Better Home Insulation by Sealing Gaps

A great product for sealing gaps and cracks around 1 inch. This is insulating foam that expands to fill the gap.
The links in this post contain affiliate links and I will receive a small commission if you make a purchase after clicking on my link.

A continuing issues I face in my old home built in 1968 is the somewhat chilly temperatures inside, mostly on the first floor. I swear it sometimes feels colder inside the house than it does right outside in the backyard. So the hunt continues on ways I can improve the temperature inside the house. So far, I've done a couple of of home fixes of varying prices:

  1. I tried the plugging drafts from outlets. Though the fix was cheap, ~$10, and easy to DIY, it didn't offer much of a change.
  2. I hired a contractor to remove and replace blown-in insulation in the attic. This cost substantially more than the outlet fix, but did have a noticeable improvement to the temperature on the second floor.

One of the things I recent noticed in the mornings is that the temperature inside the house very closely matches the temperature outside of the house in the morning. This leads me believe there is still an air leak someplace on the first floor that I overlooked.

Then, the solution happened. One evening while cleaning up the dishes and retrieving the dishwasher detergent from under the sink, I noticed that even though the heater was running and the room was warm, it was VERY cold in the cabinet under the sink! The next series of steps revealed the problem:

  • After removing all the supplies we store under the sink, I discovered a fairly large hole leading to the crawl space near where the hot and cold water enter from pipes in the crawl space. Though it wasn't conclusive if that was the issue, the hole was certainly suspicious. 
  • Shining a flashlight down through the hole and awkwardly pivoting my neck to avoiding the pipes, I swore I could see the dirt in the crawl space! Could it be that the hole actually led directly to the un-insulated crawl space with air vents?
  • The next day after work, I checked again and this time, I could see light from under the crawl space! I was convinced I had located the problem.
  • Given the gap between the water pipes, I decided to check out areas on the first floor which may lead to similar types of air gaps such as the gas pipes leading to the stove top and water pipes leading to the first floor bathroom. Not to my surprise, those pipes also exhibited the exact same problem.

Next, to find a solution to seal the gap. Doing some research online, I found many recommendations for Great Stuff: Gaps and Cracks. "Great Stuff" has many different types, but the Gaps and Cracks version was best formulated for my needs. It's an insulating foam sealant that seals gaps up to 1 inch. The product looks very similar to can of compressed air or WD-40. It comes in a can with a plastic straw. Pull the trigger to dispense. The only difference is the can is mostly a one-time use (so located all the gaps before starting), and you need to vigorously shake the can before starting (read the instructions carefully). Other than that, the instructions are fairly simple and completely DIY. Just spray the foam, enough the seal up the hole. The foam comes out like whipped cream or shaving cream. When the foam dries, it expands to fill the gap and then hardens. Any excess can be easily cut off with a razor and even painted over after it dries.

Great Stuff: Gaps and Cracks has favorable reviews on Amazon, with many of the same negative reviews occurring over and over. Here's a summary of the reviews from Amazon:

  • It's messy! You should definitely wear a pair of disposable latex gloves while applying and keep a packet of paper towels to quickly wipe up any messes. It's difficult to get off your skin and clothing (even with spirits). I got a bit on the tip of my hair and it was easier just to cut the edge off.
  • Prepare all the areas you want to seal before you start. This means removing any items stored around the area and plan how you want to attack the gap. Sometimes, fitting the can past cabinets and drawers is difficult. My suggestion is to do the difficult locations first before the Great Stuff can gets messy.
  • After you release the trigger, be prepared for a bit of excess foam to continue coming out. After a few pulls of trigger, you'll get the hang of it. If you don't have many gaps to fill, do a few practice trigger pulls on a paper towel.
  • Cover any furniture or "finished" areas just to be certain.
  • The trigger can be difficult to work, and sometimes doesn't pop back. Be prepared to either pull the trigger manually in the other direction.
  • It's not to be used in areas with extreme heat, like a fireplace. Also not recommended to seal up flower beds.
  • Suggested to have benzene or acetone for cleanup. I didn't use this, so I can't comment one way or the other.
  • You need to use the entire can at once. You can't seal up one gap and save the rest of the container for later. Therefore, if you only have a few gaps, buy the smaller can.

The result of applying Great Stuff: Gaps and Cracks was a much warmer home. Not only the the warm air from the heater last longer (the heater turns on fewer times each night), but air under the cabinets was now the same temperature as the room. Even if there are other "gaps" in the home someplace, Great Stuff did the trick in sealing up the holes. If I find more holes, I'll certain turn to another can of Great Stuff.

Ever since we moved into our home in Millbrae, our guests have commented our home is notably chilly. We felt it too, but wasn't sure what to do about it. Here's are the projects I've done to improve the temperatures inside my home. For those not familiar with Millbrae, it is a city in the SF Bay Area. The weather rarely gets to freezing temperatures in the winter and rarely gets to 100F in the summer. We never get snow.
  1. Results of Re-Insulating Attic in SF Bay Area
  2. How to Seal Power Outlets and Switch Airleaks
  3. Better Home Insulation by Sealing Gaps
  4. My Dog Door for Sliding Patio Door Is Drafty? Seal it with Insulation!
  5. Solving Water Intrusion into VERY SHORT Dirt Crawlspace
  6. Alternative to Messy "Great Stuff"
  7. How to air seal recessed lights on a budget?
  8. My Research on Vapor Barriers Before Meeting a Crawlspace Contractor
  9. How to Stop Cold Air from a Unused Fireplace
  10. Stop Draft around Gap of a Unevenly Warped Front Door
Official Thought Worthy Logo

Can't Find What You're Looking For?

Buy Stuff
Suggested Reading