Hand excavated french drains are installed so dry out your crawlspace
What do you do after your french drains are installed and the groundwater is no longer entering the crawlspace or basement? You may pull the wet moisture barrier, open the foundation vents and provide heat and air movement within the crawlspace to dry it out again. Close interior entry areas to the crawlspace to keep the moisture and any smells that may exist out of the living areas.
The most efficient time to do this is in the summer. However it can be accomplished with dehumidifiers, open foundation vents and heat, as well as fans, almost anytime. After the crawlspace has dried out, which may be many weeks in some cases, a new moisture barrier can be placed in the crawlspace. Use a 6 mil. black plastic moisture barrier, and cut around foundation spot footings overlaping the footing but not the post. Many home inspectors like to see the moisture barrier placed against the lower part of the interior foundation stem wall about a foot up as wall.
All debris such as wood or wet insulation should be removed from the crawlspace. If you have a wet basement, open windows to help vent the moisture after the french drains are installed, close basement doors, and use heat and air to dry it out. Again, this may take some time. Remove wet carpet or have it professionally dried.
There is no sense doing any of this without first installing hand excavated french drains if possible to stop the water from entering. It would be the same common sense that you would employ if you were building a home. You would not start sheetrocking the framed walls inside prior to putting on a roof.
Some properties have various limiting factors that prevent the complete abatement of the water below grade. The most common limiting factors to complete drainage success with french drains are foundation vents below soil grade on the outside of the foundation wall where water can run down the wall and into the crawlspace, window wells below grade where water can run in between the french drain and the foundation wall, windows covered partially with dirt on the bottom of the window in basements, siding too low on the foundation exterior walls preventing the raising of the grade on the foundation and the creation of a compacted splash block to slope rainwater into the french drain which is usually about 18″-24″ from the exterior foundation wall; covering siding would create dryrot. Other common limiting factors your property may have are decks built against the home with poor topography under the deck, trees or shrubs that have roots penetrating the foundation area creating ways for water to find the course of least resistance and flood below grade areas, concrete poured against the foundation wall that is flat or slopes to the foundation wall, ditches or extremely low areas or holes in the dirt that are located right on the foundation wall and cannot be filled and/or grade altered due to low siding. The installation of french drains in areas with limiting factors to success will still remove lots of the groundwater that would have entered the crawlspace or basement and reduce the severity of the water entry, but these french drains will not perform as well as french drains installed without these limiting factors to success. “It is hard to un-ring that bell” so to speak.
If you can compact a better grade at the foundation without limiting factors discussed above being present, and properly place the french drain 18″-24″ from the foundation wall, you are very likely to achieve success to the max in preventing your groundwater entry.