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If you are evaluating the option of expanding your home or buying bigger, this blog is for you. I explain the steps to follow when planning a home extension and I also talk about the costs related to this type of project. As an interior designer in the greater Montreal area, I work with many clients like you who are considering the possibility of expanding their home. I imagine that you love your neighborhood, your home and that buying a new home is rather difficult because of the low inventory and high prices. You are not alone in this situation, this blog is here to help you.


Magalie Boulerice photographer


Step 1 in planning a home addition: CHECK MUNICIPAL BYLAWS

The first step I explain to clients when they call me about their expansion project is to do the initial checks with the municipality and their borough. Each city’s planning department has its own regulations and unfortunately, on occasion, an expansion is not possible. The procedure to follow is to look online for project application information. There is probably already a lot of information available on your municipality’s website to see if your project is viable. Otherwise you can make an appointment with a consultant, bring (or send) your certificate of location and a brief description of your project (dimensions, costs …).

This first step is not very long and is very simple. You must have your certificate of location, otherwise you will have to order one from a surveyor. It is essential for a house extension project. I meet many clients who start their project with phase 3 (drawing up the development plans) without thinking about the budget and municipal regulations… This is a big mistake!


Magalie Boulerice photographer


Step 2 in planning a home extension: DETERMINE YOUR BUDGET

Once you have validated the feasibility of your project with the city, it’s time to estimate your budget to find out once again if your project is viable before spending time and money on planning. Well… So here’s the trick question: how do I know how much it will cost if I don’t have a plan for my expansion? If you dared to call general contractors, they probably turned you around and said, “If you don’t have accurate plans, I can’t give you an estimate. Discouraging… You will have to make your own estimate with the tools and information I give you here and complete with the information you can find on the internet. If a neighbor has done a similar extension to your project, it’s a great comparison to evaluate the costs! Go and ask him questions!

First, you need to define the size of your home addition in square feet. You are probably able to evaluate whether you want to add a 10’x20′ room or a whole floor. Depending on your discussion with the city, the city will likely have told you the maximum dimensions possible for your addition.

The procedure for estimating the price of your home addition is a per square foot calculation. This method is very basic and represents mid-range renovations. If you already know you want 10′ curtain walls or retractable patio doors, you can already increase the budget by a few dozen miles.

Here is a list of construction prices that our contractors estimate for expansion projects:

  • 175-225 / sqft for addition of solarium, living room, detached garage,
  • 225-275 / sq. ft. for room addition on the second floor (bedroom, closet, living room)
  • 275-300$ / sf for kitchen and bathroom additions

The price per square foot includes labor and materials.

Here are some examples to quickly illustrate the costs:

  • A 12×20′ solarium could cost around $50,000.
  • A one-story addition to a townhouse could cost around $200,000.
  • Adding a master suite above the garage with a bathroom and walk-in closet could cost around $125,000.

So now that you have an idea of the financial scope of your project, you can look into loan options with the bank financing your property. Also you will be able to better compare if it is more advantageous for you to sell and buy a new property. If you are ready to proceed with a home extension, it is often the most advantageous solution, because let’s face it, there are not many couples who want to go through major renovations in their lives. It’s stressful and risky, but the benefit of having a home that is exactly to your liking and meets your needs is well worth it! Also think about the added value to your property, you will probably be able to recoup your financial investment in the market value of your property.


Magalie Boulerice photographer


Step 3 in planning a home addition: MAKE FITTING PLANS

To carry out the layout plans for the major renovation of your property, you will have to work with a multidisciplinary team of professionals. I’m sure you’re thinking that you need an architect to make the plans and that’s it! Make no mistake, I rarely see architects working on home extension projects… It’s often too small a project for them. Most architects I know work on commercial projects. The most qualified professional to help you with your expansion is an architectural technologist. The law on architects says that for single-family homes under 600 square metres, you are not required to use an architect. An architectural technologist can work on the mandate!

When clients work with our interior design team to complete an expansion project, we work in collaboration with our two partners: an architectural technologist and a building engineer. The expertise of a building engineer is needed as soon as the structure of the building is touched. Its role is to guarantee the stability of the structure by taking into account various elements such as the dimensions of the building, the materials used, the climatic conditions, the quality of the soil and the standards in force in the region.

The role of the designer is to act as a kind of project manager in this kind of mandate, because she is the one who leads the project and knows the needs and objectives of the client. She sees the expansion possibilities defined by the technologist and the structural possibilities defined by the engineer and with that she creates a layout that fits the client’s needs! It’s not easy to put it that way, but rest assured that every professional knows their role and it’s easy to work as a team.

I recommend hiring professionals who are used to working together rather than hiring your designer, architectural technologist and engineer separately for your expansion project.


Magalie Boulerice photographer


Step 4 in planning a home addition: GET A GENERAL CONTRACTOR TO TENDER THE PROJECT

With the plans in hand, you are ready to request bids from general contractors. They will be able to accurately estimate construction costs based on the exact design of your project.

I recommend getting no more than two bids because general contractors are very busy and if they know you’re getting multiple bids they won’t bother to look at your project. It’s better to have fewer choices, but contractors who are invested in your project and take the time to give you a fair and detailed quote.

When I and my team of interior designers do projects for clients, we make the most realistic design possible based on the budget and the entire list of needs. Then, at the bidding stage if the budget is exceeded, we go back into the plan to see what we can cut and where we can save. This is a common procedure to do in a major renovation project and is also done by many design and architectural firms. I therefore recommend that you do this step in your expansion project if necessary.

To proceed to the next step, which is the permit application, you need your general contractor’s estimate.


Magalie Boulerice photographer


Step 5 in planning a home addition: APPLY TO THE CITY FOR A PERMIT

Your project is becoming more and more concrete and there is still this last important step before you say that the project is approved! For the permit application process, you really need to check with your city and borough to find out the procedure to follow, the deadlines and the costs. One thing is certain, you need the set of plans produced by the architectural technologist and your quote for your work.

On my side, I have seen projects approved in a few weeks and other decisions that took a year.


Magalie Boulerice photographer


Step 6 in planning a home addition: BOOK YOUR CONTRACTOR AND ORDER

Once your project is approved by the city, you must hurry to book the general contractor’s schedule. Note that the larger the project, the more advance planning is required.

Most are scheduled 6 to 8 months in advance for this type of project. So in summary, when planning a home addition project, you should allow 2-3 months for the design phase of the plans, 1 to 2 months for the permit application and 6 to 8 months to book your contractor. Ideally, you should plan your expansion project 1 year before the desired start date.

Once you’ve decided on a start date with your contractor, you’ll need to think about placing orders early for certain products. The following is a short list of specific time frames for certain building materials:

  • Windows: 10 months
  • Custom furniture: 8 weeks
  • Lighting: 12 weeks
  • Fittings on order: 8-26 weeks
  • Furnishings: 3 months
  • Appliances: 1 to 12 months

You can choose to place the orders yourself, but you have to consider several hours of work and make sure you don’t make mistakes in the calculations and product confirmations. If you don’t have the time to do this, the general contractor and interior designer can do the ordering for you. Our services are charged by the hour for purchases and orders.

In summary, to carry out your home extension project, you must check the city’s regulations and evaluate your budget before hiring professionals to carry out the design and plans of the project. Then, with the design plans, you can get a detailed quote from the general contractor to complete your permit application. Also remember to reserve the contractor’s schedule and place orders 6-8 months before the start of the job.

During the renovations, I strongly advise you to live elsewhere, in your cottage, at your parents’ house or to rent an airbnb for a few months. You will be much less stressed and exhausted than if you decide to stay living on the construction site in the dust! Also, as an interior designer, I’ve seen a lot of construction sites and I can confirm that it always takes a little longer than expected, so keep that in mind when you start the project. When it comes to the budget, save 10-12% for contingencies that could increase costs in the middle of the job.

If you’d like to find out more about the different professionals involved in an extension project, I invite you to read my latest article on the subject:

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