The five building construction types run from Type I, fire-resistive concrete and steel, down to Type V, wood frame. The International Building Code uses these classes to set fire-resistance ratings and where each can be built. Your type drives your materials, your code rules, and your cost. Knowing the type before you bid keeps your estimate honest. For a deeper breakdown, see our guide to the 5 building construction types.

Type I: Fire-resistive construction

Type I is the most fire-resistant class, built for high-rise and high-risk buildings. It uses non-combustible materials with high fire-resistance ratings so a fire stays contained.

  • Built from concrete and protected steel
  • Designed to hold up under severe, long fire exposure
  • Common in skyscrapers, large commercial buildings, and hospitals
  • Includes advanced fire suppression and alarm systems
  • Held to the strictest building codes

These jobs carry heavy compliance and documentation. AIA-style billing fits well here because it ties each pay application to verified progress and the G702 and G703 forms owners expect.

Type II: Non-combustible construction

Type II also uses non-combustible materials but carries a lower fire-resistance rating than Type I. It balances safety with speed and cost, which suits many commercial builds.

  • Uses steel and concrete for structural parts
  • Lower fire-resistance rating than Type I
  • Common in shopping malls, theaters, and warehouses
  • Offers solid insulation and energy efficiency

Type III: Ordinary construction

Type III, often called "ordinary construction," pairs non-combustible exterior walls with interior parts that may be combustible. That mix gives you flexibility in design and use.

  • Works for both residential and commercial jobs
  • Uses wood for floors and roofing to balance look and structure
  • Cost-effective when you need to manage budget without losing design quality
  • Non-combustible exterior adds protection from outside fire

Cost control on Type III jobs gets easier with time and materials tracking. It keeps a clear running view of what you spend so the budget does not drift.

Type IV: Heavy timber construction

Heavy timber, also called "mill construction," uses large, solid wood members. It is known for natural fire resistance because thick wood chars on the outside and holds its strength inside.

  • Wood members are large, with minimum sizes set by code (often around 8 inches)
  • Strong fire endurance from the charring effect
  • Traditionally used in old factories and industrial buildings
  • Modern jobs use engineered wood like glulam and cross-laminated timber
  • Growing in popularity for sustainability

Heavy timber projects often have detailed accounting. A QuickBooks integration keeps your job costs and books in sync without manual entry.

Type V: Wood-frame construction

Type V is the most common type in residential building. It is the most affordable and the fastest to frame.

  • Wood costs less than most other structural materials
  • Light framing speeds up the build
  • Common in single-family homes, duplexes, and low-rise apartments
  • Gives the most freedom in design and layout

Its main weakness is fire risk. Fire-retardant treatments, fire-resistant sheathing, and updated codes have improved Type V safety a lot.

How do you choose the right construction type?

Most of the time, code picks for you. The building's use, height, and occupancy set which types are allowed in your area. Start there before you fall in love with a material.

Then weigh budget and risk. Type V is the cheapest and fits most homes. Type I and Type II cost more because of specialty materials and stricter codes, but they are required for tall or high-occupancy buildings. Whatever the type, watch your material spend closely. See our guide on the best ways to save money on construction materials to protect margin on any class.

Key takeaways

  • Type I (fire-resistive) uses concrete and protected steel for high-rise, high-safety buildings.
  • Type II (non-combustible) balances safety with cost and speed for many commercial builds.
  • Type III (ordinary) mixes non-combustible exteriors with combustible interiors for flexibility.
  • Type IV (heavy timber) offers natural fire resistance from charring and growing sustainability appeal.
  • Type V (wood-frame) is the most affordable and common type for residential work.