Cost of Excavating a Crawl Space

In the past, concrete, rigid insulation, and waterproofing systems were largely underdeveloped. Consequently, houses couldn't be built directly on the ground. Therefore, to protect homes from water infiltration and excess humidity, they were built over crawl spaces. However, with today's building materials and techniques, having this type of feature built is no longer necessary. Moreover, crawl spaces are notorious for their drawbacks, rather than for their advantages.

A crawl space is a confined space anywhere between 30 and 60 cm high. Note that the primary purpose of a crawl space is to provide access to a home’s plumbing system. And, with home prices having significantly increased over the past few years, homeowners are eager to excavate their crawl spaces to enhance the square footage of their homes.

Why Excavate a Crawl Space?

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To avoid moving

In some heavily populated neighbourhoods, especially in Montréal, it's impossible to expand your home by adding an extension. The only option to increase the size of your property without having to move is to build an extension from the bottom up.

To increase the value of your property

In some areas, housing prices have literally exploded. Naturally, when it comes to selling, homeowners want to get the most out of the sale. Excavating the crawl space is the best way to increase the value of your home.

To enhance the state of your house

If your home is old and has structural or foundation problems, excavating the crawl space can increase its durability. Such a renovation project would restore the lower portion of the property while improving its stability.

To add space

Since the crawl space is a confined, restricted space, extending the space for storage purposes can be a good idea. As a result, some homeowners decide to convert their crawl space into a cellar. This project is much simpler than transforming it into a living space because the current standards are easier to meet than those for a furnished basement.

Excavating a Crawl Space: Regulations

Excavating a crawl space involves underpinning work. As such, it's imperative to check the regulations set forth by your municipality prior to undertaking any work. In addition, certain restrictions can be imposed depending on the type of work you plan on executing.

For instance, if you're furnishing a basement, you’ll have to account your an emergency exit. If you're planning to convert it into a living space, you'll need to allow for natural lighting (windows), which must amount to 5% of the room's surface area when it comes to bedrooms and 10% for dining or living rooms.

10-Step Guide to Excavating a Crawl Space

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1. Get an excavation permit from the city

2. Hire a structural engineer to assess the feasibility of the project

First, the structural engineer will ensure that your renovation project meets current regulations. They'll also analyze several elements, including the property's soil and the structural condition of the house, before providing you plans and a cost estimate for the excavation. Then, the renovation process can begin!

3. Knock down one of the foundation walls

4. Dig to the required underpinning depth

5. Set up steel piles to support the structure

6. Remove the excavated soil and dump it outside the space

7. Install wooden formwork

8. Build a new concrete foundation

9. Waterproof the new foundation and dig a drainage trench

10. Pour concrete on the new slab and proceed with the finishing work

Cost of Excavating a Crawl Space

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Excavating a crawl space requires underpinning work, which is a risky renovation technique, both for the house and the on-site workforce. Several factors impact the price of a crawl space excavation, including the condition of the house, the type of soil, the area to be excavated, etc.

Basement excavation prices range from $75,000 to $150,000. However, in some cases, this type of project can be even more expensive. For instance, take the Plateau Mont-Royal area, where most houses are built on a stone foundation with a crawl space. 

If you're planning to excavate your crawl space to expand your home, shop around prices among contractors to get the best value for your money. You'll find that quotes vary widely, and significant savings are to be had.

Are you planning a basement renovation project? We've put together a handy checklist to help you manage the various stages of the project. Click here to check it out and bookmark it! 

Cover photo: Systèmes Sous-sol Québec 

Photos: Deposit Photo