Best Practices for a Residential Concrete Pour: Part 1
"In this series, we’ll cover some basic best practices for residential concrete projects. Much of this information is specific to pouring residential slabs (flat work), but we hope this overview will help eliminate your apprehension and raise your chances of success—for any type of concrete pour."
In this series, we’re collaborating with Francis Rzegocki from Excel General Contractor. Prior to joining Excel, Francis had extensive experience working in the concrete industry with both heavy civil and residential projects. In addition to his construction industry experience, Francis holds a mechanical engineering degree from Worcester Polytechnic Institute in Worcester, Mass.
Prior to entering the concrete construction trades, Francis told me he was actually nervous about the idea of taking on a concrete pour. But he decided to embrace that fear and go learn everything he could about the craft, turning it into a strength for when he returned to the remodeling business.
In this series, Francis will cover some basic best practices for residential concrete projects. Much of this information is specific to pouring residential slabs (also known as flat work), but we hope this overview will help eliminate your apprehension and raise your chances of success—for any type of concrete pour.
Site prep and form work
A good concrete pour depends on setting up the proper foundation. If you have adequate room around the perimeter of your project, your form material will most likely be two-by-four or two-by-six lumber. When replacing existing sidewalks, though, you might choose one-by-four lumber to minimize the amount of lawn you need to remove before setting your forms. If you choose one-by-four lumber, more support stakes will be required. Form stakes can be made from wood—typically one-by-two material—or they can be round and made of steel. Steel stakes are more of an investment, but they’re worth it if you’re planning on doing more concrete work in the future.
For projects with a more decorative (curvy) nature, cedar bender board can be a nice form option. If you go this route, you’ll need even more support stakes—the round, steel variety tends to work best.
Depending on your project, you may need to consider adding some slope to your flat work. For the inside of a home or a detached shop space, your target is a level finished surface. For garages and patios, the rule of thumb is 1/4" of slope per foot. This works out to a slope of just over 2 percent.
Reinforcement methods typically take one of two forms: steel rebar or steel reinforcing mesh. Rebar may be preferable if you're tying into an existing piece of flat work. Both options can be supported by a rebar or mesh “chair”—a manufactured product designed to keep your reinforcing steel up off the ground while pouring your concrete. You can also use rocks or other primitive methods, just be sure not to use wood or anything else that will decompose over time. The key is to locate your reinforcing steel in the bottom third of your flat work, as this is the part of the slab that will take the most stress when weight is applied to the surface. Make sure to keep your reinforcing materials 3” back from any exposed concrete surface (the tops and edges of slabs, walls, footings, etc.)
Lastly, including a vapor barrier underneath your interior flat work projects will serve you well. Typically, 6-mil polyethylene sheeting is used for this purpose. Adding rigid insulation underneath slabs in homes, garages, and outbuildings is also a good idea. Both vapor barriers and insulation may be required by code in certain scenarios, so make sure to research your local requirements.
Tools of the trade
Like any construction job, a concrete project requires tools. Some of these are very common, while others are more specialized. The list below outlines most of the tools you’ll need for your concrete pour, but keep in mind that your needs might change depending on your specific job.
- Circular saw
- Tape measure and marking tool
- Screw gun and screws
- Hammer
- Stakes
- Form lumber and panels
- Mason's line
- Reinforcing steel, tie wire
- Rebar “stands”
- Leveling tools
- Shovels and rakes
- Concrete placer tool
- Wheelbarrow
- Garden hose and spray nozzle
- 1/2” edger
- 1/2” relief joint tool
- Magnesium floats
- Bull float
- Trowels
- Knee boards
- Broom finish tool (if needed)
Labor
We covered a lot of details above, but there’s one main missing piece: How do you estimate the number of people to complete your project on the day of the pour? Every job is unique, but a residential project will usually require between two to four people. The skill levels of the workers factor into this, especially when it comes to finishing. As a rule of thumb, a well-conditioned finisher should be able to trowel 600 square feet per day. But there are many other things that need to get done before and after the finishing component, so you should always plan on a minimum of two people dedicated to the project on the day of the pour.
Tips and tricks
We’ve all heard the phrase “experience is the best teacher.” I would suggest modifying that to “other people’s experience is the best teacher.” With that in mind, here are a few tips:
- Consider using screws (rather than duplex nails) to connect your form materials. This allows you to adjust or remove form materials without disturbing previously placed concrete.
- Don’t drive your screws from the inside (concrete side) of the form boards. (You will only make this mistake once.)
- When doing flat work, smooth out your sub-grade, as variations in the thickness of the slab can cause unwanted cracks.
- Since stakes are often hard to retrieve after pouring a footing, consider using wood stakes—they're less expensive than steel stakes so if you can't remove them, it's not as big of a loss.
- Set trench drains in concrete the day before to keep them from moving (floating) during the main pour.
- Apply any type of release agent to your form material before you set your forms. You don’t want to get it on the reinforcing steel. This is a big no-no and would likely require redoing your form work.
Hopefully this information has helped increase your knowledge and confidence for the next time you choose to tackle a concrete project. Stay tuned for part two of this series, where we’ll talk about best practices for ordering your concrete. For more information on residential building, check out our posts on installing clapboard siding, installing LVL beams, and repairing window trim.
