Is your house built on a crawlspace? If yes, it is very important you read our detailed guide to know everything about these crawlspaces and how to keep them insulated. First things first, these crawl spaces are ideally treated as mini-basements. These spaces should not have any air connectivity to the exterior environment. Their walls should be insulated which means they should be isolated from conducting bodies like electricity, heat, or sound. The floors must be un-insulated and ground vapor is sealed and the air in these spaces must be conditioned with indoor air only. For this, know how to insulate a crawl space.

Usually, the standard crawl spaces consist of mold, pests, and dampness. Almost all of these spaces have linked to indoor air employing numerous tiny unplanned air perforations in the ducts, floors, and partitions. Hence, to ensure the quality of indoor air and longevity, a crawlspace should be always dry, be able to control temperature and humidity, and must be sealed tight so that pests cannot enter in.

Such planning is very essential in crawl spaces that hold mechanical types of equipment—an affair that is commonly seen in buildings with a crawlspace. Thus insulating crawl space is an important and necessary aspect that must be considered and implemented on a serious note. Let us now have a look at the various steps to insulate these crawlspaces.

It is especially important to prep your crawl space for winter or repair before the cool winter months when your home will be closed up. Unwanted moisture is the problem that you will most likely find when examining your crawl space.

Step1: Securing the Dirt Floor

how to insulate a crawl space


Commonly, a crawlspace would only have a dirt floor and some un-insulated walls. This will end up increasing the humidity as moisture from the ground vaporizes into the air and can precipitate on cold walls and supports where mold can settle down.

That damp air will eventually circulate throughout the house, support humidity, mold germs, and a rather disgusting smell that will be the influencing odor of your house, furnishings, and your clothes, so you will take that fragrance everywhere you go.

Therefore, the solution to only the dirt floor does not cost much as all you have to do is to block the moisture supply to the air by spreading down polyethylene directly on the surface. A common 6 mil poly vapor curtain will work well as a basic solution. Remember that the joints must be properly sealed and if you can simply lay the cover over the ground without having skilfully fixed it to the ground; you would have a major work.  This way you will be able to reduce the moisture content in the air and even if you can contain 80% of the moisture, you will notice a major change in the dampness in the air.

Step2: Insulating Space

Spray Foams: The most common way to insulate crawl space is by starting from the ground moving up, the way you would have done it to any basement space. The best way of insulating a crawl space is by doing it with Spray foams. They do have a negative value because of the emissions involved, however, this is a very result-oriented solution and it takes care of every tiny hole by filling up and sealing them. This is no ordinary work and has to be carried out by an expert only who has been doing this as his daily business. To insulate the walls, you can frame the spray foams an inch away from the walls and rest them on small pieces of foam. This way, it will stay on the ground and soak up moisture. There is no need to install a vapor barrier as the spray foam does the work.

how to insulate a crawl space


EPS Foam: Another way to do it is to use the EPS foam board by installing them directly to the wall. You could do that by applying strapping and screws or a suitable adhesive. This will also act as a vapor barrier.

Rock Wool: You may also consider using rock wool or mineral wool boards that are made up of recycled dust. A good thing is that they are burning free and therefore do not require fire protection. However, you will be then required to set up a vapor barrier first and then the board.

how to insulate a crawl space


Fiberglass: This is one of the most common types of crawl space insulation methods. One of the main reasons for adopting this method is that it is less in terms of cost when installing the material. Also, there is no expertise or special equipment required while installing and one only needs to roll out the sheet, cut, and fit into the required space, and the work is done.  However, the issue with this method is that it can hold moisture in it. Due to this it tends to become heavy and becomes saggy leading to mold development in the material. To put it simply, once the material gets wet, it is not of great use.

Step3: Installing Vapour Barriers

Installing Vapour Barriers


It is important to have the area cleared up so that you can move around easily. Make sure that there is no possibility of water collection by setting up a proper water pump at an appropriate place. Whether you have had the water collection problem in the past or not, you must consider having the solution in place as the water collection problem may arise at any moment.

Is it right to have an air opening in the crawlspace? Technically it is not right to have an air opening in the crawlspace. To keep the humid air away from cold crawl space during summers or winters it is essential to have no air opening in the crawlspace and therefore avoiding moisture in the crawlspace. Such places that are shielded from moisture will be cooler in summers containing less humidity, so the moisture can vaporize on cold surfaces of wood and wall.  It is a good idea to keep a check on the humidity level inside your crawlspace. To do so, you may install a good dehumidifier that comes with a drain hose.

Step4: Options for Insulation

Terrablock: Terrablock is an excellent crawl space insulation option that acts as a moisture barrier as well. A layer of ¾ inch is sufficient enough to be installed which is a good clean and a dry surface option for your crawlspace. It is to be noted that the sheet is puncture free and makes the crawlspace a convenient one for anyone working inside it. Terrablock can also be installed over the drainage system that directs water to the drainage pump. You can also use these to insulate the walls.



SilverGlo: SilverGlo rigid foam from Basement Systems that comes with a graphite infusion process has a higher R-Value than the common EPS foam. These panels are equipped with a shiny integral radiant material that reflects heat for higher energy performance. SilverGlo is an ideal material for insulating crawl space because of its amazing thermal properties and endurance.



EcoFoil Bubble Insulation: EcoFoil Bubble Insulation is one of the most favored items for your crawl space. They provide pre-cut joist insulation that is created to settle between floor joists in the crawl space ceiling for vented crawl space functions. For a vented crawl space application, standard fiberglass insulation will collect moisture and begin to sink and even create undesired mold. You may utilize EcoFoil Double Bubble or EcoFoil between Joist Insulation below the floor supports to evade these moisture issues and keep the floors warm. As for non-vented crawl spaces, it is advisable to cover the complete crawlspace adopting EcoFoil Bubble Insulation, with EPS or Polyurethane foam insulation on the walls. In this application, it is important to create a sealed and secured crawlspace to avoid precipitation and keep the floors warm.

EcoFoil Bubble Insulation


Here, we have seen various types of crawl space insulation available today. Having gone through all the insulation methods, the one that is most desired can be adopted for your crawlspace. For more information, visit Homedesignnow.