Slabs vs. Crawl Spaces vs. Basements
What is it?
The most simple of the three types of foundations, a slab is simply a concrete foundation around one foot in depth below the house reinforced with steel bars. It is no surprise that it is the cheapest foundation that we will cover in this article.
In the United States, this type of foundation is far more common in Southern states, where the ground is less likely to freeze. Freezing soil can crack the foundation, leading to all sorts of problems.
Some advantages of a slab foundation include:
- A speedy construction
- The slab is a rather effective barrier against the intrusion of harmful gases such as Radon, as well as wood-boring insects.
- cost savings
- homes built on slabs are closer to ground level and thus require few (if any) stairs leading up to them, making them ideal for the handicapped or elderly.
Some disadvantages include:
- Space concerns: ductwork & appliances must be installed on the ground floor of the home.
- If the slab cracks, it is very expensive to repair. Tree roots, shifting soil, frozen soil, and earthquakes (quite obviously) can all crack a slab foundation.
- Can be difficult to wire the electrical system.
- In Northwest Michigan: cold floors in the winter!
What is It?
A crawl space is an area of limited height (usually anywhere from 1 to 3 feet in clearance) below the first floor of the house, but above the ground.
Crawl spaces are more expensive than a slab as more digging and more concrete is required.
- It is a convenient space to install items such as HVAC units & piping, as well as water and sewer distribution lines.
- Often a good choice of foundation if the ground that the home will be built upon is heavily sloped or prone to flooding.
- If there are no obstructions (e.g. low ductwork) and the clearance is high enough, the crawl space is able to be inspected.
- Our inspectors are unable to enter a crawl space if there are any unsafe conditions including, but not limited to, exposed nails, standing water, unsafe electrical work, and the presence of mold or mildew.
- Homes built over crawl spaces tend to have moisture-related issues.
- These are commonly remedied through the use of a vapor barrier (a thin plastic or foil sheet, covering the crawl space interior, that is designed to resist the flow of air into the crawl space.
- Items stored in a crawl space with undiagnosed moisture issues can bring about mold & mildew.
When we inspect a crawl space we look for signs of:
- Termites and other wood-boring insects
- Moisture damage such as mold or mildew
- Wiring or plumbing problems
- Foundation issues (e.g. cracks or shifting)
- Presence & quality of vapor barriers
If you're from the Midwest, it is more than likely that you've been in a basement at some point. A basement is really a mixture of a crawl space and a slab. It is a 8 foot (or deeper) hole beneath the house that ends in a concrete slab.
While it is the most expensive type of foundation available, basements are still the most common foundation type found in Northern Michigan. This is because a home's footing (the slab) must be placed below the frost line in order to prevent cracks and shits in the foundation. The frost line in Northern Michigan is approximately 42" underground, which makes basements an ideal choice for homes in the area. Not to mention, a home with a basement can command a higher price than one without.