[size=3] I did an inspection today on a new 2300 sf home with foam insulation. The home had vinyl double hung tilt windows. At 9am outside temperature was about 40 degrees. The windows in the shaded area had HEAVY condensation on the inside. The window rep is telling the home owners that it is from the home being to tight. The exterior brick has the weep holes at the bottom but the foam has the soffits and ridge vents blocked. The window people say that the HVAC needs to draw some air from to outside to correct this problem. Can anyone help me guide the home owner in the correct direction?
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New construction gives off a lot of moisture
A foamed house is often tigher resulting in less air movement
Ventilate the home like crazy the first year and then re-assess.
What were the weather conditions 1 or 2 days prior? Was there any rain?
It sounds like the home needs to have a HRV (heat Recovery Ventilator) fresh air system installed if it does not have one. A tight house is not a healthy house if it does not allow for movement and ventilation of fresh air. The HRV does this in a controlled and filtered manner.
The soffit and roof vents being “plugged” would not account for this as they are usd for attic ventilation. Spray foaming the entire envelope of the house is becoming more common.
My house is 4 yars old, I used spray foam insulation and have an HRV. This may not completely solve the problem as the windows will condensate ANY moisture in the house when the glass gets colder then the inside house temparature. What you will see is, when the sun hits the windows and warms them up, the condensation goes away.
JMO
We have not had rain in this area in the last three days. The owners said this has been a problem once they moved in , no rain in those 6 weeks.Does the HRV system connect to the air handler at the air intake side? A option that the owner was given was connecting a fresh(outside) air line to the air handler.
The one I am thinking of is its own system, but requires its own duct work. I believe you can install a similar system to an existing air handler to do the same job. It might be a reasonable, if not healthier system to look into.
I think the window rep. may be right, even insulated windows will lose more heat than well insulated walls and as my learned fellows have already pointed out tight construction (no airflow) has it’s benefits and problems. If the home lacks a system for air exchange it may benefit from it. Most of the guys I see installing fully insulated (attic included) closed systems here in Fla. aren’t to concerned about ducting attic space but are code required to bring in outside air. This concept is new (in the reality of ages gone by) and as time goes by farther we will have an opportunity to realize what we had failed to understand. For now I would recommend they go with an approved system that is inexpensive and hooks up to the air handler which at least filters the incoming air. (I’m assuming they have a forced air system.)If they don’t I’m sure other options exist but I’m no expert .
A good HRV is recommended. Don’t have time to set those parameters now but may have some over the weekend…have 2 inspections booked now with a third pending.
Fully foamed houses are appraqching the requirements set for R2000 and Health Houses, especially if an experienced company is used!!! They all need HRV’s.
If the windows are chosen correctly condensation can be defeated. The least windows should have is Low E coating, argon gas fill with a “warm edge” spacer. Better glass like “Heat Mirror” ( http://www.westislandglass.com/heatmirror.shtml ) has a third layer between the glass…it ends up being 2 layers of Low E surfaces, 2 gas spaces filled with Krypton gas. About R8 center glass and R5 or so at the edges. RH has to be real high (actually too high) for condensation to occur on these.
I run into this all the time here in Minnesota in my work as a contractor. Check the house for a whole house humidifier and if there is one turn it off. Give the house at least a week to dry out then educate the homeowner about the proper use of humidifiers - and if they bring out the coughing baby remind them that the baby will get a lot sicker when the mold gets going.
Honestly, condensation at 40 degrees ambient should never happen even with single pane windows if the inside humidity is kept at 30 - 40 percent. Just my 2 cents.
Bruce Cargin
Hastings, MN
You’re right on, Bruce. There’s a lot of educating left to do or maybe begun!!
Here’s a good publication on buying windows. Used it in my class for first year architects a few years back. It’s directed at the general public buit they found it a good read.
I thought that maybe this article would or might fit this thread.
http://www.healthyhouseinstitute.com/a_777-A_14_point_Plan_for_Healthy_House_Construction
A 14-point Plan for Healthy House Construction
Once you understand the basic concepts, healthy house construction is no more difficult than unhealthy house construction. However, it does involve more than just selecting non-toxic materials. It also requires an understanding of how a house functions - for example how a house “breathes” naturally (and why that may not be desirable), and how heating and ventilating systems interact. This paper will list fourteen dos and don’ts to use in designing and constructing a house that will not make the occupants sick.
- Do build in a clean locale
Site selection is the first consideration in healthy house construction because if the outdoor air quality is poor, then the indoor air quality will be poor also. It is possible to install filtration equipment to clean all of the air indoors, but this can be expensive. While filtration may be necessary in some instances, it is often easier to build in an unpolluted area in the first place.
- Do build an airtight structure
An airtight structure will minimize the amount of uncontrolled infiltration. This not only improves energy efficiency, but when coupled with a mechanical ventilation system, it gives the occupants maximum control over the indoor air. When outdoor pollution is occasionally high (e.g., neighbors applying lawn chemicals), the ventilation system can be temporarily shut off, and the indoor air will not be affected by the outdoor contaminants. An airtight structure also minimizes occupant exposure to insulating materials.
- Do install a radon removal system
It is difficult to predict if radon will be a problem in a particular house. The house must be tested for radon after it is built. It is easy to take some basic precautions in new construction, that may or may not need to be employed later. It is much more difficult to mitigate radon in a completed house if those precautions weren’t taken initially. For example, a sub-slab piping system can be installed when the foundation is being built. If measured radon levels in the finished house are high, it will be a simple matter to hook up a suction fan to the piping. If radon levels are low, the system won’t be necessary, and the sub-slab piping will remain unused. The expense should be considered low cost insurance.
- Do install a ventilation system
People need fresh air. Mechanical ventilation can supply that air at the correct rate whenever it is required. Relying on infiltration for the occupants’ air supply is unreliable at best and, more often than not, insufficient. There are many approaches: supply ventilation through a fresh air duct to the return air side of a furnace, central exhaust, heat recovery ventilation, etc. The different systems have various advantages and disadvantages, but all can provide the occupants with fresh air.
- Do use metal or solid wood cabinetry
Kitchen and bathroom cabinets are not only made of manufactured wood products that contain glues high in formaldehyde (medium density fiber board, particle board, hardwood plywood), but they are also coated with a very potent “acid catalyzed” formaldehyde finish. The finish has very high emissions for 6-12 months, after which levels decrease significantly. The emissions from the formaldehyde base glues have half lives of several years. Custom made solid wood cabinetry with a low-tox finish, or metal cabinetry with a baked-on finish, are better choices.
- Do use water based adhesives, caulks, paints, etc.
In general, water based products are more benign than solvent based products because they have lower levels of volatile organic chemicals (VOCs). However, they are not perfect because there are ingredients besides VOCs that can be responsible for negative health effects. For those interested in even healthier products, several specialty manufacturers are now offering alternative materials that are more benign than off-the-shelf products. If solvent based products must be used for some reason, plenty of ventilation is mandatory to minimize exposures. Extra ventilation is also recommended with water based products.
- Do test materials with sensitive occupants
When dealing with sensitive occupants, it is imperative that some materials be tested for personal tolerance. This is necessary because different people can have varying reactions to the same material. The most important building materials to test are those that are exposed to the interior occupied space: paints, wall coverings, flooring, cabinetry, etc. Testing should generally be done under the supervision of a physician, but the following often works well: Allow a sample to air out until it seems odor free, then place it next to one’s bed and see if sleep patterns are normal. A good night’s sleep generally indicates tolerance.
- Don’t panic
If you are apprehensive about healthy construction, don’t be. However, it is important to be cautious and make intelligent selections appropriate to your needs. There are a number of books and periodicals dealing with the subject on a variety of levels.
- Don’t believe everything you hear
There is an increasing amount of information available on healthy construction. As would be expected, some advice is better than others. When dealing with sensitive individuals, don’t believe anyone who tells you that a product is universally tolerable. People can have very unusual sensitivities to a wide variety of products. For example, most sensitive people are bothered by synthetic materials like vinyls and acrylics. However, some occasionally report problems with natural materials like cotton, while others can tolerate synthetic paints after a period of time. This is why, when sensitivities are severe, testing is imperative.
- Limit the use of carpeting for sensitive people
When it comes to poor indoor air quality, carpeting can also be an offender. New synthetic carpeting may outgass over one hundred different volatile organic compounds (VOCs). Old carpeting may be a haven for microbes, some of which are highly allergenic. Vacuuming carpet with a conventional portable cleaner blows a great deal of “house dust” into the air through an inefficient filter. House dust consists of skin flakes, hair, food particles, pet dander, insect parts, insect feces, and whatever was tracked indoors on shoes - animal waste, mold and pollen, lead dust, pesticides, etc.
- Don’t use products high in formaldehyde
All manufactured wood products emit formaldehyde. Kitchen and bathroom cabinets have already been mentioned. There are two primary types of resins used in the wood products industry - urea-formaldehyde (U-F), and phenol-formaldehyde (P-F). The U-F resins are perhaps ten times more potent than the P-F resins. P-F resins are waterproof and are used in all construction grade products (construction plywood, both interior and exterior; oriented strand board; laminated beams; fiberglass batt insulation; etc.). U-F resins are used in hardwood plywood for wall paneling and cabinetry, medium density fiberboard for cabinetry and closet shelving, and particle board. Houses should have no U-F resin containing products within the occupied space. P-F resins, since they are lower in emissions, can be used in the structure, but with sensitive occupants, they should be well separated from the living space, or eliminated entirely.
- Don’t asphyxiate the occupants
If a conventionally aspirated combustion appliance is used, make sure that backdrafting and spillage will not occur. Since they can take place in the majority of houses when under “worst case” conditions, sealed combustion, solar heating, electric or heat pump furnaces and water heaters are highly recommended. Gas ranges, in addition, are probably not a good idea. Even if backdrafting and spillage are not serious enough to kill the occupants, they can result in enough low level carbon monoxide to result in flu-like symptoms.
- Don’t create a depressurized house
Depressurization can not only result in backdrafting and spillage, but also infiltration of a variety of pollutants. A depressurized basement can pull in radon, pesticides, and other soil gases. A depressurized house can pull mold spores and particles of insulation into the occupied space. Depressurization occurs because of the HVAC system’s blower, powerful natural drafts in chimneys, exhaust ventilation equipment, clothes dryers, central vacuums, etc. In an airtight house having no chimneys or flues, depressurization causes no particular problems, but since exhaust devices will not work efficiently the occupants should be advised to open a window slightly when using such equipment.
- Don’t ignore physics
Construction methods are much more refined than they used to be. As a result, when houses are built without regard for the laws of physics, failures and health problems may occur. Moisture migration, wind and stack effect induced pressures, mechanically induced depressurization, and outgassing, all follow well defined physical laws. If those laws are properly understood, healthy, durable houses can be built.
Marcel 
It quite funny that the experts that have been working on healthy homes for 10-20 years like the American Lung Association (www.healthhouse.org) and the Healthy house Institute state things that are directly opposite to what you hear “on the street”!! Statements like “Environmentally ill people should build an airtight house to begin the journey to health” appears to be an oxymoron; how can that be???
All is not as it seems!!!
Brian;
Are you saying we should not always believe what we read or we should not always listen to what we hear on the streets.
This sounds like an oxymoron to me. ha. ha.
Marcel 
