11-02-2008 10:09 PM
In viewing a new home today, I was surprised to open a door in the basement to reveal a room with the water heater + a HUGE pile of dirt covered loosley by black plastic sheeting. When chatting with the listing agent, he told me this is called a "step foundation" and it is used in Seattle where homes are built on a slope. Apparently, during construction there are circular concrete pillars cast deep into the ground and a foundation wall is built on top of these...but there are sections between the pillars (where no foundation wall exists) that back up to the basement and hence this is where the dirt creates a pile.
So, I'm new to the area and not familar with this concept at all and must admit is pretty unnerving. How is this technique viable? When the ground shifts over time, won't the earth/dirt just push further into this room? How can this possibly be a vapor barrier when the plastic sheeting is not a sealed fit? Won't water seep in? How is this safe from creatures that might burrow from the yard into the house?
Sorry if these seem like ignorant questions but I'm really having a hard time understanding this "step foundation" deal!
11-03-2008 10:03 AM
Having a home with both a basement and crawl space is not uncommon in this area for both new construction and older homes. As the holes for the concrete footings are dug, the displaced dirt can remain in the area. And if the basement was dug out, the dirt may also remain nearby. This is typically not a problem as long as the soil is not in contact with any of the wood structure, as this would increase the risk of rot or insect damage.
The footings and foundation of the home are designed to resist structural movement and settlement. Depending on the grade of the lot and proper drainage, "ground shifts" should not occur. And certainly, the dirt pile would not grow or move.
The plastic vapor barrier does not need to be sealed, but it should cover all of the dirt in the space. This barrier acts to reduce the natural moisture seepage from the soil into the crawl space. Along with proper ventilation of the crawl space, the moisture level is controlled and the risk of organic growth is minimized.
Concern over animals burrowing under the foundation and into the crawl space is not necessary. Keeping any above grade points of entry closed, such as foundation wall vents, is a part of typical maintenance.
A qualified home inspector can give you a better sense of the condition of this particular situation or any home you are interested in. Redfin has a list of very qualified home inspectors to choose from. Talk to your Redfin agent about how a home inspection fits in to the home buying process and how it can help answer any questions you have about the condition of the home.
11-04-2008 11:01 AM
11-06-2008 11:28 AM
Thanks for the information here. I think both responses have some merit & suspect there are other details regarding the configuration of this step foundation that would need to be assessed in order to make a final judgement on the risk.
Having said that, my instinct tells me this is going to be a hassle in the future..either while we own the house or during re-sale...and I personally just don't like it...this is not an inexpensive house and I can't accept a basement half full of landfill with a open path underneath the foundation. I'll also add that during my viewing, the heat in the house had been turned up to sweltering levels...the listing agent made a point of mentioning that he needed to "reheat the home since it had been empty for a while"...I didn't understand what that had to do with the 30c temperature he chose...I wonder if he was just trying to cover up the cold & odor caused by the mound of dirt in the basement!
Thanks for all the info!