A device used to manage the movement of surface water into and out of an attenuation facility. Drainage which runs through pipework installed to a fall, and not therefore under pressure. Water that is below the surface of ground in the saturation zone. Will not allow water to pass though it.
Examine your crawlspace from both the inside and outside and find all holes and entrances into the space. If your crawlspace is reasonably dark, going inside, turning off the light and looking for sunlight coming in from outside is a great way to do this. Seal the holes with expanding foam or caulk.
The fact is, a properly insulated slab can be just as warm as a wood floor. If you have a basement, you'll have a slab at the basement level and a conventional (framed wood) system at the other floor(s). If you have a crawl space, you'll have to provide an access door of at least 18x24. You must also provide ventilation at a rate of one square foot of opening for each 150 square feet of crawl space. This is usually accomplished with rectangular foundation vents. One vent has to be within three feet of each corner.