Part1_Footings

Construction Technology
include component="page" page="toolbar_tcj2O" editable="1" Housing Unit: Part 1 | Part 2 | Part 3 | Part 4
 * HOUSING UNIT (TCJ2O)**

**House Model Section Project **



** Part 1: FOOTING & FOUNDATION **
 * Residential Foundations -** most homes built in this area of the country are constructed on a foundation to support the structure and add more living space. The most widely used is the poured concrete foundation which you will use in your model. Another common foundation uses concrete block. Both of these start with a poured footing in place.

As soon as the excavation is complete the foundation may begin it must be positioned on undisturbed soil. The purpose of the footing is to give the foundation a wider base to prevent the home from sinking. Forms made of 2 x 8 are placed on edge to form a trough. Spreaders between the two sides keep the footing to the correct size while 2 x 2's driven down into the ground will hold the footing in its proper place. A common rule to follow is the footing is the wall thickness times two as for its thickness this will be determined by the size of the structure. Some soil conditions may change this common rule. If it is required that the footing be reinforced then steel rods are placed in the footing. After pouring the concrete a groove is etched in the concrete before it cures. The groove known as the key way is made by sliding a 2 x 4 on edge down the center of the footing, its purpose is to stop water penetration and to keep the wall from sliding inward.

Footings are also needed where heavy loads are placed such as under jack posts masonry fireplaces and decks. Poured foundation is most widely used mainly because of its speed of construction, durability, and resistance to the climate and moisture. As compared to a block foundation where cracks may develop allowing moisture in, also blocks can take days longer to lay. Blocks are used when no redimix is accessible and when standard forms for a poured foundation make it economically unfeasible.

The poured foundation is made by installing temporary forms to hold the concrete in place until stable. These forms are made of 3/4" plywood with a frame on the outside for strength and usually in two foot sections. To keep them the desired distance apart steel ties are placed in the forms, they will be snapped off after the forms are removed. Any openings for windows or beam pockets may also be blocked off inside the form. In some cases the window itself is placed between the forms and the concrete poured around the window. To make the forms easy to remove oil is sprayed on the inside just before pouring. As the concrete is being poured into the form it must be tamped to prevent voids in the concrete. This is done either with sticks pushed in and out of the mixture or with a vibrating rod. As when the key way was formed in the footing the top of the wall must have anchor bolts placed in the top to fasten the sill plate.

When ordering redimix concrete you must know how many cubic yards are needed for the job, the density of the mixture and delivery time. Drivers will not stand around for long if the forms are not ready. In most cases the foundation is sub traded out and timing, and ordering will be their responsibility. Be sure and have a few quotes given and ask for other job references, the foundation could hold up the whole job site if not completed on schedule.


 * Question 1 -** When calculating concrete we need to know volumes. If the wall to be poured was .5' thick by 8' high by 20' long, how many cubic feet of concrete would you need?


 * Question 2 -**There are 27 cubic feet in one cubic yard of cement. How many cubic yards would this convert to for our 20' long wall?

** Model House Instructions ** 1. **Foot print:** (1) 1/8" * 9" * 14" Masonite. 2. **Footings:** (1) ¾ " x 1 ½ " x 18" pine. Cut stock into part C - 1 ½”, part B - 6 ½”and part A - 9" lengths. 3. **Foundation wall:** (1) 1/2” * 5" * 16" pine. Cut stock into 4 ½ " and 10" lengths. 4. **Concrete Floor:** (1) 1/8” * 3” * 3” Masonite. 5. **Beams** **and Post:** (1) 1/2" * 1/2" by 24" pine. Cut stock into 4-1/2", then cut 6”and 10" long. Mitered at 45° at one end. The 3/4" * 1-1/2" * 1-1/2" footing will support the post. 6. **Sill Plate:** 7. **Other materials:** crush rock (stone dust) and drain tile (soda straw).
 * Bill of Materials and Cutting Plan **

Beam pockets, cut out a half inch square from the upper outside corner of each piece on the band saw. They will support half the load of the floor when the beams are installed. Due this prior to gluing the foundation walls in place on the Footprint


 * Check of accuracy**: //Part of the mark will be based on you machining these pieces precisely. These are all the materials needed to complete your model foundation//

Layout your piece of Masonite so your foundation footing will be centered. You may glue the footing to the Masonite using a hot glue gun (small dabs of glue every two or three inches will work better then a long bead). Layout the footing according to the plan below:
 * LAYOUT **



** FOOTING & FOUNDATION **

Name:
 * Answer** the following questions in your notebook after reading chapter three (page 158) from "Introduction to Wood & Construction"

1) Give the definition of a footing.

2) Why and with what are footings reinforced?

3) Why is a larger footing required in soft soil?

4) Why is poured concrete better then concrete block for foundations?

5) How are sill bolts positioned in a foundation wall?

6) What is the minimum size of a post (jack post) footing?

7) Why is waterproofing done prior to laying drain pipe?

8) The text refers to a new drainage system - give four advantages to it over clay tiles. This new system is commonplace now.

9) The text says the footing key way is for waterproofing, come up with one more reason for a key way. **Hint** think backfill.

10) What is the purpose of the sill plate ?

...click on the following link for the ANSWERS