Read your crawl space estimate before you sign

Ask for inspection photos and findings that distinguish ground moisture from plumbing leaks, rainwater entry, condensation, and wood deterioration. DOE guidance calls for checking bulk water, moisture damage, pests, and foundation drainage before converting a vented crawl space. A liner is not a substitute for repairing a leaking pipe or controlling incoming water.

A ground-cover job should define the soil area covered and treatment of seams, edges, and supports. A closed-space conversion adds a coordinated plan for vents, wall coverage, insulation, and moisture control. Structural work needs its own description of affected joists, beams, posts, or footings; hiding them behind a clean liner does not repair them.

Floor area is only one measurement. Wall height, perimeter length, interior piers, irregular bays, and the access opening affect material quantities and installation effort. Tight clearance, standing water, debris, and buried obstructions can change preparation work. Ask whether measurements cover every crawl-space compartment rather than just the accessible main area.

Separate liner installation from drainage, sump equipment, mold cleanup, electrical work, insulation, and framing repairs. Specify liner product and thickness, reinforcement, seam treatment, and wall attachment instead of relying on a premium label. A thicker product alone does not explain whether penetrations and edges will be sealed.

For a dehumidifier, request the model, sizing basis, installation location, condensate route, and power requirements. If a sump is proposed, ask what water it collects, where discharge goes, and whether an alarm or backup is included. These are distinct systems with distinct maintenance tasks.

Make a side-by-side list of measured coverage, preparation, liner details, drainage, insulation, and moisture-control equipment. Mark each item included, excluded, optional, or unresolved. A floor-only liner and a sealed, insulated conversion are not equivalent bids, even if both contractors call their work encapsulation.

Ask each contractor to explain differences using your inspection findings. If one proposes a perimeter drain and another does not, request the evidence supporting each approach. For concealed damage, require a written change-order process and a description of how added work will be measured and approved before it proceeds.

DOE guidance treats an unvented crawl space as a system: ground moisture control, air sealing, insulation, and an appropriate drying or conditioning approach work together. Ask where the thermal boundary will be and how existing floor insulation will be handled. Sealing vents without a complete moisture-control plan leaves an important design question unanswered.

Confirm whether flood openings or termite inspection access constrain the design. DOE guidance calls for checking flood-vent needs and retaining pest inspection strips where required. Do not accept a blanket promise to seal every opening or conceal all foundation surfaces without checking local requirements.

If natural-draft fuel-burning equipment is present, ask how combustion air and safety testing will be handled. DOE recommends a combustion safety test after this conversion when such equipment is in the crawl space. Include post-work radon testing in the discussion; a moisture liner alone is not proof that radon has been controlled.

For deteriorated framing or displaced supports, ask who determines the repair design and whether an engineer is needed. The estimate should identify repair locations, materials, connection details, and responsibility for temporary support. Mold cleaning, wood replacement, and foundation stabilization must not be blurred into one undefined repair allowance.

Licensing and permit rules vary by state/city. Check with the relevant licensing office and building department about the actual scope, including structural changes, drainage, electrical circuits, and conversion to an unvented space. Record who handles required permits and inspections. FTC guidance recommends confirming licensing and insurance and warns against demands for full payment upfront.

Negotiate payment milestones tied to inspectable crawl-space work: preparation and repairs, liner and drainage installation, then equipment startup and closeout. Put the deposit and remaining payments in writing, subject to local rules. Do not let the finished liner become the first opportunity to learn that framing repairs were omitted.

Request before-and-after photos of seams, piers, wall terminations, access doors, and repaired framing. Closeout should include equipment startup records, controls and drain checks, agreed moisture readings, and required inspection documentation. Ask how water intrusion will be checked after completion and who responds if it recurs.

Obtain the actual written warranty rather than relying on a lifetime label. Ask separately about liner materials, installation labor, seam failures, sump or dehumidifier equipment, and structural repairs. Clarify exclusions for flooding, plumbing leaks, punctures, outages, and missing maintenance; do not assume these items share coverage.

Have the contractor demonstrate safe service access, filter changes, drain maintenance, and any sump alarm. Record who services each component, whether service visits are mandatory for coverage, and how future plumbing or pest work can occur without leaving the liner damaged.