Before you cut into the wall, compartmentalize and put the space under a negative pressure. The last thing you want to do in a building when you think you may have had a moisture issue and suspect that mold could be growing behind the wall is to disturb it and have the mold spores release into the air within the building. If you think you may have a problem and need to cut into the wall take these steps to create negative pressure in the room:
- Close the door
- Open a window
- Put a fan in the window blowing out to create negative pressure in the room
- Then you can safely cut into the wall to treat the mold
The lesson we learned from the Hindenburg relates to the smoking lounge. The lounge was kept under positive pressure and the smoke leaked out into the rest of the dirigible so that if there was a gas leak in the envelope of the dirigible, the gas could not flow into the smoking lounge to get ignited by a pipe or a lighter.
You are doing the same thing here but in reverse. You are putting the space into a negative pressure before you disturb the space so that contaminants could not possibly flow into the building.
Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation