Written by Dale Richardson - Updated: June 23, 2023
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Today we're going to talk about copper pipe in concrete, specifically the piping for your radiators and home heating system. If you recently moved into a home and have noticed an abundance of your home's heating pipes run through concrete, you likely have questions. Will you lose heat? Is it bad for the concrete or pipes? Why run copper piping through concrete in the first place? These are all valid questions that we'll answer in due time, so stay tuned.
Copper pipe in concrete is not the most normal thing, but it is manageable with proper care.
That may not mean much to you right now, but keep reading and it will all make sense soon!
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Let's start with talking about how your home's pipe system works and why we do specific things with it, like burying copper pipes in concrete. While it's not the most common approach, it is still done.
First things first - why bury pipes in the floor at all? Well, that's a simple answer - they may have nowhere else to go! If you have a basement, it's very likely that all of your piping just runs through that without being covered. But if you're in a single-floor home with limited space, pipes all over would get in the way.
Now, you can't just bury a copper pipe in concrete and call it a day - there's more that needs to be done to make it okay. If you notice bare copper pipes running through concrete in your home, it's likely that you'll want to call a professional to take a look. It's not always a problem if the insulation and proper preparations have been applied, but if not you could have some bigger issues down the line.
Another thing to take note of is that things like nitrates, ammonia, and chlorides can cause stress corrosion fracturing of copper - but none of those should be anywhere near your piping. Unless you're leaving an open bag of fertiliser or ammonia near your pipes, they should be fine.
If you're the one laying copper piping, there are a few things to know. But first, a disclaimer - I've never done this. I always let the pros lay new pipe as I'm a shaky mess that isn't the best with math. But if you're the opposite, it's good to have some basic knowledge I picked up from the plumbers while waiting.
First things first, copper and concrete can and will form a chemical reaction if left together. This can easily be avoided through coating and insulating your copper piping, but that's the main reason that most plumbers at least try to run them elsewhere.
Generally, one of two things happens when running copper piping through concrete:
One way or another, the most important thing you can do to prepare copper pipe to go through concrete is to measure, and then measure again. That's because the change in temperature causes the pipe to expand and contract. If concrete were poured directly over it (please never do this), it would crack and shift as the pipes move. That leads to a whole host of other problems that are for another article, a different day.
Generally, you don't need to worry about copper and concrete reacting poorly - assuming the concrete was mixed properly. If, however, the concrete is highly alkaline, it can cause the copper to react negatively to the concrete.
This is why we run a PVC sleeve over copper (in most cases) when it goes through concrete. Add in that copper is a surprisingly soft metal, and it's good to have a bit of extra protection. Without it, long-term exposure to limestone and limescale buildup could pierce the pipe, leading to a leak. And nobody wants that.... I hope.
In short, copper and concrete only react when there's a mistake made somewhere along the line - all the more reason to hire a pro to do this. Properly prepared concrete won't react with bare copper, though it's not a good idea to lay bare copper piping in concrete one way or another.
On the plus side, most manufacturers of copper piping now pre-coat their pipes to prevent any sort of corrosion caused by concrete.
One thing to note, though, is that copper pipes should never run close to rebar or wire mesh. If you're running a pipe through your foundation (which I can't recommend), you would need to have a dedicated space for the pipe that has no mesh or rebar. Galvanic corrosion can occur when those two metals on opposite ends of the spectrum come into contact.
There are a lot of myths and ideas that float around the internet. A common one is that concrete and copper chemically react to one another - while this can happen, it's not supposed to. Concrete reacting to copper means that somewhere along the line, someone messed up with mixing the concrete. Unless there's soluble chloride, ammonia, or nitrates in your concrete, you should be fine.
That's not to say, though, that you shouldn't properly prepare your copper piping. Giving it a protective coating (which many manufacturers do for you) can further reduce the risk of corrosion. Add a PVC pipe sleeve, and properly account for expansion and contraction of the pipes, and you're set. That's all to say - unless you're a very experienced plumber, it may be best to ask a professional to lay pipe for you. They'll make sure it's safe and properly done, preventing the possibility of damage to your pipes in the near future.
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