A practical example of home remodelling cost estimate: steps to follow, categories and items to use
In this article we’ll be taking a look at how to produce a home remodelling cost estimate (see previous article).
We will follow all the steps of the process to create some guidelines, although we will not be able to integrate some of the categories typical of building interventions (new construction, renovation, maintenance, etc.).
The article will also provide the 3D model of the estimated renovation project and the link to download the 30-day free trial version of the software used to genarate the model.
The bill of quantities is the document by which it is possible to estimate the cost of a construction project or for its maintenance.
Its use is widespread in private works, as a document for the regulation of the relationship between client and contractor, as well as in public works.
The bill of quantities is fundamental for:
- obtaining the construction estimate of a building project and correctly plan the client’s financial flows;
- requesting a proposal and inviting interested companies to place a bid for the construction works;
- having control over the applicable processes;
- having a reference for the calculation of the professional fee.
In addition, it is also useful for a company to determine the construction site cost management.
Preparing a bill of quantities for an apartment renovation
After the renovation project has been generated (an apartment project in our case), you can proceed to draw up the bill of quantities. For such purpose, we identify the price list with reference items.
For example, you could use both various national price lists and even price lists for private works that are specific for building renovations.
Distinctive elements of a bill of quantities are:
- description of individual work items (Work Description);
- measurements of work items (dimensions);
- unit price of work items;
- amount of individual work items (obtained from the product of the quantities for the unit price – amounts);
- total amount (total amount – amounts).
Classification of work items in categories
The purpose of classification of work items is to breakdown planned works into physical parts.
Generally, the designer groups work items into categories, making consultation easier and immediately corresponding to the graphic design documents, but also to have a quick comparison of quantities and amounts.
Here is an example of how to create a structure of work items of a bill of quantities for a renovation project:
- Super Categories
- new constructions
- transport to landfill
- masonry works
- plant installation systems
- Sub Categories
- doors and fixtures
- floors and coatings
- electrical wiring
- painting works
Creating a bill of quantities with a (5D) BIM software
After having produced the apartment renovation model with Edificius, the architectural BIM design software, it is possible to automatically obtain the bill of quantities, taking the advantage of the “BoQ” environment of the software.
After importing the reference price list, you can associate each model object to one or more price list items:
- on the existing walls associate the work items relating to demolition, to transport to landfill, etc.
- to new partitions associate new construction, plastering, painting items, etc.
- to new windows associate the newly installed item, etc.
- to rooms (useful floor area) associate old flooring demolition, flooring and baseboards installation, etc.
In order to obtain measurements automatically, you could use the formulas suggested by the software or create new ones according to your needs.
In this way the bill of quantities is automatically obtained, with rate analysis and measurements.
Integration between Edificius, the architectural BIM design software and PriMus, the cost estimating software
A further opportunity is provided by the integration between the architectural model (3D BIM) realized with Edificius, and PriMus. Additional functions that you can take advantage of are:
- changing the display order of the various items
- using features such as “see item”
- inserting subtotals
- other advanced features for the bill of quantities.
Any changes made to the architectural model, are automatically reflected in the bill of quantities, therefore it is always updated. Everything is then saved in the EDF file format.