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Most jurisdictions require a survey of the lot before the approval of plans. Surveyors will drive iron pins in the ground to mark the property lines. These iron pins are easily found by looking for a white wooden post driven in beside the pin. The white posts may disappear in time, but the iron pin should still be in place. The surveyor will find these or drive in new ones and draw up a Plot or Site Plan with the property lines shown.

For each property line there is a setback, a distance from the property line in which the house can be built. These vary from side to side and front to back of the property depending on your jurisdiction and location of lot, either in the city or the country. This information is readily available at your town hall. On a simple box house, a surveyor will usually stake the corners of the foundation walls right inside the trench for you, This practice virtually eliminates the need for batter boards, except for the more complicated floor designs. I’ve even persuaded my surveyor to shoot lines right on the batter boards to ensure the lines were square and at the proper set backs.

Mark out the excavation area, allowing for the extra room, with temporary 1x2 stakes or paint a line on the soil with a brightly colored spray paint. Make sure the batter boards are placed outside this excavation area so you can use the same ones to layout the footings. It is important to note that batter boards should be installed at roughly the same elevation, on a level lot, enabling the measuring of diagonals to ensure the building layout is true and square.

House plans usually don’t give elevations of the building lot, unless drawn up by an architect. The height of the top of the forms is usually decided by the house framer or builder who is putting in the foundation. His concern is to have the lot fit the plan, according to the height of the existing grade and if the existing grade will be the same as the finished, permanent grade. This is one thing—as a new homeowner—to discuss with your builder. If an architect is hired to draw up the plans, he usually oversees the building of the house as well. The homeowner then discusses existing grade and permanent grade with the architect.

The Footings

Usually footings are 6" thick and 16" wide running continuously around the perimeter of the building. Cross footings of the same size may be shown on the Foundation Plan for the building. These are footings for wood framed walls supporting a bearing wall in a basement or floor joists in a crawlspace. Since our concrete and masonry walls are 8" thick, the footing extends 4" past the wall line on each side. This is to stabilize the wall as well as to add more surface area to bear the wall and house on the soil beneath it.

Some jurisdictions require the use of rebar in the footings and walls, others don’t seem to bother. Concrete has a strange property when it is reinforced with steel, it takes on the properties of steel. It becomes elastic like steel and has the tensile strength of steel, rather than a block of concrete which is brittle and not very cohesive. Required or not, I usually place rebar in my concrete footings and walls. Rebar is made from recycled steel, so the cost is not that high. The diameter of the bars is designated in eighths of an inch. In the footings place two #4 bars (4/8 or 1/2") spaced out, running the length of the footings. Use tie wire to tie the cross pieces together in the corners, as well as to join bars together. The bars come in 20 foot lengths so not many splices are needed. If you need to extend the length of the rebar, the two pieces need to overlap each other. Overlaps for #4 bars should be at least 15" with two ties.

The footing forms are made from 2x6 lumber with a 1x3 cleat on the top and on the bottom, which keep the concrete from pushing the sides of the form apart when it's poured. The cleats are spaced about 3' apart and the bottom ones are buried in the concrete. The movement to the side is restrained by 1x3 stakes driven into the soil. The footings are not leveled if the excavation is fairly level. Rebar is placed into the footing and hung from the cleats about 3" off the soil. The footings can be poured at this stage, in which case a key is formed along the top of the footing to allow the wall to be poured into it. The vertical rebar, if any, would be in place before the concrete is poured. Generally, if the wall is 2' high, no vertical bars are required. Two horizontal bars are required within 6" of the top and bottom. For a 3' to 4' high wall, both verticals and horizontals are required at 18" on center (o.c.). For 4' to 6' high walls both bars should be placed at 16" o.c. and for 6' to 8' high walls every 12" o.c. Over 8' high, better check with an engineer or building inspector.

The Foundation Wall

If the site requires the use of a concrete pump, the footings and walls can be poured together. The cleats on top of the footing will hold the bottom plates of the wall forms. The location of the wall is marked on each end of the footing on top of the cleats, 3/4" is allowed for the wall form plywood. A line is snapped between the two ends and the 2x4 bottom plate is nailed in position along the line. Both plates can be laid out and fastened at the same time, leaving a distance of 9 1/2" between plates for an 8" concrete wall.

Depending on the height of the wall from the footings, a decision should be made to order the forms. Draw up a little sketch and take it to the form rental outlet. Here you will receive the necessary plywood and form ties and tie bars to complete the work.

If the exterior sheathing on the walls of the house are 3/4" boards, these can be used as forms, as well. In my area we use 1x8 re-sawn boards that are less costly than renting forms, but more involved in labour. In this case the tie bars will go vertically every 16" in place of studs.

With plywood forms the tie bars go horizontally every 16". The ezze snapties go in a 16"x16" pattern. With the 1x8 boards the ties lay in between the boards starting on top of the bottom board and continuing up every other board.

Usually when you rent the plywood forms the plywood is pre-drilled out for the snapties. Since the plywood forms are pre-drilled, the snapties can be inserted after the walls are up.

2x4 studs are used every 8' to help tie the forms together and hold the plywood or boards in place. If the tie bars are installed in the horizontal position, the studs are eliminated and a horizontal top plate is used to hold the plywood together. Every 8' or so, a brace is nailed to a vertical stud or toe-nailed to the top plate. The brace is usually 8' long and is staked to the ground to prevent the wall from moving and keep it straight when pouring the concrete.

For straightening the wall, a string line is run along the inside of the outside wall. To keep the string away from the wall, insert a piece of 3/4" cleat or stake at each end. Carry a third piece with you while checking the line. Have a partner move the brace back or forth until the distance between the string and the wall equals the thickness of the 3/4" piece.

Once the outside wall is up and fairly straight, braced to keep it from falling down, the top of the wall is marked with points shot on with a builder’s level. This is a very accurate way of making sure the top of the wall is level. Years ago we used to use a see through plastic garden hose filled with water. Since water finds its own level, a worker would hold one end of the garden hose near the top of the wall while the other would walk around the forms placing level marks at the top of the bubble. This worked great unless the worker tripped and lost some water out of the hose. We would then have to start over. It also was time consuming for the movement of water to settle down inside the hose. Spend an extra couple of bucks and rent or borrow a builder’s level.

Lines are snapped between level lines all around the top of the walls. A 1x2 levelling strip is fastened to the line, with the strip below the line. This strip becomes a useful aid to levelling off the fresh concrete with a float.

When the forms are stripped the pour strip leaves a 3/4" x 1 1/2" depression. Any block outs should now be put in place. A block out is a wooden form built to keep the concrete out of a certain area of the wall or footing, When the forms are stripped or removed, the block out is removed leaving a hole or pocket formed by the cement. Plumbing pipes, electrical wires, etc. can be inserted through these holes after the concrete is poured and the mechanical trades appear on the job site at a later date.

Reinforcing Steel

Rebar is now installed in the wall. Here are some guidelines:

Footings should always have rebar—two continuous lengths spaced out evenly about 3" above the soil.

For a 2' high wall no vertical bars are required, one horizontal within 6" of the top and one horizontal within 6" of the bottom.

For 2' to 4' high walls place vertical and horizontal bars every 18", within 6" of top and bottom.

For 4' to 6' high walls place vertical and horizontal bars every 16", within 6" of top and bottom.

For 6' to 8' high walls place vertical and horizontal bars every 12", within 6" of top and bottom.

For over 8' high walls check with your local authority having jurisdiction or an engineer.

To tie the rebar in place on the wall, nail a 3" nail into the wall, leaving about 1 1/2" projecting. Tie the bar to this nail to keep it away from the form as well as straight and plumb. The vertical bar should have a 90 degree bend on it to be tied onto the footing bars. The horizontals can lay on the snapties and be tied to the vertical bars.

The other side of the wall form is placed. The tie bars are slipped into the oval holes in the snapties. Try to keep the tie bars opposite each other to ensure that the snapties are square across the form. This ensures that the wall will be 8" when expanded with concrete. Usually we put a spreader across the form at the top to keep the wall at 8".

At the end or change of height of the wall form we put in a bulkhead. This is a 2x6, 2x8 or 2x10 ripped down to fit the thickness of the wall. Make it loose, like 7 7/8" or it will be tough pushing the bar through the snaptie. Another option for bulkheads is to make them with a 2x4 on each side of the inside of the form with a ripping of plywood between, to hold the concrete back. You’ll notice that the snaptie has a notch on each end on one side. This is to be able to grab the snaptie with a hammer to pry the snaptie out of the form a bit to help ease the installation of the tie bar through its hole.

When all the ties have been secured with tie bars, check that the wall is straight and strong. Once the concrete is poured it is too late to push the wall around or take any kinks out.

The Concrete Pour

On concrete day get as many hands as possible to help. Get the anchor bolts ready to be placed in the finished concrete. Get enough trowels for everyone. Even a 1x6 board about 10" long is good, nail a 1x2 handle on it. Talk to the pump operator if this is new to you, a wall over 4' should be filled in layers, not right to the top.

When the wall is filled with concrete, have a helper go before the finisher and get the excess out of the wall or fill in to the approximate level, the top of the pour strip. In my experience of forming and pouring concrete in heavy construction, working on industrial buildings, bridges, etc. we always are required to vibrate the concrete as it is filling up the form. In residential construction more times than not they don’t use a concrete vibrator (see it at Amazon). If the walls are high, exposed later, or you just want a good job, rent a concrete vibrator. It is very easy to operate. Just turn it on and let it flow down the wall by itself. Immediately, you will notice that the concrete level goes down, as well. The vibrator actually compresses the concrete, filling in any voids. There are a couple of things to know before operating the vibrator. Concrete is extremely heavy, about 150 pounds per cubic foot with rebar. This means that every 18" in height in an 8" wall weighs 150 lbs. Just ask someone who has wheeled much concrete! So you don’t want to leave the vibrator in the wall too long. You could break the forms if the wall is full and you vibrate right to the bottom every time. So vibrate only the fresh layer you are pouring, going into the existing layer just to provide good bonding. And the other thing to watch when vibrating is the air bubbles coming out. Air is entrained in concrete for freezing and thawing purposes, we don’t want to lose it. Don’t leave the vibrator in the concrete bubbling away. If using a vibrator insert it into the concrete quickly, let it do its job and pull it out and move on. The vibrator is cooled by the concrete so don’t turn it on and leave it running in the dirt or on top of a scaffold, it will burn out.

When the finisher has completed smoothing off the top of the wall to the correct level, now is the time to insert the anchor bolts. (See it on Amazon.com.) These are placed in the center of the sill plate that will be installed later. This sill plate will be a 2x6 so make sure the anchor bolts are centered for either a 2x6 sill or wall plate or possibly a 2x4 wall plate. The bolts are required to be placed every 6'. Some jurisdictions require closer spacing. My engineer wanted our 8' walls to have anchor bolts every 2'. What’s the cost of adding a few anchor bolts to the price of a new house? The top of an 8' wall is braced by the floor joists, against the backfill. So don’t go cheap on the bolts. The bottom of the wall is braced by the slab as shown on this drawing.

Stripping the Forms

After a long and stressful day of pouring and finishing the foundation a good rest is well in order. I like to leave my forms on for a couple of days, depending on the weather. I love it when I can pour a foundation on a Friday and leave it until Monday to start stripping the forms. After a couple of days the concrete is still soft or green as we call it. Be very careful removing the forms. Start with the braces. I like to take my old hammer and remove any ridges left on the top of the wall by the cement trowels or floats. While the helpers are removing the forms and pulling the nails out and scraping any concrete off, I start laying out the sill plates or wall bottom plates. Holes for the anchor bolts are drilled in the plates and the sill gasket is stapled on the bottom. If the bottom or sill plate is pressure treated, no gasket is required. I prefer a gasket since it not only keeps the wood plate from being in contact with the concrete (so it won't rot), it fills small voids keeping the cold air out.

As soon as the outside forms are stripped and the footing forms are removed, we can concentrate on the perimeter drainage piping and waterproofing the foundation wall. I’ll be discussing this phase of building our house in the next article of this series.

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Dave

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