The short answer
When you’re buying an older house in Northern Virginia, the costly surprises are mostly the same five: the water pipe, the sewer line out to the street, the age of the furnace and water heater, the refrigerant in an old AC, and any work done without a permit. Most of it you can check on your second walkthrough with a phone flashlight. Here’s what we’d look at if it were our own offer, and what to do with what you find.
What to check, and what it tells you
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Swipe to see all columns →
| Look at | What you’re looking for | What it means |
|---|---|---|
| Water pipe where the main comes in | Gray flexible plastic stamped PB2110, or dull gray threaded steel | Polybutylene or galvanized. Ask about a repipe before you close. |
| Furnace or heat pump label | The year it was made | Past 15 years, plan on replacing it soon. |
| Water heater label | The year, and any rust at the base | Past 10 or 12 years for a tank, plan on it. |
| Outdoor AC unit label | R-22 on the nameplate | Old refrigerant. Repairs get hard to justify. |
| Basement floor and walls | Stains, a sump pit, a musty smell | Water has been here. Ask when and how often. |
| Trees between the house and the street | Big ones, on a house from before about 1980 | Roots and old sewer pipe. Get a camera down it. |
| Service stickers on the equipment | Dates and a company name | Somebody took care of it, or nobody did. |
The $67 Heating Check
We check your furnace, heat pump or boiler before winter. Through December 31. See the offer
The water pipe
If the house was built or replumbed from 1978 to 1995 and you see gray plastic with crimped fittings, that’s polybutylene, and it’s the clearest case for a repipe there is. Check how to identify it and what to do. A house can be part copper and part something else, so look in more than one spot. Dull gray threaded steel on an older house is galvanized, and it rusts from the inside, which is why the whole house can lose pressure.
The sewer line
This is the one that gets people. Fairfax County says plainly that the homeowner is responsible for the private sewer line from the property to the county sewer, and a standard inspection doesn’t put a camera down it. On a house from before about 1980, especially with mature trees in the front yard, a sewer camera inspection before closing is about the best money in the deal. If it turns up trouble, here is what replacing that line involves, and you can talk about it while you still have leverage.
The heat and the AC
Read the year on the label. Don’t take “recently updated” from a listing at face value. Here’s how long a furnace really lasts, and if the inspector already told you to replace it, read this before you take that as final. It’s often a judgment call from a generalist with a three-hour appointment.
On the outdoor unit, look for R-22 on the nameplate. The EPA ended new production and import of it in 2020, so a leak on one of those systems usually turns into a replacement talk. Here is what new systems use. And while you’re touring, walk into every room with the heat running. A cold room now is a cold room for as long as you own the place, and leaky ducts are a common reason.
The water heater and the basement
The year’s usually right on the label. Check how long a water heater lasts and look for rust or water at the base. On a crawl space house, take a flashlight and see if pipes run near the vents, where they freeze. If there’s a sump pit, ask the seller how often it runs and pour in a bucket to watch it work. Then ask to see where the main water shutoff is. If nobody can find it, that tells you something about how the house has been kept.
Ask the seller for these
- Service records for the furnace, AC and water heater.
- Permits for any finished basement, added bathroom or new system. Your county can look these up too.
- Any past water in the basement, backups or frozen pipes, and what was done.
- Whether there’s a home warranty, and what it leaves out.
Once it’s yours
Don’t stop here. Our first-month list for new homeowners takes it week by week, and most of it’s free. Before the first cold night, run this test on the furnace.
Questions people ask
Does a home inspection check the sewer line?
Usually not. A standard inspection runs water and watches the drains, and it doesn’t put a camera in the line out to the street. If you want to know, ask for a sewer camera inspection.
How do I tell if a house has polybutylene pipe?
Look for gray flexible plastic, sometimes blue or black, stamped PB2110, where the main comes in, at the water heater and at the shutoffs under sinks. It went into houses built or replumbed from 1978 to 1995.
How old is too old for a furnace in a house I’m buying?
Age alone doesn’t kill a deal, but it tells you what to plan for. Read the year on the label, and if it’s past 15 years, plan on replacing it sometime in the next few.
Can a plumber or HVAC tech look at a house before I close?
With the seller’s OK, yes. It needs to be set up through your agent during your inspection window. Ask early, because that window is short.
Book it
Already closed? Have someone walk it with you. The $99 water heater flush includes a walk through the house’s plumbing with photos. Book it from goswiftpro.com/cookiesoffer and free MOLTN cookies come with the visit. Or call (703) 997-9757. SwiftPro is rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
