How much does crawl space encapsulation cost in Virginia?

The short answer

There is no dependable, dated published price for crawl space encapsulation in Virginia. The price for your house is set by three things: the size and shape of the space, the materials in the scope, and what has to be fixed before the space can be sealed. The third is often the biggest, and it is the one a phone quote cannot see.

The way to a fair price is a clear, itemized scope that you hand to three licensed contractors, then compare line by line.

What is in a full encapsulation job

A complete job usually has these parts, and each is its own line on a good quote:

• Water control. Gutters, downspouts and grading so water stays out. If water already pools on the floor, as in the photo above, expect a drain with a backflow valve or a sump pump at the low point,^[1] before anything is sealed.
• Preparation. Removing debris and stored items, and smoothing the floor. Old fiberglass batts in the floor or draped over the foundation walls should be removed and discarded,^[2] which adds labour and disposal.
• The liner. Specify "a minimum 10-mil or cross-laminated puncture-resistant 6-mil poly",^[2] and thicker reinforced polyethylene is more durable than unreinforced 6-mil sheeting.^[1] Heavier liners cost more and last longer where people crawl.
• Sealing. Closing the foundation vents, the rim joist and every pipe, duct and cable hole.
• Wall insulation. Usually rigid foam. Most codes require a thermal barrier or an ignition barrier over foam insulation unless the product is documented for use without one,^[2] so the product choice changes the price.
• Drying. A dehumidifier with a drain, or conditioned air supplied from the house's system, plus any new outlet or duct that needs.
• Monitoring and service. Experienced installers usually offer one or more of these: a humidity monitoring system, a water alarm, a repair kit for small tears in the liner, or an annual monitoring service.^[1] Ask which are included and which are extra.

What changes the price of the same scope

A good installer will explain how the price is affected by the number of piers in a crawl space, its height above or below grade, and how complex the foundation footprint is.^[1] A low, cramped space with dozens of piers takes far longer than a tall, open rectangle of the same area.

Then come the problems found on inspection, which can cost more than the encapsulation itself:

• An old furnace or water heater that draws combustion air from the crawl space. The fix is often replacing natural-draft appliances with sealed-combustion, direct-vent furnaces or all-electric heat pumps.^[2]
• Mold on the framing. In Virginia, a mold remediation contractor must be "certified by a nationally or internationally recognized certifying body for mold remediation".^[8]
• Radon. A radon problem is almost always fixable.^[6] In a crawl space an effective fix draws radon from under a plastic sheet on the floor with a vent pipe and fan,^[7] so have it priced together with the liner rather than as a separate job later.
• Wiring, termites or rotted wood, each of which is its own trade.

Ways to bring the net cost down

Utility rebates. Some electric and gas utilities pay rebates for insulation, but programs vary by utility and change, and many require approval or an energy audit before the work starts. Ask yours before you sign.

Energy savings. The EPA estimates that "homeowners can save an average of 15% on heating and cooling costs (or an average of 11% on total energy costs) by air sealing their homes and adding insulation in attics, floors over crawl spaces and basements".^[3] That is a whole-house figure, not a crawl-space-only one.

Doing the liner yourself. If the space is dry and has no gas appliances, the liner and air sealing are a homeowner job; see how to encapsulate a crawl space. Pay pros for the parts that need a licence.

Comparing the quotes

The Board for Contractors advises that you "get at least three written bids or estimates using identical plans and specifications".^[4] A bid substantially lower than the others probably means a mistake or missing work.^[4] Virginia law requires licensed contractors to give you a written contract for residential work,^[4] and the Board's tip on deposits is plain: "Limit your deposit to 10% down or $1,000, whichever is less."^[4]

Check the licence yourself. In DPOR's words, "A license number in an advertisement or on a business card does not necessarily mean the contractor's license is valid."^[4] The class should fit the price: A Class C contractor may take on a single job worth over $1,000 but less than $30,000; a job of $30,000 or more but less than $150,000 needs a Class B licence, and $150,000 or more needs Class A.^[5] For the trade work inside the job, the same section adds: "The Board shall require a master tradesmen license as a condition of licensure for electrical, plumbing, and heating, ventilation, and air conditioning contractors."^[5] "Licensed contractors should apply for and obtain all building permits",^[4] not you.

In writing, ask each bidder for the liner's thickness and type, how seams and walls are sealed and fastened, whether a termite inspection gap is left, how vents are closed, what dries the space and who does its electrical and drain work, the humidity target, and what is excluded.

Stop and call a pro if

• Water stands on the floor or comes in after rain.
• Mold is growing on any of the framing. The Department of Energy guide says a mold remediation professional will need to be hired^[2] before the space is sealed. Soft wood needs a pro too.
• A gas or oil appliance, or a gas regulator, is in the crawl space.
• You see exposed or damaged wiring, or the plan needs a new circuit.
• You find termite damage, sagging joists or cracked piers.

See whether encapsulation pays off for your house in is crawl space encapsulation worth it in Virginia, browse restoration answers, or find licensed firms in the Blacksburg restoration directory. When you are ready for quotes, describe your crawl space on Loclis.