Interior construction

Harvard Graduate School of Design

Technical criteria for interior construction

1. Safety regulations governing material behavior in fire/natural disaster

2. Durability relative to impact loads (humans, furnishings, etc)

3. Ease of maintenance

4. Tactile environment

5. Acoustic environment (reflective/absorptive surfaces)

* Weathering and waterproofing concerns less important

Fire safety regulations: building codes classify buildings by

1. Use or occupancy:

assembly, business, educational, factory, hazardous,

institutional, mercantile, residential, storage, utility

2. Construction type (types 1 thru 5):

combustible, noncombustible, and combination

These classifications together determine: • allowable building footprint• height + number of stories• applicable fire safety requirements

Construction types: based on fire ratings of structural and enclosure materials

Types 1 + 2

All noncombustibleconstruction

Types 3 + 4

Noncombustible exterior walls + combustible interior structure

Type 5

Combustible structure

Construction types: based on fire ratings of structural and enclosure materials

Interior finish materials and assemblies are given fire resistance rating.

Class I (ASTM* 0 - 25) least combustible

Class II (ASTM 26 - 75)

Class III (ASTM 76 - 200) most restricted use

Ratings based on material composition, thickness, conditions of substrate and attachment.

*American Society for Testing and Materials

Special areas of regulation:

1. Fire stairs and means of egress

= very strict in most occupancies

2. Vertical shafts, duct penetrations

3. High-ceiling spaces

4. Doors and their hardware

5. Glazed areas

* Many traditional flooring materials (wood, vinyl tile, terrazzo) exempt from restrictions except in cases of unusual danger.

Maintenance issues:

1. Porosity of finish surface

= acceptance of dirt, grease, dust

2. Exposure to water

3. Exposure to human touch/ interaction

Acoustical dilemma:

Hard, non-porous surfaces are easy to maintain but can create reverberant, harsh acoustic environments.

Quiet spaces generally require combination of hard and soft finishes.