green building construction and moldThis segment is a continuation of “Green Building Construction And Mold – Part 2,” where we found that two soya-based types of insulation were mold-resistant.  As you remember, we also found that sample A insulation was compact, while sample B was spongy.

We live in Florida where every year we brace for hurricanes.  We have investigated countless homes that suffered hurricane damage. To evaluate which of the two soya-based insulation are best, let us suggest a hurricane scenario where the roof has been compromised by a couple of shingles being blown away, and water gets into the wall cavity of a room.

Let us imagine two wall assemblies built using green building construction materials.  One with sample A compact insulation and the other with sample B spongy insulation, and both wall assemblies have regular sheet rock.

With the information we learned in Part 2 of “Green Building Construction And Mold,” we know that sample B insulation will soak up and hold water like a sponge. Then, the water will permeate the sheet rock and mold will start growing on both sides of the sheet rock.  Wet walls will cause the relative humidity (RH) inside the room to rise.  An RH above 60% encourages mold to grow on walls, furnishings, and clothing. We have recorded up to 90% humidity in a room compromised by a hurricane.  The occupants will be unaware of what took place inside the wall, unless they find the carpet wet.  Within a few days they will detect a musty smell and they will start seeing mold on walls and elsewhere in the room.  That’s when they’ll realize they have a serious problem.

Sample A insulation might fare a little better, provided water finds space to drain inside the wall between the insulation and the sheet rock.  In this case water will find the path of least resistance and drain right into the room. If the occupants are around they will be able to minimize the damage by sponging up water as water enters the room.  That is if the amount of water is manageable, and the carpet does not become saturated with water.  If the carpet becomes soaked, the humidity inside the room will rise and the room will experience similar conditions with mold as sample B insulation above, because of the elevated relative humidity (RH).

Often, green building construction gives homeowners a false sense of security.

Because of having gone through hoops in getting a green certification, and since the building is rated “green”, homeowners believe that it must be impervious to mold.  We must repeat the fact that mold needs three things in order to grow – a surface to grow on, food, which is dead organic material, such as wood, and water.  Adding more organic and biodegradable materials in a building to make it green can spell trouble unless homeowners double their efforts in controlling water or moisture problems.

We must remember that materials are tested in isolation in laboratories. It is not enough to know that insulation is biodegradable, that it is organic, like shredded blue jean insulation, or that it is mold and fire resistant, and that it has a good “R” value; we must also learn how it will fare in the real world.  In subtropical climates where hurricanes are prevalent, spongy type of insulation may not be a good idea.

We must not only look at the intrinsic quality of a product, we must also evaluate products in relation to adjacent materials.

When choosing a building material, ask yourself the following questions:
  • What will happen if this material gets wet? And,
  • How will it affect nearby materials?

Written by Charles & Danielle Dobbs – Professional mold assessors, expert witnesses, authors of several books on mold, and mold education bloggers

Charles & Danielle Dobbs - Professional mold assessors, expert witnesses, authors of several books on mold, and mold education bloggers


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