Home Renovation and Improvement

3 Ways To Care For Your Crawlspace

Today’s post is written by Garrett, our Project Manager. From the start, he has proved to be a valuable asset to our team and we feel blessed to have him. Learn more about Garrett here. He came to us with a great wealth of knowledge and today, we pass some of that knowledge onto you as Garrett covers a commonly neglected task in home maintenance: the crawlspace. Take it away …

When looking for a home it is easy to focus on the aesthetical improvements over the practical ones. My wife, Shea, and I began looking for a home last Spring. Our “must have” list included things like an open layout or the ability to open a wall, three bedrooms, a functional bathroom and a functional kitchen. So, when the time came to put an offer in on a house, we thought we had all the important bases covered. As it turns out, we didn’t. Our inspector uncovered a crawlspace with $7,500 of water and termite damage. Thankfully, we were fortunate to find that out in our due diligence period, but not everyone is that lucky.

The Enemy Of All Crawlspaces

Once a person is sure the structure of their home is sound, it is important to do everything you can to protect that space. In my experience, enemy number one of the crawlspace is water. We need it to survive but it has no place in the structure of your home. There are a variety of places water can enter a crawlspace, but right now I would like to focus on the primary and least predictable way in which water enters a crawlspace: the ground.
H20, particularly when the ground around a home has become saturated, can evaporate into your crawlspace creating and trapping humid air. Humid air and wood creates a perfect ecosystem for mold, mildew, wood rot and the ever prevalent termite.

Protecting Your Crawlspace

All of these nasty symptoms of water can be prevented. The first line of defense against evaporating groundwater is a vapor barrier. The simplest form of vapor barrier is a 6 mil plastic that is rolled over the entire surface of a crawlspace. This first line of defense will significantly decrease the probability that moisture will enter the crawlspace. There is a significant range in cost and type of vapor barrier. Let’s take a look at your options.

1. Vapor Barrier

The first, and most simple, process is to lay overlapping pieces of heavy (typically 6 mil) plastic across the entire surface of the crawlspace. It is recommended that you overlap each piece of plastic 6-12 inches to assist in keeping the evaporated water from getting through the barrier. These are typically done in vented crawlspaces.

vapor barrier crawl space


Cost: $70-$100 per 2,000 sq. ft.

Pros: Most affordable. Least time-consuming. Will be sufficient if you can be sure your crawlspace is very dry.
Cons: Gases rise and can still find a way through the seams of the vapor barrier. It is also common for moisture to enter through the concrete or cinder block foundation walls, particularly if they are below grade (ground level). It does not address the fact that, especially in the South, humid air is still always going to enter a vented crawlspace and come into contact with the structure.

2. Partial Encapsulation

Although more expensive, partial encapsulation addresses the issue of a below grade space as well as any rising ground vapor. This process involves:

vapor barrier crawl space moisture prevention foundation home maintenance

  • Taping 6 mil plastic to the wall of a crawlspace with butyl tape. If you have ever tried to tape anything to concrete, especially cinder block, you know it will not adhere for any reasonable amount of time. So, to combat this issue we use a product called butyl tape. This tape is double-sided, extremely sticky and will hold for a considerable amount of time. Figure out how far below ground the lowest point of your crawl is, and run the tape at ground level around the crawl. We recommend doing it in smaller sections, because working with butyl tape can be challenging.

butyl tape vapor barrier adhesive sticks to concrete

  • Cut the plastic so it is at least 6” longer than the height between the tape and the ground. You will want to be sure to keep your vents free from plastic to allow air flow. If your crawlspace is large enough to require piers to support the structure, do the same process using butyl tape to adhere the plastic at least half way up the pier. Again, be sure that you have six inches of plastic overlapping the ground. Next, you will pin the plastic to the ground using garden stakes, which kind of look like mega staples.
  • Lay out your plastic vapor barrier. We recommend using at least a 12 mil reinforced plastic. This will withstand much more abuse as you and your handyman crawl under the house to repair any future issues. Again, run your plastic from wall to wall. Make sure it overlaps the plastic that has been taped to the wall at least 6 inches. Like the standard vapor barrier, you will want to also overlap each consecutive piece of plastic 6 inches. Finally, you will then tape all seams using PVC seam tape. It is not uncommon to see duct tape or gorilla tape in crawl spaces, but this tape will deteriorate, losing its adhesion, much faster than a tape designed for plastic seams. Finally, use the garden stakes every several feet to ensure that the vapor barrier is secured.

Stakes Crawl space vapor barrier install how to

Cost: $300-$500 per 1,200 sq.ft.
Pros: This will ensure no water enters your crawlspace from the ground or walls. It will prevent insects from entering the crawlspace. It is relatively affordable and is a big upgrade from the standard 6 mil vapor barrier.
Cons: More time-consuming. Slightly more expensive. Still allows moist vented air into the crawlspace.

3. Full Encapsulation or Conditioning

This method will, by far, be the most expensive. If moisture has been an issue in the past, or you live in a very moist climate, this is going to be your best bet. Full encapsulation nearly guarantees that your crawlspace will be free from humid air. This process is often used in newer homes and old homes can be retrofitted for encapsulation.

Insulated crawl space how to maintain

Full Encapsulation assists in:

  • insulating


  • maintaining the structural integrity of the home

This process is almost identical to the partial encapsulation, except you will cover the entirety of the block wall and piers, including the vents with plastic. Many companies will even use an insulation board between the wall and the plastic to improve energy efficiency. It is also common practice to cover the main structural girders with plastic.

Encapsulation is really great at keeping moisture out but what happens if moisture gets in? It is inevitable. Pipes and HVAC systems often sweat, things get spilled, washing machines overflow. So, you must have a game plan in place to remove the water. The best way to do this is to install a dehumidifier. This will either need to be connected to a sump pump, have a line pumping the water outside, or it will need to be emptied regularly. It is not an impossible scenario that a humidifier breaks, or overfills, so they must be maintained to be effective.

Cost: I have seen prices as low as $2000 dollars and as high as $7000. A crawlspace dehumidifier will cost around $800 dollars uninstalled.
Pros: Eliminates moist air and is your best defense against the humid southern air, ground water and pipe sweat.
Cons: $$$$$. Requires humidifier maintenance. Is the most time-consuming process.

It is important to remember that no matter what you choose to do, a vapor barrier is extremely important for the longevity of your home. Crawlspaces are no fun, but the peace of mind that comes with knowing your home is going maintain its value makes it worth the time in easily the creepiest part of a house.

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We hope this article was helpful and would love to hear from you! Leave a comment below.

ps. If your home happens to be a money pit and you don’t want to take on the task of home maintenance any longer, would you consider selling it as is? We’d love to give you a free home buying consultation. We buy in Raleigh, Cary, Durham and surrounding areas. Let’s start the conversation!

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