Basement insulation has a tendency to get wet in Michigan. Most of Michigan is in clay soil and clay soil is expansive. This means that it absorbs moisture and that expels moisture throughout the year. It expands and contracts and as it does, it pushes through your basement wall. If it's cinder block or if its poured concrete it can also push through into the rim joist. Fiberglass insulation is an organic material. Moist fiberglass in a rim joist is bad. It can actually cause mold, mildew, rot, and whole bunch of other things.
There's only one type on insulation to put in a basement
Two part closed cell spray foam. Again, any type of fiberglass or foam board, will have an air gap between the wall and board. This is where moisture will begin to accumulate, you can get condensation, and it can start to deteriorate the insulation. Where, with our two-part spray foam, these issues cannot occur.
The best way to insulate a basement ceiling is to have two inches of closed cell spray foam on the entire ceiling. And where applicable, you would want to spray foam the duct work as well. For not only a high r-value, but a vapor barrier, moisture barrier, radiant barrier. If you are doing a grow room that will contain the smell.
Framing out your basement walls, you would want to make sure that you have your electric and plumbing ran through. Spray foam can be applied after the electric and plumbing are done. Getting you an encapsulated and insulated wall as well. Then you can put up your basement drywall or paneling.
Spray foam in a basement does not waterproof it
Just spraying the wall isn't going to stop the water from coming in. It will channel it down to the floor if water comes through. You may have a crack in your wall or cinder block walls. In this case it will also channel it down to the floor. Technically for waterproofing you have to put an interior drainage system in the floor. This will catch that water and run it into a sub pump.
Spray foam in the rim joist is all that's required in an in ground basement. If you have a walk out basement then insulating the walls would be beneficial. The best basement insulation is closed cell spray foam because mold can't grow on it. A basement with fiberglass in the rim joist, will be yellow or discolored. This is because air and water just pass through it. If water gets into it then that's when all the mold and other things can grow. This is not something that can occur with spray foam. Closed cell spray foam in basements lasts forever!
Basement insulation is an investment, but there's still a cost
It's one of those few things that you can do to your house that will over time pay you back. This is because you're closing down the air drive. This will make your furnace last longer, and make your home more comfortable. Basement insulation is not required, however it is necessary. You want your home to be as efficient as possible. It's part of a process of creating a total thermal envelope on the home. Thus, making all your mechanicals work how they should. This will in turn, keep your floor warm in the winter months and cooler in the summer months. Another perk is lowering the cost of your energy bills.
A minimum of 2 inches of spray foam is recommended to achieve all your barriers. The more inches of spray foam you add, the higher r-value you're going to obtain. Also the higher the barriers and sound proofing you're going to get. More is always better!
It's also a good idea to get duct insulation
Having a furnace on one side of the house and a bedroom on the other side makes things difficult. All that air has to travel sometimes up to 60 feet through the duct work. During that trip it's losing its conditioned state. Pushing cold air through in the summer, the air will be warmer by the time it gets to the room.
So, if you encapsulate or spray foam those ducts, you're insulating that duct work. Again, you're going to make your heating and cooling system work less hard throughout the year. This will make your house more energy efficient. If you ever notice condensation forming on those ducts, eventually that will lead to rust. Leading you into having to get those replaced, which is not cheap. Encapsulation will stop that process and make your home healthier.
You can have injection foam installed if you have a finished walk out basement. This will achieve the same r-value- the 20.4 if its 2×4 studs because technically that wall is the same as the wall on your first floor. If its not insulated properly, your home is not as efficient as it could be. Sealing all air gaps in the basement and eliminating them will prevent mold and mildew.
50% of the air you breathe inside your home comes from your basement or crawlspace. If you have mold, mildew, or rot in the basement, what do you think you're breathing in inside your home? This takes us to foam board. Foam board for basement insulation is not a really good Idea. The problem is that they're perfectly flat. Against a concrete wall, you're going to have thousands of little air gaps between your concrete wall and foam board.
All those gaps are places where you will get moisture pushing through your wall. When you get air in there with condensation, its places where mold will occur. Foam Board also has a very low r-value. Foam board installed wrong in a basement, causes a thermal break between the boards. This would then have to be sealed with some type of foam as well.
The building science for basement insulation
The building science for basement insulation all goes back to the stack effect. What's always constant in a home is total volume of air. What that means is when your furnace kicks on in the winter months, it's pulling air from the rim joist. This air is then traveling across your basement ceiling. Fiberglass insulation in a basement is a terrible idea. If you were to pull out your furnace filter, you would see its made out of fiberglass.
Fiberglass is a great insulator in the right application
However, when its stuffed into the joist, all its doing is filtering the air that's coming through. It's not actually stopping or slowing down the air drive of the home. Fiberglass is also an organic material. Moisture gets caught up in the rim joist when air comes through It. That's why when you pull the fiberglass out of the joist in the basement, you'll see that its discolored. It's a great place for the mold and mildew to grow on the fiberglass insulation.
Not only is it not doing anything as far as insulating or keeping your home comfortable. Its also potentially leading to health concerns with the amount of mold growth. This is why you want to do a minimum of 2 inches of closed cell spray foam. In a basement insulation application, it needs to be applied everywhere. Especially in the rim joist. This way it will never mold and will continuously give you a vapor barrier, moisture barrier, and radiant barrier. It will completely stop the air drive of the house, plus it will stop any moisture coming through. Bonus- most people don't like spider webs, this will eliminate this problem as well.