I know I’m gonna go against convention wisdom here. People may think I’m crazy or they’ll be p.o.’d that they spent money doing this the wrong way. I know, I can hear you now. “A friend of a friend’s grandpa said this was the way to do it!” Or,”The handyman who touches up paint or built those shelves out in the garage said this was how you do it!” Well, they are wrong, alllll wrong. Most likely they told you to put insulation between the joists in the floor of your first floor/ceiling of the basement or crawlspace. The crawlspace is a whole other post which 90% of homes get completely wrong in my humble home inspector opinion. I’ll deal with this later. For now we are going to go over a little know aspect of home insulation. The attic is child’s play. I expect more out of myself for my readers.
To start with, I don’t think I’m going out on a limb if I say we can all agree that heat rises? If you aren’t with me at this point just find a blog about what Lindsey Lohan or Justin Bieber is up to and leave me alone. Back to said heat rising, if we cut off any airflow between the basement and the first floor the only thing that will happen is heat will rise and there will be a big temp difference between the floor and your thermostat where it is mounted on the wall. Trust me, this was happening at my house and cold feet are unhappy feet! The floor temp was 60 degrees and the thermostat was set on 68 degrees. By insulating the floor you are also actually not helping to keep any heat IN the house. “But Travis, the basement is cooooold and it feels like it comes up through the floor and makes my tootsies cold!” That brings me to the second point, you need to get some open heat vents directing heat into the basement area. If you think about it, and I do because that’s how I roll, you really need less heat output to the second floor of your home and more to the basement and first floor. This is where most of us spend the most time while awake at our casa.
Now, where to insulate since you are asking? The rim joist is the first spot. Along the top of the wall in the basement above the wood sill plate there will be spaces where you can cut pieces of foam board or fiberglass insulation to fill in the space. If it is foam board try to fit it in snuggly. If it is fiberglass, it should fit in and stay without falling out but not be packed in there. If you pack it in tight it will lose its fluff and insulating capabilities.
The next spot? Your basement walls! Wow, did I just blow your mind? Seems strange, huh? We all know about insulating behind walls but not on the outside of the wall. Here is the dealio and I may just blow your mind again. This tip is called the “Rule of 55”. The ground stays a constant 55 degrees at 55″ down from the ground level. This means that your basement walls from 55″ down (from ground level) and up will get very cold in the winter. Downright freezing. That is why we have to bury water lines, foundations, etc at least 48″ down below what we call the frost line (If you are in Florida or some other climate that does not get winters, well, I hope you’re happy with yourself. We’re freezing up here! Send us some oranges or peaches or something). If you insulate down from the sill plate to AT LEAST 55″ below outside ground level you will be doing a service to the heat retention and comfort of your whole home, not just the basement. If you disregard me and insulate the ceiling of the basement, you will have a very cold basement and a cold floor on the first floor (again, the feet!) and you deserve it. This also keeps the basement from being isolated from the house and holding in moisture which is also not good for the house. You will get a mustier basement and could also possibly get mold and mildew growing on things.
Well, that’s it for now. Thanks for reading,
That Home Inspector Guy