Everything You Need to Know About Slab Heating

Hello and thank you for joining this month's webinar entitled "Everything You Need to Know About Slab Heating." My name is Scott, and I'm from WarmlyYours. Joining me is Anatoly, who is also from WarmlyYours. We are so glad that you were able to join us today. If you have any questions at any time, feel free to click on the "Ask a Question" section at the bottom of your screen. We will be glad to answer any questions that come in. Now, let’s go ahead and get started.

In today's webinar, we will discuss slab heating uses, the different ways you can heat a slab, slab heating systems, and the steps necessary to install that heat, whether it’s on top of or inside the slab. While we will primarily focus on heating the inside of the slab today, we will also mention the various methods to heat a floor over a slab.

One of the significant benefits of having a heated slab is the thermal mass it creates. By heating the slab, you are effectively heating the foundation, allowing that heat to transfer and radiate into the entire room or even the whole house, depending on the amount of heat installed. This system minimizes heat loss, which is a considerable advantage over other heating sources. For instance, in a forced air system, heat rises from above, often leaving your feet cold, especially in spaces like basements. In contrast, with slab heating, your feet are the first to feel warmth, making it a superior choice in such environments.

Now, let’s consider a scenario where you already have a finished slab and wish to heat the floor above it. The key element here is to add a thermal break by insulating over your existing concrete slab. This insulation ensures that your floor heating system operates efficiently, allowing it to reach higher temperatures without attempting to heat the already finished slab. For instance, using a synthetic cork underlayment creates a thermal break that enhances the efficiency of the floor heating installed on top.

When heating a floor over an existing slab, you are typically heating a thin layer of material, usually less than an inch to an inch and a half thick. This allows for faster heating and quicker temperature adjustments compared to heating a concrete slab, which takes significantly longer. This method is particularly useful for those who are remodeling and working with an existing slab.

If you are building a new home or adding an extension, this is the ideal time to incorporate heating into the slab itself. When planning for slab heating, it’s essential to understand how the customer intends to use the system. For example, if the heating is only needed for short periods, it may be more practical to install heating on top of the slab. However, if you are pouring a new slab and wish to use polished or stamped concrete as the final flooring surface, slab heating products such as mats and cables are the best options. Our cables typically use about 5 watts per linear foot, while mats can provide up to 20 watts per square foot, making them durable and effective for these applications.

When working with a large concrete pour, such as in a basement, it’s crucial to locate any expansion joints. Heat should not be placed under these joints, so it’s essential to communicate their locations to your concrete installer. This ensures that the heating system is designed appropriately around these areas.

Returning to the topic of heating an existing slab, it’s important to clarify that insulation is necessary when heating a floor above a finished slab. However, if you intend to heat the slab itself, insulation should not be used, as it would block the heat from reaching the floor surface.

Let’s discuss the two types of slab heating systems: cables and mats. While both products serve the same purpose of heating, they are suited for different applications. Cables offer flexibility, allowing you to cover various shapes and areas, while mats are faster to install. If your project allows for 20 watts per square foot, using mats can significantly speed up the installation process, which is crucial when working against time constraints, such as waiting for a concrete truck.

Regarding installation, it’s essential to adhere to local building codes, particularly concerning the minimum concrete thickness and cover. Most codes require a slab thickness of at least four to six inches. The heating cables should be positioned in the middle of the slab, with at least an inch and a half of concrete above them, as specified by the National Electric Code.

As we move forward, it’s vital to ensure that the heating product is correctly positioned within the slab. This involves using proper supports to suspend the rebar or wire mesh, allowing the heating cables or mats to be placed at the correct depth. The goal is to have the heating elements situated two to three inches below the finished surface of the concrete.

When preparing for installation, it’s also important to mark the locations of any predetermined expansion joints. This will help prevent any damage to the heating cables during the concrete pouring process. Using spray paint to mark these locations on the walls will provide a reference point once the concrete is poured.

Now, let’s discuss the SmartPlan for a cable installation in a new construction bathroom. The SmartPlan, or installation plan, outlines the layout of the heating product and provides essential information for the electrician, including the type of breakers needed and the total wattage of the system. These plans are typically available within 24 hours and are invaluable for ensuring a successful installation.

Testing the heating system is crucial to ensure it is functioning correctly. A digital multimeter and a mega ohmmeter are essential tools for this process. Testing should be conducted upon arrival of the product, after securing it to the mesh, and after the final layer of concrete is poured. This helps identify any potential issues before the system is permanently installed.

To effectively control the heating system, a floor sensor must be installed at the same depth as the heating elements. This sensor allows for accurate temperature regulation, ensuring that the system operates efficiently. It’s important to use a capped conduit for the sensor, allowing for easy replacement if necessary.

Finally, once the concrete is poured and finished, the heating system will be ready for use. The thermostat connected to the floor sensor will maintain the desired temperature, providing a comfortable environment. It’s important to remember that the heating system does not add height to the slab, as it is integrated within it.

In conclusion, slab heating systems offer an effective and efficient way to heat spaces, particularly in areas like basements. With proper planning, installation, and control, these systems can provide lasting comfort and warmth. Thank you for joining us today, and we look forward to answering any further questions you may have.