How water vapour affects a building structure

How water vapour affects a building structure


Water Vapor (“WV”) has the potential to cause structural and building damage. It can also have damaging effects on structures, such as dry rot, corrosion and mold growth. Recent scientific studies have shown how water vapor affects structures, and what can be done for them to resist its effects.

What is water vapor and what are its effects?

WV refers to the gaseous water in the atmosphere that causes condensation on the exterior and inside of buildings. It can also pass through walls and be spread by air currents. Materials can either vaporizer distributors be porous or not porous to water vapour. Wood, insulation, and other building materials are porous. They absorb water vapor easily and, once they become too heavy, can create liquid and condensation. This creates the perfect storm for mold and rot.

Is Water Vapor a Real Thing?

How does it get in?

Vapor Drive

Perm rating

Condensation can occur in walls, roof cavities and inside windows of buildings. The most common areas where condensation occurs are in the walls, ceilings, wallpapers, and around windows. Condensation can also build up outside on roofs and exterior walls. Water vapor can be introduced to a structure through air leaks, such as openings in walls. However, it can also be spread mechanically by means of air conditioners. The humidity of your home or building will determine how much water you find. Another way WV can create condensation is through diffusion. When water molecules move from high moisture levels to low moisture levels, it is called Diffusion.

The vapor drive is the force that water molecules exert on a surface such as a wall when WV passes through it. The vapor drive is greater if there are more water molecules than extreme temperatures. Condensation can occur on cool surfaces due to vapor drive. Every part of a building, and each material, will have a different resistance against vapor drive. This is known as a perm rating.

How To Keep Water Vapor At Bay

Permaculture is shorthand for permanence. It uses factors such as permeability, thickness, and resistance to vapor drives.

Perm Ratings

Air Barrier And Vapor Barrier Explained

Types Of Air Barriers

Types Of Vapor Barriers

WV is stopped by a Perm Rating for a Class I vapor substance, while Class III is permeable to water. There are two ways to stop water vapour, since WV is transported via air and vapor diffusion.

While air barriers protect buildings from moisture carried by air, vapor barriers prevent water vapor from vapor diffusion. There are many types of air barriers. They can be used to seal and protect all six sides and prevent air leaks. You can choose from spray-on foam or flexible wraps. Because they are easy to set up and require less effort, they are most commonly placed on the exterior of buildings. An air barrier should not be used in areas where there is high levels of water vapour. This is because the wetness of diffusion is greatest in these areas, as water vapor moves to lower moisture levels. Vapor barriers, which restrict water diffusion within buildings, are often installed. Foam insulation, coatings and membranes are all examples of vapor barriers.


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