For many years, engineered stone has been regarded as the go-to choice for benchtops, offering…
When it comes to your new home, you probably have lots of hopes and dreams about the number of bedrooms, kitchen layout, garage size, benchtops, and more. But you may not have thought too much about HVAC yet.
However, according to the Australian Energy Council, about 40% of homeowners’ energy bills stem from heating and cooling. New construction planning is the perfect time to think about how you are going to heat your home. You are starting from a clean slate, so you can choose something that is cost effective, energy efficient, and suitable to your heating needs.
Pivot Homes has been building in Geelong and Bellarine Peninsula since 1990, so we have watched trends in HVAC evolve over the years. Under slab heating is becoming more and more popular for Australian residents as an alternative to traditional systems. In this post, we want to show you why.
We’ll explain how under slab heating works, examine the benefits and drawbacks, and answer your most pressing questions about costs, types, installation methods and more.
What Is Under Slab Heating?
Under slab heating, also known as under floor heating, is exactly what the name implies: a means of heating your home from beneath the flooring.
In fact, in an under slab system, the flooring itself is heated in order to allow the warmth to radiate to the rest of the room. This process works whether you have tile, timber, laminate, carpet, or any other type of flooring.
Unlike traditional forced air or radiator systems, under slab heating doesn’t steal any of your floor space with vents or radiator units. There is no need to worry about optimal placement of heat output because the entire floor is heated.
Types of Under Slab Heating
To understand how underslab heating works, you need to get to know the two types of systems on the market: electric and hydronic.
In this section, we’ll explain how these systems differ in order to help you decide which one is right for your new home build.
Hydronic Under Slab Heating
Hydronic systems rely on hot water to heat your home. They can be thought of as radiators that are buried beneath your floor.
Hot water flows from your boiler through a long series of polyethylene pipes that are installed in your subfloor in a pattern that provides optimal heat distribution. As the hot water travels through these pipes, the heat is passed to the flooring and radiates up into the room above.
Hydronic systems aren’t zoned. When turned on, they will heat every room where your underfloor heating is installed. Furthermore, they require a good amount of time to fully heat the home—sometimes as much as two days.
For this reason, hydronic systems are generally turned on at the beginning of the cold season and left on until fall. Most residents in the Geelong and Bellarine Peninsula areas can turn their heating on when the winter begins and leave it set to around 21 degrees straight through till the middle of September.
Although it might sound like a drawback, the benefit is that once the system is engaged, it requires much less energy to maintain the temperature. So, if you live in an area with a predictable cold season, hydronic systems can be very energy efficient. The trick is to not turn them off mid-winter because then you will need to go through the process of heating up the home again.
Electric Under Slab Heating
While electric under slab heating has the same effect as a hydronic system, the method is a little different. Instead of pipes, the flooring is heated by a network of wires. Therefore, there is no water used in the system and no need for a boiler or pump. This means that electric systems are much less likely to require maintenance or repair.
Electric systems are generally zoned, allowing you to turn the heat on in a single room at a time. You could, for example, warm up your living room on a chilly winter morning without having to heat the entire house. Furthermore, electric systems function much more quickly than hydronic ones, coming to temp in a matter of hours rather than days.
However, this added convenience does come at an additional cost. Electric systems aren’t as energy efficient hydronic ones. If you were to heat all of the rooms in two similar homes, throughout the entire winter, an electric system would use more energy and cost more.
How To Choose The Right Type For You
We work with The Heat Shop Geelong for all of our under slab heat installations on new home builds, and they are professionals in both types: hydronic and electric. During the home design process, we will work with you to find the best solution for your needs. But this quick summary might help you decide:
Choose electric under slab heating if…
- You want the convenience of heating different rooms in different ways.
- You don’t need to run the heat all winter long.
- You don’t want to deal with boiler maintenance.
- You don’t mind a higher energy bill.
Choose hydronic under slab heating if…
- You want the lowest possible energy consumption.
- You are looking to reduce your heating bill.
- You generally use heat all winter long.
- You don’t need zoned heating.
In addition to the type of heating, you have three different methods of installation to choose from: in-slab, in-screed, and under-tile.
Slab is the thick layer of concrete that forms the foundation of your home. With this installation method, your pipes or wires are installed directly into the slab. The concrete is literally poured over them.
Obviously, this type of installation can only be done at the time of construction. The advantage, though, is that it is the most cost effective of the three methods.
Because in-slab heating needs to warm up the entire slab, it can take longer to raise the temperature. Therefore, in-slab installation may be better for hydronic systems, though it is still a viable option for electric.
Screed is a thin layer of flooring very similar in properties to concrete that is poured on top of your home’s slab. Often, screed is meant to level out uneven concrete, or even to be used as flooring itself. When it comes to underfloor heating, though, screed houses the pipes or wires that heat the floor.
In-screed heating is best suited for bathrooms because it works especially well with tile, stone, and travertine. However, it is suited for almost any flooring or room. This method is particularly energy efficient if a layer of insulation is installed between the slab and the screed. More heat will make it to the flooring and less is lost beneath the screed.
With under-tile heating, the wires are installed directly beneath the tile, not in the screed. Because there is less material between the heating and the floor, rooms will heat up especially quickly. Therefore, this method is ideal for electric systems in which you may be switching the heat on and off regularly. In fact, under-tile heating isn’t typically available for hydronic systems.
Under-tile heating is often used for renovations or retrofits because it can be managed even though the slab and screed have already been poured—and because it does not raise the floor height by much. However, it is still a perfectly viable option for new builds as well.
Benefits of Under Slab Heating
Heating your home from under the floor seems like such a wild switch from the norm. So why do people do it? Here are the main advantages of under slab heating versus traditional systems:
With forced air or radiator systems, each room tends to have a single place where heat is output—sometimes two. You are probably familiar with the uncomfortable warm or cold spots that this can create from one room to the next.
An under slab heating system, on the other hand, radiates heat throughout the entire floor. Every inch of the room will receive the same amount of heating, so you will never suffer with uneven temperatures.
Remember coming down from bed on a chilly morning as a child and huddling around the heating vent? That warm and toasty feeling on your toes?
Under floor heat captures the essence of those memories without forcing you into a single corner of the room. There’s just nothing quite like radiant warmth of heated floors on cold feet in the morning.
Underfloor heating, in general, uses less energy than older types of heating systems. Results vary based on the installation options and type—as well as other factors in your home—but most owners can expect about 15% lower energy bills than other heat choices.
Improved Air Quality
Forced air systems can be problematic if anyone in your home suffers from allergies. As they circulate air through vents and into rooms, they kick up all manner of dust and allergens. Whenever the air is flowing, these allergens are flowing with it.
Because under slab heating relies on radiant heat, it isn’t going to cause the same problems. The heat rises from the floor without moving the air.
One of the biggest downsides of other heating methods is working around the vents or radiators. Traditional systems steal a few square feet from every room of the house.
It might not seem like much, but you probably don’t realise how big of an influence vents and radiators have on how you arrange couches, shelves, desks, and other furniture. Underfloor heating opens a whole new world of possibilities when it comes to maximising your square footage.
Although the concept of underfloor heat seems complex, the actual components that make up your system are quite simple. So when it is properly installed, your under slab heating system requires virtually no additional maintenance.
However, hydronic underfloor heating (see the next section) does rely on a boiler, so this will require the typical upkeep and maintenance that is to be expected.
Disadvantages of Under Slab Heating
There are plenty of ways to heat your home, and most of them are perfectly fine choices under different conditions. Under slab heating might not be for everyone, and here are some of the drawbacks to consider as you look for the best heating solution for your new home.
Complicated To Retrofit
Adding underfloor heating to an existing home is certainly possible, but it can present a lot of complications. For example, floors will need to be pulled up, and you won’t have the option of in-slab installation because the concrete has already been poured. Typically, the floor will be raised a bit, so your room height will decrease.
We know this guide is meant for new construction, but these potential future complications are important to consider. Basically, if you want underfloor heating, choose it now—at the time of construction. The worst decision would be to choose another type of heating and plan on adding under slab later down the road.
Fitting an entire home with under slab heating can cost more than double a forced air system. However, by installing during a new home build, you will save significantly. You won’t incur the added labor and material costs involved in pulling up and laying flooring (and sometimes walls as well).
However, the operation cost of radiant underfloor heating is so much lower that over the years you will recoup the costs. Furthermore, underfloor heating is significantly easier to maintain, so you can expect to pay less in repairs and maintenance over time.
Works Better With Some Flooring Than Others
As we will explain in detail later, under slab heating works well with any flooring. However, certain floors provide better energy efficiency than others. Tile and stone conduct heat well, so they work best. This is why many homeowners choose underfloor heating for their bathrooms especially.
Timber, vinyl, laminate, and carpet aren’t as quick to conduct heat, nor do they hold it as long. So they will still work with under slab heating, it’s just going to take a little more energy and time to get them to come to the proper temperature.
How Much Does Underfloor Heating Cost?
According to HiPages, the national average installation cost for under slab heating in Australia ranges from $33 to $105 per square metre. Depending on type and installation method, the numbers are a little more specific:
Electric Under Slab Heating Costs:
- In-slab: $40 per square metre
- In-screed: $115 per square metre
- Under-tile: $70 per square metre
Hydronic Under Slab Heating Costs:
- In-slab: $70 per square metre
- In-screed: $105 per square metre
- Under-tile: Not available for hydronic systems.
In general, the cost of installation for under slab heating is higher than other systems. However, you need to consider the energy efficiency of running the systems, as well as your specific pattern of heating, in order to decide which will be most cost effective for your home.
How Does Under Slab Heating Work With Different Types of Flooring?
Rest assured that under slab heating won’t limit your flooring options. It works well with all types of floors—just better with some than others. Here are the most important things to keep in mind for different floors:
When choosing timber flooring, you want to consider two factors: thickness and density. Since wood doesn’t hold heat well, thinner woods are preferred. You also want a dense timber because they are more conductive. Choosing the right wood is also important to prevent warping that could result from moisture releasing.
Engineered timber will perform similarly to sold timber. The main difference is that you don’t have to worry about moisture as much. However, engineered wood doesn’t hold heat quite as efficiently as solid.
Tile is the ideal flooring for under slab heating. Ceramic, porcelain, and stone all hold heat very well so they are quite energy efficient. Although thicker tile will take longer to heat up, the thickness doesn’t actually affect the transfer of heat once the tiles are warmed.
Carpets can work well as long as you choose one with a TOG (thermal overall grade) under 2.5. TOG is a measure of how much a material resists thermal energy. If the carpet’s TOG value is too high, it will basically act as an insulator instead of a conductor. The good news is that we can help you choose a carpet that works with your heating system perfectly fine.
Because it is constructed of PVC, vinyl flooring is more reactive to changing temperatures. This doesn’t pose an obstacle to underfloor heating, it just means that vinyl plank is best adhered with a hard-set glue. Nothing you need to worry about, but certainly an element we take into mind during construction.
Laminate works pretty well with under slab heating. It stands up better to temperature and moisture than timber, and even conducts heat better than wood because it tends to be both thinner and denser.
Can Hydronic Underfloor Heating Leak?
With any system in your home that relies on water, leaking is always a reasonable concern. The good news is that the tubing used for hydronic under slab heating is specifically designed to stand up to long term use.
Leaks are exceptionally rare. Typically, they result from uneven flooring placing too much stress on the system. This is mostly a concern with retrofits, renovations, and do-it-yourself jobs. When you get a professional installation during new home construction, you won’t have to worry about bad floor jobs and the resultant leaking.
Pivot Homes Can Help You Find The Best Under Slab Heating For Your New Home
As you can see, under slab heating is an ideal choice for many reasons. But there are a lot of decisions to make…
- Electric or hydronic?
- In-slab, in-screed, or under-tile?
- Will it meet your home heating needs?
- Is it the best choice for you?
If you have questions like these still running through your head, don’t hesitate to let Pivot Homes offer our professional advice. We aren’t trying to push one heating choice on you over another. We just want to help you build the new home of your dreams.
Reach out today to learn how Pivot Homes can help.