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HOUSE EXTENSION PROJECT: Budget and Techniques

HOUSE EXTENSION PROJECT: Budget and Techniques

Exterior renovationsHOUSE EXTENSION PROJECT: Budget and Techniques

Your house may be running out of space, but why leave the ideal setting where your kids grew up? Since moving out is off the table, building onto your family home becomes mandatory. If you happen to find yourself in this situation, you’ve definitely come to the right place! Our article will detail everything you need to know about building an extension onto your house.

Basic Process of Building a House Extension

Source: Canva

As you’ve probably figured out, building an extension onto your house is a great way to create a bigger interior layout. However, there are many different ways to go about a project like this, and it'll ultimately depend on your home's current layout and property as well as the space available to you. 

In most cases, the obvious solution will be to add living space above the garage, onto the side or behind the structure itself. In some cases, pre-existing spaces such as a porch can be converted into a house extension.

Another option is to add a new floor (or home addition). However, this way of adding space will be more expensive since you’ll have to remove a portion of your roof as well as knock down a few walls. If this is the option you choose, you’ll need to be sure to plan for enough space on the first floor for the staircase that will lead to the new floor. Again, the decisions you make regarding the steps of this project will depend on what you're looking to achieve as well as the resources available to you.

Determine What You Want

It’s no secret that this type of renovation project is major, and thus will involve a lot of planning. Before actually undertaking any concrete renovations, it's important to first identify your needs. Ask yourself key questions, such as:

  • Why do you want to expand your house?

  • Do you need additional rooms or is it that you don't have enough space with your current setup?

  • How much are you willing to spend?

Knowing what you want is the most important part of the planning process.

Once these questions have been answered, you'll be able to further work on and determine a budget. From the get-go, it’s important to be realistic about how much money you want to invest in this project. Setting a fixed budget with some wiggle room in case of any mishaps will allow you to find ways to finance your renovations and prevent you from experiencing any type of financial setback.

A home extension can cost anywhere between $24,000 and $240,000, depending on the size of the project as well as the chosen materials. Although, the amount is limitless... For more information about planning a budget for a home extension project, check out our article The Cost of a Home Addition Project.

House Extension Professionals & Permits

Source: Canva

Once you're past these initial steps of planning out the details of the project, we’d recommend that you contact an architect or an engineer who can draw up plans for your house extension. You’ll be able to talk about your project with them and see if your ideas are feasible as well as make any changes to your original plans. Working with an architect or contractor can provide you with a different point of view, and help you find the best alternatives.

Once an architect or professional has drawn up detailed plans of the layout, it'll be your responsibility to contact your municipality or city to obtain a construction permit. Based on the blueprints made by the architect or the engineer, your municipality will decide if you can move forward with this project. If so, they'll issue you the right construction permit. It's crucial that you don't move forward with the project before obtaining the proper permits! In most cases, municipalities won't accept home extensions built onto the front section of the house.

As we've previously mentioned, you’ll probably have to choose between an extension built onto the side, or back, or simply adding another floor altogether.

Last but not least, look for a qualified contractor who has knowledge and expertise about the general structure of a house. In some cases, especially when plumbing has to be moved and rewiring is involved, you may need to hire more than one professional. Meet with different contractors and request quotes.

Cost Estimate of a Home Extension Project

  • Roof decking: $150- $300/sq.ft.

  • Additional storeys: $120-$240/sq.ft.

  • Installing collar ties: $35-$60+ each

  • Installing lateral bracing on collar ties: $120-$240+

  • Replacing decking (sheathing): $5-$8/sq.ft.

  • Adding an extra floor: At least $120,000 (can be upwards of $240,000)

  • Adding a floor above a garage: At least $60,000

  • Adding a room on the ground floor: At least $70,000

  • Cantilever addition: At least $30,000

  • Building a wall with a doorway: $600-$1,200

Building a home extension involves complicated financial calculations. This process includes set fees, which means that a small extension will cost more, per metre square, than a larger extension would. However, the smaller the square footage, the lower the total cost of the extension, and this is due to material costs.

When all is said and done, the cost of a home extension won't matter as much when considering the benefits of living nearby work, the kids' school, amenities, and family. 

Various Ways to Expand Your House

Photo: Fotolia

Note that as a general rule, municipalities don't allow front-facing extensions. Consider adding an extension onto the side or back of your house instead. Another option is building upwards. Simply adding a side or back extension to the structure is expensive, but adding one or several floors is even more expensive. This type of addition involves removing the roof, tearing down walls, and planning for enough space for a staircase leading to the new storey. 

Oftentimes, it's just way easier to add a floor above your garage. Depending on your needs and on the current municipal rules, you can increase the size of your home by taking over the backyard. So, why not turn your back porch into a sunroom?

This glass-enclosed space will allow you to enjoy your backyard during the cold season, whilst adding more space to your kitchen or living room. Ideally, the extension will cover the whole length of the house without affecting the architecture.

There are several other types of house extensions: building a basement, adding a garage, building an extension on foundations, cantilever addition, and an extension atop a concrete slab.

For more information about house extensions, check out the following articles:

  • The Average Cost to Build a Home Addition

  • The Cost of a Home Addition Project

  • Home Extension Guide

  • Everything You Need to Know About the Cantilever Extension

  • Can you build a home addition?

Are you planning a house extension project? Check out our House Extension Guide and checklist to organize your project. Click here to check out our guide.

Author: René-Maxime Parent

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Last modified 2023-12-06

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