Relative Humidity and Why It Matters

You can control a key variable associated with proper air quality in your home by maintaining relative humidity levels.  

Anyone who has watched the Weather ChannelEverybody’s heard the weather report and grasp the concept that excess humidity is muggy and low humidity is dry. New Englander’s know that basements should have a dehumidifier to lower the humidity. Physicians recommend humidifiers to increase humidity in the winter when its’ dry or to relieve coughing and congestion. So what’s the big deal with humidity in the home and what’s the ideal range? For indoor air quality purposes the ideal range is between 35-45% relative humidity.

Let me try to clear the air regarding some of the basic terms which are not interchangeable.

Relative humidity is a ratio of the amount of water in the air compared with the amount of water the air can hold at a given temperature. Air’s capacity to hold water vapor increases with increasing temperature. Warmer air can hold more vapor than colder air. This is why 60% relative humidity at a temperature of 95F feels muggier than 60% humidity at a temperature of 40F.

Dew point is an absolute measure of the amount of water in the air. It is the temperature at which the air, at the current amount of water vapor, will be 100% saturated. Reduce the temperature any further and water will condense out and form dew or fog, hence the dew point. In fact, you'll often see fog forming even before you reach that point.

Mold spores and dust mites will increase exponentially when the relative humidity exceeds 60% for a sustained period of time. A typical basement without a dehumidifier will read between 65-75% relative humidity during summer months and between 45-60% during winter months.

Most people will know when it’s dry or below 20% RH or muggy when above 70%. However while the average person will notice a five degree change in temperature they are not able to notice changes between 20-70% relative humidity. This is why monitoring the relative humidity in your home or basement is so important, yet few people do. 

Relative humidity is measured using a hygrometer. You will want to set your dehumidifier to around 35% or continuous mode to ensure the relative humidity at the opposite end does not exceed 55%. Don’t rely soley on the relative humidity reading on your dehumidifier. These displays are notorious for being inaccurate. We recommend a quality digital hygrometer like the Extech brand sold through Professional Equipment for around $45. 

Ten Things You Can Do On A Weekend To Improve The Air Quality In Your Home

1) Cap your sump pit. A properly capped sump pit will reduce radon gas, which is the second leading  cause of lung cancer in the United States. An added bonus: you deter the mice and rats from an unnecessary watering hole.

2) Change your air filters. Clean air filters will reduce the amount of harmful debris and particulates in the air.

3) HEPA Vac your house. Vacuuming your home with a functional HEPA filter vacuum containing a bag that is no more than halfway full will reduce organic matter (skin cells, dust, dirt, debris) leading to mold growth and dust mites. Make sure to use the correct vacuum attachment for your flooring. If you outsource your home cleaning, provide your housekeeper with a HEPA vacuum only to be used in your home to prevent unnecessary cross contamination of unwanted allergens.

4) Disinfect your bathroom. A proper disinfectant will kill off the nasty bacteria, viruses and fungi which thrive in your damp, moisture-rich bathroom. Let the solution sit for an appropriate dwell time of at least 5 minutes.

5) Run your dehumidifier and measure its effectiveness (especially in the basement). The typical dehumidifier at the hardware store typically lasts for 3-5 years. You can monitor the effectiveness of a dehumidifier with a hygrometer. The ideal range for humidity in the basement is below 45% (a warning: this is is tough to achieve unless your basement is drained with a sump pump or existing plumbing line). Newer dehumidifiers have a convenient hygrometer already built in so you can set the appliance to 40%; when the moisture in the air rises above 40%, the dehumidifier kicks on and consequently turns off when the air saturation dips below 40%.

6) Safely dispose of unwanted paint cans and other volatiles. The pyramid of toxic fumes in your garage or basement can off gas into living areas and contaminate the air quality with excess volatile organic compounds (VOCs). When in doubt, safely throw it out.

7) Run a high quality room air purifier in your bedroom and living rooms. Most purifiers that we test don’t live up to what the manufacture states. However, a few really do improve air quality. We like the IQAir (www.iqair.com) and Austin Air (www.austinair.com) brand purifiers based on before and after testing. These brands are top picks with our clients who want the best possible air quality in their home. www.allergybuyersclub.com is an excellent resource to compare products and read independent reviews.

8) Open the windows. Encourage fresh air whenever possible. Take a look to see if there is an opportunity to install a standalone ventilation system like EZ Breathe (www.ezbreathe) in your basement or if you can retrofit your AC unit with a recovery system. Also make it a habit of running the shower exhaust fan for at least 30 minutes after bathing. The exhaust should be firmly secured through the exterior or soffit vents.

9) Declutter. Not only is it satisfying to lighten your load, but you’re also improving airflow and reducing the overall surface area in your home for dusts and allergens to cling on to. The closet crammed with porous clothing or that nook under the stairwell packed full with cardboard boxes create a most favorable environment for molds, dust mites and odors.

10) Encase your mattress. Even if you doubt that your mattress is 50 pounds heavier with dust mite matter, it’s still a good idea to protect your body from unwanted allergens and your mattress from excess sweat. Have you looked at the water stains on your pillow or mattress pad lately?

Basement Flooring Options and Issues

There are many materials from which to choose, and professional floor refinishers who aren't out to sell a particular product can recommend materials based on the dryness/dampness of your basement floor and its condition, whether it's smooth, cracked or nicked. Have floor cracks fixed before any basement remodeling project to avoid headaches in the future, experts say.

You can you can test the dampness of your basement floor yourself before calling a professional floor refinisher or embarking on a do-it-yourself project. Take a good-size sheet of impermeable material -- a big trash bag, for example -- and lay it flat on the basement floor. Tape it down on all sides so that no air gets underneath. Repeat this in a couple of corners, in areas by walls and in the center of the room. Leave the bags there for at least 24 hours, and then check under them to see if moisture has accumulated. If it is damp under the bag, you have a moisture problem that needs to be resolved before you proceed.  Often times you won't notice the dampness because it just evaporates away and your concrete can appear dry. However when you cover concrete with carpet, tile, paint or coatings you are in effect sealing the surface and trapping the moisture between the concrete's surface and floor covering, creating a perfect breeding ground for mold and mildew.

What are some of the options?

1. Concrete Overlays - concrete overlays are also referred to as skim coats. They are thin coats of very fine concrete. They are mixed to the consistency of pancake mix in 5 gallon buckets with a drill and inexpensive mixing paddle. They are applied with 2 coats about 1/16th of an inch thick. After the concrete dries it gets sealed. Chemical bonding vs. mechanical bonding is an important element of the product selection.  When a concrete floor cracks, the thin mechanical bond also cracks which can lead to deterioration.  A chemical bond remains with and on the concrete regardless of floor shifting or movement.   Now you have a thin seamless floor in any color. Clean, easy to clean, breathable so moisture can pass through. Mold resistant, any mold can be easily cleaned. Thin so height is not an issue.

A concrete overlay solves just about all basement floor covering issues. Add area rugs for warmth and decor. They can removed to clean or thrown out and replaced. Many area rugs are inexpensive. Cost for materials is below $2.00 per square foot.Due to new improvements and developments with overlays there are a few systems on the market that are easy to apply.   We do not recommend it, but you can also put down area rugs and runners. The area rugs and runners can be removed for cleaning or easily replaced.

2 Hardwood - doesn't work. Two  reasons. First it raises the height of the floor at steps and doorways. Few homes were designed for basement floors other than concrete, its always an afterthought. Raise the floor height and you violate code at steps and have a doorjam issue. Second moisture will cause hardwood to expand and contract causing floor to buckle.  Engineered flooring is a good alternative product because it is constructed from three to five layers of different hardwood material with a higher density. The layered construction offers a higher resiliency to humidity changes.

We do not recommend that you install a laminate in the basement, however, if you really want to, there are certain precautions that are absolutely necessary - that is if you don't want to re-install another type of flooring shortly after the laminate.  Test the concrete first for moisture, for at least 24 hours. Be sure to use at least a 6 mil polyethylene moisture barrier (plastic sheeting) and the plastic coated foam that the manufacturer of your laminate recommends. 

3. Ceramic Tile - Like hardwood there is the height issue at doorways and steps. The negative is the grout lines where dirt and moisture settle. A big advantage if height is not an issue is you can install a radiant heat mat, then install tile. A great solution, but expensive.

4 Vinyl Tile - Thin and inexpensive. Moisture coming through a concrete slab can delaminate tile. Vinyl or linoleum are not breathable so moisture will not penetrate. Instead it will trap moisture. If you get water in basement it will settle in joints where tile meets tile and you will have to replace the floor.

5. Carpet - carpet will warm up a cold damp basement floor . However,  it will work like a sponge for moisture and collects dust.   If you just have to have carpet, make certain to put down the best vapor barrier you can and be sure to select a mold resistant material and use interlocking squares with no adhesive for easy replacement.

Improve Your Home's Indoor Air Quality With A Recovery Air Exchanger

In the winter, fresh air is cold air. And your home and business are built to keep the cold air out. But you can keep the air inside fresh year-round and conserve energy at the same time with the use of a heat-recovery air exchanger, also called an air-to-air heat exchanger. 

An average home should have at least .35 air changes per hour (ACH). Newer, high-efficiency homes generally have ACH of less than .35, with many as low as .05, which leads to poor air quality and consequent health conditions such as headaches and allergies.

In addition to providing a fresh air supply, air exchangers help reduce allergens and unhealthy indoor air pollutants such as radon and smoke. They are required by new construction building codes in some states.

Heat-recovery air exchangers capture up to 85 percent of the heat from indoor air and transfer it to the fresh incoming air before exhausting. 

Heat-recovery air exchangers capture heat from stale moist air and transfer that heat to the fresh air intake so that your heating system will not have to work so hard to condition that air. 

Benefits

• Provide a constant, controlled supply of fresh air to your home.
• Control build up of excess moisture from daily activities such as showers, whirlpools, and cooking.
• Reduce the concentration of allergens such as pollen, dust, and dander.
• Reduce unhealthy indoor air pollutants, such as formaldehyde and smoke, and those emitted from paints, sprays, and cleansers.