Minimum height and main hygiene and health requirements of habitable rooms
Summary
TAV. 00Sets the dimensional and hygiene minimums that make a room habitable: clear internal height, floor area of rooms and dwellings, natural light and ventilation, bathroom fittings, heating and acoustic protection. Together with the municipal building code, this is the rule that decides whether a space can be called a dwelling.
Scope of application
TAV. 01Applies to rooms intended for habitation, in new buildings and in works that alter their layout. It is the technical benchmark against which fitness for use is assessed under Presidential Decree 380/2001. Municipal building codes and regional laws may impose stricter requirements, not looser ones. Statutory derogations for buildings of cultural interest, and those introduced for the existing stock, remain in force.
In depth
TAV. AIt is a half-page decree from 1975, and it remains the rule that most often decides whether a residential scheme stands up. It says nothing about structure or energy: it says how tall a room must be, how large, how much light and air it must receive. These are the figures an architect checks before anything else, because getting them wrong means designing a space that can never be declared fit for habitation.
| Quantity | Prescribed minimum |
|---|---|
| Clear internal height, habitable rooms | 2.70 m |
| Clear internal height, corridors, bathrooms, storage | 2.40 m |
| Height in mountain municipalities above 1000 m | 2.55 m |
| Bedroom for one person | 9 sqm |
| Bedroom for two people | 14 sqm |
| Living room | 14 sqm |
| Studio dwelling, one person (services included) | 28 sqm |
| Studio dwelling, two people (services included) | 38 sqm |
| Habitable area per occupant, first four | 14 sqm |
| Openable window area | 1/8 of the floor area |
| Average daylight factor | 2% |
The most misunderstood point is the light and ventilation ratio. The decree asks not for one thing but for two, and both must be satisfied: the openable window area must not fall below one eighth of the floor area, and the average daylight factor must not fall below two per cent. The first is a geometric check done in a minute; the second is a lighting calculation that depends on orientation, external obstructions, room depth and glazing type. A deep room facing a narrow courtyard can meet the one-eighth rule and still fail the two per cent.
The articles on services are equally operational. Bathrooms may be internal, but then mechanical extraction is required and open-flame appliances are absolutely prohibited: this is why a boiler cannot sit in a windowless bathroom. A cooking area attached to the living room must open widely onto it and have forced extraction over the hob, which legitimises the open kitchen but not a kitchen shut into a recess without extraction. And at least one bathroom per dwelling must have a WC, a bidet, a bath or shower and a washbasin.
The decree has been substantially amended only once, by the Health Ministry decree of 9 June 1999, which added a derogation for rooms in buildings within mountain communities undergoing building rehabilitation, where the building has typological features worth conserving and the design still guarantees adequate hygiene conditions. Derogations for buildings of cultural interest protected under the Cultural Heritage Code also remain in force.
Key points
TAV. K- Minimum clear internal height 2.70 m in habitable rooms, 2.40 m in corridors, bathrooms and storage
- Openable window area no less than 1/8 of the floor area and average daylight factor of at least 2%
- Single bedroom at least 9 sqm, double at least 14 sqm, living room at least 14 sqm
- Bathrooms without an external opening require mechanical extraction, and open-flame appliances are prohibited
- Studio dwelling: at least 28 sqm for one person and 38 sqm for two, services included
State-exam tracks that call it into play
TAV. EWhere this rule shows up in past architect qualification exams — study the rule, not just the theme.
Frequently asked questions
TAV. QCan a room 2.50 m high be habitable?
Not in new construction on level ground: the minimum is 2.70 m, and 2.40 m applies only to corridors, hallways, bathrooms, WCs and storage. Exceptions are mountain municipalities above one thousand metres, where it drops to 2.55 m, and the existing stock, for which the Salva Casa opened a derogation down to 2.40 m under precise conditions. When in doubt, always check the municipal building code as well, which may be stricter.
Is meeting the 1/8 ratio enough to comply?
No. The decree sets two simultaneous requirements: openable window area no less than one eighth of the floor, and an average daylight factor no less than two per cent. The first is checked as a ratio of areas, the second with a lighting calculation accounting for orientation, external obstructions, room depth and glass transmission. In narrow courtyards and deep rooms it is the second requirement that fails.
Did the Salva Casa abolish the 2.70 metres?
No, and the distinction matters. The 1975 decree still governs new construction. Decree-Law 69/2024 introduced into the Building Act a derogation for rehabilitating the existing stock, allowing dwellings with heights down to 2.40 m and reduced areas to be declared fit for use, subject to conditions and a professional certification. It is a targeted derogation, not a new general rule.
Is a windowless bathroom allowed?
Yes, provided it has mechanical extraction in place of an external opening. The decree adds a prohibition that is often forgotten at design stage: in bathrooms without an external opening, open-flame appliances may not be installed. That is the technical reason why an open-chamber boiler cannot be placed in an internal bathroom.
Glossary
TAV. G- Altezza interna utile
- Distance between the finished floor and the finished ceiling of a room, measured net of suspended ceilings and floor finishes.
- Superficie finestrata apribile
- The part of the window that can actually be opened for air change: it coincides neither with the glazed area nor with the structural opening.
- Fattore medio di luce diurna
- Ratio between the average internal illuminance of a room and the external illuminance under overcast sky, expressed as a percentage.
- Alloggio monostanza
- Dwelling in which living, cooking and sleeping areas are not separated by walls: the decree sets its minimum area including services.
- Posto di cottura
- Meal-preparation area attached to the living room: it must open widely onto it and have forced extraction over the hob.