November 8, 2022

“Encapsulation” can be a catch-all term for all types of work in a crawlspace. But all work in crawlspaces is not the same! Specifically, Encapsulated and Conditioned Crawlspace are very different things. In this blog, we’ll discuss the difference between an Encapsulated and a Conditioned Crawlspace and why one might be a better option than the other, given the circumstances.

Let's start with Encapsulations!

On its face, an Encapsulated Crawl Space is just a way to control Relative Humidity. But in order to do this job correctly and effectively, it’s got to be installed the right way. If it’s not, you could wind up exacerbating your moisture problems and dramatically increasing your utility bills. 

Controlling the Moisture:

First things first; a continuous vapor barrier must be laid over the dirt floor, with its seams overlapped and taped together. The Vapor Barrier must be fastened and properly sealed to the foundation walls and any interior pillars throughout the crawlspace. Basically, if you want to go in and find dirt, you’ll need to bring a knife and cut through the plastic.  

After your plastic is down, Air Seal!  Any and all gaps, cracks, or voids that connect the crawlspace with the exterior need to be diligently sealed. That includes all the old vents, holes in the foundation wall, and the entire perimeter of the Sill-Plate, Rim-Joist, and Sub-Floor connections. After that, all holes in the floor of your home or the ceiling of your crawlspace must be sealed. If you have insulation in the floor, follow the water lines, electric wires, and any HVAC equipment.  Don’t forget cut-outs in the subfloor for your tub traps!

“Sealing” an Encapsulation is a critical element of the work to ensure you don’t wind up increasing your utility bills, which actually happens a lot. Warm and damp exterior air does everything it can to get into your cool and dry crawlspace. Vapor moves through unsealed areas mentioned above and can even create condensation issues around the perimeter of the crawlspace. Even if the vapor doesn’t condense, it always increases the run-time on your dehumidifier. You must eliminate the source of your problem through air-sealing or your dehumidifier will continue to pull vapor from the exterior in, constantly removing it from the space while simultaneously replacing it with new vapor.  Longer run times on the dehumidifier mean higher utility bills and a shorter life span of your equipment. Here’s a tip: If you hear your dehumidifier running in the winter, you’ve probably got a problem!


Every Encapsulation needs a dehumidifier. While the make and model of the dehumidifier may vary based on the square feet, volume, and layout of your space, you’re going to need this piece of equipment.  In almost all situations, a commercial-grade dehumidifier is going to be your best bet. FLC Energy uses the Santa-Fe Compact 70 or AprilAire E070 in our Encapsulations and Conditioned Crawl Spaces. The dehumidifier is necessary in these applications because even though you’ve sealed this space off from the exterior, nothing is ever perfect. Materials expand and contract with seasons and building materials are not vapor barriers. Wood and Concrete are porous and moisture will move through them into your Encapsulated space. The dehumidifier needs to be there to remove this and maintain a relative humidity level under 60%.  FLC Energy aims for our Crawl Spaces to sit around 55% Relative Humidity in most situations. Those with more severe allergies may want to consider keeping their spaces in the 45% or lower range.

Always have your dehumidifier installed on its own 15 Amp GFI Circuit. Having a GFCI circuit or a Blank-Face GFCI outlet in an accessible space will allow you to reset power to the unit in the event of a catastrophic water event in the crawlspace or even your basement. If your crawlspace were to flood for some reason, it’s imperative you DO NOT ENTER the space.  Entering a body of water with a power source will result in electrocution and death. No piece of equipment is more important than your’s or anyone else’s life.  


There are a lot of companies out there claiming that Encapsulated Crawl Spaces don’t need to be insulated so long as they have a dehumidifier. This is wrong. In an encapsulation, the Framed Floor or Ceiling of the Crawlspace must be insulated. The specific R-Value needs for your space will be dependent on your location and Climate Zone, but it will likely be between R-19 and R-30. 

In most cases, FLC Energy recommends removing and replacing the old insulation during the Encapsulation process.  Removing the old material allows for a deeper inspection of the space; making it easier to find mold problems, structural concerns, and air-sealing opportunities. It also creates a much better indoor air quality for the crawlspace and the home. Old and existing insulation has usually been saturated over the years and often has animal feces scattered throughout it. This is not the type of air you want to be breathing in your home every day. 

So What's a Conditioned Crawlspace?

Unlike an Encapsulation, a Conditioned Crawlspace controls both Temperature and Relative Humidity in the space.  Almost everything else about the system remains the same, but the location of the insulation changes. If you want to be really technical, there are true Conditioned Crawlspaces and also Indirectly Conditioned Crawlspaces. In a true Conditioned Crawl Space, you’d be actively supplying and returning conditioned air from the space, while in an Indirectly Conditioned Crawl Space you’re just allowing the energy losses from the home or ductwork to provide residual effects to the space. In any case, these spaces remain warm and dry throughout the winter and dry and cool throughout the summer!

Where Does the Insulation Go?

In a Conditioned Crawlspace, you'll find the insulation on the Foundation Wall and Rim-Joist, rather than in the floor or ceiling of the space. Think of it like the exterior walls of your home running all the way down to the dirt floor. By installing the insulation on the foundation, we bring the volume of the entire crawlspace inside the home's heated and cooled space.

Using the right type of insulation is important for this project too. Closed Cell Spray Foam is the best option for this application. The ability of Closed Cell Spray Foam to properly air-seal the foundation and rim-joist of the home, while acting as a vapor barrier at the same time make it the right material for the job. It also has the highest R-Value per inch out of all insulation options; coming in at 7.5! In a Conditioned Crawlspace, air and moisture permeable materials like fiberglass cannot be used.

So, Which is Right for Me?

A Home Performance Company like FLC Energy can help you make an informed decision on which option better suits your home. Things like the location of your HVAC System and Duct-work, the size of your crawl space, and the location of your home can all play a roll in this decision. The best tool for assisting in this choice is a Professional Energy Audit.

If one or all of your home's HVAC systems are located in your crawl space, conditioning the space is probably going to be the best option for you. By bringing your HVAC system inside the conditioned space of your home, you'll increase comfort, decrease utility bills and also improve your indoor air-quality. When you eventually upgrade the unit in the future, you might even be able to adjust the size based on the new-found efficiency of your home.

A conditioned crawl space can also be a once and done approach to this space. Yes, dehumidifiers will need replacing eventually, but the mechanical systems will last longer in this scenario and you won't have gravity pulling down the insulation in the floor over the years. Finding pipes, running power and changing the home's layout in renovations is also made easier when you're crawl space is conditioned.

All that considered, an encapsulation might be the better option if the crawl space is very deep and without any HVAC system or heating source inside of it. In this situation you might not want to increase the volume of your home so dramatically. Since heat also rises, conditioning a big crawl space could leave you with colder floors in specific situations.

As you can see, there are plenty of considerations to be had when moving forward with a project to transform your home's crawl space. Make sure you discuss these options with a Home Performance Professional like FLC Energy.

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Doreen Bowman

The guys that were here doing the work were excellent! Well-mannered and stayed on task throughout. They explained everything! The best!