Moisture Problems - Why Does Condensation Occur on Interior Surfaces?


Visitors: 307

Condensation on inside of window and condensation on inside of window in cold weather. . .

Condensation can occur on any surface that is below the “dew point" of the air with which it is in contact. The “dew point" is the temperature at which condensation will occur for a given humidity level.

In most houses in winter, the inner surfaces of the windows are the coolest surfaces in the home. Condensation will typically appear there before it appears on other surfaces. Condensation is less likely to occur on interior walls, because they are typically warmer than “dew point. "

Occasionally however, condensation may occur on cold spots such as nail heads, in corners of outside walls where insulation is reduced, or in confined spaces where the circulation of warm room air is restricted. In extreme cases, condensation may lead to mildew and the growth of mold.

What To Do

To reduce or eliminate excessive condensation, the humidity level must be decreased and/or the ventilation increased.

To reduce humidity levels:

* Turn down humidifiers Ensure dryers are vented to the exterior

* Do not hang clothes to dry inside the house

* In extreme cases, operate a dehumidifier. Dehumidifiers generally are capable of removing 7.5 to 20 litres of water from the air per day.

Typical household dehumidifier.
A household dehumidifier.

To increase ventilation:

* Operate bath fans when showering or bathing

* Open windows or operate an exhaust fan as soon as significant window condensation appears, until the source of the humidity is remedied.

* Operate furnace with fan switched on for continuous air flow


* Have range hoods vented to exterior

* In extreme cases, consider installation of an mechanical air exchanger or Heat Recovery Ventilator (HRV).

Heat Recovery Ventilator - A typical heat recovery ventilator.

If the obvious solutions don’t eliminate the problem, before investing in a dehumidifier or an HRV, check the structure for other possible moisture sources. Ensure the appropriate insulation and moisture barriers are installed in the attic, basement or crawlspace. Check for seepage in the basement.

Attic ventilation is normally provided by vent openings in the soffits or gables and roof. The total area of ventilation should equal one square foot for every 200 to 300 square feet of ceiling area. Not less than 50% of attic ventilation should be throught the soffits or gables. Not more than 50% should be through the roof.

Copyright Gil Strachan - All rights reserved.

Gil Strachan is a professional home inspector, representing Electrospec Home Inspection Services in east-central Ontario, Canada since 1994. Visit to learn more about home inspections.

"The Home Reference Book"
You can probably find a home inspection for a little less than what we ask, but you probably won't find the Home Reference Book. A $60 value, this solutions-oriented reference tool comes free with every inspection we perform.
It's the first tool you should have around the house!


Article Source:

Rate this Article: 
Intend to Start Your Career in Interior Designing? Join Interior Design Study ..
Rated 4 / 5
based on 5 votes

Related Articles:

Moisture / Mildew Problems: Q & A

by: Gil Strachan (November 20, 2005) 
(Home Improvement)

How Do You Handle IT Problems When They Occur?

by: Jane B Smith (April 13, 2008) 
(Computers and Technology)

What to do when problems occur while breastfeeding?

by: Petar Genchev (July 08, 2011) 
(Home and Family/Babies Toddler)

Decorative Interior Painting Can Give Surfaces a More Distinctive Look than ..

by: Roger King (June 30, 2006) 
(Home and Family/Interior Decorating)

Very Bad Credit Loans - Assistance When Problems Occur

by: Tom Dikkin (December 17, 2007) 

Interior Paint Problems

by: Mario Sanchez (July 09, 2008) 
(Home Improvement/Painting)

Fixing Condensation on Skylights

by: Gregg Hicks (September 21, 2006) 
(Home and Family)

Reducing Condensation on Sliding Sash Windows

by: Joel Tarplin (December 08, 2010) 
(Home Improvement/Windows)

Eco friendly Interior Design A Guide to Creating a Sustainable and Ecological ..

by: Innis Desborough (June 20, 2008) 
(Home Improvement/Interior Design and Decorating)

Intend to Start Your Career in Interior Designing? Join Interior Design Study ..

by: Tanesha Harris (January 19, 2015) 
(Home Improvement/Interior Design and Decorating)