Home Systems: What They Cost to Replace and When to Do It

I've been fixing houses since before cordless drills. You don't have to learn the hard way. When I say "home systems," I mean the bones: electrical, plumbing, HVAC, and sometimes the water heater and sewer line. These aren't sexy. They're expensive. And if you ignore them, they'll wreck your renovation budget faster than any backsplash tile.

Let me give you the numbers up front. A full rewire of a 1,500-square-foot house runs $8,000 to $18,000. Replacing all the copper plumbing with PEX: $4,000 to $10,000. A new furnace and AC: $6,000 to $12,000. And a sewer line replacement? That's $4,000 to $15,000, depending on how deep the tree roots are. These are the numbers I've seen across 38 years of bidding jobs in Cleveland. They hold up in most markets.

No one wants to spend money on stuff they can't see. I get it. But I've also seen a homeowner spend $60,000 on a kitchen remodel and then realize the knob-and-tube wiring in the walls is a fire hazard. That's an expensive do-over. So when you're planning a renovation, start with the home systems that keep the house safe and comfortable.

How Much Does a Home Systems Overhaul Cost?

Let's break it down by system so you know what you're looking at. I'll use mid-range contractor prices for a typical 1,500-square-foot house built in the 1950s. Your mileage may vary, but these are the numbers I've written into hundreds of estimates.

• **Electrical panel upgrade (100 to 200 amps):** $1,500 to $3,500. If you have an old fuse box or a small panel, this is required before any major reno. New circuits for a kitchen or bathroom add $500–$1,000 each.
• **Whole-house rewire:** $8,000–$18,000. Includes running new Romex, swapping outlets and switches, and bringing everything up to code. Takes a crew of two about a week.
• **Plumbing repipe:** $4,000–$10,000 for PEX. Copper is $8,000–$15,000. PEX is easier to install and won't burst if it freezes. I switched to PEX on jobs around 2005 and never looked back.
• **Water heater replacement:** $800–$1,500 for a tank; $1,800–$3,500 for a tankless. Tankless saves energy and space. But it needs a dedicated gas line and venting. Factor that in.
• **HVAC (furnace and AC):** $6,000–$12,000 for a mid-efficiency system. High-efficiency (over 95% AFUE) runs $8,000–$15,000. If you're ductwork is old or leaking, add another $2,000–$5,000 for sealing or replacement.
• **Sewer line replacement:** $4,000–$15,000. If your cast iron pipe is corroded or tree roots have cracked it, you'll need to dig up the yard or do a trenchless repair. Ask me how I know: I once paid $12,000 to replace a sewer line that a previous owner had patched with tape.

These numbers are estimates for a finished job. Permits and inspections add 5–15% overhead. But here's the thing: replacing a home system after you've put up drywall costs double. So do it before you finish the walls.

Signs Your Home Systems Are Begging for Help

Home systems don't fail overnight. They send signals. You just have to recognize them before they become emergencies.

**Electrical:** Lights flicker when the microwave runs. Breakers trip more than once a month. Outlets are warm to the touch. You still have two-prong outlets. Or you see old fabric-covered wire (cloth wiring) when you open a switch plate. That stuff is a fire waiting to happen.

**Plumbing:** Water pressure drops when two faucets run. Drains gurgle. You see rust or green stains on pipes under the sink. Low water flow at all fixtures? That's often a sign of scale buildup in old galvanized pipes. Time to repipe.

**HVAC:** The furnace is over 20 years old and the AC is over 15. You're adding $50 a month to your energy bill every year. Rooms are unevenly heated. The system cycles on and off constantly—short cycling. That's a sign of a failing compressor or heat exchanger.

**Sewer:** Slow drains, frequent backups, or water in the basement during heavy rain. Sewer line issues often show up after a major storm. A camera inspection costs $300–$500. It's the cheapest insurance you'll ever buy.

If any of these sound familiar, don't wait. Call a licensed pro. A $500 inspection can save you from a $10,000 emergency repair.

The Order of Operations for Replacing Home Systems

If you're doing a full-house renovation, the order matters. Here's the sequence I've used for 30 years.

1. **Sewer line and foundation work first.** Fix any leaks, cracks, or root damage before you touch anything inside. You don't want to finish the basement and then dig it up.
2. **Electrical and plumbing rough-in.** Both go in the walls and floors. They need to be done before insulation and drywall. Coordinate with your contractor so electricians and plumbers aren't in each other's way.
3. **HVAC ductwork and equipment.** Install new ducts or modify existing ones. Then set the furnace and AC. This comes after the rough-in but before drywall so you can run ducts through open walls.
4. **Insulation and drywall.** Now you can close up the walls. But only after all the systems are inspected and signed off.
5. **Trim, doors, cabinets, and finish work.** These are the last things. Don't paint until the drywall is up and mudded.

If you skip the home systems step, you'll be cutting into finished walls later. I've seen it a hundred times. "Oh, we'll just add an outlet later." No. That's a $200 fix if you do it during the rough-in. After drywall, it's $800.

How to Pick a Contractor for Home Systems

Not all contractors do all systems. You'll need specialists: an electrician, a plumber, and an HVAC contractor. But you can hire a general contractor (GC) to coordinate them. That GC should have 10+ years experience with whole-house renovations. Ask for five recent references and call them.

Get at least three bids. The lowest is rarely the best. I've seen bids for a rewire range from $8,000 to $18,000. The cheap guy will leave Romex exposed or skip permits. The expensive one might be padding the price. The mid-range bid with a detailed scope of work is usually the one.

Also, ask about warranties. Most pros give a one-year labor warranty on home system replacements. The equipment itself (panels, water heaters, furnaces) has a manufacturer's warranty of 5–10 years. Get that in writing.

Ask Me How I Know

I've screwed up plenty of jobs. That's why I'm telling you this. About 10 years ago, I convinced a client to finish her basement without replacing the old galvanized plumbing. Two years later, a pipe burst and flooded the whole thing. Total cost to repair: $18,000. Cost of repiping during the original reno: $6,000. She didn't yell at me. She just said, "You told me." I've been carrying that one ever since.

So here's my bottom line: don't treat home systems like an afterthought. Budget for them first. Check their condition before you start picking out faucets. And if you're unsure, pay for an inspection. A good contractor will walk through your house and tell you what's worn out. That inspection costs $300–$500. It's the cheapest education you'll get.

Of course, I've screwed up plenty of jobs too. That's why I'm telling you this. Do it right the first time, and your home systems will last another 30 years.