What is a "Basement" foundation?

Basements are not just for hanging out, they can be the heart of the house.

Basements are typically used in areas where freeze lines exist. For this and other purposes, the basement foundation is typically built stronger and better reinforced than a typical shallow foundation like a concrete slab-on-grade. Basements are not a good idea where the water table has the potential to rise or substantial excavation obstructions like rock exist. If you are considering using a basement with your new construction project, consider a full-height foundation of eight feet high. This will provide the necessary height requirements for building in the basement for living space and optimizing your investment. 

Like slab foundations, gravel is generally placed below the poured floor for drainage control. Walls have been traditionally built of brick or block construction but modern methods include insulated concrete forms, and reinforced concrete. Floors of a basement are simply a slab-on-grade foundation with a water proofing system as part of the design. Most basements can be damage by water intrusion so waterproofing is essential for this type of foundation system. Basements are typically not used as sleeping rooms unless adequate emergency egress windows are installed to provide emergence egress and natural lighting.

Basements are typically used to contain important systems like HVAC, heating oil tanks, other utility, storage and even parking.  There are different types of basements including the walkout or daylight basement, lookout, walk-up and cellar styles.

Walkout basements are typically situated on sloping lots to take advantage of the area under the house.  A doorway is usually located on the higher part of the basement for walk in access.  These types of basements are also called "daylight basements" since there are usually windows on the descending parts of the sloping lot to allow light to enter the area.  With a daylight basement, emergency egress can be accomplished by the location of escape windows and doors so rooms can be used as living and sleeping areas.  The big advantage of a daylight or walkout basement is the opportunity to use the additional living space as appraised square footage increasing the value of the home.

Lookout basements are those basements partial underground with windows near the top part of the walls.  These basements can not be use as sleeping areas safely so they do not have all the advantages of a walkout or daylight basement.

Walk-up basements are generally below grade and are walked down into via a stairwell.  There are generally no windows or the windows are partially accessible making use of this space less appropriate for habitation.

Cellars are likely the original form of a basement.  For a cellar to be effective, it must be cool all year round and not get close to freezing.   Wine and some foods will store well in cellars for some time.  They also second as a shelter for storms and in times of war safety from air raids.

The critical factor for all basement construction is making sure the floor is below the freeze line.  Freezing soils will expand causing excessive pressures that will push the house up causing potential damage.  Walls are typically only seven foot and ten inches high unstead of the typical eight foot of most living space walls.


Regardless of they type of house you have, there are some necessary tasks you will have to do stay on top of things.  Learn more and keep up with your house with a free My Healthy House.com profile.  Stay tuned and make your house the best it can be.  

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© Healthy House, Inc. 2009

What is a "Concrete Slab" foundation?

Shallow foundations such as slab-on-grade are also know as slab-on-grade, spread footings and mat-slab foundations.

Concrete slab foundations are usually built in areas where freezing soils are not common.  A slab foundation is a concrete and steel structure placed over a moisture barrier and the house's plumbing systems and allowed to mold to the compacted ground below.  Footings are required to help stabilize the structure over time and fight against the ongoing and changing pressure of the ground below as moisture changes take place in the soil. Footings for a slab should be numerous and be dug to a depth where load-bearing materials are found.  Forms, usually made of wood are constructed to hold in the concrete as its poured to mold the foundation.  Once the foundation begins to cure and is considered "Green", the forms are removed.  Later, a plaster coat is placed over the edges of the foundation to cover up the impressions left by the forms and make the edges of the slab more attractive.

Since plumbing is installed under the foundation, there is substantially more difficulty in accessing these items in case of a repair.  In addition, the copper plumbing supply lines must be protected by sleeves to prevent the corrosive components of the concrete from making contact.  Over time, if steel or concrete are in contact with copper, corrosion or dielectric reactions occur causing deterioration and eventual leaking may occur. Another problem related to slab foundations is the difficulty to repair or level slabs once excessive movement occurs or failing sections break away. 

A slab foundation has the advantage of warmer floors in the winter and a good choice when expansive clay soils are not an issue on the construction site.  However, even in Texas and California where expansive clay soils are prevalent, the cost to performance ratios still show the benefit of using lower cost concrete slab foundations in theses areas.

There are two basic types of concrete foundations used today.  The mild steel foundation is usually used on custom or higher quality homes.  It involves engineered drawings of specific placement of steel components and other criteria.  Post tension cable foundations are generally used on track homes and rely on steel cables in plastic conduits.  After the concrete is place in the forms, tens of thousands of pounds of pressure is used to tension the cables and hold sections of the foundation from failing if cracking takes place.

Regardless of they type of house you have, there are some necessary tasks you will have to do stay on top of things.  Learn more and keep up with your house with a free My Healthy House.com profile.  Stay tuned and make your house the best it can be.  

If you have any comments or suggestions on how this blog can be improved including suggested articles or constructive criticism, please send us feedback.

© Healthy House, Inc. 2009

What is a "Pier and Beam" foundation?

Pier and beam foundations are also know as raised foundation, block beam and perimeter beam.

Known as one of the first built and more sustainable foundation types, pier and beam/crawl space construction is still used today.  If your house is on a pier and beam foundation, you should have better access to the items under your house than a slab foundation allows. In contrast, a slab foundation has the plumbing buried under the house which are not accessible without digging under or breaking through the concrete.

For proper access, a crawl space door should be provided at the perimeter and should have a minimum of eighteen inches of head clearance and twenty-four inches of width.  There should be hinges and a latch to secure the door.  Preferably, the door will close tight, will swing to the side and not be in contact with the ground.  Doors that swing up have to be held in place for access.  In some cases, there is a removable portion of a floor, usually located in a closet, that can be removed so a person can access the crawl space.  The minimum opening for a drop down door should be twenty-four by twenty-four inches and there should be at least thirty inches below this area for the person to safely move from a standing to a crawling position.  The head clearance in a crawl space should be a minimum of eighteen inches from the ground level to the bottom of the floor joists. This provides access to areas of the house for inspection and repair. In most cases, the electrical wiring and plumbing is routed to all areas of the first floor from under the house and is secured by attachment to the bottom of the floor joists.

A crawl space should be ventilated to prevent accumulation of moisture which is damaging to the wood components as well as foundation movement and termite activity. The rule of thumb is to have evenly distributed vents around the perimeter of the building that allow a minimum of one square foot of ventilation per one hundred fifty square feet of crawl space surface area. In general, if you have a vent around the bottom of the house ever eight to ten feet, then you are probably fine. Often, homeowners will cover the ventilation openings in the perimeter to keep out the cold in the winter. This can be detrimental if the winter is damp. Decreasing the ventilation can prevent moisture from escaping the foundation crawl space and can cause damage. Some power ventilation systems can be designed to include a humidistat and baffles so that when the moisture is to high under the house, a fan turns on venting the moisture out. Once the moisture is vented out and the area under the house is dry, the fan turns off and the baffles close keeping out the cold. 

Your crawl space should be inspected annually for plumbing leaks, wood damage, pest access and any other problems. Always be careful when accessing a crawl space by wearing protective equipment like proper clothing and a respirator for proper health and safety.

Regardless of they type of house you have, there are some necessary tasks you will have to do stay on top of things.  Learn more and keep up with your house with a free My Healthy House.com profile.  Stay tuned and make your house the best it can be.  

If you have any comments or suggestions on how this blog can be improved including suggested articles or constructive criticism, please send us feedback.

© Healthy House, Inc. 2009