We have utilized Steve and Indoor Environmental Systems to completely seal the crawlspace, upgrade HVAC ductwork, and other energy tweaks in three homes of varying sizes, over a five-year period. One of the crawlspace projects was exceptionally large (nearly two stories high in some areas). The primary objective was to eliminate any potential for humidity and mold issues, while incorporating some passive strategies to reduce radon levels. (All three homes were already below EPA standards, but for personal peace of mind we wanted to push the numbers as low as possible). In short, the work was meticulously engineered and delivered, and the sealed spaces perform exceptionally well. Steve has a great crew. The resulting “rooms” are nearly NASA-grade clean, remain completely dry, maintain the temperature of the living space (reducing energy use), and all have significantly reduced radon levels. An additional benefit is that sealed crawlspaces remain pretty much bug-free… The IES team always responds quickly whenever we have a question, concern, or require a fix (stuff happens). I would highly recommend.