Our Bungalow

We highly recommend the services of Val Riedman (Croix Valley Radon Mitigation). He and his son finished the job on Thursday. They were thorough and thoughtful. Thanks Val!

Radon Pipes

This is a shot looking into one of our crawl spaces (under our kitchen). The pipe on the right is the main venting pipe that comes up from the drain tile and vents to the roof. The other two pipes are pulling air from beneath plastic sheeting in each crawl space. You can see where one of them goes down into the plastic on the floor of this crawl space. The pipe going off to the left ends up in the other crawl space (beneath the family room).

So, it’s done. In a few weeks we will do another radon test. Val thinks it will be down below 1 pCi/L (which is good).

The radon mitigation system taps into our existing drain tile, which runs around the inside perimeter of the foundation. The continually running fan draws the air up from the drain tile. To access the drain tile, a hole needs to be drilled into the basement floor. A pipe is run up through the house and out through the roof.

Drain Tile Access Hole

Radon Vent Pipe

One of our faithful readers asked how we know if the radon mitigation fan is working. The pipe in the basement has a guage on it that shows the pressure (relative to the room). See how the left side is higher than the right? That means there is a lower pressure in the pipe. The fan is working. (Aside: It reminds me of a big mercury barometer I used to have in my classroom. If the administration knew it was there it would have been removed, since it required a large vat of mercury.)

Pressure Guage

We have two crawl spaces in our basement. These are spaces underneath the kitchen and back family room which were both added on sometime after the house was built, and thus they are outside the foundation. So there are two openings in the foundation (see photo) to access these spaces. Some of our radon problem could be because of the dirt ground in these spaces, which allows radon to seep in. The crawl space under the family room actually has an old cistern underneath. The cistern is half filled with construction waste (see close up photo), including pieces of plaster and concrete block.

Crawl Space

Cistern

For radon mitigation, the floor of the crawl spaces need to be sealed with plastic and a pipe connected to it to draw out the radon that accumulates underneath. The cistern is problematic, because the plastic sheet would not be supported underneath. Solution? We decided to “temporarily store” some of our demolition waste (sheet rock, plaster, lathe) in the cistern until it was full. Now the plastic sheet can be laid on top. Problem solved.

Radon mitigation involves pumping radon gas from under the foundation up and out through the roof. This is accomplished with a PVC pipe and a fan unit connected to the pipe. There are two ways to do this: The hidden way, or the ugly way.

The hidden way: The pipe from the basement comes up through the house, hidden in the back of a closet or in a wall. The fan unit sits in the attic out of sight and pumps the radon up through the roof.

The ugly way: The pipe runs out the basement, up the side of the house, around anything that gets in the way, and up onto the roof. Here’s an example. We REALLY want to avoid this.

All of the radon mitigation contractors we talked with said that we would have to use the ugly way. Our house does not appear to have a clear, hidden path from the basement up through the roof. But finally we found someone who said he could figure out a way to hide the pipe in the house, and he did.

He’s running the pipe up the inside of a wall that used to be the outside of the house (before the kitchen was added on), so it’s a thick wall with room for a pipe. To do so, he had to remove one of the corner cabinets in our dining room (which we were planning to take out someday anyway). The fan will sit in an attic space (that was closed off) above the kitchen.

Behind the cabinet was a rough coat of plaster (but no second, finish coat) on the lathe. He cut that away and installed the pipe. Inside the wall was some very interesting insulation (see photo). We’re guessing that it’s just a little flammable…

Cabinet Removed

Insulation

Nathan Inspects the Wall

Vent Pipe Installed

Plastic Covered Walls

Now that the foundation is exposed, we are ready for the plastic sheeting to cover the walls. We hired a waterproofing company to do this. They worked fast (a little too fast, in fact). They covered the walls in plastic, sealed the tops and seams in the plastic sheets with a gooey acoustic caulk (who knew there was such a thing?), simply because it had the right consistency for sealing the plastic to the wall (not because it would help make a quiet basement).

Tape

Then they tucked the plastic behind the dimpled plastic sheet and sealed it with wide tape (see photo).

So, in theory (and hopefully in practice), the plastic should now encapsulate the walls. When a radon mitigation system is connected to the drain tile (where the dimpled plastic sheets are coming from), it should suck the plastic against the walls.

We have a radon mitigation guy coming tomorrow, so we’ll see. I’m skeptical.

The basement project has begun! We are starting with the essential radon mitigation.

Partial Wall Removal

If you click on the image, you’ll see an enlarged version of it. If you look at the base of the wall, you’ll see a dimpled plastic sheet coming out from the floor. This is what it is, and this is why it’s there. It provides a gap between the wall and the floor that allows moisture to run down into the drain tile. The problem is, it also lets radon gas up into the basement. So, how do you allow it to serve it’s function while also sealing it up to keep the radon out? Good question! The answer is, to line the walls with plastic, and seal the plastic down onto the dimpled plastic sheet. The plastic on the walls is sealed at the top, so it is air tight.

So, we hired someone to come in and seal the foundation with plastic. But, to prepare, I needed to give them access to the entire foundation. So I borrowed our friend’s reciprocating saw (thanks Wendell!) and cut the plaster and lathe walls back about 18 inches wherever a wall butted up against the foundation (see photo). Fun!

Also, there was a finished “office” in the basement that the previous owners built. For some reason. So, the sheetrock and trim in that room had to be ripped out. It took very little time to cut the plaster and lathe walls, but the sheetrock in the office took much of the day for me, Matthew, and Nathan to rip out (Justin is on a canoe trip).

The "Office" Before

The "Office" After

Matthew Removing Sheetrock