Wet Where and Wet When

What Makes My Window Panes Wet?

Problem:  The window is wet on the room side of the glass for a few weeks in fall.

Solution:   Moisture has accumulated, over summer, in the structure of the house from cooking, showering, and even the family breathing. This can be overcome by having fans exhausting to the outside in the kitchen, bathrooms and laundry.

Problem:  The window is wet or has frost on the room side of the glass in the winter.

Step 1:  Keep window drapes up 2-3” above the window sill to allow for air circulation.

Step 2:  Install bath and kitchen exhaust fans that vent directly to the outside of the home.  Turn on the fan when room is in use.

Step 3:  Put timer switches on all exhaust fans; keep the fan running for a half hour after the user leaves the room.

Step 4:  Install a continuous rated exhaust fan in the highest level hallway or bath.  This fan should be variable speed from 30 to 110 cubic feet per minute (CFM).  Be sure there is an outside air supply into the furnace room in the basement.  Leave fan running 24/7.

Solution:  Take this slowly, one step at a time.  You may not need to do all 4 steps.

Problem: The window glass is wet or fogged in between 2 glass panes all year round, but most noticeable in the winter.


Insulated glass:  The air seal is leaking and glass must be replaced.

Storm windows:  Glass putty must be in place and sealed tight to wood sash.  Wood sash must be sealed tight to the window frame.

All humidity problems are fixable.  Winter relative humidity levels are typically 30 to 40%.  On super cold days you may need to reduce the humidity to 25%.

Doug Hastings
MN Home Inspector, Minneapolis & St. Paul
ASHI Certified Inspector, ACI
Kaplan University, Home Inspection Lead Instructor

‘Pops’ Rob Leslie
Kaplan Professionals, Retired


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Does Your House Breath?

I never had frost buildup on my windows before!

Like many houses my 1974 rambler was in need of attention.  For the past 5 years my justification for postponing the needed exterior maintenance was the bad economy.  I felt investing a large sum of money in the house was not wise.  Some of you may agree with this and some will not.  Regardless, at the insistence of my wife, last summer became the year of THE HOME IMPROVEMENT.  We contracted for new roof, windows, doors, siding, soffits and fascia.  Keep in mind to meet new state building and energy code requirements housewrap, window and door flashing, caulking, weather-stripping, and low E glass need to meet a very high standard of insulation and heat loss.  This old leaky house no longer leaked.  It is warm and comfortable inside, but this lack of breathability resulted in very large frost buildups on all of our windows and doors as soon as the weather changed.  Any home inspector would quickly recognize this as a problem that needed to be resolved now.  By ignoring this very obvious moisture sign, which many homeowners do, the next concern is going to be mold.  (http://bit.ly/19ut8aA)

I never had radon before!

But…it didn’t stop there.  As a MN home inspector radon testing is a big part of our business operation.   I had tested the basement previously and my radon concentration was at the minimum EPA standard of 4.0 picocuries.  Upon re-testing after the exterior remodeling was completed, my radon level is 3 times higher.  What is the lesson to be learned from these 2 events? (http://bit.ly/1huOoxd)

Houses work as a system.  By changing the exterior envelope of a home it will have a huge impact on how the interior functions.  What was never a problem yesterday may be a major problem today. 

Doug Hastings
MN Home Inspector, Minneapolis & St. Paul
ASHI certified inspector, ACI
Kaplan University, Home Inspection Lead Instructor

Rob ‘Pops’ Leslie
Kaplan Professionals, Retired

What Is Ventilation?

Ventilation is not just air blowing in through an open window and it certainly isn’t the bathroom fan turned on to get rid of a bad smell. 

In a previous blog, I stated that many older houses are now much tighter than the owners believe. Remodeling, changing surfaces and even a coat of paint can do a lot towards tightening the house and reducing its ability to breath. You should, if you own a house that has new siding, exterior windows or doors installed, be concerned that there is an inadequate amount of ventilation. High humidity levels can cause all sorts of visible and concealed moisture damage to a home. Some clues are frost buildup on windows, ice dams, mold and wood decay.

Ventilation, broadly, is an equal exchange of stale air being continually exhausted from the house shell while being replaced by clean atmospheric air at code specified rates.

There are two general methods of ventilation:

  • The first is balanced ventilation. This requires design by an expert in the field. In balanced ventilation two fans of equal volume will be installed. One will suck air into the housing shell from outside and the other will blow stale air from inside the shell to the outside. Often the two air streams pass, side-by-side, through a heat sink material so that the heat being exhausted from the house may be captured and returned in the incoming air. Systems that employ this kind of heat exchange are usually about 70% efficient.
  • The other method is unbalanced ventilation. Unbalanced ventilation can be a fan sucking air into the house from outside and exhausting, by the pressure created, through an existing vent. Or, more typically, it would be just the opposite. Outside air would come in to the house through a lowering of pressure caused by an existing exhaust fan operating in the home. This method is not nearly as efficient as balanced ventilation but it will do the job.

The easiest and most economical way to ventilate your home is unbalanced ventilation. This is something that you can do yourself at a cost of a few hundred dollars. Some homes may already have the equipment in place and it will take little effort to implement. First you will need to select an existing exhaust fan in the bathroom or perhaps in the kitchen that is vented to the outside. Next, you need to create a vent opening in the basement, connect an insulated flexible air duct, and extend this pipe to the floor. The outside vent cover will need a screen to prevent vermin from entering the home. You may already have this pipe; it would be an open pipe near the furnace called an outside air supply. Finally, turn on the exhaust fan and run continuously. This will remove the stale warm moist damaging air in the home , replace it with fresh cold dry outside air and not depressurize the home. You are now controlling the quality and moisture level of the indoor air.

Any exhaust fan in the home will give you a result. Just remember that the smallest fan required by code is 40 CFM. The higher the CFM fan rating the quicker the home will complete a complete air change. Fans are typically rated from 40 to 130 CFM.

Doug Hastings
MN Home Inspector, Minneapolis & St. Paul
ASHI certified inspector, ACI
Kaplan University, Home Inspection Lead Instructor

Rob ‘Pops’ Leslie
Kaplan Professionals, Retired

Are Leaky Houses Healthier?

State of MN doesn’t think so and has adopted a new energy code.

Most realtors and homeowners don’t realize since June 1, 2009 our housing has been subject to new residential energy requirements.  If interested you can download the full Energy Code called Chapter 1322 at www.dli.state.mn.us/ccld/pdf/sbc_1322.pdf

The entire MN Energy Code is essentially about 2 principles…

Envelope Performance
This is all about the rate of energy loss through the shell of the building.  Heat loss is caused by the continuous energy load within the house which is called Base Load.  This includes things such as lights, water heating, and cooking power.  We can control these losses by installing more efficient appliances and devices.  Outside air temperature also effects heat loss and this is called Seasonal Losses.  These losses are reduced by the proper installation of quality insulation, vapor barriers, and efficient sealing.

Because our homes have become so tight the rate of air exchange is practically nothing.  The new code requires a complete air change each hour.  Half of the air in a home can be exchanged by a continuously operating mechanical system and the other half by a passive means, like opening a window.  This can be accomplished with kitchen and bath exhaust fans that run continuously, but this isn’t the most efficient method.  A better way are with either a heat recovery ventilator (HRV) or energy recovery (ERV), but this way is very expensive.

Without these 2 principles in balance and working together, there can be great risk to the air quality of the home.  

Can you hear the whisper of stale air or mold?

Doug Hastings
MN Home Inspector, Minneapolis & St. Paul
ASHI certified inspector
Kaplan University, Home Inspection Lead Instructor

Rob ‘Pops’ Leslie
Kaplan Professionals, Retired

3 Easy Tips for Prepping Your Home for Winter

Trim the bushes…then fix the grade!

Winter is closer than you think, and it’s time to begin winterizing your house. Obviously I’m not talking about cleaning gutters at this stage! That will wait until after the leaves have fallen.

Prune shrubs and bushes first. This will let you see if adjustments to grade are necessary and it will make it possible for you to inspect all of the wall surfaces. Plants and bushes damage the house. If bad enough, you could even hear a scratching or rubbing noise inside. Second, check that the grade slopes away from the house, so that snow, turning to ice doesn’t just lay up against the walls for months. Remember with grade, you need it to be falling away from the house at an angle of 6 inches in the first 10 feet. Landscape rocks and wood chips are not the grade, they are decorative. It must be the earth below that slopes properly.

Have you purchased your tube of silicone caulk yet?

Well, I hope that caught your attention! Step 3, this is a great time to seal up any air leaks in the walls of your home. Finding and sealing wall penetrations is the most important part of your winterizing program! Your house is most likely under slight negative pressure. That means that air will be sucked from the outside atmosphere into your home when the furnace or other fans are operating. You don’t want that to be happening in the cold of winter!

Check any existing caulking carefully, particularly around doors and windows. Caulking deteriorates over time, and it will shrink or crack letting cold air into your home. Check for small holes and be certain that air is not leaking around such things as water faucets, TV and cable wires. Small holes can make a big difference. Can you hear the whisper of the wind blowing through the cracks in your house?

How do I know I filled all the cracks and holes?

There is a simple way to check for leaking around door and window frames. Turn on the furnace and any exhaust fans that you have in the kitchen and bathrooms and approach each frame with a burning candle. If the flame remains vertical, even when you are very close to the frames, you do not have a leak. Confirm this by keeping the candle very close to the frame and taking it all around the edges. If the flame bends into the room you have a frame leak that must be sealed. If the flame bends towards the window or door frame, your house is under positive pressure and this requires examination by an expert home inspector.

Listen for the soft sound of a breeze inside your home…Find and caulk all wall leaks and you will…be warm andsave a lot of money!

Doug Hastings
Certified Home Inspector, Minneapolis & St. Paul
ASHI certified inspector
Kaplan University, Home Inspection Lead Instructor

Rob ‘Pops’ Leslie
Kaplan Professionals, Retired