Net internal area NIA
[edit] How is the area of a building measured?
The area of a building can be measured in a number of different ways:
- Gross external area (GEA).
- Gross internal area (GIA).
- Net internal area (NIA).
- Total useful floor area (TUFA).
- Usable floor area.
It is very important when describing the area of a building to be clear about which measure is being used, for example in property sales, planning applications, building regulations applications, lease negotiations, rating valuations, and so on.
[edit] What is the net internal area of a building?
The net internal area (NIA) of a building is the usable area measured to the internal finish of the perimeter or party walls, ignoring skirting boards, at each floor level. Net internal area includes all areas that can be used for a particular purpose. The UK government’s Valuation Office Agency (VOA) Code of measuring practice: definitions for rating purposes suggests that Net Internal Area includes:
- Kitchens.
- Any built in cupboards or units that occupy usable areas.
- Perimeter skirting boards, mouldings and trunking.
- Open circulation areas such as atria, corridors and entrance halls.
- Partition walls and other dividing elements.
Net internal area excludes:
- Internal structural walls.
- Walls (whether structural or not) enclosing excluded areas.
- Piers, columns, chimney breasts, ducts and other projections.
- Cleaner’s cupboards.
- Lifts, lift rooms, lift wells.
- Stairwells and landings.
- Stairwells, entrance halls, atria, landings and balconies used in common or for the purpose of essential access.
- Corridors and other circulation areas used in common with other occupiers or of a permanent essential nature.
- Boiler rooms, fuel stores, plant rooms and tank rooms other than those of a trade process nature.
- Car parking areas.
- Spaces occupied by cooling and heating equipment, air conditioning systems and ducting which renders the space substantially unusable.
- Areas with a headroom of less than 1.5m.
- Toilets and associated lobbies, unless additional toilets have been installed.
- Areas under the control of service or other external authorities.
NB Essential access does not include reception areas or areas capable of use and situated within entrance halls, atria and landings etc.
In relation to the term 'permanent essential nature' the code of measuring practice suggests that, 'apart from areas used in common with other occupiers, corridors excluded from NIA are those of a permanent essential nature, i.e. internal corridors between structural walls (usually found in older buildings). Fire corridors and smoke lobbies which are defined by non-structural walls - but only where they are permanent and essential to any prospective tenant of the property and do not merely serve the needs of the actual occupier. If the latter, they should be included.'
The RICS Guidance Note, A guide for Property Professionals, 6th Edition Code of measuring practice 2007, is in general agreement with the Valuation Office Agency definition, of net internal area.
[edit] Related articles on Designing Buildings
- Area.
- Case notes for rating valuation.
- Floor area ratio.
- Gross development area.
- Gross external area.
- Gross internal area.
- Gross site area.
- International Property Measurement Standards.
- Measurement.
- Measurement of existing buildings.
- Rating valuation.
- Site area.
- Size.
- Space.
- Total useful floor area.
Featured articles and news
Amendment to the GB Energy Bill welcomed by ECA
Move prevents nationally-owned energy company from investing in solar panels produced by modern slavery.
Gregor Harvie argues that AI is state-sanctioned theft of IP.
Heat pumps, vehicle chargers and heating appliances must be sold with smart functionality.
Experimental AI housing target help for councils
Experimental AI could help councils meet housing targets by digitising records.
New-style degrees set for reformed ARB accreditation
Following the ARB Tomorrow's Architects competency outcomes for Architects.
BSRIA Occupant Wellbeing survey BOW
Occupant satisfaction and wellbeing tool inc. physical environment, indoor facilities, functionality and accessibility.
Preserving, waterproofing and decorating buildings.
Many resources for visitors aswell as new features for members.
Using technology to empower communities
The Community data platform; capturing the DNA of a place and fostering participation, for better design.
Heat pump and wind turbine sound calculations for PDRs
MCS publish updated sound calculation standards for permitted development installations.
Homes England creates largest housing-led site in the North
Successful, 34 hectare land acquisition with the residential allocation now completed.
Scottish apprenticeship training proposals
General support although better accountability and transparency is sought.
The history of building regulations
A story of belated action in response to crisis.
Moisture, fire safety and emerging trends in living walls
How wet is your wall?
Current policy explained and newly published consultation by the UK and Welsh Governments.
British architecture 1919–39. Book review.
Conservation of listed prefabs in Moseley.
Energy industry calls for urgent reform.
Comments
[edit] To make a comment about this article, or to suggest changes, click 'Add a comment' above. Separate your comments from any existing comments by inserting a horizontal line.
Can someone explain the design calculation? from architect point of view.
ie - lets say we have a plot of 25X10 meters in Hendon, London.
How can i calculate what is the allowed Net Ground Floor? and on the Net First Floor..?.
How to decide the allowed building contour based on plot contour?
I read that the building border should be 3 meter smaller than plot border on width and 10 meters on length - so in that case - 15 (length) on 7 (width) - which its net ground floor of 105 SQM. is it right?
what are the rules in terace house plot? in triangle plot?