I prefer to do my own cement work because foundation contractors can be really expensive. Apart from digging out the foundation, the cement work is quite simple. Besides the cement is calculated and delivered by the cement company. That’s a lot easier than buying and mixing your own cement.
After you get the inside form complete, brace the outside and inside forms together with strong, but removable braces. Check once again, the diagonal measurement, to make sure it’s still in square.
Then use wooden spikes to hold the forms in place because the heavy cement can bow the forms out if not braced properly. Next you can set up the rebar.
The amount and size of rebar depends on your local building code. Areas where there is a lot of earthquake activity will require more and probably thicker rebar. Here are a few examples how to join rebar and use it around corners.
Any place you have rebar that crosses, be sure to tie it up with wire so the cement doesn’t force it apart.
Also a very important part of the footings is the key or the rebar connector that holds the foundation wall onto the footings itself. Pressing a beveled 2×4 into the freshly poured cement while it’s being leveled can make the key. You can also run rebar that sticks up about 4 inches out of the footings every 2 feet or so.
You will have to pour the footings and the foundation wall separately to let the footings cure. I would wait at least one week between the two. Besides, construction of the forms for the foundation can start just a few days after the footings are poured.Many contractors that specialized in foundations will cover the cement to keep it clean.
Now, the foundation wall obviously goes on top of the footings. The building codes will determine its height. The codes will also determine the thickness requirements of the foundation wall. I went with an 8” thick foundation. There are several ways to set up the forms. Here are two ways with the first being supported with form studs and braces.
We see how to use wire by drilling small holes in the boards or plywood, running wires through and twisting them around wood pieces. Once the cement is hard, you can cut the wires or even break them off with a hammer so you can release the forms.
Now the things that actually hold the house to the foundation are the anchor bolts. That’s why foundation contractors are extra careful to place the anchor bolts evenly and securely.
Gravity does a pretty good job holding the house on its foundation, but in unusually high winds, poorly fastened houses have been blown off their foundations. If you forget to put the anchor bolts in the wet cement, you’ll hate yourself for a week.
While the foundation wall forms are in place and before the cement is poured, mark where the bolts will be placed. Usually, they will need to be placed 4’ to 6’ on center. You can fudge them an inch or two either way to avoid putting them where a joist will be.
Also, it’s a good idea to hang the anchors using a piece of 2×4 because the board is the same thickness that your sill plate will be. Try to plan ahead before laying out the spacing of the anchor bolts so you don’t put one where a joist will be because the floor joists will rest upon the sill plate.
By the way, making your own cement isn’t a very practical idea. Have it delivered and poured by the local cement companies. Have a shovel to settle the cement into all the forms so no air pockets remain. You can use a flat board as a screed to make a smooth surface so the sill plate rests evenly on the foundation.
Once the foundation is poured and has cured for a couple of days, you can remove the forms. Professional contractors make sure that the cement doesn’t freeze while setting up when building a foundation. Clean up the forms. Remember, you can save money by using the forms as part of the framing.