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Building Science and Home Inspections



Most people walk into a home and look at the flooring, the light fixtures, and the overall aesthetics. This is good. A home should be beautiful and comfortable. However, some builders, contractors, and homeowners focus too much on the aesthetics and not enough on the science of a building, specifically the building envelope.


The building envelope is the barrier from the outside to the inside of the home. The best time to get this right is at construction. When you think about the building envelope you have to think about 4 major areas and in this order.

  1. Water Barrier

  2. Air Barrier

  3. Vapor Barrier

  4. Thermal Barrier

As a home inspector there is not much I can do to see how well the envelope was constructed. Its covered in siding, roofing material, drywall, etc. What I will look for is evidence of failure of these systems.


Water is the biggest danger to a home in ordinary circumstances. Fire can ruin a house quickly, but water will ruin it (outside of a flood) slowly and often times with little to no warning until it's too late. As a home inspector this is the main thing I look for. I want to see if there is any evidence of water intrusion. If there is evidence action should be taken immediately. Using moisture meters, thermal cameras, and just putting my hands on the home is the best way to see if water is causing issues. For many leaks evidence doesn't appear for a long time. That is one great reason for annual home inspections.


The problem areas for water intrusion is the roof (especially at any penetration like plumbing vents), windows, vent caps, and the bottom of the siding closest to the ground.


The failures in the Air and Vapor barriers are much harder to detect. Outside of feeling some drafts or seeing some mold on surfaces not much can be seen. Using thermal cameras can help, but again it is not perfect. Some evidence of air or vapor barrier leaks will be drafty rooms, damp felling air, bug intrusion, moisture on windows on the inside, among other similar signs. Fixing defects in the air and vapor barrier will be difficult since you have to get behind the finished materials.


If you do not have concerns with the first three, you can focus on the thermal barrier (heat transfer). This will be difficult to fix outside of doing a deep retrofit with more insulation inside or outside. If you are adding new siding on the outside or doing a full remodel of the inside this is a great time to add to the thermal barrier. Wood studs can have thermal transfer. If you look at studs through a thermal camera you can see heat transfer through the studs (thermal bridging). This can be fixed by insulation on the outside and making sure the other barriers are taken care of. These issues can be addressed at construction or at a time when a full remodel is already scheduled.


Building science is obviously much more complicated than this. Each climate zone is different and the science will need to be reflective of this. Building a house to "code" will not necessarily mean it was built with proper science. The codes are the minimum standard.


If you want to have your home inspected with science in mind give Jon a call at 762-525-0263 or request a quote today!

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