Local Conditions
What Columbia Air Does to a Rug’s Foundation
Damp is a shoulder-season problem in Columbia rather than a summer one. 141 days a year sit at or above 75% relative humidity and 87 of those reach 80%, but they are bunched into spring and fall, with 48 days over ninety degrees in between and 22 freezing nights at the far end. Rugs here are damaged by the transitions more than by either extreme.
141
Days a year at or above 75% relative humidity
32
Longest unbroken damp run, in days
22
Nights a year at or below freezing
45.9
Inches of rain a year
Two damp seasons and a dry middle
141 damp days a year, 32 days at the longest stretch, 48 days over ninety degrees and 22 nights at freezing: Columbia distributes its moisture across spring and fall and takes it away in between.
Twice a year, then, a rug's foundation takes up moisture over several weeks and gives it back over several more, while the wool pile lags behind it both times.
87 of those damp days reach 80% relative humidity, where mold stops needing much time, so the risk is real without being constant — and rugs that sit undisturbed through one of those windows are the ones that surprise their owners.
Where the house puts the rug
The housing descriptions for Shandon, Wales Garden and Lake Carolina all mention crawlspaces, and a crawlspace is the reason a rug can be damaged from a direction nobody inspects.
Soil under an unvented crawlspace gives up moisture into the void, that moisture moves up through the floor, and the rug on top of it acts as the lid. The foundation loads from beneath while the pile stays dry to the touch.
In Lake Carolina, Blythewood and Irmo the rugs are mostly on slab, which behaves nothing like a joisted floor.
A slab is in direct contact with ground moisture and, in older construction, often has no vapor barrier under it; a rug laid straight onto one is being wetted from below continuously rather than seasonally, and the cotton foundation is the part in contact with it.
The oldest housing on the collection route goes back to the 1900s, and construction of that age was not built to keep ground moisture out of the rooms above it — which is worth remembering before blaming a rug's condition on the rug.
What that actually sends in for repair
Foundation loss, not surface wear
Cellulose held damp loses strength, and 32 unbroken days above 75% is long enough for it to matter.
A foundation going that way gives no cosmetic warning, so the test is mechanical: fold a corner and see whether it flexes or crackles, and pull gently on a fringe tassel to see whether it is still anchored in anything.
Fringe, because fringe is the foundation
Fringe is the warp ends of the rug, not a trim, so 141 days a year of damp working on cotton warps shows up there before it shows up anywhere else.
Once the ends let go the rug starts unravelling from the edge inward, which is why a fringe that has begun to shed is worth dealing with while it is still a fringe job.
Backings and sizing letting go
Hand-tufted rugs are held together by adhesive and a cloth backing rather than by knots, and 48 days a year over ninety degrees combined with 141 damp days is hard on that construction.
It fails as a fine grit that comes out of the back, a backing that lifts away from the body of the rug, and a smell that returns after cleaning because the source is the adhesive layer rather than the pile.
Figures above are from the ERA5 reanalysis record for the five years from 2021 through 2025,
taken at the center of the the Midlands service area. If what you are seeing on your rug
matches any of this, send photographs and we will tell you which of these it is.