Why does a crawl space stay wet after the surface has dried?
The ground under and around the house keeps releasing moisture, and a crawl space with little air movement holds it. The wood and ground cover stay damp for a long time after the surface looks dry, which is why readings are taken rather than judged by eye.
Soil holds water, and it gives that water up slowly to the air. A crawl space with a bare ground and little ventilation keeps its humidity high. A layer of ground vapor barrier, where present, slows the moisture but does not stop it, and a torn barrier lets the ground vapor rise freely.
The joists and the sill are wood, and wood takes up moisture from the air around it. A crawl space that stays humid keeps the wood damp, which is what allows rot and growth to develop in the framing. Drying the crawl space is the step that stops that cycle.
How does the crew get into a crawl space that is very low?
The crew uses the access that is safe for the work, and it may need to enlarge an opening or use lower-profile equipment for a very low space. Access is recorded, and the crew explains what it can and cannot reach before work starts.
Some crawl spaces are only a few feet high, and a person cannot move through them easily. The crew assesses the access first, and it may work from the hatch or the side opening rather than crawl the full length of the space.
If the access must be enlarged to remove water or dry the framing, the crew explains what will be opened and how it will be closed afterward. An enlarged opening is a repair item, and it is recorded.
What affects the cost of crawl space work?
The size and height of the crawl space, the amount of standing water, the condition of the ground cover, the access and the extent of drying in the joists and subfloor all change the work. The price is explained and approved on site before any access is opened or any equipment placed.
A small crawl space with a little standing water and a sound barrier takes a short visit. A large space with deep water, torn barrier and wet joists across its length takes more equipment and more readings, and it may need several visits to bring the framing to target.
Access adds to the price where the crew must enlarge an opening or use a special method. That work is shown on the survey, and the quote follows it.
Should I add a vapor barrier or ventilation after the crawl space dries?
A vapor barrier and ventilation are decisions for a qualified contractor, based on the house, the ground and the climate. A crew can record the moisture and the ground condition, which gives that contractor a clear starting point.
A vapor barrier covers the bare ground and slows the rise of ground vapor. Ventilation moves the air in the space. Both have trade-offs, and the right choice depends on the house and its surroundings.
Do not seal a crawl space vent or close a crawl space completely without advice, because a closed, damp space can hold moisture against the framing. Ask the contractor what applies to your house before any change is made.
Can water in my crawl space affect the floor above?
Yes. Wet joists and subfloors can soften, stain and cup the floor above, and mold can grow in the framing and insulation. The crew checks the floor above from below and from the room, and the drying covers both.
A subfloor that stays damp from below can lift flooring, loosen fasteners and leave a musty smell in the rooms above. Carpet can stain from the underside, and hardwood can cup. Those signs can appear weeks after the water has gone, so the record includes a note of the floor's condition at the visit.
If the floor feels soft or springy, stay off the affected area until a qualified contractor has looked at the framing. The crew reports what it finds, and the structural repair is a separate job.