6 Places to Insulate Vented Crawl Spaces
If your crawl space is open or vented, here are 6 places to insulate your vented crawl space that could save you money and keep out pests. Remember, there is more to properly insulating your crawl space than just throwing up fiberglass batt insulation. You want to make sure you focus on air sealing and making it more difficult for critters to enter your crawl space.
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What Does the Department of Energy Say about Crawl Space Insulation?
Before I begin I want you to know that I am not an advocate for open or vented crawl spaces. I believe and research shows that crawl space encapsulation is better than open crawl spaces. Sealed crawl spaces control moisture and making your home more energy-efficient than unsealed crawl spaces.
However, I do recognize not everyone shares my enthusiasm for sealed crawl spaces. Plus, not all crawl spaces can be sealed based on many factors. Hopefully, this article will assist those of you that have a vented crawl space. But first, let’s see what the Department of Energy has to say about crawl space insulation.
“How you insulate a crawlspace depends on whether it’s ventilated or unventilated. Most building codes require vents to aid in removing moisture from the crawlspace. However, many building professionals now recognize that building an unventilated crawlspace (or closing vents after the crawlspace dries out following construction) is the best option in homes using proper moisture control and exterior drainage techniques.
1. Insulate Rim Joists of the Vented Crawl Space
The Building Science folks say that insulating and air sealing the rim joist is critical. If that is true, then why didn’t your builder air seal and insulate the rim joists? I think we all know the answer to that question. If you have a basement, garage, or crawl space you should insulate the rim joists and air seal them. Rim joist insulation will benefit your home if the crawl space is vented or sealed.
Installing air-sealed rim joist insulation will stop or slow air movement from the crawl space to the living space. This is a great way to make your home less drafty. It will also slow the transfer of cold air, crawl space odors, and moisture into the living space. If you are dealing with a moist or stinky crawl space I would recommend the Ninja Crawl Space Encapsulation System.
2. Insulate Sill Plate – Maybe
Sill plate insulation is not that common nor do we do much of it. But if your sill plate shows major gaps, it should be insulated. If your sill plate sits well on the foundation wall with minimal gaps, don’t bother.
If you do insulate the sill plate, make sure not to destroy the termite gap. Covering the sill plate could void a pest control warranty if not done properly. I’d recommend using caulk to seal between the sill plate and the foundation wall. Caulk is easier to control with very little expansion. Spray foam could over-expand and cover the termite inspection area.
3. Air Seal the Sub-floor
Air sealing the sub-floor is hardly ever done. This is a crucial part of the crawl space insulation project. Of course, you may need to remove the batt fiberglass insulation to accomplish this but it is worth it. If your current sub-floor insulation is not in good shape or damp, go ahead and throw it away when air sealing the sub-floor. Air seal major gaps around plumbing, electrical, and HVAC ducts. Do not spray foam the entire sub-floor. This could cause other problems in the future. For larger gaps, use spray foam and foam board to air seal the sub-floor.
4. Always Insulate the Sub-Floor of a Vented Crawl Space
If you are keeping your crawl space vented, sub-floor insulation is required by building code. If your crawl space requires mold treatment and the sub-floor insulation is removed in the process. Make sure you replace the sub-floor insulation. Don’t let the contractor talk you into not having insulation in the sub-floor. Code requires it and it creates a valuable thermal break between your cold crawl space and your living space. The type of insulation can vary from rock wool to fiberglass. As I mentioned in the air seal section, do not spray foam the entire sub-floor.
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5. Duct Insulation and Air Sealing
If your crawl space is vented, this is more important than if it is encapsulated. Since you are allowing cold or hot air to enter the crawl space freely. You must make sure the air ducts of your HVAC system are sealed and insulated. This will not stop them from condensation if the dew point is reached, but will make sure the air does not get lost in the crawl space through duct leakage. If your ducts are located in the attic or other non-conditioned areas, air seal and insulate them properly to save energy. This will increase your comfort too.
6. Plumbing Pipe Insulation
Since your vented crawl space is open to the elements, plumbing pipe insulation is vital. If you live in a cold climate, the cold air freely enters the crawl space through the open vents. This is not the case in a sealed or encapsulated crawl space. Pipes should be well insulated and maybe have a pipe heat tape added for extreme winters. The heat tape is only used as needed but could make a difference in preventing a plumbing leak.
What Next?
Do you need help with mold removal, crawl space encapsulation, crawl space insulation, vapor barrier, waterproofing, foundation repair, or controlling humidity in your crawl space and you live in Georgia, Delaware, North Carolina, South Carolina, Tennessee, Ohio, or Kentucky? If so, please contact us to schedule your assessment. Also, let us know in the comments below if you have an idea for a new blog topic.
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