Choose roofing materials for the whole roof system

The temptation with roofing is to choose a material by look and price and treat everything underneath as plumbing. But a roof keeps water out as a system — deck, underlayment, flashings, covering and the path water takes to leave — and the covering you choose has to suit the roof you actually have, starting with its slope.

A roof is a system

Beneath the visible covering sit the structural deck, an underlayment that provides a secondary barrier, and the flashings that seal every edge, valley and penetration. The details at edges, valleys and penetrations are where an assembly is most tested, so when you choose a material you are really choosing a compatible assembly: the right underlayment, the right flashing approach, and a moisture-control and ventilation strategy suited to the roof assembly. Judge bids on the whole assembly, not the brand of shingle alone.

Slope decides first

The single biggest constraint is pitch. Steep-slope roofs (2:12 and steeper) shed water quickly and commonly use lapped materials like shingles, tile and slate that overlap to guide runoff downhill. Low-slope roofs — below about 2:12 — shed water slowly and are usually covered by membrane or coating assemblies rather than lapped products; the permitted system depends on the product, the manufacturer's instructions and local code. If any part of your roof is low-slope, treat it as its own problem; our low-slope roofing guide covers those systems in detail.

The main coverings

The Cool Roof Rating Council groups the common steep-slope residential families this way:

• Asphalt shingle. The most common residential roofing — relatively inexpensive and simple to install. It comes in architectural (generally thicker) and 3-tab options.
• Clay or concrete tile. Available in clay and concrete, resistant to fire, hail and moisture, in a range of styles and colours; heavy, so the structure must be able to carry it.
• Metal. Commonly steel, aluminium or copper, as standing-seam or panel systems or as shingle, shake or tile facsimiles; often factory-coated for colour and durability.
• Polymer or composite. Manufactured to mimic natural shingles, shakes or slate; typically lightweight, and can be fire-resistant or made from recycled material.
• Slate. Natural stone in a range of colours, shapes and textures; heavy, and specialised to install and repair.
• Wood. Typically cedar, in shake and shingle varieties; check local fire code and maintenance needs.

By family, and what to confirm

We deliberately give no price figures here: real roofing costs depend on your roof's size and complexity, your region, tear-off, decking condition and current material prices. Any single number quoted out of that context is more likely to mislead than help.

Maintenance and questions

Roofs generally benefit from routine upkeep — keeping the roof and gutters clear and maintaining flashings — and many assemblies rely on adequate attic ventilation to shed heat and moisture. When you talk to a roofer, ask which underlayment and flashing approach they will use, how the roof will be ventilated, what the covering's expected service life is in your climate, and what maintenance it needs to reach it.