Renovating or remodeling a house isn’t cheap—the average renovation costs around $22,000, and the cost to totally gut and renovate a house can be as much as $200,000. The most frustrating aspect of a home renovation isn’t the cost, though—it’s the unpredictability. No matter how meticulous you are with your budget, just about every home renovation project goes over budget—you’re well advised to set aside an extra 10-20% of your initial budget for the unexpected. There’s a way to offset these costs that most people overlook, though: scrap metal.

If you’re gutting a room or an entire house, you’re likely pulling some valuable materials out of the walls, floors, and ceilings. If you’re just ordering a dumpster and tossing it away, you’re losing money on the deal—sometimes a lot of money. Here’s what to look for if you’re ripping stuff out of your home as part of a renovation.

Plumbing and wiring

Copper isn’t considered valuable in the same way gold or silver is—but its importance as a construction material and the ease of recycling it makes it worth salvaging (and also worth stealing). If you’re having your house re-wired and/or replacing old copper pipes with new plumbing, you should check the current scrap prices in your area. Copper typically commands the highest price in the scrap world.

It doesn’t matter what condition it’s in, either. Old, banged-up stuff is just as valuable to a scrap dealer as any other kind. Keep in mind that the copper in your home might be mixed with other metals, so you might get an unwelcome surprise when the dealer examines it and makes an offer; but if it’s pure copper, you’ll be in the money.

If you’re renovating an older home, lead pipes also have value. While lead pipes are terrible for someone who lives in the home, the lead itself is valuable. Not all scrap dealers handle lead because of its toxic nature, so make some calls before you load up your car.

Gutters and roofing

If your house has an old metal roof you’re replacing, chances are those panels have some value, even if they look like they’re in rough shape. Common metal roof materials include copper, aluminum, steel, and tin, all of which have some value as scrap metals.

Old gutters may be made of aluminum, so if they’re rusted and dented and need replacing, you might as well check to see how much you can get for them from a scrapper.

Fixtures and hardware

Another potential source of scrap profits from a renovation or remodeling project is the fixtures and hardware in the home—faucets, doorknobs, drawer pulls, and light fixtures. These are often made from brass or other metals with some scrap value. If you’re pulling them out of a large house, you might wind up with quite a lot of them.

A final potential source of scrap metal is steel, including stainless steel. Steel is relatively low value in terms of scrap—it’s usually priced by the ton, whereas copper and other metals are priced by the pound. That means it’s probably not worth scrapping all the steel in your home unless you have a lot of it—but if you’re going to be scrapping other metals, you might as well throw in those steel panels from your kitchen appliances.

How to scrap

If you’re planning a home renovation and you want to cash in on all that sweet scrap, it’s a pretty straightforward process: Identify and organize your scrap by metal type, contact a local scrap dealer, and transport the scrap metal there. Not all scrappers are looking for all materials, so you might need to contact more than one if you have multiple kinds of metal to sell, and you can certainly compare prices between different scrap dealers to make sure you get the best price for your scrap.

The iScrap app is a useful tool. It can help you locate local scrap dealers and keep you updated on the national prices for different materials (right now it puts the national average for copper at $3.15 per pound) so you’ll know if you’re getting a fair offer for your trash.