10 things every estimator needs to know about concrete

Working as an estimator means learning about construction methods and materials, figuring out how to calculate different types of construction, and probably a binder full of cheat sheets and formulas.

Even if you use the best construction estimating software, you still need to know what goes into every item and assembly so that you can calculate an accurate price. In this article, we’re going to look at some of the things that can affect the cost of concrete and how you can factor it all into your quotes and calculations.

1. Site Access Affects Concrete Pouring Options

You might think that all you need to do to calculate the cost of your concrete for a particular job is work out the volume and get a quote from the closest ready-mix supplier. However, it’s always a good idea to visit the site to see exactly where you will be pouring concrete.

Sometimes, it’s not possible for ready-mix trucks to get close enough to use the chute to pour concrete, so you might need to use a pump or, if all else fails, use wheelbarrows to move concrete where it’s needed.

All of these things can affect your labour costs, which will change the price you quote your customer. So always ensure you know what site access is like before you quote any concrete work!

2. Concrete Shrinks As It Cures

You probably already know that concrete drying and curing are two different processes. Concrete will dry pretty quickly, but curing and hardening is an ongoing chemical process that continues for weeks or even months.

During the drying and curing process, concrete will shrink a little, so it’s always a good idea to build a little waste into your concrete calculations, whether you use construction estimating software to create quotes or do your calculations manually. Five to ten percent should be more than enough to cover shrinkage and any waste on site.

3. Ready-Mix Suppliers Will Charge Standing Time

If you’re not used to quoting jobs that include concrete, you might be a little confused at how ready-mix companies quote for your project. Their quote will usually include the cost of the concrete as well as a rate for standing time.

This is the time that the concrete truck spends on your site, whether they are placing concrete or not. So if you schedule concrete too early, and the truck has to wait around before it can pour concrete, you could pay hundreds of dollars extra for that pour.

Always ensure you don’t order concrete until you’re absolutely ready for it, and make sure that your client also has your standing time rates, so you can recoup the costs if something does go wrong.

4. Concrete Requires Special PPE

Concrete is a very alkaline substance, which means that just like acid, it is capable of giving people very serious burns if their bare skin comes into contact with it.

Whenever you quote any project that includes concrete work, you will need to include special PPE that could include rubber boots for foot protection, gloves, goggles and more.

Workers who work directly with concrete should also have safety training so that they know how to work with concrete safely, and all of these costs should be built into your labor rates in your construction estimating software.

5. When It’s Cold, You Might Need to Pay for Heating and Hoarding

Concrete needs water in order to dry and harden properly. It needs to stay moist during the curing process so that it can reach the desired compressive strength.

Of course, when the weather gets cold, the water in your concrete could freeze before this process is completed, which will mean that the concrete will never reach the desired strength. This is a chemical process that can’t be restarted once it’s been interrupted. So if your concrete freezes before it cures, it will need to be repoured.

One way around this is to heat and hoard the concrete, which means covering it and providing a heat source that will prevent it from freezing. How this is done depends on where the concrete is installed, but it can be very costly, so if you’re planning to pour concrete in the winter, build these costs into your construction estimating software!

6. Sugar and Water Quality Can Affect Concrete

As we’ve already mentioned, the process of concrete drying and curing is a chemical one. The cement, sand and stone, combined with water in the right proportions, will trigger an “exothermic” reaction that creates heat, and that heat is part of the hardening process.

However, like all chemical reactions, you have to get the mixture just right.

All kinds of ordinary chemicals will affect how concrete dries and hardens. Sugar, for example, can slow down or even prevent concrete from hardening, depending on how much is added. Hard and soft water can also have a different effect on how concrete dries and hardens and whether it meets the required compressive strength.

If you are not sure that you can control all these chemical factors enough to mix your own concrete on site and reach the required specification, you should rather choose to build the cost of ready-mix into your construction estimating software.

7. Bubbles Are Not Your Friend!

If you’re not used to working with concrete, then you might not know about bubbles or voids that can form in concrete when it’s poured and placed.

These voids weaken the concrete, which means that even if the concrete mixture is correct, the finished product may fail because there’s too much air trapped in the concrete when it dries.

There are various types of poker and vibrating equipment that are used to remove bubbles that are trapped in wet concrete. So make sure you research what is required for the type of concrete you are pouring and include both the equipment and extra labor costs in your construction estimating software or calculations.

8. Concrete Is REALLY Heavy!

Working with concrete is not always about pouring new slabs, beams or walls. Often, you need to demolish and remove concrete from a site too. In this case, you will probably need to include the cost to remove it from site in your quotation, and that means transport to an approved dump site. Concrete weighs about 4,000lbs per cubic yard, or if you work in metric, a cubic meter of concrete weighs about 2.4 metric tons.

Broken up, concrete will also take up more volume, so even if you can fit it all in a dumpster or on a truck based on weight, you won’t be able to fit the demolished concrete volume in one load.

If you’re quoting for concrete demolition, make sure you factor the high cost of removing heavy concrete from your job sites into your calculations and build it into the rates in your construction estimating software.

9. Don’t Forget Finishing!

In most cases, placing or pouring concrete is only part of the job. You will also have to build the cost of finishing concrete into your quote and into your construction estimating software.

There are a wide variety of concrete finishes too. Some concrete is stamped, some has a float finish, and some has a broom finish, among others. You will need to know what kind of finish is required so that you can build the cost of equipment and labor into your estimate.

10. Concrete Testing Is Expensive!

The final tip we have for estimators when they are calculating concrete costs as part of their quotes is to remember that concrete testing is expensive.

Often, architects, engineers or building inspectors will require you to provide slump tests, cube tests and other concrete tests to prove that the concrete you’ve provided meets or exceeds their specifications. Always ask if this is required before you submit a quote, and if it is, find out what local concrete testing

companies charge. You will usually have to have these tests done on every pour, so make sure you factor it into every truckload of concrete you will receive.

You Don’t Have to Reinvent the Wheel for Every Quote

If you’re still working out your quotes manually or using spreadsheets, you probably have to refer to all those binders and material data sheets every time you have to do a quote that contains something out of the ordinary. It’s one of the things that makes manual estimating so time-consuming. It’s also a common cause of errors because you have to remember all these little things every time you do a quote.

Modern construction estimating software like Bolster is designed to ensure that you don’t have to reinvent the wheel every time you do a quote. You can research materials and labor costs associated with various applications of those materials and build custom assemblies based on that information.

That means that when you need to quote a similar project again, you have all the information you need built into your construction estimating software. Bolster even takes it one step further, thanks to a clever web crawler that always captures the latest pricing from all your suppliers.

Don’t waste time creating every new quote from the ground up. Contact Bolster and find out how our innovative, one-of-a-kind estimating platform makes quoting easier, faster and more accurate.