, and bids.
Use the buying kit