Submitted by foodtower t3_108izdt in personalfinance
Specifically, the basement/crawlspace and attic are very cost-effective places to insulate. This is especially true for houses older than a couple decades. I have no personal stake in the insulation business and say all this as someone who learned from working on my own home. Here are some tips:
- Basement/crawlspace: are the walls just bare concrete? Is there any insulation between the joists under the house's floor? If no to both--or if there is insulation under the floor but it's sagging or damp--the insulation is inadequate and you're losing tons of energy (and money) through the foundation walls.
- These days, most people advise insulating the inside of the foundation walls and not under the first floor (though if you already have insulation under the floor and it's in good shape, you can keep it). Insulating the walls also helps keep any pipes in your crawlspace from freezing, and will prevent additional heat loss if you have any ducts/furnace/AC/water heater down there.
- I'm a fan of EPS foam board because it's cheap, works well, easy to DIY, and causes less pollution than other types of foam. Colder climates will probably want 2 layers of foam board (R-15); warmer climates might be ok with 1. In my case, I calculated a payoff time of around 2-5 years for adding these; it would be even faster if I kept my house at more typical heating/cooling temperatures.
- If you have a crawlspace, you may want to seal the crawlspace floor with a vapor barrier ("encapsulation"). If you have a moisture problem down there, you should definitely do that. Now is a good time to run a cheap test for radon in your house to protect you and your family from lung cancer; if you have radon, encapsulating the crawlspace will be a big part of the treatment.
- Attic: if you have an attic, blowing in insulation is cheap and you can rent a machine to DIY it if you want. Take a look up there and use this site to determine if you have enough, and how much you should add.
- Walls: unlike attics and crawlspaces, walls are harder and more expensive to insulate. However, if you're doing a remodel project that involves removing wall sheathing already, you should definitely assess whether you wall insulation is adequate, and improve it if needed. This site has some notes on wall insulation at the bottom.
- Sealing leaks: this is potentially the most cost-effective item on the list. Search for leaks in the crawlspace and attic (easiest before insulation is added). Leaks in the house matter too, but leaks at the top and bottom of the house matter most. There's a good chance you'll find holes big enough for a cat to crawl through, and those should be blocked with wood or foam board. Smaller leaks can be sealed with spray foam or caulk.
- Energy assessment: you can hire an expert to come out, assess how leaky your house is and whether the insulation is adequate, and recommend fixes. Your state or utility may offer incentives for this, and it also benefits from the federal tax credit.
Update: info on new tax credits. Also, this work will improve the comfort of the house (e.g., avoiding the situation of 70-degree air but cold floors and ceilings) and make it so when you replace your furnace/AC, your replacement can be smaller, cheaper, and more efficient.