House construction on turnkey contracts is based on per sq. ft. construction cost, which requires the covered area according to drawings. All the costing articles & videos of Team Overc's are based on covered areas. Clients often get confused between covered area and land area — today we will explain the difference between the two, and the way to calculate them for per sq. ft. construction cost.
Video guide accompanying this article.
We will take a 5 Marla plot as a sample for this article. Land area is also known as plot area, and its dimensions are most commonly 25×45 or 125 sq. yards. The way to calculate land area is very simple — multiply the length of the plot by its width and you will get the land area. For instance in this case we multiply 25 by 45 and get 1,125 sq. ft., and that is the land area, or plot area, of the house. This figure of land area cannot be used in calculating the construction cost of your house.
Whereas covered area is the area that is actually constructed on that land. The open area of the land will not be considered in covered area, as there is no construction done in that area — only the area where the construction is done counts. So if the land area is around 1,125 sq. ft., and we take out the side that will not be constructed, we will be left with around 75% of that, which is 900 sq. ft. — this is the covered area of one floor. If you're making a multi-storey building, you can add the covered area of each floor to this figure — for example, if the covered area of both floors is the same, you add 900 sq. ft. of ground floor to 900 sq. ft. of first floor and get 1,800 sq. ft., which will be the covered area of the house.
In another scenario, your constructed building may not be rectangular — the constructed area may be in different shapes and blocks. In this case it may not be possible for a layman to calculate the covered area by hand. The best way to do the calculation is to divide your constructed area into different blocks — if your blocks are rectangular, or the walls are at 90 degrees, it is possible to calculate the covered area manually. If your constructed area is not rectangular or square-shaped, you will need to use software such as AutoCAD to calculate the covered area of the house.
To calculate the total covered area of a house made up of several blocks, take the covered area of block A — for instance 10×20 = 200 sq. ft. — and then repeat the same formula for block B and C, and add all three figures together to get the total covered area of the construction.
In another case, if the house has chamfered corners or any rounded area in the constructed area, there is no way to calculate the covered area manually — you will have to consult a draftsman or an architect, or use software such as AutoCAD if you're fluent in it, to calculate the constructed area's covered area.
We hope that the difference between covered area and land area is now clear and won't be confusing anymore. Please make sure to use the covered area for your per sq. ft. construction cost from now on, and not the land area.