The short answer
Ask every contractor for an itemized, written plan, then line the plans up on the same rows: liner, sealing, drainage, drying method, insulation, mold work, framing repair, permit and warranty. Most of the gap between two prices is usually scope, not markup. Then read each warranty for what it covers, for how long, whether it transfers, and what keeps it valid. Raleigh Crawl Space & Foundation doesn’t issue or back any warranty; the contractor who does the work does.
Line up the scope
| Item | What to compare |
|---|---|
| Ground liner | Product name and thickness; the North Carolina minimum for a closed crawl space is 6-mil polyethylene or equivalent |
| Seams and edges | Taped seams; liner sealed to walls and piers, with the termite inspection gap left open |
| Walls | Liner on the walls, a sealant or foam board, or nothing; NC code allows any of these approaches |
| Vents, rim and gaps | Which openings get sealed, and with what |
| Drainage | Grading, an interior drain, a sump pump, and where they discharge |
| Drying method | Which of the code’s methods, the equipment model and size, and where it drains |
| Insulation | Removed, replaced, left in the floor, or moved to the walls |
| Mold and cleanup | What gets cleaned or treated, and what debris gets hauled out |
| Framing repair | Any joists, sills or girders being sistered or replaced, and how many |
| Permit | Who pulls it, and whether the fee is included |
| Monitoring | A humidity monitor, a water alarm, or nothing |
If one quote is missing a row, ask whether that item is excluded or just not written down. “Options” listed below the total aren’t in the price.
Compare the drying method closely
The dehumidifier or other drying method is the part of a closed crawl space most likely to differ between quotes, and the part most likely to need attention later.
- Size. Advanced Energy notes there is no standard protocol for sizing a crawl space dehumidifier; manufacturers give general guidelines. Ask each contractor why they chose that unit.
- Target. Advanced Energy’s guide recommends setting the humidity to the desired level, 70% or lower. Ask what setting they’ll use and how you’ll see the reading.
- Drain. Where the condensate goes, whether there’s a pump, and whether there’s an overflow pan with a shutoff switch.
- Power. Whether a dedicated outlet is included in the price.
Reading the warranty
A warranty is only as good as its wording. NC DOJ advises getting guarantee terms in writing. Then check:
- What’s covered. The liner? Labor? The dehumidifier, or only the manufacturer’s warranty on it? Any framing repair? Humidity performance?
- For how long. If it says “lifetime”, whose: yours, the company’s, or the house’s?
- Transfer. Does it pass to a buyer if you sell, within what time, and for what fee?
- Conditions. Does it require a paid annual service visit? What happens if you skip one?
- What voids it. Plumbing leaks, floods, damage by other trades, power outages that stop the dehumidifier, unapproved changes?
- How to claim. Who you call, how fast they respond, and what they’ll need from you.
- Who stands behind it. The contractor alone, or a manufacturer too, if the company closes?
Advanced Energy describes what a performance-based guarantee can look like: relative humidity held below an agreed target, for example relative humidity not to exceed 70% at a specified monitoring point for more than 7 consecutive days, with exceptions for leaks outside the installer’s control. A guarantee tied to a measured humidity level tells you more than one tied to a material.
Extras an installer may offer
Advanced Energy says quality installers usually offer one or more quality assurance options, such as:
- a monitoring system that reports crawl space humidity,
- a water alarm for liquid water buildup,
- a posted sign identifying the system’s parts,
- a repair kit for small tears in the liner,
- a guarantee that humidity stays below an agreed target, and
- an annual monitoring service, replacing sensor batteries and checking the system.
If two quotes are close on price, these are often where the real difference lies.
Payment and paperwork
- A written contract first. NC DOJ advises a written contract listing all the work, its costs and a completion date before work begins.
- No full payment up front. NC DOJ says to inspect the work before you pay, pay nothing without a written contract, and avoid cash. Wake Forest’s inspections department adds: never pay in full until the job is complete and all inspections have passed.
- Financing. If a contractor offers a payment plan, get the interest rate, the term and the total cost in writing.
- Cancellation. A contract signed at your home can be canceled under state law up to three days after signing, according to NC DOJ.
Red flags
- Pressure to sign today, or a price that’s only good if you sign during the visit.
- A small advertised job that turns into a list of alarming, urgent problems; NC DOJ warns about exactly this.
- Advice to skip the permit. North Carolina requires one to convert to a closed crawl space regardless of cost.
- A scope written as “encapsulate crawl space” with no materials or quantities.
- A warranty described in the brochure but not in the contract.
- Cash only.
A worked comparison
Example: Quote A is $7,800 for liner, sealing, a dehumidifier and the permit. Quote B is $11,500 and adds an interior drain, a sump, wall insulation and a five-year monitoring plan. Quote B isn’t overpriced if the crawl space gets water after storms; Quote A isn’t a bargain if it leaves that water under a new liner. The question is which scope matches what the inspection found.
Want a contractor to look at it? Call to schedule an inspection.