| Q: Gil, I think we have a mildew problem. It | | | | on an exposed foundation wall or floor with a |
| causes problems for my daughter when she | | | | hair dryer. Tape a 12 inch square of heavy |
| comes to visit ... We think we may have to | | | | plastic over the spot, and check it in one or |
| remove all the panelling and carpeting, apply | | | | two days. Seepage will cause the underside |
| something to kill the mildew on the walls and | | | | of the plastic to be wet, but condensation |
| floors and refinish the affected basement | | | | will form on the top side!Q: We have a |
| rooms. -Helen BatesA: It might not be | | | | dehumidifier, but it is in the sump pump |
| necessary or advantageous to tear up the | | | | crawl space and probably doesn't do much |
| whole basement at this point. At any rate, if | | | | good. If we turn it up very high, it just |
| you don't remove the conditions which are | | | | runs all the time. Maybe this is because it |
| supporting the growth of mildew, you'll | | | | is pretty old, I'm not sure. It seemed to |
| likely have a recurrance. It's somewhat | | | | work fine in our last house.A: The required |
| difficult to speculate, not having seen your | | | | size of dehumidifier will vary with |
| home, but here are some things to | | | | conditions, and the size of the house - but |
| consider...Mould and mildew can occur in a | | | | in any house with a severe humidity problem |
| house at almost any time of the year, if the | | | | such as yours, a new 60 pint (minimum size) |
| moisture content of the building materials is | | | | dehumidifier with a drain hose directed to |
| about 20 percent or greater. High relative | | | | the sump or laundry drain should start to |
| humidity, or saturation at or below grade, | | | | produce results. If you prefer to keep the |
| can create this condition.A good plan of | | | | crawl space closed, you'll likely need two |
| attack begins with decreasing dampness and | | | | machines.THE BOTTOM LINE: First things first |
| increasing ventilation. Maintain a negative | | | | - look for external sources of moisture, then |
| grade slope away from the house; and ensure | | | | internal; and then study ventilation |
| that evestroughing, down-spouts and drains | | | | followed by dehumidification, and if |
| are free of debris, and properly directing | | | | necessary, insulation and/or vapor barriers |
| water at least two meters away from your | | | | where required.A FEW QUESTIONS FOR HELEN:1. |
| foundation wall. Even if your house is | | | | How is your lot grading? (any slope toward |
| relatively new and has properly installed, | | | | house?) Settlement around the perimeter of |
| working footing drains, excessive surface | | | | the foundation?2. Downspouts and drains in |
| water can saturate the foundation wall, and | | | | place?3. What type of heating/ventilating |
| evaporate to the interior faster than it can | | | | systems do you have? Same in basement?4. Is |
| be drained away. Check to see if water pools | | | | your kitchen range hood directed to the |
| anywhere beside the house during a downpour | | | | outdoors?5. Bathroom exhaust fans installed |
| or period of melting.Severe mould on inside | | | | and used regularly? Vented through the wall |
| wall and ceiling.Moisture problems can | | | | or roof (not into the attic, hopefully).6. |
| originate inside or outside the house, or | | | | Clothes dryer vent directed to the |
| both. In cooler weather, condensation will | | | | outdoors?7. Is ventilation provided for the |
| occur on any surface that is below the dew | | | | basement?8. Are any windows sweating?9. How |
| point of the air in contact with it | | | | old is your house?10. Construction: solid |
| (temperature at which condensation will occur | | | | brick/brick veneer/siding etc.11. Are roof |
| at the existing humidity level). This | | | | ridge/gable vents visible?Also, check the |
| moisture usually appears first on the inside | | | | lowest course of bricks for the presence of |
| surfaces of windows, and may also appear | | | | "weep holes" about every fourth mortar joint. |
| around door jambs and where outside walls | | | | (If your home is wood-framed with a brick |
| meet the floor or ceiling. Closets can also | | | | facing, the mortar should be left out, to |
| become damp due to reduced air circulation. | | | | allow any condensation between the exterior |
| In warm, humid interior conditions, | | | | sheathing and the brickwork to escape to the |
| foundation walls may "sweat" profusely at any | | | | outdoors.)Copyright Gil Strachan - All rights |
| time of the year.Dehumidifiers can remove | | | | reserved.Gil Strachan is a professional home |
| large amounts of moisture from the home, and | | | | inspector, representing Electrospec Home |
| in summer, an air-conditioner is also a | | | | Inspection Services in east-central Ontario, |
| powerful dehumidifier;. Air conditioners | | | | Canada since 1994. Visit to learn more about |
| however, consume considerable amounts of | | | | home inspections."The Home Reference Book" |
| energy and may not be useful in spring and | | | | |
| fall, when cooling is not | | | | You can probably find a home inspection for |
| required.Ventilation is an effective and | | | | a little less than what we ask, but you |
| inexpensive means available to you for | | | | probably won't find the Home Reference Book. |
| reducing humidity, and can be obtained by | | | | A $60 value, this solutions-oriented |
| opening windows or operating an exhaust fan | | | | reference tool comes free with every |
| as soon as significant window condensation | | | | inspection we perform.It's the first tool you |
| appears.HANDY HINTThroroughly dry a damp spot | | | | should have around the house! |