How to Calculate Number of Blocks from Floor Plan

About to start your construction project but wondering what your budget for materials should be? How many blocks can build a single room or 4-bedroom bungalow or what number of blocks will fence your plot of land?

It can be quite a headache finding straight answers to such questions. And available estimates may not fit your particular building design. However, knowing how many blocks your project requires can help you with planning and budgeting.

Instead of working based on guesses, you can pay a quantity surveyor to do the material estimates. Nevertheless, you can calculate the actual blocks to complete your 3-bedroom bungalow by yourself.

This article will show you how to get an accurate estimate of blocks you need to complete a building project using the floor plan. All you need is your building plan, a calculator, a pen, paper, and your favourite drink. Let us begin.

We will be using the sample 2-bedroom floor plan below.

Note:

The width of the common sandcrete blocks are 9" or 225mm and 6" or 150mm

The length of a sandcrete block (both 9" and 6") = 450mm or 0.45m or 18"

For this tutorial, we will divide the building project into four stages:

1. Foundation to Damp Proof Course (DPC)
2. DPC to the window base
3. window base to the window top
4. window top to the roof base

Also, we will use an average number of coaches/level/layer of blocks for each stage of the project.

Assuming:

• Foundation to DPC — we need four (4) coaches of blocks
• DPC to the window base — we need four (4) coaches of blocks
• Window base to the window top — we need five (5) coaches of blocks
• Window top to the roof base — we need three (3) coaches of blocks

With the assumptions above, let's follow the steps below to get how many blocks will build the sample 2-bedroom bungalow:

STEP 1: Get the total length of the external walls

                6.15m + 5.85m + 6.15m + 5.85m

The total length of the external walls = 24m

STEP 2: Get the total length of the internal walls

That is, the length of the walls dividing the various rooms in the building.

Vertical Internal Walls 

Length of vertical internal walls = line A (the wall between the bedroom and the toilet, including the door space) + line B (the wall dividing the toilet and the kitchen) + line C (the wall separating the bedroom and the living room, including the door space)

                 = 3.15m + 2.10m + 3.0m

>>>Length of vertical internal walls = 8.25m

Horizontal Internal Walls

Length of horizontal internal walls = line D (from the wall dividing the two bedrooms to the small wall dividing the living room and the kitchen) + line E (the wall holding the toilet door, including the door space)

= 5.85m + 1.35

>>>Length of horizontal internal walls = 7.20m

The total length of internal or dividing walls = vertical walls + horizontal walls

= 8.25m + 7.20m

Total length of internal or dividing walls = 15.45m

STEP 3: Get the length of the window spaces

The total length of windows = bedroom window + living room window + kitchen window + toilet window + bedroom window.

                = 1.80m + 1.20m + 0.60m + 0.90m + 1.35m

>>>The total length of window spaces = 5.85m

Now, let's get how many blocks in each layer/level/coach for the windows by dividing the total window length by the block length.

Number of blocks per coach = the total length of windows / the length of a block

                = 5.85m / 0.45m

Number of blocks = 13 blocks per coach of window spaces.

STEP 4: Get the length of the door

The total length of door spaces = door into the living room + door to bedroom 1 + door to bedroom 2 + door to toilet + back door from the kitchen

                = 0.90m + 0.90m + 0.90m + 0.75m + 0.90m

The total length of door spaces = 4.35m

Now, let's get how many blocks in each layer/level/coach for the windows by dividing the total window length by the block length.

Number of blocks per coach = the total length of windows / the length of a block

                = 4.35m / 0.45m

Number of blocks = 10 blocks per coach of door spaces.

STEP 5: Get the total length of the building walls 

Total length of building walls = total length of the external walls + total length of internal or dividing walls

                = 24m + 15.45m

Total length of entire building walls = 39.45m

STEP 6: Get the number of blocks per layer/level/coach for the entire building.

Do this by dividing the total length of the building by that of a block.

Number of blocks per coach = total length of the building / the length of a block

                = 39.45m / 0.45m

                = 87.6667 blocks

Number of blocks per coach = 88 blocks per coach/level/layer of the entire building length (approximately).

STEP 7: Get the number of blocks for each construction stage

Stage 1: From Foundation to DPC

The soil on the sample land is dry and firm, and the foundation will use blocks instead of concrete. That means the blocks will run through both the internal and external length of the building. We are setting four (4) coaches/levels/layers of blocks for the foundation (as indicated at the beginning of this tutorial). That means

Total blocks = total blocks per coach of the entire building length x number of coaches

                = 88 blocks x 4 coaches

                = 352 blocks

The number of blocks needed for the foundation to DPC stage = 352 blocks.

Note that a concrete foundation will require fewer blocks for the foundation to the DPC stage.

Stage 2: From DPC to Window Base

For this stage, we will lay four (4) coaches/levels/layers of blocks from DPC to the base of windows (as indicated at the beginning of this tutorial). Hence,

Total number of blocks = blocks per coach of the entire building length x number of coaches

                = 88 blocks x 4 coaches

>>>Total number of blocks for entire building length = 352 blocks

But the door-base also begins here, and we don't need blocks in the spaces for doors. So, get the number of blocks for door spaces for this stage and subtract them from the total number of blocks.

Total number of blocks for door spaces = 10 blocks (from step 4 above) x 4 coaches

>>>Total number of blocks for door spaces = 40 blocks

The actual number of blocks = Total number of blocks for entire building length - Total number of blocks for door spaces

                = 352 - 40

                = 312 blocks

The number of blocks needed for the DPC to window base stage = 312 blocks

Stage 3: From Window Base to Window Top

Here, we have set out to lay five (5) coaches/levels/layers of blocks (as indicated at the beginning of this tutorial). So,

Total number of blocks = blocks per coach of the entire building length x number of coaches

                = 88 blocks x 5 coaches

>>>Number of blocks for the entire building length = 440 blocks

But we don't need blocks in the spaces for doors and windows. So, get the total blocks for doors and window spaces for this stage and subtract them from blocks for the entire building length.

Number of blocks for doors = 10 blocks (from step 4 above) x 5 coaches

                = 50 blocks

Number of blocks for windows = 13 blocks (from step 3 above) x 5 coaches

                = 65 blocks

The actual number of blocks = blocks for the entire building length - blocks for doors - blocks for windows

                = 440 - 50 - 65

                = 325 blocks

The number of blocks needed for window base to window top stage = 325 blocks.

Stage 4: From Window Top to Roof Base

Here, we will be using three (3) coaches of blocks (as indicated at the beginning of this tutorial).

Total number of blocks = blocks per coach of the entire building length x number of coaches

                = 88 blocks x 3 coaches

                = 264 blocks

The number of blocks needed for the window top to the roof base stage = 264 blocks

STEP 8: Get the number of blocks for the entire construction

The total number of blocks that will build the 2-bedroom flat from foundation level to roof base

                = stage 1 + stage 2 + stage 3 + stage 4

                = 352 + 312 + 325 + 264

                = 1,253 blocks.

Then, add 10 per cent more blocks to account for wastage during construction.

                10% of 1,253 = 125 blocks (approximately)

Total number of blocks = 1,253 blocks + 125 blocks

                                        =1,378 blocks

Hence,

Total number of blocks that will complete this project = 1,378 blocks

Following the steps above, you will be able to correctly estimate the number of blocks you will need for any building project as long as you have the plan. Just make sure that you are consistent with your units when doing the calculations. For instance, using ft for the windows but inches for the doors will give you inaccurate results.

See how to calculate quantities of cement, sand, granite for a concrete foundation from a building plan and how to estimate the quantity of paint to buy for a house.

Have questions? Leave them in the comments section below.