## Taking off construction quantities

The drawing below is a simple foundation and solid ground floor. We will use this drawing and the specification for our construction takeoff.

The example is only a small section of work on a project, but it will give you an idea of how to develop a bill of quantities from the takeoff.

## The takeoff process

### Excavations

The first item to takeoff is the removal of the topsoil; I have measured the outside face of the foundation trench in the calculation. The soil depth from ground level to the underside of the stone fill is 250mm. The topsoil is 150mm, leaving 100mm to the reduced dig level.

The depth of the foundation trench has now been reduced to 750mm. The trench has a mean girth of 30m. I have taken the masonry dimensions to be the centre of the trench; this is not quite correct, but close enough, as the difference would be minimal.

The excavated material needs to be stored on-site or removed from the site. I have allowed the topsoil to remain on site for re-use in the landscaping works and have removed the remainder to a tip.

The spoil is inert and is to be removed using a grab and wagon. If the material was contaminated, the cost of disposal would be a lot higher.

Other ways to remove the spoil would be skips (more expensive) or 20-ton wagons (less expensive but the project is too small). The size of the project dictates the method of disposal.

There are two items to measure with the foundation trench: earthwork support and the surface treatment to the bottom of the trench. These are risk items. The trench may hold up, but if not, we have a budget to prop and strut the sides of the excavation. If the trench gets wet before pouring concrete, the level and ram item allow the trench to be cleaned up before the concrete is poured.

### Concrete

The next item to quantify is the foundation concrete.

### Masonry

I have used the mean girth to the external wall to measure the masonry; this is only partially accurate as you could measure the mean girth to the centre of the brick, then the blockwork to be more accurate. The difference would be minimal and not worth the effort of the calculation.

I have allowed for two courses of facework to be below ground level, then below this level common brick. The cavity has been measured using five brick ties per m2.

### Solid ground floor

The solid floor slab is measured from the inner face of the blockwork. The visqueen DMP measurement includes the upstand to the perimeter.

The rest of the takeoff is self-explanatory.

### How to calculate a Mean Girth

If you had a 100mm brick wall built in a rectangle with the outside dimensions of 10m x 5m as our example, you would calculate the mean girth of the 100mm brick wall as follows:

(10m x 2) + (5m x 2) = 30m – (4 x 100mm = 0.40m)

The mean girth = 29.6m

## Bill of Quantities

The information from the takeoff sheet is then transferred into the bill of quantities spreadsheet. The top of the sheet gives the assumptions for the measured work.

The bill of quantities in this format is called the blank bill of quantities and can be used to obtain prices for materials and contractor prices if you wish to go out to tender to trade contractors.

## Taking off by hand

I normally take by hand using takeoff paper and a pen. I find it faster. You use abbreviations when you do this to make it quicker. For example

- Not exceeding is NE
- Depth is DP
- Hollow wall is HW
- Load and cart away is L and CA

## Frequently asked questions

**How long does a construction takeoff take?**

The construction takeoff on this page took five minutes. Then another 25 minutes to set up the bill of quantities spreadsheet ready to be priced.

**Who completes a construction takeoff?**

Construction takeoffs are carried out by construction estimators. Despite the fact that every project is different, estimators rely on their extensive experience of construction projects. In order to find savings, they draw on their prior, successfully completed projects.

**What is the standard method to takeoff quantities?**

The first standard SMM1 was published in 1922, and the latest publication was SMM7 in 1988. The standard was due to be updated in 2006; however, the RICS and other construction bodies decided to develop a new standard NRM due to changes within the construction sector. The NRM standard was first published in 2012 and is readily available for quantity surveyors and estimators. Learn more about the standard method of measurement.

## More estimating lessons

A very simple set of estimating lessons to get you started. Everything you need to know to take off quantities, then pricing them. The lessons are short and to the point. I hope you find them useful.

**Lesson 1**– Introduction and the standard method of measurement**Lesson 2**– Taking off construction quantities**Lesson 3**– How to obtain accurate labour, plant and material costs**Lesson 4**– How to price the bill of quantities using built up rates**Lesson 5**– Productivity constants and pricing books**Lesson 6**– How to plan your project using the bill of quantities data