Home Addition or Extension - Your Go-To Project Checklist

A home extension or addition is a significant upgrade that can add value and square footage to your property. However, what questions should you ask to ensure your project is executed flawlessly? How can you ensure the extension or addition blends with the rest of your house’s style? What should you know about materials, building permits, and associated costs?

This guide will outline all the steps and important details to bring your extension to fruition, from the initial design to the final touches, while also considering the challenges and decisions ahead. Discover how you can turn your extension or addition project into a flawless endeavour by exploring the best practices for transforming your home according to your needs and aspirations.

Before Building a House Addition or Extension

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Home Addition and Extension Project Keywords

Cohesive 

Given that the primary goal of a home addition or extension project is to increase the property’s square footage, pondering the shape and size of the intended new space is paramount. However, people tend to overlook matching the addition or extension to that of the rest of the house’s facade, ensuring that the extension doesn’t stick out like a sore thumb in terms of design, siding, and other architectural details.  

Indoors as well, it’s better to opt for materials similar to those already used throughout the home, unless you plan to have two very distinct spaces.  

Efficient 

Avoid building an addition or extension simply because you want to make your house bigger; this new structure should have a specific purpose in terms of layout. And since you won’t want to go over budget, make sure that your extension is efficiently designed to meet your needs without resulting in wasted space.  

Resistant 

Home addition or extension projects are undeniably expensive, so to save money, some homeowners tend to cut costs by opting for inexpensive materials. Such materials can be lower on the quality scale and for that reason, the outcome won’t be as hard-wearing and durable. Focus on materials with good value for money. 

What Questions Should You Ask When Adding Onto a House?

What do you need to add to your house? Is your family growing in numbers?

Whether you’re welcoming a new family member, designing a space for a loved one, or wanting to give your teenagers more privacy, an extension or addition can meet several needs of a growing family. Beyond the family aspect of it, some choose to add square footage to build functional spaces, such as a home office, art studio, or gym, depending on their lifestyles. 

However, an extension remains a major remodel that mandates a lot of commitment, both in terms of time and money. Before jumping in, it’s essential to thoroughly understand why this additional space is needed. Such a project must improve your quality of life or your home’s overall functionality to justify such an investment of money, time, and effort.

How will the extension or addition change your house's layout or design? 

It may impact the shape and size of several rooms in your house, meaning that the layout could change more than you’d think. For example, you may have to build a new staircase to access the new storey you’re building or install columns to reinforce the structure.  

You may also want to add or remove walls. All of this could affect the amount of natural light in certain areas or create wasted space (hallways, corners) that you might have otherwise overlooked.

Will you take advantage of the situation to renovate other areas of the home?  

While you’re embarking on a major renovation project, why not take advantage of the situation to remodel some features that need replacement or refurbishment? For example, while you lay flooring in the extension, why not replace the worn and scuffed one in adjacent rooms too?  

Also, if your exterior siding is weathered, look into acquiring a new material that works wonders for your project. The addition or extension will need siding, so why not revamp the whole house while you’re at it?  

The same applies to doors, windows, and masonry, including any other component or material featured in the rest of the house. 

How much space do you have to build an addition? 

There are two important factors to consider when tackling this question. First, take into account the type of addition or extension you want to build, but be as precise as possible when calculating the square footage limit the new structure can have based on the size of the yard, upper storey, or main floor.  

Next, check with your local authorities to understand your options. There’s a general building code that regulates certain aspects, as well as municipal bylaws. At times, you’ll be bound by rules that vary from one neighbourhood to another, especially if you live in a heritage house.  

Will the addition or extension be cost-effective?

Thinking that your project will systematically increase the value of your home isn’t a hard feat to envision. However, the latter isn’t necessarily true. Your house may be worth more, but if the project fails to be recognized as added value, you may not be able to justify all the spending associated with such a transformation.  

For example, even if you spend $125,000 to build an extension or addition, by no means does it guarantee that you’ll be able to bump your asking price by $125,000. 

As such, if the main goal behind building an addition or extension is selling your house shortly thereafter, chances are your project won’t be financially worthwhile. Unless you’re planning on flipping a house purchased below market value.

However, if you’re thinking of staying in your house for several years to come and know that the extension will have a positive impact on your and your family’s daily life, profit potential isn’t as important. Moreover, if you decide to build a multigenerational dwelling, the addition or extension could be profitable for you and your loved ones as you may be able to avoid having to buy another full-priced house.  

Can’t I just remodel a space that’s already built? 

Instead of building an extension or addition, consider whether your current layout is fully streamlined and optimized. Are all the rooms in your house used efficiently? Could knocking down walls, rethinking a specific space’s function, or reconfiguring certain parts of your home that aren’t used as much—basement, garage, attic—be remodelled instead of adding square footage? Talk to layout and design experts, such as interior designers or architects; they’ll help you see things more clearly.  

What type of home extension yields the best results? 

There are several types of home extensions, which will be outlined down below, detailing their specific characteristics. However, at this stage of the project, you probably already have an idea of the type of extension you want to build.  

Here are some examples: 

• Storey addition

• Second storey above a garage

• Basement excavation

• Side extension

• Rear extension 

• Cantilever addition

Which of these options will best suit your needs? Keep reading our detailed guide for more information.  

Do you have a mobile home and are looking to add some square footage? Take a look at this article: Mobile Home Addition: How to Expand a Mobile Home

As mentioned above, there’s likely a specific goal behind your home extension or addition project. Unlike bathroom or kitchen remodels, home extension projects rarely focus on aesthetic transformations.

Given that one needs significant sums to carry out a project, best not to embark on this sort of project on a whim. Even if you find great ideas on Pinterest, consider everything thoroughly before jumping in.  

Consider the criteria below to better define your needs:    

• Extension that increases property value

• Extension that truly improves your home’s layout

• More square footage to fully benefit from natural sunlight 

• New wing for your parents, teenagers, or friends

To help you plan your project, check out these articles:

• Home Extension Guide

• Home Addition or Extension - What Are the Main Steps?

• How to Build a Home Addition

Home Addition or Extension Plans

Source: Canva 

Budget

If you’re committed to seeing your project come through, set aside a sizable budget. Meaning that experts agree that this type of project rarely costs under $100,000. Naturally, there are always exceptions to any rule, and you might get by for a little over $50,000, but in most cases, you’ll need access to much more funds. 

Since several factors will affect the final amount you’ll be shelling out, detailing precise numbers isn’t all that practical. So, meet with several contractors so they can provide you with project-specific quotes.  

Moreover, as is the case with all renovation projects, you should set aside an additional 15% of your budget for unplanned expenses.

Below are some articles detailing in-depth information to help you determine your budget:  

• Home Addition or Extension Project - How to Gauge Budgetary Needs  

• Cost Estimator: Home Extension 

• The Costs to Remodel Your Basement

• Home Extension and Addition - How to Plan Your Project

• 10 Old Houses That Have Been Renovated and Enhanced

• Home Extension and Addition Cost Guide 2024 - How Much to Budget?

The Different Types of Home Extensions

The Different Types of Materials

A home addition will imply a wide variety of materials. In the following paragraphs, we will explore the different elements that are a part of most additions, as well as the materials that you can choose from. 

The structure and foundations 

You will likely need to work on the structure and foundations of your house. You have three options:

• reinforce the existing structure,

• replace them,

• or add a new section of structure and foundations where the extension is located.

As for materials, most house structures are built with wood, steel, or concrete.

Check out our Foundation Price Guide.

Interior walls 

In general, building a new interior wall is one of the relatively simple projects, but it shouldn’t be taken lightly. Several things need to be considered:

- Do you want to build a load-bearing wall?

- Will the wall include insulation and soundproofing materials?

- What will the exterior surface of the wall be? (see the section on wall coverings)

Plumbing and electricity 

There’s a good chance your expansion project will involve some additions to your home’s plumbing and electrical systems. If there are areas where you shouldn’t attempt DIY renovations, it’s definitely plumbing and electricity! In many regions, most of this work is even required by law to be done by professionals.

Check out our price guides for this type of work:

Plumbing Price Guide

Electrical Price Guide

The floors 

When we think of a floor, we mostly consider the surface beneath our feet. It’s less common to think about the layers that make up its structure. However, these layers play a crucial role in ensuring the strength of the flooring and its durability.

There are various types of floor structures, and the type of extension will need to be considered to determine the right structure to build.

Check out our Flooring Price Guide.

Insulation and soundproofing 

Comfort and privacy are two important factors in ensuring a good quality of life for a home’s occupants. In this regard, materials used for insulation and soundproofing are essential allies.

Check out our Insulation Price Guide.

Exterior siding 

Some people building a home extension make the aesthetic choice to go with exterior siding that differs from the rest of the house.

If you decide to keep the same siding, take this opportunity to do a cleaning once the extension construction is finished, so there’s no difference in cleanliness between the different sections of the house.

Check out our Exterior Siding Price Guide.

Doors and windows 

Does your extension involve installing doors and windows? To ensure your addition is a success, consider the following factors:

• Harmony of door and window styles with the overall appearance of the house;

• Quality and durability of the materials;

• Caulking and protection against drafts that can impact the home’s energy efficiency.

As with other phases of work, you could also take this opportunity to replace any doors and windows that need updating.

Check out our price guides for this type of work:

Interior Doors Price Guide

Entry Door Price Guide

Windows Price Guide

Home Extension and Building Standards

Source: Canva

If your home extension project isn’t compliant with current building standards effective in your area of residence, you’ll have a hard time getting permits and may not be covered by home insurance, subjecting yourself to potential fines.

Don’t forget to check with your municipal authorities to know whether there are rules specific to your neighbourhood. Since RenoQuotes.com offers services across Canada, noting city-specific rules and regulations country-wide is rather daunting, especially since these are often amended and rewritten. 

That said, contact your municipality and visit its official website to find the exact information you’re looking for.  

Permits

Without a doubt, you need to apply for a building permit to carry out a home extension project. Get the process going as early as possible to avoid delays and be sure all paperwork is in order before greenlighting your project. As mentioned, contact your local authorities to know what type(s) of permit(s) you’ll need.  

Ask about requirements and collaborate with experts (contractors, architects, architectural technologists) to submit a file in good working order. In doing so, you won’t have to pay several times over to acquire the same permit. Check out these articles for more info about renovation and building permits: 

• How to Know Which Building Permits You Need for Your Renovation Project

• Renovating a Property in Montréal

Quebec Only: Home Extensions and Act R-20

It's important to highlight that complying with local bylaws for your renovation project is mandatory, especially for large-scale projects like home extensions.

Note that in Quebec, home extension projects are subject to Act R-20, requiring projects to meet certain obligations. For example, if you choose to oversee the project yourself, this law stipulates that you’ll then become the construction site’s employer, technically employing the hired labourers. You’ll then be forced to comply with several CCQ (Commission de la construction du Québec) requirements. 

If you fail to comply with the rules, you risk facing fines and lawsuits. Note that CCQ agents are especially keen on finding wrongdoers! Odds are that your jobsite will be visited by CCQ agents, requiring proof that your project is law-abiding.

However, if you hire a contractor to handle the project, make sure that they have the right trade licence to carry out the work. Also, contractors should only hire workers who have CCQ-issued competency cards.

Check out the CCQ’s website for updated information on the matter.

Other Canadian Provinces

Every province has unique building regulations for home extension projects. While we don’t currently have extensive information regarding the latter, check out the following province-specific building regulations for up-to-date information:

Alberta: Alberta Building Codes and Standards

British Columbia: BC Building Code

Nova Scotia: Nova Scotia Building Code Regulations

Ontario: Ontario Building Code

Looking to build a home extension in the Toronto area? Check out the following article to help plan your project: Building an Addition in Toronto.

Contractors

Source: Canva

If there’s ever a renovation project needing a structured approach, it's a home extension! Even if you choose the self-build route (see the section below), you still have to collaborate with experts for several project-specific jobs, especially when it comes to acquiring building permits, drafting plans, and installations requiring certified experts (varies from one city to the next). 

As such, you’ll have to work with contractors and architectural design experts.

Bear in mind the following: Always have written agreements or contracts with hired contractors. Want to know why? Check out our article Renovation Project: 3 Reasons to Sign an Official Contract.

Home Remodelling Steps

Here’s an overview of the steps involved in building a home extension or addition. Bear in mind that the specific process may vary depending on factors such as the type of extension, its size, and the scope of work required.

1. Establish project budget and scope: Start by researching and detailed planning to define the project size and cost. Costs may vary significantly depending on the added square footage and materials used. 

2. Get financing: Look for a loan or a line of credit based on the gross value of your house. If needed, consider other financial options and consult with a financial advisor to avoid risky loans.

3. Hire a contractor: Hire a reputable contractor who can manage framing, subcontractors, and the job calendar. Negotiate terms and conditions, especially payment terms and project management.

4. Work with an architect (if necessary): Hire an architect for complex designs or opt for a design-build construction contract, combining both the design and build parts of the project to streamline coordination.

5. Get building permits and prepare jobsite: Make sure all required permits are posted on the jobsite, then prepare the site, including clearing and levelling the land to allow access to worksite equipment.

6. Build the foundation: Build a full foundation, whether a slab or basement, for structural support. This includes pouring the footing and foundation walls, allowing them to cure.

7. Framing: Once the foundation is ready, erect the floor, wall, and roof structures. A team of experienced workers can carry out this step swiftly.

8. Install roofing: Add weatherproofing layers, such as wall and roof coverings, air barriers, and roofing to protect the extension from adverse weather conditions.

9. Hang windows and doors: After roofing, hang windows and doors to secure the structure. Doing so protects the interior in preparation for the next steps.

10. Carry out plumbing, electrical, and ventilation work: Install the essential systems behind the walls before sealing them shut. Inspections will ensure they’re compliant before moving forward.

11. Add insulation and gypsum boards: Insulate the walls and finish by hanging gypsum boards to shape the inside of the add-on—a significant step, visually speaking.

12. Interior finishes: Install the flooring, cabinets, moulding, and paint the walls. This step is often outsourced to specialists for flawless results.

13. Hook-up installations: Connect all plumbing devices, lighting, and heating to finalize utilities. Such fittings should be done by licensed subcontractors. 

14. Finish landscaping (if necessary): Restore land disrupted by work, fill in the space around the foundation and replant shrubs or trees as you see fit.

15. Cross everything off your checklist: Work out any loose ends as per your checklist, then carry out a final inspection to confirm that everything is in order.

Final Walkthrough

What should be on my checklist?

Once your home extension or addition is done, meticulously inspect the add-on to ensure everything is done according to plans and initial specifications. Doing a final walkthrough with your contractor can be very practical, as they might help you spot any flaws or inconsistencies. Take some time to look over every aspect of the new construction, including finishes and installations.

Then, test all systems, whether it’s the AC, lights, faucets, or sinks—make sure everything works accordingly and is installed safely. Beware of unusual sounds or leaks, and don’t hesitate to ask your contractor questions if you have any concerns.

For large-scale projects, keep track of your investment and inform your assurance agent as you may be able to adapt your home insurance policy to reflect your property’s added value. Also, consider registering all new appliances or products purchased during the renovation to facilitate potential insurance claims. Lastly, make sure all necessary permits and inspections were obtained and carried out to ensure compliance with local regulations.

Warranty

Once your home addition or extension project is completed and after having done the final walkthrough, it’s essential to know the project-specific warranties. The warranty is a promise from your contractor regarding work quality and durability.

Types of Warranties

Material warranty: Covers all defects involving materials used during the home addition or extension project.

Labour warranty: Ensures the work is done according to specific standards and quality benchmarks.

Claims Process

If problems occur during the warranty period, it’s important to understand the claims process. Keep all the paperwork related to the work done and records of communication with the contractor to facilitate your claims request.

Importance of a Warranty

Having a warranty gives you peace of mind, protecting your investment into a home extension or addition. It ensures that you may claim repairs or replacements in the event of defects, which is essential to maintain the value of your property in the long run.

Useful Tips for Tackling a Home Addition or Extension Project

What should I consider when hiring a contractor?

• Experience

• References

• Insurance

• Quote comparison

• Rates

How can I keep track of the jobsite?

• Visit the worksite regularly

• Verify the quality of the work done

• Report any issues to the contractor

• Check all invoices and payments

How can I cope with unexpected circumstances?

• Plan for some leeway in your budget to deal with unexpected circumstances

• Define change management methods ahead of time

How do I manage stress during the project?

Given that home additions or extensions are large-scale projects, you’ll likely need to move out for the duration of the work or set up a separate living space where your daily routine won’t be too affected. According to some experts, living on-site could actually delay the process.

If your kitchen and bathroom are out of order, choosing to move out for a few days, or a couple weeks, is all the more convenient. There are several solutions, including living with relatives or close friends or booking a hotel room for the duration of the work.

Here are some questions to ask yourself to figure out what works best for you:

• Will I stay on-site for the duration of the work?

• Can I set up a temporary living space in another part of my house (living room, bedroom, etc.)?

• How long with the work take (if everything goes according to plan)?

• Do I have a Plan B if the work takes longer than anticipated?

Here are two articles published on our blog about living through renovations:

• From the Ground Up: Stages of a Renovation Project

• How to Survive a Kitchen Renovation

In Conclusion

When considering a home extension or addition, it’s essential to understand the motivations behind such an endeavour and the commitment implied. Whether your family is growing in numbers, have a sudden need for additional space, or simply want to increase your property’s market value, every reason comes with a specific set of considerations. By carefully weighing all factors, homeowners can make well-informed decisions to better meet their long-term needs and goals.