We have our forms set and we’re ready to prepare for the pour.

Let’s look at different views on the gravel or sand underlayment. The old time way of placing gravel was done after plumbing, which is the more proper way. Many contractors will put the gravel in after they pin the corners, and even before the ditches are dug. The reasoning is simple, it’s a lot easier to place gravel on a piece of ground before you have forms set and ditches dug, and it takes less time. Usually, the plumbing is not in at this point either, making it harder on the plumbing contractor. He not only has to dig his ditches, but he has to roll the gravel out of the way first, and then put it back, too.

Another way that is a hybrid of the first procedure is to dig the footings, put the plumbing in by measuring off the string lines for the slab, and then add the gravel. This is some better than the first way, but the gravel gets shifted around some during the form setting, and it has to be rechecked before the pour anyway. Also, the plumber is a lot more likely to miss on his layout trying to pull measurements from a string rather than a form board.

The oldest way and, to my way of thinking, the best way is to dig all ditches and set all the forms except for a section large enough to get inside with a backhoe or bobcat. The plumber can dig and place his piping and can pull strings to make sure his floor flanges are at the right height. He can compact his backfill and feel pretty good about all his dimensions.

After the plumbing and any other trades are finished laying their work, bring in the gravel or sand. Some contractors prefer to stay with gravel, but there are several substitutes that work better. Sand is good because it is easy to move and can be graded more accurately. A couple of other materials are available in some areas that are cheaper than gravel and sand. This is dependent upon where you live, but if there is a quarry near you, there are some byproducts left from making the gravels that can be used. These are basically materials that are too small to be classified as stone or gravel, and the materials spread well and stay in place. These materials go by several names, so you just need to ask the truckers that haul materials to find out what is available.

After the underlayment is in and the termite treatment is down, you place the poly and then the steel. If you are using wire, that will go in last.

I suggest checking the grades on the top of the forms just before the pour. It is best done with a laser level, allowing one person to do the checking. If there is much variation (more than 1/4”) adjust all the forms to the lowest place. This can be done carefully with a sledge hammer by bumping down on the stakes. Check for square and dimensions one more time.

Pouring concrete is best started early on a house slab to give finishers plenty of time to get a good finish. The preparations with termite treatment, poly, steel, and wire are best done close to the time of the pour. Nothing is much worse than getting your prep done and then having a torrential downpour right after. You end up pulling steel, wire, and poly out so you can clean out the ditches from the washes. If you have possible rain in the forecast, it’s better to wait about the prep work until the morning of the pour.

You should always put your name in the hat a day earlier to get concrete on the day you need it. Do this before you prep the slab because concrete companies sometimes get booked up and won’t be able to delivery the day you want. Tell the plant you want to be on “will call” for a certain time, and then you don’t run the risk of having concrete show up before you are ready for it. Of course, you will have to call the day of the pour to give the the go ahead or cancel the pour.

Have anchor bolts ready to place along the perimeter walls after the concrete is poured. When you pour a monolithic slab, you have the advantage of marking the forms where you have exterior doors so you don’t put an anchor bolt in the middle of a door (and, believe me, it will happen). If you really want to get the anchors in the right places, you can layout your stud framing on the forms so that every bolt should not be under a framing stud, tee, or corner.

We’ll talk more on concrete work later.

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