Seal out ground moisture for good. 20-mil reinforced vapor barrier, taped seams, wall & pier wrap, sealed vents, and a dedicated dehumidifier — installed in one to three days for most Charlotte homes.
A licensed local crew — usually out in 24 to 72 hours. Written scope, fixed price, no pressure.
Two Junes ago I got the call from a 2009 Firethorne custom off Firethorne Country Club Dr, 5,400 SF two-story on a half-acre backing to the seventh green. The owner had bought it new, lived in it 17 years, and finally hit the wall when her HVAC guy told her the compressor on the upstairs three-ton was short-cycling because the return air was pulling 68 percent RH off the second floor. She had already spent close to five figures chasing indoor humidity — a whole-house dehumidifier tied into the return, a plug-in Frigidaire in the master closet, twice-a-year duct cleanings — and the RH gauge on her Nest still read 63 percent every August. Nobody had ever told her to look at the crawl. Nobody had ever opened the crawl access door. I keyed the exterior hatch on the side elevation, dropped down 46 inches, and stood up inside the exact scene I have seen 200 times in this town: 2009 builder 10-mil clear plastic on the ground, skirted around 28 CMU piers with tape that had walked off years ago, ten 8-by-16 aluminum vents all still open behind their exterior screens, no dehumidifier anywhere, and a marketing sticker on the mechanical room door that said the crawl had been encapsulated to Firethorne standard. Hygrometer read 83 percent RH at 78 degrees. That is Marvin builder encapsulation from 2003 through about 2016 in one snapshot.
Marvin builder crawls fail in a specific pattern that is different from what fails in Ballantyne, Cotswold, or Piper Glen. In this town the crawls are tall, the block perimeters are dead-square, and the ground liner the builder rolled out was actually decent material — 10-mil or 12-mil with a manufacturer stamp, not the 6-mil garbage you tear out under a 1970s brick ranch off Sharon Amity. The problem is not the material grade. The problem is the install: skirted piers instead of individually wrapped, tape on dusty block instead of mechanical termination, and no dehumidifier of any kind because the builder called the ground liner alone encapsulation. Fifteen years later the tape is gone, the plastic is off the walls, every pier is off-gassing moisture straight into the sealed crawl, and the humidity is exactly what it was the day the house was framed. Every one of the four flagship HOAs in Marvin — Firethorne, Longview, Marvin Creek, The Vineyards — has this exact same failure pattern on the 2002-through-2016 stock. Finishing those partial builder jobs is what pays my mortgage in the summer.
Every Marvin encapsulation starts with the same inspection walk-through and it usually goes the same way. Key the exterior hatch, drop 44 to 48 inches into a pleasant working crawl, hygrometer on the ground for 20 minutes while I map the perimeter. First thing I look for after the RH reading is radiant floor tubing under the master bath and the kitchen — roughly a third of Marvin custom builds from 2006 forward have hydronic PEX loops stapled up between the joists, and the builder always insulated them with R-19 kraft-faced fiberglass. If that fiberglass is present and black on the underside, the whole scope changes. Pull the fiberglass first, schedule a licensed spray foam sub for a two-inch closed-cell application over the PEX and the aluminum heat-transfer plates, ventilate the crawl for 24 hours, then come back for the encapsulation. That coordination adds a day or two to the schedule and it happens on every Firethorne, Longview, and Vineyards job where radiant is present.
Second on the walk-through I count piers. A 5,000-to-7,000 SF custom in Marvin typically has 26 to 34 CMU piers on the interior. Every one of them gets individually wrapped with 20-mil liner in the finished scope, mechanically banded top and bottom, and sealed against the ground liner with a bead of SikaFlex-1a. That is the single biggest departure from the builder job — where the builder skirted around the pier, we cut a piece of liner for each pier and wrap it like a Christmas present. Skipping this step is why the builder encapsulations run 78 to 85 percent RH by August; every pier is a moisture pump straight into a sealed room.
Third I look at the block perimeter. Builder termination in 2003-to-2016 Marvin was almost always plastic taped or acoustic-caulked to the block about 18 inches up the wall. The tape lasted three summers. I look for it, I do not find it, I plan for mechanical termination bar — 1-inch by 1/8-inch aluminum stock, 2-and-a-quarter-inch masonry screws every 12 inches, bedded in SikaFlex-1a. That fastening runs the full perimeter and is the connection that has to last the life of the system. Nothing less than mechanical holds in this climate.
Fourth is HOA notification. Firethorne wants a one-page scope for any exterior condensate discharge — where it exits, what elevation, and confirmation that the PVC will be painted to match the trim. Longview is stricter and has formal Design Guidelines, so any discharge visible from a street or a fairway needs a landscape screen designed into the scope, usually a boxwood cluster or a small lattice panel. Marvin Creek is the easiest — a courtesy email with the site photo satisfies them. The Vineyards is similar to Marvin Creek. I have submitted probably 40 scopes across the four HOAs over the years and never had one denied. They just want to see the plan on paper before we cut through the block. That submission goes in as part of the scope, not as an afterthought.
Fifth is the electrical permit. Marvin sits in Union County, and the dehumidifier goes on a dedicated 20-amp circuit permitted through the Union County office in Monroe. Union inspectors are stricter than Mecklenburg about pier footing depth if we are also doing any structural work — 12 inches minimum on undisturbed soil, they will fail you otherwise — but for straight electrical rough-in for a dehumidifier they are reasonable. I pull the permit as part of the scope. Homeowners never see the paperwork; I just show them the inspection sign-off at closeout.
The install itself runs three to four days for a standard Firethorne or Marvin Creek job — tear out the old plastic, wrap every pier, run the aluminum termination bar, seal the vents with closed-cell foam and exterior mechanical covers, install the dehumidifier on the new circuit, drain to daylight or to a condensate pump depending on the grade. If the house has radiant heat, add a day for the foam sub and a day of ventilation. If it is one of the true estate lots along Marvin Rd or New Town Rd with specialty mechanical systems in the crawl, add another two to four days for trade coordination with whoever installed the radiant, geothermal, or wine cellar systems.
Standard Marvin encapsulation spec is 20-mil reinforced polyethylene on the ground, either YellowGuard or Viper CS depending on supplier availability that week — both are woven scrim laminated between poly layers, boot-traffic rated, and hold seam tape long-term. Seams overlap 12 inches minimum with double-sided PSA tape, Polyken 337 or Nashua 357, and every seam gets top-taped for redundancy. Every CMU pier is individually wrapped and mechanically banded — no skirting. Aluminum termination bar (Insul-Bar or 1-by-eighth aluminum stock) runs the block perimeter, fastened with 2-and-a-quarter-inch masonry screws every 12 inches, bedded in a continuous bead of SikaFlex-1a. All vent openings get closed-cell foam blocks friction-fit inside the opening and mechanical exterior covers over the aluminum vents. Insulated gasketed crawl hatch replaces the flimsy louvered door if the builder left the original.
Dehumidifier sizing for a Marvin crawl runs bigger than the Charlotte tract average because the footprints are bigger — a 2,400-to-3,200 SF crawl footprint at 44-to-48-inch clearance is standard in the four flagship HOAs, plus the mechanical load from the oversized HVAC systems and any radiant loops that dump BTUs into the space. Default spec is an Aprilaire E100, Santa Fe Ultra98, or AlorAir Sentinel HDi90 — 100-pints-per-day rated units. Portable residential 70-pint units like the Frigidaire and GE plug-ins some Vineyards builders installed in 2014-2016 are undersized by half for these footprints and ice up by the second summer. The unit hangs from the joists with vibration-isolation straps, discharges to a humidistat set at 55 percent RH, and drains to daylight through the closest exterior wall where grade allows or to a condensate pump discharging into a landscape bed where it does not.
Rim joist gets open-cell spray foam (Icynene or equivalent, 3 inches minimum) as default, or Rockwool ComfortBatt R-15 mineral wool when the homeowner wants no foam or needs future access. Any fiberglass batts in the joist bays or under radiant tubing come out and do not go back. On the six-mile-creek-adjacent lots in Longview backing to the greenway, we add a perimeter interior drain system with a Zoeller M53 primary and a Wayne WSS30V battery backup before the liner goes down, because the water table pushes up in February and March and passive systems will not hold.
Yes — Marvin is a regular encapsulation route. Free on-site inspection anywhere in Marvin, fixed written quote before we touch anything.
Marvin encapsulation is almost always a finish-what-the-builder-started job on tall pleasant-to-work-in custom crawls, with two Marvin-specific wrinkles nobody else has: radiant heat insulation to strip out first, and HOA architectural review boards that want to see the discharge routing before you cut through the foundation.
28173. All Union County addresses covered.
Almost certainly yes. Firethorne builder encapsulation from 2003 through about 2016 was 10-mil or 12-mil plastic on the ground, piers skirted instead of wrapped, tape stuck to block walls that walked off in year three or four, and no dehumidifier. The result is a mid-grade vapor retarder with a marketing sticker. Drop a hygrometer on the crawl floor for 20 minutes in July — if it reads over 65 percent RH, the system is failing, and every Firethorne builder job I have tested is over 75 percent by August. Real encapsulation is 20-mil reinforced liner, every pier individually wrapped and banded, mechanical termination on the block walls in polyurethane sealant, and a real dehumidifier sized to the cubic footage on a dedicated Union County-permitted circuit. About half our Marvin work is finishing exactly this kind of partial builder job.
Probably yes on the encapsulation, and definitely yes on replacing the dehumidifier. The residential 70-pint portables the 2014-to-2018 Vineyards builders installed — Frigidaire, GE, sometimes a LG — sit on a plywood pad on the ground, plug into a regular outlet on a shared circuit, and are undersized by half for a 2,000-plus SF crawl footprint. They ice up by the second summer, get unplugged by the homeowner, and the crawl runs 80-plus percent RH after that anyway. The underlying encapsulation was still the same skirted-pier, tape-on-block builder spec. When we finish one of these we remove and dispose of the portable, redo the liner properly, and install an Aprilaire E100 or Santa Fe Ultra98 on a new dedicated 20-amp circuit. Net result is the crawl runs 54 percent RH through August instead of 80.
Yes, significantly, and this is a Marvin-specific issue you have to flag on the walk-through. Roughly a third of Marvin custom builds from 2006 forward have PEX radiant tubing stapled between the joists in specific rooms, and the builder always insulated the bays with R-19 kraft-faced fiberglass over the tubing. Fiberglass in a humid crawl is a moisture sponge — eight years in it is black on the underside, sagging out of the bays, and the aluminum heat-transfer plates on the PEX are showing corrosion. Correct install is 2 inches of closed-cell spray foam directly against the subfloor over the tubing and the plates, no fiberglass anywhere. Our scope pulls all the fiberglass first, schedules a licensed foam sub, ventilates the crawl for 24 hours, then does the encapsulation. Adds one to two days to the schedule and it is not optional if the goal is to protect the radiant system from another decade of moisture exposure.
Yes, they always have for us, but you have to submit the plan first. Longview has formal Design Guidelines that get updated every few years, and any exterior equipment or discharge visible from a street, fairway, or neighboring lot needs a landscape screen designed into the scope. We route to a side or rear elevation as default, paint the PVC to match the trim, and include a landscape screen — usually a boxwood cluster, an ilex hedge, or a small lattice panel — in the submission. One-page scope with a site photo and a plant list, submitted through the ARC portal, comes back approved in 48 to 72 hours in my experience. I have submitted probably 30 Longview scopes over the years and none have been denied. If your lot geometry forces a visible run and screening is not practical, we can route interior to a condensate pump and discharge into an existing plumbing stack instead.
Free on-site Marvin inspection. Fixed written quote. Call (980) 227-1769 or book below.