MEASURING AREAS?
There is a heap of abbreviations linked to the measurement of building volume, floor areas and the like that start at the feasibility & council level with approvals linked referring back to GFA. This measurement is also valid when a landlord wishes to either sell or lease a floor space. Internal and walls and the outside spaces are separated but the primary measurement is the Gross Floor Area. (For Builders – this measured is terrible for benchmarking and record keeping).
Then a tenant needs to know how many car spaces they have and how much useable space they are going to get. The volume of the space is also important as power must be used to light and ventilate the space.
Builders are interested in areas where their contracts say need to achieve an “NLA” (Net Lettable Area), but normally this is a secondary thought (but still checked extensively). Builders are more interested in the overall construction area and its associated cost per square metre of everything.
- Councils, PCAs, banks, developers all operate on a measurement called “GFA” (Gross Floor Area).
- The end user – Developers, Land Lords, and real estate agents and tenants are interested in “NLA” (Net Lettable Area).
- Finally – Builders are interested in a measurement loosely known as “CFA” ( Construction Floor Area) which generally covers all of a building. Now just to throw another couple of abbreviations in the mix we have also UCA and FECA that is widely used.
From a bench marking and cost planning point of view once you are in a company – Make sure you settle on a measurement rule and then never change it. All projects MUST be measured the same way or else your data will get corrupted.
MEASURement DEFINITIONS
GFA – Gross Floor Area
GFA & GBA (Gross Building Area) is often confused within the industry. GFA is used by councils to define the floor space that can be developed on a site based upon its Floor Space Ratio. It can be used for determining the development potential of sites. This number is often produced by an architect at DA stage. The calculation often misses the external thickness of the perimeter walls, Garages, balconies, terraces, external walls are left out of the equation.
The sum of the area of all floors of the building measured from the external faces of the exterior walls, or from the centre line of walls separating the building from any other building, excluding an area used solely for rooftop fixed mechanical plant and/or basement car parking”. In the circumstances listed below GFA will be calculated as detailed:
- stairwells and liftwells should be counted as contributing to GFA once only (these components are not considered to be floor area for subsequent levels).
- basement parking also incorporates parking for bicycles, where such areas are designed in accordance with the relevant Australian Standard, and can be excluded from the GFA calculation.
- Balconies, external stairs, External suspended structures as ramps, walkways and Terraces can be excluded from the GFA Calculation.
- voids within an atrium design can be excluded from the GFA provided the initial floor area of the atrium is included.
- mezzanines are considered to be a floor and should be included in the calculation.
NLA – Net Lettable Area
The area of a building that can be let to tenants. It is less than the gross building area as it excludes such things as walls, common areas, and lift wells. The inside area of a building to be leased. Sometimes called “carpet area”. The calculation of the NLA will depend on the particular formula used by will exclude common and service areas.
In the case of an existing tenant, the NLA is normally taken from the face of the shopfront and in a situation of a sublease the perimeter of the tenancy wall is often a shared wall and would be taken from the centre of the wall.
NLA is one of these calculations that need to be defined clearly in a contract as the big discrepancy is normally the extent of where the outside boundaries are taken. Check the fine print.
CFA – Construction Floor Area
Builders are interested in a measurement known as “CFA” ( Construction Floor Area) which generally covers all of a building. Builders have gone down a root where they break up the building cost in three components.
- Unenclosed Covered Area (UCA)
- Fully Enclosed Covered Area (FECA)
- External Works outside CFA
Elements outside the above (Like road works, Landscaping, etc) could be picked up as a separate number however for benchmarking of CFA is the number we need. The CFA can then be broken data useful for future projects.
So the CFA = UCA + FECA. These are the abbreviation that count to an estimator.
Fully Enclosed Covered Area (FECA)
The sum of all fully enclosed and covered building areas at all floor levels, including: basements (except unexcavated portions), garages, floored roof spaces and attics, penthouses, enclosed porches and attached enclosed covered ways, equipment rooms, lift shafts, vertical ducts, staircases and any other fully enclosed spaces and useable areas of the building. The FECA is computed by measuring from the face of exterior walls, ignoring any projections such as plinths, columns or piers. It excludes open courts, light wells, connecting or isolated covered ways, and net open areas of upper portions of rooms, lobbies, halls, and interstitial spaces etc which extend through the storey being computed.
Unenclosed Covered Area (UCA)
The sum of all unenclosed covered areas at all building floor levels, including roofed balconies, open verandahs, porches and porticos, attached open covered ways alongside the building(s), useable space under the building(s), unenclosed access galleries (including ground floor) and any other trafficable covered areas of the building which are not totally enclosed by full weight walls. The UCA is computed by measuring from the inside face of any enclosing walls, balustrades or supports, but excludes connecting or isolated covered ways, and eaves, overhangs, sun shading, or awnings unless they relate to clearly defined trafficable covered areas.
BENCHMARKING HISTORIC DATA
So the CFA = UCA + FECA.
Within the Tender schedules (Priced Criteria) – the categories of all the costs can be grouped into a few areas that can vary and also screw the data.
If you are interested in keeping good records I would suggest the following format.
- Noted GFA (m2)
- UCA Area (m2)
- FECA Area (m2)
- Design Cost
- Authority Fees
- Trade Costs UCA
- Trade Costs FECA
- External Works (outside Boundary)
- Preliminary Costs
- Program duration
- Overhead Recoverable
- Margin
- Competitors
- Win / Loss amount
If you wish to read more about
Estimator Records – Click Here
If you wish to read more about
Tender Process – Click Here
Hi Scott, I’m studying for my RICS accreditation and this is very helpful.
Question re FECA basement above. In brackets, it’s stated that unexcavated basements are not factored into FECA.
Is this therefore assessed as UCA?
Also, what is assumed to be “unexcavated basement”?
I would consider above ground basement (podium) level parking to fit the definition of unexcavated basement. But given this were enclosed, surely it would be considered “Fully Enclosed Covered Area”?
On the other hand, I suppose a typical city carpark (open walls) is effectively a large open terrace for purposes of construction costing so this may therefore fall under the category of Unenclosed Covered Area (UCA).
Anyway, would be interested to hear your response.
Thanks,
Ed
Ed
I operate in Australia – the best description for most of these definitions is from the “property council of Australia”.
Fully Enclosed Covered Area (FECA) is very close to GFA however it is basically the perimeter of the wall measured from the outer skin with a floor or roof over.
So if you had a high rise tower with a trafficable roof over – that would technically be a measure of Unenclosed Covered Area (UCA).
So a garage or basement with a trafficable terrace roof over it would be measured by UCA (but from the out skin).
In record-keeping – the gold is trying to get like information overtime on a number of projects using the same measurement template. The goal – so you can use it for Benchmarking.
What you are trying to get to is CFA which is Construction Floor Area (or Built floor area).
(In Australia our national codes are called BCA – that is why we use CFA to save a bit of confusion).
The trick is – once you have a definition that an organization is happy with – So rightly or wrongly – it should be set in stone and your record keeping is based on that definition.
Over time – very powerful data.
The devil is in the detail – Garages, Basement caparks, outdoor carparks, Verandahs, & a porch with no roof – all UCA.
There is a real grey area for a porch/verandah open on all sides with a roof over – all UCA.