The difference between BOM and BOQ
The Difference between BOM and BOQ
BOQ stands for Bill of Quantities
and is defined as a document used in tendering in the construction industry in which materials, parts, and labour (and their costs) are itemised.
BOM stands for Bill of Materials
as is defined as a list of the raw materials, sub-assemblies, intermediate assemblies, sub-components, parts, and the quantities of each needed to manufacture an end product.
The relationship between the BOM and BOQ is very much inter-dependant. The Bill of Quantities generally uses a Bill of Materials to extract its information.
A BOM is also referred a Formula, Recipe, Ingredient List or Product Structure. BOMs are often of hierarchical nature, with the top level representing the finished product which may be a sub-assembly or a completed item. BOMs that describe the sub-assemblies are referred to as modular BOMs. A Bill of Materials in the construction industry will often be drawn up using technical drawings.
A BOQ is used when a tender is put out and it provides a list of all the materials and the relevant quantities with their units of measure required for the project or construction. In this way each company quoting for the tender works off the same list of materials and are not trying to work out the requirements from the technical drawings or Bill of Materials. It is not hierarchical in nature, but simply a list of all the materials and quantities that will be required. The companies that tender for the project will send back the BOQ adding in their prices for the various materials. A BOQ is mostly used on larger projects.
A simple example of the relationship between a BOM and a BOQ is the recipe to make a two layered cake. The recipe or BOM will be dived into two sections. One section will list the ingredients to make the two layers. The other section will list the ingredients to make the filling. The BOM will therefore have a cake as its end product. This will be comprised of the two sub-assemblies, being the layers and the filling. These sub-assemblies will each contain the list of ingredients to make them. This is a very simple example of a hierarchical Bill of Materials.
The BOQ in this example might also be referred to as the ‘shopping list’. It will be a list of all of the ingredients needed to make the cake. It may be that some ingredients are used in both of the sub-assemblies, for example sugar and butter. However, the Bill of Quantities will show the total amount of sugar and butter required in order to make the cake.
The BOM or recipe will look something like this:
- 500g Flour
- 3 Eggs
- 100 ml Milk
- 50g Sugar
- 40g Butter
- 1 tsp Baking Powder
- 1 Egg
- 50g Butter
- 40g Sugar
- 100g Chocolate
The BOQ would look something like this.
- Flour – 500g
- Sugar – 90g
- Butter – 90g
- Eggs – 4
- Milk – 100ml
- Baking Powder – 1tsp
- Chocolate – 100g
Should the there be a requirement for two cakes, then the BOQ would reflect each quantity multiplied by two.
A priced BOQ will also :-
- Assist with the agreement of the contract sum with the successful tenderer.
- Provide a schedule of rates assisting with the valuation of variations.
- Provide a basis for the valuation of interim payments.
- Provide a basis for the preparation of the final account.
Provide a basis for the preparation of the final account.?
The BOQ is sometimes also to control payments. During the course of the project, regular payments are made by measuring the actual quantities used on-site and multiplying them by the price in the BOQ.
The BOM and BOQ go hand in hand. A Bill of Materials can be in a wide variety of circumstances, where a finished product is made up of components and can be very simple or highly complex. A Bill of Quantities is mostly used in larger projects especially in the construction industry and usually where the project is put out to tender.
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