Grades of basement

Grade of basement Usage Performance level Performance level
Relative humidity Dampness Wetness Temperature
1 (basic utility)

Car parking
Plant rooms (excluding electrical equipment)

Some leakages and damp areas tolerable. Local drainage may be required > 65% normal UK external range Visible damp patches may be acceptable Minor seepage may be acceptable

Car parks: atmospheric

Workshops: 15-29 oC

Mechanical plant rooms: 32oC max. at ceiling height

2 (better utility) Workshops and Plant rooms requiring drier environment than Grade 1 storage No water penetration but damp areas tolerable dependant on the intended use. Ventilation may be required to control condensation. 35-50% No visible damp patches, construction fabric to contain less than air dry moisture content. None acceptable

Retail Storage: 15oC max.

Electrical Plant rooms: 42oC max.

3 (habitable) Ventilated residential and commercial areas including offices, restaurants, and leisure centres etc. Dry environment. No water penetration. Additional ventilation, dehumidification or air conditioning appropriate to intended use. 40-60%
55-60% for restaurants in summer
None acceptable.
Active measures to control internal humidity may be necessary.
None acceptable

Offices: 21-25oC

Residential at 18-22oC

Leisure Centres
- Spectators: 18oC
- Squash courts: 10oC
- Changing rooms: 22oC
- Swimming pools: 24-29oC

Restaurants: 18-25oC

Kitchens: 29oC max.

4 (special) Archives, Landmark buildings, and stores requiring a controlled environment Totally dry environment. Requires ventilation, dehumidification, or air conditioning appropriate to intended use. 50% for art storage
>40% for microfilms and tapes
35% for books
Active measures to control internal humidity probably essential None acceptable

Art storage: 18-22oC

Book archives: 13-18oC