DIY Crawl Space Guide: Vapor Barrier Removal Week 8

Timing is everything when it comes to successful crawl space encapsulation, especially when tackling old vapor barriers and hidden debris. This deep dive into Week Eight of our Crawl Space Repair Challenge reveals why patience pays off and rushing could sabotage your entire project.

Most DIYers and even some contractors make the critical mistake of ripping out old vapor barriers on day one. I'm showing you why this strategic delay actually accelerates your overall project success. By maintaining that old plastic during the initial drying phase, your dehumidifier can focus exclusively on reducing wood moisture (targeting 15% or less) rather than fighting a losing battle against constantly evaporating soil moisture. The existing vapor barrier also provides a cleaner work environment, protects your equipment, and prevents excessive dust during early repair stages.

The removal process itself addresses one of the most common complaints in crawl space work – that mysterious "cat pee smell" that sometimes develops after encapsulation. I explain how hidden contaminants beneath seemingly clean plastic (from old plumbing leaks to organic matter) can create this issue, and why complete removal is non-negotiable. You'll also learn the critical window between removing old materials and installing new ones to prevent re-contamination of dried structural wood.

Your timing doesn't end with removal, though. I share strategies for maximizing efficiency during the drying period, including installation of foundation insulation barriers and water management systems to maintain momentum in your encapsulation project. Whether you're handling this as a DIY weekend warrior or vetting professional contractors, understanding these strategic timing elements transforms your crawl space from perpetual problem to permanent solution.

Chapters

• 0:00 Introduction to Week Eight
• 1:40 Why Wait to Remove Vapor Barrier
• 3:02 Checking Moisture Before Removal
• 3:50 Avoiding the Cat Pee Smell
• 5:00 Don't Leave Dirt Exposed Long
• 6:10 Maximizing Your Drying Time
• 7:15 Final Thoughts and Resources

Transcript

Speaker 0: 0:00

Hey, michael Church, crawl Space Ninja. We are on week eight of the Crawl Space Repair Challenge and today I want to go over removing old vapor barrier and debris that is located under the vapor barrier. What is the importance of this step in the Crawl Space Encapsulation Project? Some things we'll be covering in this video include why am I asking you to wait this long in the Crawl Space Encapsulation Repair Project before you remove the vapor barrier? Some people want to remove the vapor barrier as a step one and I'm having you wait, so why am I asking you to do that? What are some things that you need to know before removing that vapor barrier and debris? Preventing cat pee smell why is that important? The timing of not waiting too long between removing the debris and the next step, and then making use of your drying time. I encourage you, if you have not already, make sure you check out week two and week three of this video series. They go hand in hand with this video and I know that we're on week eight. I'm not saying it takes you eight weeks to get to this step. If you're doing crawl space encapsulation, we're just taking each of the steps and making a new video for each step. This could be done in as little as four days. We do 2,000, 3,000 square foot crawl space encapsulation projects in a short amount of time. But most people can't get it done in that amount of time because, of course, we've got two to three ninjas doing it and we've been doing it for a long time. So if you're looking to DIY this project yourself, this is the steps that it would take in order to do that. Or if you're looking to hire a contractor, these are the steps that we recommend that are taken during the encapsulation process to make sure that it all goes very smooth.

Speaker 0: 1:40

Why wait until now to remove the vapor barrier? Why wait until now to remove the vapor barrier? Well, basically, we needed the wood to dry out. As I talked about in week two and week three, part of the phase one process is getting that wood to dry. So I want all of that wood to dry out.

Speaker 0: 1:54

Another thing is leaving that plastic down gives that dehumidifier the ability to dry out the wood without drying out the soil. If I was to remove the plastic on phase one, day one, then that dehumidifier is going to be fighting to dry the soil and the wood and normally there's more water in the soil so the wood takes longer to dry. It's also going to make the crawl space less dirty so that you can crawl around and do things. If it's a really dry crawl space, for example, you're going to be kicking up a lot of dust if you don't have that plastic down on the ground. So leaving that plastic does make it less dusty in the crawl space and it's going to protect you. If you do have a flooded crawl space, if it's real muddy down there, that plastic is going to help protect you as you maneuver and do some of the steps involved in encapsulating the process and, believe it or not, it'll actually keep that dehumidifier clean, which is really nice. So if you've got that dehumidifier that we talked about in step two and three of the process, then you want to make sure that filter stays clean so that that dehumidifier gets that crawl space dry and works efficiently.

Speaker 0: 2:59

So these are some of the reasons why you would want to leave the vapor barrier in place up until this moment. Before you remove that vapor barrier, I want you to make sure that the moisture levels in the crawl space are in good shape. I would like for that humidity to have been kept under 60% up until this point so that it could dry out that wood, and I would like to see that wood moisture level around 15% or less. This is actually too high at 53% that's pegging my meter, which is why we've started the process of getting the crawl space dry up until this point. So make sure you check the moisture readings in the crawl space before you remove that vapor barrier, because once you remove it, that dehumidifier that's been working for a little bit is going to try to dry the ground.

Speaker 0: 3:44

This is one of those phases where you can avoid that cat pee smell that we hear everybody talking about so much. So basically, as you can see in these two images, I've got a nice looking plastic on the left and I've got bare dirt on the right. So if you were to put new vapor barrier over this old plastic, even though it looks really good, there could be debris, there could be some wood trapped under this plastic. Perhaps you had an old plumbing leak that you were unaware of from the washing machine and that gray water made it down into the crawl space on top of the old vapor barrier. So I would rather you remove the old plastic and any debris under that plastic that could grow mold or bacteria, because that could also cause a that was originally installed in the crawl space or one that's been in there long enough to get something on top of it, like I mentioned, where the washing machine flooded or maybe an animal died in there or something like that. So make sure you get all of that vapor barrier and the debris under it out as part of this process. Don't leave the dirt exposed too long. In other words, after you take out the vapor barrier, I want you to move to the next phase in the crawl space encapsulation, which will be next week's video. As soon as you pull that vapor barrier out, we're going to move to week nine's video, so I'll let you know when that video comes out. I'm not going to share with you what it is yet, but don't wait too long, because if you leave that dirt exposed and that dehumidifier has been installed, trying to keep that crawl space dry, that dirt could actually re-infect the wood. Now it won't look as bad as this picture here. I'm using this more for dramatization, but basically you want to make sure that you remove that plastic before moving to week nine's video, but don't leave too much time left.

Speaker 0: 5:50

We were installing insole barrier while that old vapor barrier was installed. So the dehumidifier is working and drying out the crawl space. We had some time. We're utilizing our time well. We are going ahead and installing that insole barrier.

Speaker 0: 6:18

Now, this particular crawl space on the left did not have a lot of high wood moisture levels, so we left the insulation between the joists have a lot of high wood moisture levels, so we left the insulation between the joists. That was per the homeowner's request. We didn't see a lot of mold, so they wanted to leave that fiberglass in place, so that way it could be a benefit to insulate the subfloor as well as the foundation walls. Once we sealed the vents and then, obviously on the right, you could go ahead and start installing that water management system using that Hydraway system on the right. So there are some things that you can do in order to maximize your time while the crawl space is drying out. So these are some good things that you can do.

Speaker 0: 6:58

As I've mentioned in many of my videos, we've got our book Crawl Space Repair Myths Busted located on Amazon. If you get a chance to check that out. If you'd like to do a consultation with me, you can do that at buymeacoffeecom and, of course, we hope you'll like and subscribe to our channel. Let me know down in the comments what you think of this series so far. Really appreciate your feedback. I'm Michael Church with Crawl Space Ninja. We hope you make it a happy and blessed day and we'll see you later.