The Fairfield County Buyer’s Due Diligence Checklist: What to Check Before You Make an Offer

The short version: in a market where buyers finally have a little more time, the smartest thing you can do is use it. Before you make an offer on a home in Darien, New Canaan or Rowayton, these are the checks that protect your money, your timeline and your peace of mind.

In my September Market Update, I wrote that one advantage for buyers this fall is time for proper due diligence. Here is exactly what that looks like. Some of it happens before you write an offer, and some of it happens during your inspection period, which is set in your contract.

1. Pull the Town Records Before You Fall in Love

Every town keeps files that tell you what has been approved, and what has not. I review these with my buyers before we make an offer:

• Building permits. Were the finished basement, addition or new kitchen permitted and closed out? Open or missing permits can delay a closing or become your problem after it.
• Zoning. Setbacks and lot coverage limits decide whether you can add a pool, garage or addition later. If you are buying with future plans, check them now.
• Wetlands and coastal rules. Properties near water or wetlands may need extra approvals for changes, especially along the shoreline.
• Property card and taxes. Confirm the square footage, lot size and assessment match the listing.

2. Sewer or Septic? Know Before You Offer

Not every home in Fairfield County is on town sewer. Many Darien and New Canaan homes are on private septic systems, and that changes both your inspection and your future costs.

• On septic: ask for pumping and repair records, and plan a septic inspection during your inspection period. The town health department often has the system’s original plans on file.
• On sewer: confirm the connection and ask whether any sewer assessments or fees are outstanding.
• Planning to add bedrooms? A septic system is sized for a specific number of bedrooms, which can limit expansion.

3. Check the Flood Zone and Get an Insurance Quote Early

For waterfront and near-water homes in Darien, Rowayton and Norwalk, this step is essential. Look up the property’s FEMA flood zone, ask the seller for an elevation certificate if one exists, and get a homeowners and flood insurance quote before your inspection period ends. Insurance costs can change the math on a coastal home, and you want that number while you can still negotiate.

4. Schedule the Right Inspections

A general home inspection is the starting point, not the finish line. Depending on the house, I usually recommend adding:

• Radon. Connecticut recommends testing, and the EPA action level is 4 pCi/L. Mitigation is common and usually straightforward to fix.
• Well water, if the home is on a private well, including radon in water.
• Oil tank sweep. Older homes may have a buried oil tank, even if the house now heats with gas.
• Chimney, roof and pool inspections for older or higher-end homes.
• Wood-destroying insects, standard for most lenders.

5. Read the Seller’s Disclosure Carefully

Connecticut sellers are required to provide a Residential Property Condition Report before you sign a contract. If they don’t, the buyer receives a $500 credit at closing. Read it line by line. What the seller says about water in the basement, the roof’s age or past repairs tells you where to point your inspector.

6. Line Up Your Pit Crew Before You Need Them

Due diligence moves fast once your offer is accepted. Have your team ready from day one: a real estate attorney (in Connecticut, attorneys handle the contract and closing), a lender with your full pre-approval, an inspector, and an insurance agent. My Buyer Roadmap walks through each step.

Your Quick Checklist

Want the full step-by-step version? Download my free Home Buying Checklist (PDF), eight stages from getting pre-approved to getting your keys.

• Building permits and zoning checked
• Sewer or septic confirmed
• Flood zone and insurance quote
• Radon, well, oil tank and specialty inspections scheduled
• Seller’s Property Condition Report reviewed
• Attorney, lender, inspector and insurance agent ready

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Want the Complete Roadmap?

This checklist is just one piece. My free 2026 Fairfield County Buyer Guide walks you through the full process — the 4-L Framework for choosing the right home, the complete due diligence playbook, and how to assemble your Pit Crew before you make an offer. Buying in Darien, New Canaan or Rowayton? Start here.

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Frequently Asked Questions

What should I check before buying a house in Darien, CT?

Check building permits and zoning with the town, confirm whether the home is on sewer or septic, look up the FEMA flood zone, get an insurance quote early, schedule a general inspection plus radon and any specialty inspections, and read the seller’s Residential Property Condition Report.

Do Connecticut sellers have to disclose problems with the house?

Yes. Connecticut requires sellers to provide a Residential Property Condition Report before the buyer signs a contract. If the seller doesn’t provide it, the buyer receives a $500 credit at closing.

Is radon common in Connecticut homes?

Radon can be found in homes across Connecticut, which is why the state recommends testing. The EPA recommends fixing a home if radon levels are 4 pCi/L or higher, and mitigation systems are common.

Do I need a lawyer to buy a house in Connecticut?

In Connecticut, real estate attorneys typically handle the purchase contract, title work and closing. It’s one of the first members of your team to line up.

This article is for general information and is not legal, tax or insurance advice. Requirements and town procedures vary, so confirm details with your attorney, inspector and the relevant town office.

Buying this fall? Let’s talk strategy, or set up free listing alerts so you see new homes first.