It’s cold outside at the moment. For a brief time of year in the Brazos Valley, your home is chillier and draftier than you like. Should you do something about it? You wonder if insulating your crawl space is a good idea. Or you might be looking at a series of home improvements all around and are wondering if crawl space insulation should be included in the list of projects.
At Anchor Foundation Repair, we’ve inspected and repaired all types of Central Texas foundations for 40+ years. We’ve crawled under thousands of pier and beam and block and base homes at this point. We’ve seen how insulation holds up over time in the homes that have it and observed the kinds of issues that can potentially develop as well.
In this article, we cover whether insulating your crawl space foundation is something to consider for our local climate. We’ll also explore your insulation options and pros and cons as well.
Do I Need to Insulate My Crawl Space? (Necessity)
Out of the couple thousands of crawl space homes I’ve inspected, only a few hundred have had any sort of crawl space insulation. This leads me to believe that most crawl space foundations are not insulated and for the most part it’s likely unnecessary. Many of these crawl space homes are older and have been standing uninsulated since as early as the 30s, 40s, and 50s.
If it was really needed, someone would have already insulated that crawl space by now . . .
Our weather is temperate in Central Texas. Since it only gets *a little* below freezing for a week or two out of the year, it doesn’t make a ton of sense to spend money on crawl space insulation for most folks.
So, do you need an insulated crawl space in our area? No. Could it be nice to have? Maybe, but maybe not. Let’s look at the options and pros and cons before you decide.
What Are The Insulation Choices For Crawl Spaces? (Options)
If you were going to insulate a crawl space, you’ve got a few ways to go about it:
- Fiberglass batts,
- Foam board,
- Polyurethane spray foam, or
- A combination when appropriate.
Using Fiberglass Batt Insulation for a Crawl Space
Fiberglass batt insulation is relatively inexpensive so the cost is likely bearable for most. It’s also flexible so it can bend or wrap around things as needed and be cut to fit easily.
Batt insulation is difficult to install in a crawl space because you have to figure out how to attach it to the underside of the home. We’ve seen people use chicken wire to hold it up, fabric strips and staples, thin wood strips, and all kinds of random fasteners. Crawling around under a home trying to get it all in place is likely awkward and physically challenging.
Using fiberglass batts in a crawl space has other downsides too:
- Doesn’t last long and will require frequent checks and replacements,
- Absorbs and traps moisture, facilitating mold growth and/or wood rot,
- Falls easily no matter what is used to hold it in place,
- Attracts critters who think it’s a nice place to stay warm or take the material away, and
- Is a beast to remove if you decide it’s not working and want something else.
Using Foam Board Insulation for a Crawl Space
Foam board insulation is also a cheaper material and relatively inexpensive to install. It’s easy to remove and replace small sections when needed and can be cut to fit the nooks and crannies of your crawl space. Foam board insulation is flat and compacted meaning critters can’t make their bed in it. It’s not fluffy or easy for little paws to carry off either.
Foam board sounds pretty good, but also has some drawbacks:
- More difficult to install due to inflexibility and only works on flat surfaces,
- Working around in tight crawl spaces with large pieces of foam board will be difficult,
- Placement around plumbing, electrical, and HVAC obstacles adds to installation challenges.
Using Spray Foam Insulation in a Crawl Space
Newer on the market is polyurethane spray foam insulation. Spray foam expands and fits any space it’s sprayed on making it easy to work around obstacles, fast to put in place, and great at sealing up any gaps that other forms of insulation can leave open. Installers don’t have to custom cut or fit anything, they just spray it on and it’s done.
Spray foam sounds amazing, but it isn’t perfect either:
- It’s the most expensive option,
- Awkward to install in a crawl space (vs. an attic or wall) due to clearance limitations
- Difficult to remove and replace if needed for under-home leaks or other repairs,
- Even though deemed safe, it’s still a chemical material,
- Sealing up every airflow opportunity may not be the best idea for year-round ventilation,
- It can cover up mold and wood rot issues that should be handled before installation. Hiding them from view doesn’t make the situation go away and could cause more problems, not to mention deceive future home buyers if you sell later.
In my opinion, this product is still too new to observe its long-term effects and effectiveness. It might be better to wait on this sort of option and see how it works over time. I’ve seen rumblings on the interwebs about issues with this product in other countries that have been using it longer.
Using a Combination of Insulation Types in a Crawl Space
Given the drawbacks of the different insulation types, a combination approach might be your best choice. If you want, use batt where you need flexibility, use foam board where it works on flat surfaces, and spray foam when you’re working with a lot of complexity in the crawl space. There are no rules here.
One combination that works well for pier and beam foundation homes is a combination of foam board on the perimeter beam, bridged by spray foam along the perimeter joist. This option insulates the sides of the foundation but leaves the subfloor and joists clear for visual inspection and still facilitates airflow, ventilation, and dehumidification.
Benefits and Drawbacks of Crawl Space Insulation (Pros & Cons)
We’ve talked about the benefits and drawbacks of each insulation type, but now let’s talk about the overall pros and cons of choosing crawl space insulation vs. no insulation – this is the more important issue over picking a type of insulation. Should you insulate or not insulate?
Pros of Choosing to Insulate Your Crawl Space
- Makes those few weeks of winter more tolerable,
- *Might* keep pipes from freezing,
- Could help lower your heating and cooling bills,
- Keeps bad air/smells/humidity from entering your home from below the house (with spray foam only).
Cons of Choosing Crawl Space Insulation
- It’s a big expense and may not be worth the cost compared to any utility savings,
- Installation can be challenging under an existing home,
- Insulating joist cavities, in particular, will cover up developing issues like plumbing leaks,
- Insulation hides surfaces from visual inspection for wood rot, mold, and termites,
- Insulation holds damp, humid air against timber, increasing chances of dry rot,
- Extra warmth and fluffy stuff might attract pests looking for a toasty spot or nest material,
- Crawl space insulation may disrupt pathways for natural ventilation in a home, which is very important at other times of the year in our hot, humid climate.
While insulation is a great way to increase the efficiency of your heating and cooling systems, insulating your Texas crawl space may also cause more problems than it solves.
My two cents: boost the insulation in your attic first and then in your walls before worrying about your crawl space. Both are cheaper and easier to do with more of a return on investment. But there’s even more you need to consider . . .
Should You Insulate Your Crawl Space Foundation?
Homes should generally be insulated to keep both heat and cold from entering your living space. You would then think that crawl spaces would always have insulation. However, they usually are not insulated here in Central Texas, especially in older homes. You’ve got to wonder why that is.
As mentioned before, out of all the crawl space homes I’ve inspected, only a fraction have had any sort of crawl space insulation. This does seem counterintuitive if insulation is supposed to be so beneficial.
Based on some of the long-undetected issues I’ve seen in crawl spaces, it makes sense that most homes don’t have crawl space insulation around here. It’s too humid. Many crawl space homes end up with drainage and ventilation problems that are way more important to address.
If you’re going to insulate the crawl space in your older home, first make sure that you have optimized and dealt with any issues in your:
Make sure that under-home moisture is controlled and airflow is sufficient before turning your focus toward insulation in an existing *mature* home.
Suppose you’re building a new crawl space home with *all the right stuff* like proper pad site development, appropriately sized HVAC, plus great guttering and drainage from the beginning. In that case, you might consider crawl space encapsulation as well as insulation.
In other words, if you’re starting from scratch building a new home with a crawl space foundation, you can do it right with insulation. But if you’re working with something older, then you’ve got bigger fish to fry first.
Make Sure Your Crawl Space Is Ready For Insulation
Now you’ve considered everything there is to think about with crawl space insulation. Do you still think insulation is the right path for you? If so, confirm that your crawl space foundation is ready. First, make sure your crawl space is clean. Then, do a moisture check to see if your drainage or ventilation needs any work – this step could take some time.
At Anchor Foundation Repair, we’re here to help guide you through your foundation decisions, even when it’s not a service we provide. After 40+ years in business, that’s what’s best for our Brazos Valley community and for exceptional homeowners like you. Ultimately, you’re the one in charge and we simply offer the info so you can make the right decision for your situation.
If you’re concerned about excess moisture under your home, we’ve developed some water management packages appropriate to our Texas crawl space conditions.
