Installing spray foam underneath your concrete slab is an ideal method to make sure that your new home will be energy efficient for the entire time it’s in use! It’s required for a lot of new structures in building codes in order to protect the concrete from water damage.
To guarantee the foundation of your home isn’t a prime source for loss of energy, it is recommended to put in spray foam insulation before pouring concrete. By doing this, you protect the concrete from water ahelplps keep heat in the home as required under numerous modern construction codes.
At the time your reading is done you’ll understand the advantages of rigid insulation and the various material options, as well as the fundamentals of installing spray foam insulation.
Should You Put Spray Foam Under Your Concrete Slab?
Concrete may seem like a waterproof material however it’s extremely vulnerable to moisture and is terrible at holding heat. While many codes today recognize the value of concrete and demand it, it’s not mandated by all building codes. The application of spray foam insulation underneath the concrete is a crucial element in the construction process.
The use of the SPF (sprayable polyurethane foam) to insulate a foundation can be compared in price to rigid foam panels, however the labor costs are much less. Therefore applying sprayable foam underneath the concrete slab would be the most efficient option. The foam insulation is the ideal solution to cut down on heating expenses while safeguarding the structure of your house’s concrete slab. It’s a popular choice within green circles of construction due to the fact that it dramatically reduces energy use. It also does a fantastic job at keeping water from the slab, thus preventing fractures or structural harm!
At least 10 percent of the heat that enters the home – and therefore 10 percent of your energy cost escapes through the floor. Two inches of spray foam insulation is 40 times more efficient in capturing heat than concrete on its own. While spray foam can be a bit pricey it’s savings over time will far outweigh this cost.
The average house in America is spending around $1200 on heating every year. If you’re reducing the cost of heating to 10% it amounts to around $120 per year, which is thousands of dollars saved throughout the duration of your home’s lifespan. That makes it nice for resale value, too, especially considering the rising importance of environmentally-friendly lifestyles.
If you live in a region that experiences brutal winters – then spray foam insulation beneath your concrete slab is essential! Since you won’t experience the winter cold and thawing, it’s unlikely that your heating costs will significantly alter.
Spray foam is sprayed on the top of the gravel and covered with a vapor barrier. Reinforced concrete is laid directly on top.
Why not try it in reverse with concrete first?
Heat-wise, you might not feel any difference; however, you will notice that your foundation is likely to crack and fall apart over time because of water damage.
What kind of Insulation Is Best To Use Under Concrete?
It is imperative to use a 2-pound closed-cell SPF because any other sprayable foam wont be dense enough to support the slab.
Compressive strength – the weight that foam can support is a key determinant for under-grade insulation. The insulation installed under slabs must be able to meet strength standards, otherwise it will slowly fall apart when weighed down, damaging the foundation of the house. Compressive strength is determined in PSI and is the measurement of how much weight one square inch of insulation can support.
Because it is true that the burden of the concrete slab is evenly distributed over the entire foundation and the insulation does not have to be as durable as you’d like. ASTM standards require that you have a minimum for 10- PSI for spray foam insulation and 15 is the standard.
Foam insulation that is rated at 25 PSI will be more durable than the ground underneath it! Of course, you’re allowed to select foam insulation with higher compressive strength however, your expenses might increase unnecessary. It could be beneficial, however especially if you reside in an area that has wet or loose soil, or clay-rich areas.
Do you need a Vapor Barrier Under The Concrete Slab?
A vapor barrier is an important component of a sound slab foundation. Because soil water gets absorbed in the insulation over time so it is necessary to create barriers to keep it between foam as well as the concrete. In the past the 6-mi (6/1000″) barriers to vapor were fairly common, but they are no longer the norm. American Concrete Institute now states that vapor barriers should never be less than 10 meters (10/1000″) in thickness.
The polyethylene material isn’t waterproof and it’s not only how thick the barrier that’s important. It must be strong enough to block even tiny water droplets. It is essential that a vapor barrier has permeance (moisture permeance rate) of 0.3 perms, which means it is only 0.3 grain of water vapor will traverse the barrier.
If you’re in search of a vapor barrier that can effectively stop water in its tracks, you should look at vapor barrier products that are in compliance with ACI specifications. In the event that a particular product is marketed as”vapor retard “vapor retard” then it probably isn’t fully meeting the ACI requirements and should not be used for under-slab construction.
How to Insulate Concrete Slab Before Pouring
It’s not as straightforward as digging a hole and filling it in. But it is a rather easy process.
Before the concrete is poured, these steps must be taken to provide construction quality, code compliance, and structural integrity:
- Dig to the appropriate depth. This could vary from a few inches to several feet, depending on the kind of construction.
- Smooth and tamp the excavated soil. Rake out rough spots, and fill in low spots with dirt. Then, tamp the ground until it is soft and firm. This packs the soil down, delivering more strength.
- Spread a 4-inch layer of crushed stone/gravel over the dirt. Make sure it is raked smooth and level, with no jagged edges sticking up.
- Spray foam insulation across the whole surface of the foundation. Butt the boards together lightly. Ensure all the boards stay flat to ensure maximum efficiency. You’ll also need to spray a 4-inch tall section of foam about the perimeter of the foundation- enough to be level with the concrete after it is poured and set.
- Lay down the vapor barrier according to the manufacturer’s instructions. Make sure there is a 6-inch overlap on the edges per roll.
- Make sure everything is level and continuous, and now you’re ready to pour!
Best Under Slab Insulation
The best way to purchase under-slab insulation is directly from a supplier; home improvement stores will likely inflate prices. Below, you’ll find the best, most highly-recommended spray foam insulation distributor.
ArmorThane is a company with a far reach and a long history of supplying quality products. They have received numerous rewards in the industry and have perfect reviews. With locations in most countries, you can be sure they can supply you with what you need no matter where you are. If you drive past local residential construction sites, the odds are high that you’ll see ArmorFoam being used.
Conclusion
Spray foam under a concrete slab can be a bit complex but it is vital to a green home. Not to mention, sometimes it is necessary when building codes come into play. Using foam insulation under a slab drastically lowers your energy bill, complies with modern codes, and protects the life of the slab. So, did you learn what you needed for your project? Let us know in the comments section below! Still, have questions or suggestions for other readers?
