Cast Iron Pipes Before You Remodel | Revolution Contractors

If your St. Petersburg home was built before 1975, there's a good chance you have cast iron plumbing — and a better chance it's not in the shape you think. After 50 to 80 years of use, cast iron pipes corrode from the inside out. The question isn't whether to deal with them. It's whether you deal with them now, while your contractor already has the walls open, or later, when it means tearing into a finished remodel you just paid for.

Here's what you should know before your kitchen or bathroom project starts.

How to Tell if You Have Cast Iron Pipes

Most homes built in the St. Pete area between the 1940s and mid-1970s used cast iron for drain and waste lines. Supply lines (the ones that bring water to your faucets) were usually copper or galvanized steel. But the drains — the pipes that carry wastewater out — those are almost certainly cast iron if your home is from that era.

You can check a few ways:

Look under the house. If you have a crawl space, look for dark, almost black pipes with raised ridges at each joint. Cast iron is thick, heavy, and unmistakable once you've seen it.
Check exposed pipes. Garage ceilings, utility closets, and behind access panels often have visible drain lines. Cast iron will look dark gray or black with a rough texture.
Check your home's age. Built before 1975 in Pinellas County? Assume cast iron drains unless someone already replaced them. PVC (white plastic) became standard in Florida residential construction in the late 1970s.
Get a camera scope. A plumber can run a camera through your drain lines for a few hundred dollars. This is the only way to see what's happening inside the pipe — and it's the single best pre-remodel investment you can make.

What Goes Wrong With Old Cast Iron

What your plumber sees: cross-section of bathroom wall showing 80-year-old cast iron drain with internal corrosion buildup

Cast iron was a solid material when it was installed. The problem is what happens over 50 to 80 years of daily use.

Buildup and Corrosion

Decades of grease, soap, food waste, and bathroom products coat the inside of the pipe. Jeremy Wharton, owner of Revolution Contractors, puts it bluntly: “You've got 80 years of bacon grease in there.” That buildup narrows the pipe diameter and slows drainage — sometimes to the point where your drains barely work.

Chemical Damage

Drano, drain cleaners, and other high-pH solvents are the worst thing you can pour down cast iron. They eat through the iron itself, causing rust, thinning, and cracking from the inside. Fifty years of pouring drain cleaner into a cast iron pipe does more damage than the grease does.

Bellying and Sagging

Florida's sandy, shifting soil can cause underground pipe sections to sag over time. Water pools in the low spot, sediment collects, and the pipe corrodes faster at that point. This is especially common in St. Pete neighborhoods with older housing stock built on fill.

Root Intrusion

Tree roots find the smallest crack or loose joint in a cast iron pipe and grow into it. Once inside, they create blockages and accelerate the pipe's deterioration. A camera scope will show roots immediately.

Cracks and Breaks

Eventually, corroded cast iron cracks. When it does, you get sewage leaking under your slab or into your crawl space. By the time you smell it, the damage is already significant.

Why You Should Handle It During a Remodel — Not After

The $300 scope that saves $20,000: corroded cast iron pipe with 50 years of buildup compared to clean corrosion-resistant PVC and color-coded PEX supply lines

This is the single most important thing to understand: the cheapest time to replace cast iron plumbing is when your walls are already open.

During a kitchen remodel or bathroom renovation, your contractor is already doing demolition. The walls, floors, and ceilings are exposed. Your plumbing is visible and accessible. Adding pipe replacement at this stage is incremental work — the demo is already done, the space is already open, and the crew is already on site.

If you skip it and close everything up, replacing those same pipes later means:

Tearing out the new tile, drywall, and finishes you just paid for
Paying for demolition a second time
Living through a second round of construction
Spending two to three times what it would have cost during the original project

As Jeremy puts it: “Usually on any remodel of any size, that cast iron gets replaced because the best time is now, while walls are open.”

A $300 Decision That Saves Thousands

A camera scope costs a few hundred dollars. That one step tells you exactly what condition your pipes are in before construction starts — not after your plumber discovers a problem mid-project. At Revolution, we almost always scope the drain lines during pre-construction so there are no surprises once hammers start swinging.

What 70 years looks like from the inside: camera scope view of cast iron pipe interior showing grease narrowing the pipe, root intrusion, and barely draining opening

Ready to find out what's behind your walls before your remodel starts? Contact Revolution Contractors for a pre-construction consultation. We'll scope your pipes, assess your systems, and give you a real budget — not a guess. Call us at (727) 888-6161.

What Cast Iron Replacement Actually Costs

Let's talk real numbers for the St. Pete market.

Scope	Typical Cost Range
Camera scope (diagnostic)	$200–$400
Single bathroom drain replacement	$2,500–$5,000
Kitchen drain replacement	$3,000–$6,000
Full house drain replacement (to the street)	$10,000–$20,000
Slab penetration (cutting concrete for under-slab pipes)	$1,500–$4,000 additional

These numbers come from real projects in Pinellas County. The range depends on your home's layout, how much pipe needs replacing, whether drains run under a concrete slab, and how far the main line extends to the street connection.

The key context: when you're already mid-remodel, replacing drain lines during the project adds $3,000 to $8,000 for a typical kitchen or bathroom. Doing the same work as a standalone project — after your remodel is finished — easily doubles or triples that cost because of the demolition and refinishing required to access the pipes. For a full breakdown of what a bathroom remodel costs in St. Petersburg, see our cost guide.

What Goes Back In: PEX and PVC

Nobody puts cast iron back. Modern drain replacements use PVC (white plastic pipe) for waste and drain lines. For supply lines, PEX tubing has become the standard.

PEX Advantages Over Old Copper or Galvanized Supply Lines

Flexible — runs through walls with fewer fittings and joints
Corrosion-resistant — won't deteriorate in Florida's mineral-heavy water
Color-coded — red for hot, blue for cold — so future contractors know what they're looking at
Faster to install — fewer joints means less labor time and lower cost

PVC Advantages for Drain Lines

Smooth interior — resists the buildup that destroyed your cast iron
Lightweight and durable
Easy to repair if something goes wrong decades from now

How Revolution Handles Cast Iron Discovery

Most contractors treat cast iron plumbing as a “surprise” — something that gets discovered mid-project and dropped on the homeowner as an unexpected change order. That's not how we work.

Pre-construction scope. We get a camera down the drain lines before construction starts, not after. This happens during our pre-construction process while we're sharpening the budget and locking in costs.

Transparent pricing. We work on a time-and-materials basis, which means pipe replacement gets priced openly and added to the budget before it becomes a problem. You see the plumber's bid, you see our markup, and you approve it before any work starts. No hidden costs. No padded change orders.

Same crew, start to finish. Our 20-plus W-2 carpenters handle the demolition that reveals the plumbing and the rebuild after the plumber finishes. That's one crew that knows the project — not a rotating cast of subcontractors trying to piece together what the last guy did.

Weekly budget updates. You'll see exactly what the pipe replacement costs as part of your weekly budget review. If the scope changes during construction — say the camera shows the main line to the street also needs replacement — we discuss it, price it, and get your approval before touching anything. Learn more about how our remodeling process works.

Frequently Asked Questions

How Do I Know if My House Has Cast Iron Plumbing?

If your home was built before 1975 in the St. Pete area, you almost certainly have cast iron drain lines. Look for dark, heavy pipes in your crawl space, garage ceiling, or behind access panels. A camera scope ($200–$400) gives you a definitive answer about what's in your walls and what condition it's in.

Can Cast Iron Plumbing Be Repaired Instead of Replaced?

Sometimes. Epoxy lining can extend the life of cast iron that's corroded but not cracked. But if your pipes are bellied, cracked, or have root intrusion, replacement is the only real fix. And if you're already mid-remodel with walls open, replacement is almost always more cost-effective than a repair that might fail in a few years.

How Long Does Cast Iron Plumbing Last?

Cast iron pipes were designed to last 50 to 75 years. Many homes in St. Petersburg are now hitting 70 to 80 years — well past their intended lifespan. Pipes that have been exposed to drain cleaners, heavy grease, or Florida's corrosive soil conditions may fail sooner.

Will My Homeowner's Insurance Cover Cast Iron Replacement?

Typically not for normal wear and deterioration. Insurance may cover damage caused by a sudden pipe failure — like a slab leak that damages flooring — but the pipe replacement itself is usually considered maintenance. Check your policy, but plan on cast iron replacement being an out-of-pocket cost.

How Long Does Cast Iron Pipe Replacement Take During a Remodel?

For a single bathroom or kitchen, a plumber can usually complete the replacement in one to two days. A full-house replacement to the street may take three to five days. When done during a remodel, this work happens in the rough-in phase — before tile, drywall, or finishes go in — so it doesn't add significant time to the overall project.

Should I Replace All the Cast Iron at Once or Just the Section Near My Remodel?

If the camera scope shows deterioration throughout the system, replacing everything at once is almost always the smarter financial move. You're already paying for demolition and access. Leaving corroded cast iron in place means you'll likely face a more expensive standalone repair within a few years. Jeremy's recommendation: “If we're already in there, deal with it now.”

What's the Difference Between Supply Lines and Drain Lines?

Supply lines bring clean water to your fixtures (faucets, showerheads, toilets). Drain lines carry wastewater out. In older St. Pete homes, supply lines were typically copper or galvanized steel, while drain lines were cast iron. Both may need replacement during a remodel, but cast iron drains are the more urgent concern because they carry corrosive waste and deteriorate faster.

What to Know About Cast Iron Plumbing Before You Remodel