ESTIMATION AND COSTING
What is estimation & costing?
Estimation is the process of predicting the cost of construction projects by comparing the project to a similar one that has already been completed. Costing is the process of calculating the overall cost of a construction project considering all aspects such as labor, materials, equipment costs, and taxes.
Estimating and Costing for Interior Designers teaches readers a logical process for calculating materials and estimating the costs of installed products based on their math calculations. Utilizing step-by-step examples and worksheets, this text simplifies the math used in the interior design field.
Why estimation and costing is important for interior design?
An accurate estimate helps one validate their costs and the fee charged. Also, if the clients want some room for reduction, a clear-break-up cost sheet makes it easy to choose which components one can save upon or eliminate to bring down the cost.
The first step is to calculate the amount of work needed in terms of square feet (sqft). This is done by multiplying the height and width of each of the components (of the front side). If your wardrobe is 5 ft wide and 7 ft tall, the total sq ft of the furniture is 7 ft x 5 ft, i.e. 35 sq ft.
If you are looking to supplement your loft with shutters, calculate the width and height of the loft and multiply them to find out the sq ft value.
For false ceilings, simply use the breadth and width of the ceiling under consideration for the calculations.
Before determining the amount of woodwork needed, you need to know that woodwork can be categorized into five types, broadly. All types of furnishing come under these, and it is essential to know the types as each of them have a different cost per square feet. The five types are as listed:
Box:Many kinds of woodwork can be categorized into this one, as you might have guessed. Wardrobes, crockery units, or anything that possesses a basic box structure, i.e, of 3 dimensions providing space, can be considered under this type.
Frames and Shutter:
As the names suggest, these are woodwork that creates enclosures i.e. provide with closing a space. Examples would be creating ‘doors’ for shelves, cabinets, lofts, etc. This only requires work in 2 dimensions technically, as it doesn’t create space but rather separates space.
Having found out the amount of work needed, you need to choose the kind of materials you want to use for the woodwork. There are various combinations and materials available in the market currently, but for the sake of simplicity, we will consider the most commonly used and available materials today: Solid wood, Plywood, MDF, and PVC.
Solid wood is expensive and is rarely used these days as other materials offer flexibility and functionality at cheaper rates.
MDF and PVC are used when the budget is low. They have their own shortcomings and are usually found in rental homes for that reason. The average price per sq ft of MDF is around ₹700-800
Plywood is the most commonly used material as it balances between being durable and affordable at the same time. There are a wide variety of plywoods available, differing in quality. The average price per sq ft for the different types of work is:
Below Kitchen Counter (BWR): ₹1100 /sqft
Box/Above Kitchen Counter: ₹1000 /sq ft
Frame and Shutter: ₹500 /sq ft
False Ceiling: Starting from ₹50, varies with a lot of other factors.
Calculating the total Budget
Now that we have all the values required to find the total budget, just multiply the values found in the first step with the average rate per sq ft listed in the second step according to the materials you choose.
Tip: The calculation should look like this: Total budget = (Total sq ft of the woodwork) x (average price per sq ft of the chosen material)