Encapsulating a Crawl Space is the Only Way to Go

CampFireJack

CampFireJack

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I just went downstairs to visit my freshly encapsulated crawl space and was shocked. I was shocked by the absence of smell. Have you ever smelled a crawl space that hasn’t been encapsulated? If you have or if you’re living above one, you surely know what I’m talking about. It’s like smelling dirt. Ugly, wet and rotting dirt. That’s the only way I know how to put it.

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This post is part of a series about me fixing my wet basement crawl space. Read all the posts by clicking the links below. They're super exciting.

Installing a Sump Pump in a Crawl Space
Covering Basement Crawl Space Floor With Plastic Vapor Barrier
Filling In a Basement Crawl Space
I Finally Filled the Basement Crawlspace with Sand
Encapsulating a Crawl Space is the Only Way to Go

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It took about two hours to lay down the final pieces of plastic sheeting and to tape them up to the rigid foam insulation, but I did it. This entire project has been much tougher and longer lasting than I anticipated. First, I had to muster up the energy to even start the project. That took about four years.

Then, I had to figure out what I was going to do and how I was going to get any fill I ordered into the area. That took about a day.

After that, I had to order 20 yards of sand and actually shovel that sand down into the crawl space and smooth it out. That took about three weeks.

And finally, I had to encapsulated the entire crawl space with insulation and plastic. That took about a week.

The job is almost entirely complete. I’m expecting delivery of a dehumidifier next week. That will remove any remaining humidity from the area and then we can enjoy some easy breathing. No more waves of musty odors coming from who knows where. It’s going to be so nice.

Here’s what I did to encapsulate the area down there. I had to think of a way to stop any moisture from condensing on the concrete block walls. The air is humid and warm, the walls are cool, you know what happens under those conditions. Wetness. Moisture. Dampness. Whatever. I decided that one inch rigid foam insulation would work best to hide the cool walls during the summer and would even help out keeping things warmer in the winter. I bought a case of construction adhesive and put blobs on the back of the boards and then placed the boards up against the walls. I had to creatively use tape and small strips of rigid foam to keep the boards in place, but I managed it and those things are now permanently there. That adhesive is solid.

basement-crawl-space.jpg

I taped all the rigid foam seams and used Great Stuff spray foam for any corners.

spray-foam-insulation.jpg

Mind you, the ceiling of this crawl space was previously insulated with closed cell spray foam that acted as a vapor barrier.

Anyway, once the walls were finished, I just had to roll out my 6 mil plastic sheeting and cover the floor. My plan was to tape the plastic about a foot up the walls to make things extra good. I did that, but for some strange reason, the plastic pulled and sort of sloped. It’s not a big deal and it won’t harm the performance or goal of the vapor barrier, but I wish it didn’t look like this. If this cheaper plastic begins to degrade in a few years, I’ll purchase the good stuff and cover the walls straight down first and then lay the floor down flat. I’ll worry about that later though.

vapor-barrier.jpg

I can’t even begin to tell you how much cleaner it is down there. I just went down there with my camera to take these photos and miraculously, I don’t need to take a shower. Incredible. Here are a few more photos.

rigid-foam-wall.jpg

insulated-crawl-space.jpg

taped-seams.jpg

covered-floor.jpg

encapsulated-alcove.jpg

I still have to figure out what I’m going to do with the dryer vent. I may run it through a wall upstairs. We’ll see.

Since I didn’t want any moisture from the walls to leak out from above the rigid foam, I used the canned foam to seal those areas.

great-stuff-foam.jpg

Okay, okay, I may have had some extra foam and had to use it up. I decided to cap off the tops of the cement block walls with it. The more foam, the better.

Here are two more shots of the seams. I’d say the area is completely sealed. I made it my mission to seal any cracks anywhere. Now, any moisture from the walls will simply slide down behind the insulation into the sand. From there, it’ll just absorb into the earth. There’s no floor under there. Only sand and dirt.

sealed-seams.jpg

great-stuff-foam-1.jpg

It’s kind of hard to wrap my head around the idea that there’s no way for moisture to get up through that vapor barrier. I guess that’s why they call it “encapsulation.” I can tell you that last night, the humidity level was 84%, right after I was done with the project. Today, I’m sure it’s much lower. I can feel that it’s dried up down there. I’ll measure it tomorrow. As I said, I have a dehumidifier coming next week and that’ll suck any excess moisture right up. The humidity level needs to stay below 50% to be sure no mold and mildew grows.

Actually, I’ll write another post after I get that machine. I’ll take some photos of my little hygrometer. That should be fun.

Check this out. I took a video when I was sitting down there a minute ago. It’s basically a 360 degree view of where I’ve been hanging out for the past month. A guy can get attached to an area like that. It’s weird. I sort of miss it down there. Luckily, we have another section to do in the spring.

Encapsulated Basement Crawl Space

 
KristinaW

KristinaW

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Something of a fellow traveler writing you from the Canadian side our North American thing. Came across your posts with great interest as it’s in many ways identical to something I’m dealing with in our four season cottage. Been working through a bunch of entertaining projects of our own and I’m dealing with an almost identical one as you did here. Preparing to get at it in the coming month. Wondered how this turned out for you? I’ve left my email, would appreciate if we could share thoughts/ experience on this.
 
CampFireJack

CampFireJack

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KristinaW said:
Something of a fellow traveler writing you from the Canadian side our North American thing. Came across your posts with great interest as it’s in many ways identical to something I’m dealing with in our four season cottage. Been working through a bunch of entertaining projects of our own and I’m dealing with an almost identical one as you did here. Preparing to get at it in the coming month. Wondered how this turned out for you? I’ve left my email, would appreciate if we could share thoughts/ experience on this.
Hi Kristina,

It’s been working out very well. It’s mud season in my area and that means the water table is extremely high. Luckily, the basement hasn’t filled up like a bathtub, which means I was correct in my assumption that the water was filling from below. The sand was a good choice for this project. It has kept the water down below and the plastic is blocking any moisture that’s trying to come up. I can see all the droplets of condensation on the other side of the plastic. I’m guessing the insulation on the walls has done its job, but I wasn’t down in the basement much this winter, so I can’t be sure about that. All in all, the basement is sealed which means that it’ll be much drier this summer season. I’m looking forward to finishing the other side down there in a month or two.

Jack
 
Encapsulating a Crawl Space is the Only Way to Go was posted on 08-19-2021 by CampFireJack in the Home Forum forum.

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