A dirt crawl space under a Mahoning Valley home is the humidity source for the whole house. Ground moisture evaporates up through the dirt, saturates the wood framing above, and travels into the living space through the stack effect. That's the musty smell you can't get rid of, the warped hardwood floors, the condensation on the ductwork. Sealing it off with a full encapsulation system stops the moisture at the source and usually drops the whole house humidity by 15 to 25 percent year-round.
A real encapsulation is a 20 mil reinforced polyethylene liner sealed across the floor, up the walls, and taped at every seam. Cheap installs use a 6 mil painter's plastic laid loose and call it done, that tears in a year and traps condensation underneath. We use mechanically fastened 20 mil liner, 2 inches of overlap taped with butyl, and a termination bar on the wall so the whole thing stays put for 20 plus years. The seams are the difference between a real vapor barrier and a decoration.
Older Struthers crawl spaces often sit on fieldstone or hollow clay tile foundation walls that leak groundwater through the mortar joints. We tie the liner to a new perimeter drain pitched to a sealed sump before we seal the vents and insulate the rim joists. Otherwise you encapsulate standing water, which is worse than the original dirt. Sequencing matters, drainage first, then vapor barrier, then dehumidifier, then sealed vents, then rim joist insulation.
The dehumidifier is what keeps the sealed space at target humidity. We size by cubic feet and set it to maintain 50 to 55 percent relative humidity, with a condensate pump tied into the main sump or a dedicated discharge. Standard pint-per-day crawl space units from the big box don't cut it on a 1,000 square foot encapsulated crawl, you need a true 70 to 90 pint commercial unit with a drain. Full system with dehumidifier, drainage, liner, and rim insulation runs $6,500 to $12,000 for most Struthers homes.
What we handle
Full Encapsulation with Dehumidifier
20 mil liner on floor and walls, taped seams, sealed vents, insulated rim joists, perimeter drain to sealed sump, and commercial dehumidifier. The complete package.
20 Mil Vapor Barrier Install
Reinforced 20 mil polyethylene liner mechanically fastened to the walls, overlapped and taped at every seam, terminated with a bar. Builds the sealed envelope the rest of the system depends on.
Crawl Space Drainage and Sump
Perimeter drain tile and sealed sump installed under the liner for crawl spaces with active groundwater intrusion. Required sequencing before encapsulation on older fieldstone foundations.
Vent Sealing and Rim Joist Insulation
Foundation vents sealed with rigid foam and gasketed covers, rim joists sprayed or boarded with closed-cell insulation. Stops winter air infiltration and seals the thermal envelope.
Crawl Space Dehumidifier Install
70 to 90 pint commercial dehumidifier sized to crawl space volume, condensate pumped to the main sump or a dedicated discharge. Maintains 50 to 55 percent relative humidity year-round.
Mold Remediation Before Encapsulation
Remove, treat, and seal visible mold on framing and subfloor before liner install. Required step on crawl spaces that have been wet long enough for growth to get established.
How the job goes
1. Free Crawl Space Inspection
We pull the vent, crawl through with lights and a moisture meter, photograph standing water, mold, and framing condition, and spec the right sequence of fixes.
2. Written Scope and Sequencing
Drainage first if needed, mold remediation, liner, vent sealing, rim insulation, dehumidifier. Each step priced on one page before you sign.
3. Prep and Drainage
Clear old insulation, debris, and any standing water. Install perimeter drain and sealed sump where needed. Address mold on framing before the liner goes down.
4. Liner Install and Sealing
20 mil reinforced liner cut to fit, overlapped 2 inches minimum, butyl-taped at every seam, mechanically fastened to the walls, terminated with a bar at the top of the wall.
5. Dehumidifier, Vents, Walkthrough
Vents sealed and insulated, rim joists insulated, dehumidifier set and condensate line run. We walk you through the whole system, hand over written warranty and manufacturer paperwork.
What's included
- Free crawl space inspection with photos and moisture readings
- Debris and old insulation removal and haul-away
- Perimeter drainage and sealed sump installed where needed
- Mold remediation on framing before liner install where applicable
- 20 mil reinforced polyethylene liner on floor and walls
- Butyl-taped seams and termination bar at the top of the wall
- Foundation vents sealed with rigid foam and gasketed covers
- Rim joist insulation with closed-cell foam board or spray
- Commercial-grade dehumidifier sized to crawl volume
- Condensate pump tied to main sump or dedicated discharge
- Written workmanship warranty handed over at walkthrough
What it costs
Most Struthers crawl space encapsulations run $3,500 to $12,000 depending on size, whether drainage is needed, and whether a dehumidifier is specced. Free in-home inspection with written per-square-foot scope.
| Job | Typical price | Notes |
|---|---|---|
| Basic 20 Mil Liner, Floor and Walls | $3,500 to $7,500 | Liner only on a dry crawl, no drainage, no dehumidifier. Priced by square foot and wall height. |
| Full Encapsulation with Dehumidifier | $6,500 to $12,000 | Liner, taped seams, sealed vents, rim insulation, commercial dehumidifier, condensate tie-in. |
| Crawl Space Drainage and Sump | $2,500 to $6,500 | Added when there's active groundwater intrusion. Priced by linear feet and sump complexity. |
| Mold Remediation on Framing | $600 to $3,500 | Hand scrub, antimicrobial treatment, and sealing of affected framing. Priced by square feet affected. |
| Dehumidifier Only, Installed | $1,400 to $2,800 | 70 to 90 pint commercial unit, condensate pump, discharge line. For already-encapsulated crawls. |
| Free Crawl Space Inspection | Free | Full crawl walkthrough with photos, moisture readings, and written scope. |
Ranges are typical for Crawl Space Encapsulation jobs in Struthers and confirmed with an exact written quote before any work starts.