How to prepare a home remodelling cost estimate

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.

Construction estimating

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:

1. obtaining the construction estimate of a building project and correctly plan the client’s financial flows;
2. requesting a proposal  and inviting interested companies to place a bid for the construction works;
3. having control over the applicable processes;
4. 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).

Manual method vs. digital takeoff from 3D model

The critical decision in estimate preparation revolves around the fundamental approach: traditional manual measurement or advanced digital extraction from a BIM model:

• manual method – this is tRepresenting the conventional technique, this approach relies on meticulous interpretation and direct measurement of technical documentation (floor plans, sections, elevations). It demands exceptional precision and careful manual transcription of quantities, making it optimal for smaller-scale projects or scenarios lacking sophisticated digital representations;
• digital method via 3D model – Leveraging sophisticated BIM technologies, this approach enables automated quantity extraction directly from comprehensive three-dimensional models. This methodology significantly accelerates the estimation process, minimizes computational errors, and provides dynamic adaptability when project specifications evolve, rendering it particularly advantageous for intricate and expansive architectural and engineering initiatives.

Quantity Takeoff software free download

Choosing the price list

The second step involves choosing the most suitable price list, that is, the reference list of unit prices for construction works and materials:

• updating – always use price lists updated to the current year to avoid underestimations or overestimations;
• territorial relevance – prefer regional or local price lists, as prices vary significantly based on geographical area;
• specificity of the project – for particular works (restoration, infrastructure, special systems), a specialized price list may be useful, such as those issued by DEU, ANCE, or other technical bodies in the sector.

Calculation of quantities and application of prices

After selecting the price list, the calculation of the quantities of individual works and the determination of unit costs follows:

• identification of calculation items – for each work, the corresponding item is sought in the price list;
• measurement of quantities – 2D drawings or BIM models are used to calculate:
  • m² for surfaces (plastering, flooring, painting);
  • m³ for volumes (excavations, concrete);
  • ml for linear elements (pipes, cables);
  • nr. for point elements (doors, windows);
• application of unit prices – each quantity is multiplied by the unit price from the price list;
• calculation table – everything is organized in a table with:
  • item number;
  • description;
  • unit of measure;
  • quantity;
  • unit price;
  • partial amount.

Determination of the total amount

Finally, the total cost of the project is calculated, including all economic elements:

• sum of partial amounts – all costs are totaled item by item to obtain the direct cost of the works;
• addition of accessory charges:
  • safety charges – costs for implementing safety measures on site;
  • overhead costs – percentage to cover the indirect costs of the company (administration, logistics, etc.);
  • company profit – profit margin applied to the total works;
  • VAT – to be calculated on the total amount according to the current rate;
• final verification – the accuracy of the calculation, the correctness of the applied prices, and the inclusion of all works are checked.

By carefully following these steps, it is possible to obtain an accurate, professional estimate that meets the needs of the construction project.

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
  • demolition
  • new constructions
• Categories
  • demolition
  • removal
  • transport to landfill
  • masonry works
  • finishings
  • plant installation systems
• Sub Categories
  • doors and fixtures
  • floors and coatings
  • plumbing
  • electrical wiring
  • partitions
  • screeds
  • painting works

Creating a bill of quantities with a (5D) BIM software 

After having produced the apartment renovation model with Edificius, the architectural 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.

Now you can save the BoQ document obtained.

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.

Online cost estimating for renovations

Currently,  online cost estimating applications offer advanced digital platforms that enable comprehensive calculation management across multiple devices without software installation, enhancing accessibility, efficiency, and precision of professional workflows.

Cloud-based document management systems, exemplified by solutions like PriMus online, facilitate seamless real-time collaboration among professionals, companies, and technicians across diverse geographical locations, ensuring secure data accessibility through automated backup mechanisms and eliminating traditional file exchange complexities.

Seamless integration with updated regional and national price lists, coupled with intelligent guided formulas for quantity takeoff, significantly streamlines calculation processes for intricate projects like renovations. The capability to generate professional reports in multiple formats further simplifies communication with clients and contracting authorities.

This innovative approach provides enhanced economic oversight of construction interventions, supporting comparative design analyses and contributing to improved construction quality and project sustainability.

Moreover, the platform’s collaborative features allow multiple users to simultaneously connect and collaboratively refine calculation items, transcending physical location barriers and promoting dynamic, efficient teamwork.

• Find out more about Edificius, the BIM estimating software
• Download the 3D BIM model (.edf file) of an apartment renovation project

Watch the tutorial video on how to prepare a detailed bill of quantities using Edificius

FAQ on the calculation for a renovation

What is the metric calculation and what is it for?

The estimative metric calculation is a technical document that allows estimating the amount necessary for the realization or maintenance of a construction work. It serves to plan costs, request offers from companies, control works, and calculate the professional fee of the technician.

When is it necessary to prepare a metric calculation?

The metric calculation is mandatory in public works as part of the executive project, but it is also frequently used in private works to regulate contractual relationships between the client and the company.

Who must prepare the metric calculation?

The metric calculation is prepared by the designer, who develops a forecast of the costs of the work based on the project and the prices of the works.

How is an estimative metric calculation prepared?

The necessary works are identified, quantities are measured, and multiplied by the respective unit prices, using an updated price list. Everything is organized in a table with description, unit of measure, quantity, unit price, and partial amount.

What is the difference between manual calculation and automatic calculation from a 3D model?

The manual calculation requires measurement from 2D technical drawings, while the automatic calculation from a 3D model (BIM) allows for automatic extraction of quantities from the digital model, making the process faster, more accurate, and dynamic.

How do you choose the price list to use?

It is advisable to use updated price lists, relevant to the territory and suitable for the type of project (renovation, restoration, systems, etc.), such as regional price lists or those specialized issued by technical bodies.

What elements make up a metric calculation?

A metric calculation includes: description of works, measurements, unit prices, partial amounts for each item, and the total amount of the work.

Why divide works into categories and subcategories?

The division improves the readability of the calculation, allows for more organized management, facilitates cost analysis, comparison between projects, and management of variations and work progress statuses (SAL).

What are the advantages of the metric calculation from a BIM model?

BIM allows for precise calculations that are automatically updated with the project, reduces errors, improves traceability of quantities, allows for real-time management of variations, and promotes savings in time and costs.

Is it possible to do a metric calculation online?

Yes, there are software and online platforms, such as PriMus online, that allow you to create and manage metric calculations from any device and in collaboration with other professionals, without installing software.