Home Foundations - Slab or Crawlspace?

Growing up here in North Carolina, I was only familiar with crawlspace foundations or the occasional basement home.  In the early to mid 1970’s, you would not have even heard of a slab foundation. Since then, slab foundations have become more popular especially amongst home builders.  There are lots of factors that are taken into consideration when choosing to build a home and whether it is built on a slab or crawlspace foundation. 

Below are some of the main factors to consider and reasons homes are built with either a crawlspace foundation or a slab foundation:

Crawlspace foundations are more expensive to build than a slab foundation.  In general, a crawlspace will cost a builder approximately double that of a slab home on a similar/same home.  Slab foundations are less expensive in materials and man hours for install.

Slab foundations require proper preparation of the homesite.  This starts with professional grading of the lot to insure the proper leveling of the ground but also proper drainage away from the home site.  Reinforcement rods are added to the foundation area to strengthen the slab and help again cracking once the concrete cures. Prior to pouring the concrete slab, necessary plumbing and electrical conduit has to be installed.  All HVAC lines, ductwork and equipment are run through the attic to allow access to the components during the home construction phase.

Crawlspace homes require a good bit of preparation and professional grading of the lot also.  Concrete footers have to be poured and assured of being level. They are the backbone of the home and without them being solid, the whole house crumbles.  While a slab is a “quick” pour of concrete, a crawlspace has to be built by hand, block by block and brick by brick. This is time consuming and leads to a lengthier process than a slab foundation.  

Some additional things to consider when you have the option of a foundation type:

-Efficiency when it comes to heating and cooling:  a slab home can be much more energy efficient. A crawlspace has air flow going through the area which is typically a loss of efficiency.  A slab does not have that air flow and it acts as a better insulator.

-Comfort:  A slab is made of concrete which is  not soft at all. A crawlspace being built on a suspended wood surface allows for some “give” and allows for a more comfortable surface for walking on.  No matter what the floor covering and padding that is placed on a slab, it is not going to be as “giving” as a crawlspace foundation.

-Storage:  Some crawlspaces, depending on the grade of the land can be their own storage building.  I have seen homes that have a full size door to walk in and have a poured concrete area in the crawlspace for additional storage.  There is zero storage with a slab foundation.

-Accessibility:  Slab homes are typically closer to ground level than a crawlspace.  If the owner is challenged with step or perhaps confined to a wheelchair, a slab foundation may be more appealing.  Even on a flat lot, there is going to be at least 1 or 2 steps to maneuver with a crawlspace foundation.

Pros and Cons

Slab Crawlspace

Pros:

Less Expensive More comfortable for walking Faster to Build Can be used for additional storage More Energy Efficient Plumbing, Electrical, HVAC Access Zero Entry (steps not necessary) Lot can be sloped Stronger/More Durable Easier to detect pests/treatment

Cons:

Repairs are more expensive More Expensive than slab Plumbing/Electrical Harder to Access Takes longer to construct Less comfortable on joints over time Less Energy Efficient

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