Installing a Footing

by Mr.500
(Plainfield NJ)

Installing a footing tips for carpenters and handyman. First, install a concrete footing an which to erect the wall. If you don't, the wall will soon crack and list. Dig a footing trench that is twice as wide as the wall and at least 6 inches deep. If you live an area that gets extreme frosts, extend footing down below frost line. Build forms by first setting sakes every 18 inches along bath sides of trench. Attach form boards to stakes so that lumber is 1/2 inch above ground. Using 1 by 6 boards for a 6- inch footing or 1 by 8 for 8 inch footing, nail boards to inside faces of stakes. Tie sides of form together with 1 by 2s nailed across at 2 foot intervals. Reinforce footing and wall with rebar. To determine position for rebar, lay out a run of concrete blocks beside or in footing ditch, carefully spacing them 3/8 inch apart. Mark position and remove blocks. Every 4 feet, place dobies (small concrete piers) to support a horizontal length of rebar, holding it 3 inches above ground level (a code requirement). Wire vertical lengths of L-shaped rebar to horizontal piece avoiding ground contact. Rebar should be long enough to extend through two finished courses of blocks. Pour footing and screed flush with tops of form boards. Before concrete sets up, make sure upright lengths of rebar are plumb.

Laying Concrete Block Lay out a dry run of first course. Space blocks 3/4 inch apart and check for level and fit. When satisfied, remove all blocks except 2 end ones.

Spread a layer of mortar on footing. Mortar should be ap-proximately 1 inch thick and about 1 inch wider than the block on both sides. Press end blocks firmly into mortar bed and then stretch a mason's line between end blocks. Use line as a guide but check often with a level, complete first course. Butter one end of each block before pressing it in place. If you are building a straight wall, the second course (and every alternate one) starts and ends with a half block so that joints overlap. On the third course, you will need to extend rebar. Wire on an extension piece and fill cell with concrete, tamping it to make sure the cell is completely filled. Check constantly for plumb and level. Set up a mason's line as a guide, or use a long, straight 2 by 4 to make sure your courses are level. As you V, work, keep scraping excess ( mortar from joints. As long as it has not hardened, this excess can be reused. Continue until wall is the height you require.

Installing footing on long walls, 60 feet or more, incorporate expansion joints to prevent wall from cracking. There are several products sold for this purpose, including special tongue-and-groove blocks. Check building supply stores for products that will best suit your purpose. Concrete block walls are commonly capped with flat concrete blocks, which are simply mortared in place. If you prefer, use flagstone or brick mortared in place. If you wish to install a wood cap, fill cells with mortar, embedding anchor bolts that will secure the wood cap to the wall.

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