Foundations

3/26/2010

What is a Foundation?

• The part of a building that rests on and extends into the ground. It provides support for he structural loads above.

Lets Recap In the building of our house

• We have set aside $$ and or received a loan• Researched and purchased land. • We have met with an architect and/or contractor to

design our dream house• We have looked over and reviewed all local ordinances

and filed for proper building permits• The land has been surveyed and a perk test has been

preformed.• The contractor has excavated the site and leveled the

base.• The foundation walls where staked out • The contractor has now dug out a hole where the

foundation will rest.• Now this brings us to foundations…….

Hold on a Minute

WHAT TYPE OF SOIL DO WE HAVE AND HOW DOES THIS EFFECT OUR

FOUNDATION?

How much weight can the ground take before there is failure.

• Remember: Your foundation is only as good as the ground it rests on.

• Clay: 2000lbSqFt• Sand: 3000lb/SqFt• Sandy Gravel: 5000lbsSqFt• Sedimentary Rock: 6000lbsSqFt• Bedrock:12000lbsSqFt

• Best left to a structural engineer if questionable. Same type of person that would be checking concrete composition and compression testing.

Options for foundations

• Full basement- – Pros: adds additional space for storage and

possible living area, shelter in event of natural/unnatural disaster (bomb shelter?), naturally cool storage place for food.

– Cons: Not included in houses SQFT unless finished, can lead to flooding problems if not properly cared for, costs more, leaves a bigger carbon footprint due to amount of concrete needed. RADON

RADON GAS• Radon gas is a naturally occurring Radioactive gas that

comes up from the ground. • It is dangerous in basements and crawl spaces because

over time it can lead to cancer.• In the natural environment it is immediately dissipated

into the air where when it come up though a foundation into a house it is trapped.

• You cannot smell, Taste, or see Radon gas• There is no ways to prevent Radon, However there are

ways to expel it from your foundation through exhaust fans and other forms of abatement.

• What does this mean for the home owner…..$$$$$• Is it common?............. YES especially in lower Michigan.

The best thing to do when building or purchasing a house get it checked so you can make informed decisions. The cost for having it checked is very small compared to potential consequences down the road.

Options for foundations cont.

• STD. Foundation, A.K.A. Crawl space.– Pros: Cheaper than full basement, less

environmental impact due to less concrete, Still as structurally sound and supportive as a full Basement.

– Cons: No additional space gained, Still can have water issues, RADON, harder to inspect and maintain I sense of working conditions.

Post Foundation

• Not common in any modern home. • Very common in pole barns, and some

northern cottages.• Will not meet code in MI for livable

structure, however there is a loophole• If you use it solely as a vacation home you

may live in it. So no full time residency is allowed.

• Check local ordinance just to be sure.

Types of Foundations

• Concrete foundation-Most common-

• Masonry: A.K.A. Brick or block

• Wood- This type of foundation may or may not meet local code in parts of the country.

Parts and terms of a foundation.

• All foundations consist of the following 2 major parts

Foundations Parts Cont.

• Parts for you to know– Sill Plate– Anchor Clips

• Different forms and types all accomplish the same task

Rules for all foundations

• In order to carry structural loads all Footers should be twice the thickness of the foundation wall wide.

• So therefore the footing would project ½ the thickness of the wall on the left and right side of the foundation wall

• The footing height should be at minimum the same as the thickness of the foundation wall.

Lets take a closer look

Here is a cutaway of a standard foundation with crawlspace.

Foundation with Full Basement

Typical wood Foundation

Lets take a closer look at a wood foundation in a home

• They have been around for years. • They are proven to work, however for how long?• Must be made of rot/insect resistant material• All fasteners must be corrosion resistant.• All framing lumber must not have a moisture content

above 19% and the plywood must not be above 18%• Modern wood foundations are a result of collaboration of

the National Forrest Products Assoc, Wood Preservers institute, and the US dept of housing and urban development. And regional code agencies.

Wood Foundations Continued

• Basically a wood foundation is constructed the same as a stud wall. AKA walls in your house.

• Only difference for the most part is the material used

• Can be built off site in sections and quickly assembled at the job site.

• Eco friendly, because it is a renewable resource and leaves a smaller carbon foot print than concrete or masonry foundations.

Wood Foundations pictures.

Key Terms• Please write down and Define the

following Key terms from this week

FoundationSill PlateFooterRadonCraneBackhoeCement Pumper

Scissor LiftMaterial LiftPost Hole digger/AugerSurveyorLocal OrdinanceSub Soil Drainage

ExcavatorBulldozerConcretePortland CementGravel Train