Custom Homes and Renovations

Concrete is one of the most economical, versatile and durable building materials available.  They are used to support everything from patio furniture, to foot traffic, to vehicles in your car garage.  Proper attention to the standard practices and procedures for constructing exterior or interior concrete slabs for your custom home or home remodel can yield long-lasting concrete surface.

A slab pour requires efficient planning so that all of the elements that go into producing a high-quality slab are done in time (before the concrete sets) and done correctly. Knowing the right finishing tools to use and the right time to start bull floating and final troweling are essential to preventing dusting, scaling and craze cracking of the slab.

Here are a few tips that you need to know before you build and pour a concrete slab:

1. Remove all vegetation, soft soils, and rocks so that support for the slab is uniform. Be sure to excavate a few inches below the thickness of the slab. Neglecting this critical step can result in serious slab settlement and cracking problems, especially in slabs placed on poor subsoil or exposed to heavy traffic conditions.
    
2. Set forms so that the concrete slab surface slopes a minimum of 2% (20 mm per m, or 1/4 in. per ft) to provide adequate drainage.
    
3. Once you have a solid base to work, the next step is reinforcement. This can be done a few different ways either with rebar or welded wire mesh; the purpose of reinforcement is to minimize cracking. Whether you decide to use 2×4 material or a bender board for forms make sure stakes wood/steel are placed close enough together so when the concrete is placed it does not collapse. When building forms over 6 inches kicker boards may be necessary. Kicker boards are simply braces to secure forms in place and are braced to another stake 12 to 16 inches away. This ensures that forms stay firm and in place. Be sure to keep stakes out of the way either hammer all the way down or as far as they will go then cut them off flush with form material. Proper positioning and support of wire reinforcement is also important to control and minimize cracking.
    
4. Depending on the size of the slab or walkway you may need to consider ordering concrete and having it delivered to the jobsite. Most custom homes required at least two trucks of concrete. Keep in mind concrete companies have a minimum usually 2 yards and additional fees may apply if you don’t surpass the minimum. When ordering concrete you may need to ask them to set up a pump to go with the truck depending on slab location.
    
5. When pouring concrete from the truck, as shown in the video, never allow wet concrete to saturate clothing, enter boots, or to stay in contact with the skin. It will burn you.
    
6. Strike off the surface while keeping a small amount of concrete in front of the straightedge to fill in low spots. This helps to prevent birdbaths in the finished surface.
    
7. Use a screed board to set a rough height, its best to use a screed board in a sawing motion to move concrete.  Depending on the size of your project you may need a bull float before the concrete begins to bleed otherwise a mag float is acceptable for smaller projects like walkways, and patios.
    
8. After concrete placement, you have a whole new set of issues to address, such as proper placement and spacing of control joints and adequate curing. The timing and execution of these post-pour activities are equally essential to good slab performance, since rapid drying of a slab and improper installation of control joints can lead to inadequate strength and unwanted cracking.
    
9. Do not perform any finishing operation while bleed water is present on the surface. Do not dust dry cement on the surface to soak up bleed water.
    
10. Control Joints: Those grooves in the concrete have a purpose, control joints minimize cracking they also limit cracks that may form later. The idea here is that if the concrete has the chance to crack it will crack along the control joint. There are a couple of ways to make a control joint by either using a groove tool or cut them in after the concrete has cured for a day or two. Control joints should be no more than 7ft on slabs. If you plan to cut the control joints with a concrete saw snap all the lines first then using a clear spray paint over the chalk lines doing this will ensure the lines stays when water is applied during cutting.
     
11. Depending on the weather it may be necessary to cover the concrete with 6 mil plastic, or apply a concrete cure both of these methods work well for slowing down the cure time.  In addition, Water in the concrete can freeze causing the top to pop. Check the temperature before scheduling your pour.

To learn more about home building and construction, visit us at buildwithgbgroup.com.