蒸汽入侵是环境顾问和建设科学家每天交易的常见问题。从环境的角度来看，蒸汽入侵可以来自旧的干洗化学溢出物，各种溶剂，汽油和柴油材料等等。作为一个建筑科学家，我主要处理水蒸气形式的蒸汽侵入。原则大致相同，但重要的是要了解建筑物如何生活和呼吸在整个终身期间，帮助防止有害蒸汽进入建筑物。

有一些自然的发生，如空气运动，高度和天气的物理可能导致建筑物的不利影响，但即使是我们结构的方式或机械通风的方式也会导致无法预料的效果。水蒸气可以通过地下室的混凝土板进入建筑物，并对地板粘合剂产生影响。这种水分通过混凝土中的小垂直毛孔发现了它的方式，其中在混凝土放置期间出血。在施工期间在混凝土板下施加局部气旋器，虽然不便宜，是将蒸汽从蔓延中停止的首选方法。类似于环境蒸气，然后将其粘贴和密封。

Vapors can be pulled into buildings via hollow cores in concrete block foundations, or through mechanical systems that exhaust air. This needs to be considered no matter what kind of vapor you are dealing with. Today, internal building systems are asked to do a number of things: heat, cool, ventilate, dehumidify, and also deal with vapor. With the desired improvements in building energy efficiency, we are reducing the amount of outside air that comes into mechanical systems. Typically we like to see buildings maintain a slight positive pressure to the exterior to prevent drawing in cold or hot air during the different seasons. If not controlled, this can seriously increase your energy costs.

Some systems now use special ventilation methods of stack effect, solar vents, carbon dioxide monitoring and active wall opening systems to allow mechanical systems to be shut off for up to 45% of the day. This can greatly change how air enters or exits a building, so the system must be dependable in its operation for the vapor mitigation system to work properly. If the natural, mechanical and mitigation system don’t all work together, then additional engineered systems may be required. For example, we are currently working on a high rise in Chicago. The exterior walls of the building are being subjected to positive and negative pressures of the wind or the suction of the wind, in the range or 120-150 pounds per square foot. Small leaks in the building can now pull air into the structure when the building is operating about neutral, once the wind picks up.

Vapor mitigation systems are not usually thought to address these additional building and weather influences, but deal primarily with creating a barrier in a mitigation system. The more we understand how a building works, however, the better we can address the influence it has on a mitigation system. For more information, contact Steve Flaten, or click这里to view a webinar recording on this topic.