How Far Out Of The Ground Should Your Floor Joist Be In A New Home?

Q:

How close can the floor joist be to the ground level when building a new home?

A:

There is no set rule, some regions and municipalities have rules and regulations but it’s more common sense rule for you and your builder than anything else.

The floor joist of your home are usually set on top of the concrete or block foundation and then have a rim joist that is attached to them that runs around the entire outside of the perimeter sitting on the foundation wall. This rim joist is not engineered or designed to deal with any kind of moisture and because of this efforts need to be made to keep it from coming in contact with moisture from outside.

The easiest way to make sure that your rim joist does not become saturated with moisture is to build the house so that it is fairly far out of the ground. Do not be worried that you are building your home to high out of the ground; the worry should always be “are you building your home too deep into the ground?”

How you ask can you not worry about building your home to high out of the ground? Contractors have a saying that we tend to live by, it is "you can always grade up to the house, you can’t grade down". Having a house that is “high and dry” is something that everyone should want; this will mean that you never have to worry about water problems.

Back to the question that you had about the floor joist/rim joist. You want the house out of the ground so that when the rain comes off the roof it isn’t going to roll or splash back against the foundation and rot the siding or joist behind it. You should be at least 18 inches out of the ground to the bottom side of your rim joist. Every area has a different thinking on this and some building codes differ so it is best if you check with your local building department.

Rob Abbott
Village Builders Inc.