Types of Rebar Support and Rebar Chair Spacing

Rebar Support Are Manufactured From Different Materials and for Multiple Uses

Rebar Chair spacer
Plastic rebar spacer. Photo J Rodriguez

 

erIn order for rebar to be effective in the concrete, it must be spaced and have the right concrete cover following specified information on drawings and building codes. Many builders can face challenges due to inaccurate spacing or rebar not meeting the necessary cover, affecting thus the concrete overall performance. There are many choices available in the market for you to use as rebar chairs but all of them will depend on the type of surface underneath the concrete or the type of concrete formwork being used.

Let's go over some details and let's see some of the available solutions.

Types of Rebar Chairs

The most common type of chair is the one that will raise you rebar off the ground, providing the right concrete cover. These chairs, are usually on foundation work, like slabs and cast-in-place concrete slabs. They provide stability and they are lightweight, economical and easy to install. Normally, they are made of plastic or non-corrosive material.

Another great product is the spacer wheels, used on columns, walls, beams, pre-cast formwork and round formwork. These chair spacer can provide a double fastener method that could work from wire mesh and rebar maintaining then at the center of the spacer, eliminating the possibility of tipping over. The lateral spacer is strong and light with minimal surface contact, and it is available for different rebar sizes.

Multi-Level or Multi Chair Type

If you are working on mats or any other configuration that requires you to have multiple layers of steel, this is the right chair for you.

The multi-level chair can be placed in multiple heights allowing you to install, a bottom layer, intermediate layer and then a top layer, maintaining spacing between all rebar layers. The normally provide great stability and allow a proper concrete flow in between the spacers. This solution can save time and money and will reduce the amount of special rebar-made configurations to locate your rebar accordingly.

It will definitely save you time and money.

Tip or Round Cap Rebar Spacer

This is a great product used when your rebar needs to be installed vertically and you need some bottom or top concrete cover. The cap is installed at the end of the rebar with a thin but prolonged tip that will be used as support to the rebar, allowing it to be installed at the exact height. The tip is also designed to give you better concrete flow, to prevent breakouts.

Additional Rebar Chair Variations

Since the concrete industry is changing so much, there are many alternatives suited to meet your demands. Now you can get flat bottom chairs, that will prevent the chair tips from punctuating the vapor barrier and providing a more stable surface.

There are also steel chairs with plastic tips, normally more economical, and they can be used when little spots of corrosion can be spotted on the surface. Stainless steel chairs are also available, but these ones will cost more than traditional ones, and when plastic is not allowed into the concrete or when the weight is too much for the plastic chairs.

Rebar Chair Problems

These products are not 100% effective or they are as effective as long as you know how to handle and work with them.

Sometimes, chairs will be tipped over, when required cover is over 2.5 inches, as the height to width ratio might not be enough, to allow workers from walking over. Also sometimes, when they are too far apart, the rebar will bend in the middle due to its weight, and some areas will need additional chairs or the chairs can actually break due to excessive weight. Some steel chairs with a plastic tip might loose the plastic protection during the installation process, creating a potential area on which rust can start damaging your concrete surface.

Rebar Chair Cost

The type of chair will essentially determine how much it will cost. A box with 100 chairs costs about $60 and a 50-pack is around $30 or $35 per box. Other complex systems can cost over $15 per each chair but they are more durable and will not tip over.

There are multiple combination and boxes that can provide over 500 units, so the more you buy the better price you will get. Remember the installation cost is minimum and will eventually help you get the right concrete cover.