The Crawl Space Team
Getting a crawl space sealed and repaired is the number one priority of the entire New York City crawl space team. This is why the trenchless mortar system has been used for so long. After all, you can seal the space right after the structure has been poured and it will never be an issue. However, if you want to keep the moisture out in the future, then it would be a good idea to have the space sealed as soon as it is finished.
The best way to seal a space with a damp proofing product is to dig a trench around it and then install rows of this perimeter product and then put plastic sheeting over it. This will act as a vapor barrier and prevent moisture from getting underneath the plastic sheeting. By doing this, you are also going to get rid of that unpleasant musty smell that sometimes comes from wet concrete. Other products that the New York City team uses include:
Once, a month they go to the job and work on all the cracks and holes that have started to appear throughout the whole building. They also work on large areas that have just sprung up, because sometimes these can take months to fix. During this time they use high-pressure water jets to blast away any loose soil that is on the exterior walls. By doing this they help to seal up the space and make it ready for the next contractors to come in and start working.