Fixing a Wet Basement - The Final Step

Once the perimeter is re-cemented and the walls / floor look good - make sure that the sump crock (or floor drain) are functioning properly. This means that once the crock fills up to 3" - 4" below the tile, the pump should discharge the water - typically to the downspout connection. Make sure that if a drain is used, the drain is clear of debris. If you have a drain system, periodically check the flow outwards by using a bucket of water.

If you have a sump crock and are in an area that has many long lasting power outages during storms, you may want to spend money for a battery back-up. During an outage, this backup ensures that your pump continues to discharge during storms - eliminating the water backup which can result.

The attached photo is the "after" picture that was presented originally. The floors had not been painted at this time, however you can see how much better the basement looks.

Next Topic: Actual Happenings...

Fixing a Wet Basement - Step 3

Once the paneling is secure throughout the perimeter, more muscle time - GRAVELING. Unfortunately, 5-gallon buckets are the best way to cart gravel from the dump truck to the basement, one step at a time. Be prepared to be tired after you're done. This is why HZG's company has a division simply for this - people don't like doing it.

Gravel must be placed in the open perimeter pit, covering the footer tile in its entirety; as well as covering the newly popped weep holes. This gravel becomes the positive connection between the weeps and the footer tile, allowing water to flow as it should.

Once the gravel is in place, the area can now be cemented back to a smooth floor. The cement goes directly up to the plastic shield, anchoring it permanently into the floor.

Next Topic: Fixing a Wet Basement - Final Step

Fixing a Wet Basement - Step 2

Once you have the footer tile in place and the weep holes "popped" at the first course, make sure that the wall is not clay tile. Clay tile is usually a smaller block and very smooth. If it IS clay tile, you need to pop weep holes into each course starting from the bottom and moving upwards. This is due to the fact the cores of the block run horizontally versus vertically, so the water that is inside them drains left and right, not top to bottom. This will also necessitate a full wall shield to ensure that water travels to the footer.

Once ready, plastic shields are to be inserted, either 12" or full wall - depending on the walls wetness spots. If water is strictly coming out at the floor level and there is no sign of staining above, a 12" shield is all that you'd need. The shields are placed directly on top of the footer, covering the weep holes. This way the water that comes through will be directed to the footer and the footer tile. The shields are attached to the wall using place button rivets. There are also panel connectors to give the wall a "paneled" look.

The entire area excavated of concrete should have paneling attached.

Next Topic - Fixing a Wet Basement - Step 3

Fixing a Wet Basement - Step 1

Continuing from the last post, we are going to go through a step by step process that almost all waterproofing companies go through when completing the job from the interior.

The first step is to install a functional interior footer tile. Around the perimeter of the basement floor, the concrete needs to be broken and removed down to the footer. This space should come out from the wall from 12" to 18". All of the concrete is removed, leaving the footer exposed.

From this point, weep holes are drilled into the first block off the footer. This will allow water that was previously trapped in the block and forced onto the floor to travel out of these holes.

Next, a PVC footer tile is installed with the hole openings positioned on the bottom. This allows for the water that flows out of the weep holes to collect and travel in the PVC piping.

Next Topic: Fixing a Wet Basement - Step 2

Dry Basements Cont'd - Below Grade Walls

I hope everyone had a Happy Holiday! Now, back to basements...

Below grade walls are the most common type of wall leakage. There are many different types of applications done to the home during construction to attempt to prevent water penetration issues; parge and tar, waterproofing and foam board, waterproofing and fiberglass board...all work to some degree - all FAIL to some degree.

Parge and tar is what builders used most 15 years ago...only recently have they switched to an emulsion with more elasticity. The parging cracks and the tar doesn't move well with cracks, causing leaks. To repair from the outside is expensive, however, due to the removal of earth, landscaping, etc. Interior systems are the only known guarantee against water penetration, due to the system incorporated. Regardless, moisture needs to be kept out of basements.

The attached photo shows a clay tile home with extremely bad leakage. Notice the stains, mold (and mildew) on the walls.

The next few days the writings will be shorter, explaining the step by step process of waterproofing a basement from the interior.

Next Topic: Fixing a Wet Basement

Dry Basements Continued...

Taking a break from wrapping gifts...let's talk basement issues - footer tile.

A footer tile issue is the easiest to diagnose; the most expensive to repair. Reason? It's the farthest issue below earth. Diagnosing is easy. Water is coming onto the floor, ONLY at the wall floor seam. Footer tile failure can result from several issues. They are...

Clay pipe - some older homes have clay pipe as footer tiles. Well, clay tile breaks. Tree roots and earth's pressures are the largest culprits causing the destruction of the tile. The only repair is to excavate to the footer and replace. This is why the majority of new homes use hard plastic piping (PVC).

Installed incorrectly (1) - The new PVC footer tile has a pair of holes that run alongside the bottom, allowing water to enter and be channeled away from the home. Unfortunately, HZG has seen his share of incorrectly installed tile - holes up. Yep, simply installing the piping upside down will result in water not being able to gain entry into the pipe...then into your basement it goes.

Installed incorrectly (2) - The footer tile needs to be relatively level next to the footer. HZG has seen several tiles installed over clumps of dirt, creating severe "humps." These humps cause a belly, not allowing water to travel - except into your basement.

Installed incorrectly (3) - Only once I've seen this, but once was enough. The footer tile was installed ON TOP of the footer, next to the wall. The water was right there as the basement wall, begging to come in. And it did...

Not enough gravel - If there isn't enough gravel installed over the pipe on the footer, dirt compacts over the tile. This dirt blocks water from entering the tile (once again, allowing it to enter the basement).

Besides excavating to repair the footer tile, the abundance of water also causes damage to waterproofing and repelling systems. These systems are designed to get water away from the structure. They are NOT designed as pool liners.

Next Topic: Dry Basements Continued...Below Grade Walls

Holiday Writings

Good evening all -

Please be advised that for the next few days, writing will be sporadic. HZG needs to spend some quality Holiday time with the little HZG's. Plus Momma HZG says I better (and I always listen to Mrs. HZG.)

We will resume discussing Dry Basements soon!

A Dry Basement Part 2 - Water Issues

As I've previously stated, water is a nasty beast. There are various ways water can get into the basement and crawl space. The following are the most popular breaches; however there are many more...

Footer Tile: If the footer tile gets clogged by dirt and water is unable to pass through it, it will rise into the first course of your basement and go onto the floor.

Below Grade Block: If there is a breach in the waterproofing or water repellent, the water will wick its way from the breach downwards to the interior block. From this point, based on volume, it will continue to wick downwards.

Above Grade Block: The majority of homes have 1 - 3 courses of block that are exposed to weather. If they are not sealed, heavy rains will saturate the block and will wick its way inwards again.

Non-functioning Sump Pump: If the sump pump is burned out, or electric power is out, the water that the crock collects has nowhere to go. Nowhere that is, except out onto your floor.

Bad Grading: Every home needs proper sloping of earth away from a foundation; also, it is important to keep mulch to a proper level so that water does not pond.

Animal Urine: Yes, HZG has been called to a home to investigate a wet floor. It was animal urine. Animal urine...

Next Topic: A Dry Basement Part 3 - Footer Tile

A Dry Basement - Part 1 (of many)...

Moisture in a home can cause great damage...to the home AND to the occupants. However, the HZG isn't one that's on the "black mold" bandwagon. Mold can be serious. When I grew up, it was "mildew" - not the all inclusive toxic variety. I turned out just fine...or maybe I should rethink this. Anyway, I feel mold is this year's lead based paint is this year's carbon monoxide is this year's radon...you get the picture.

With this being said, the damage that moisture can cause to the building's shell and its contents is what concerns me the most. Mildew, appearance, smells - air quality in general - can grow from a water problem.

Prior to discussing how to solve the problems, we must first understand how basements are made. I will keep this discussion to lay person's terms, however you can find other detailed information on various websites.

A block basement is comprised of many components. The footer (the base of the wall), the wall (blocks put together with mortar), the footer tile (PVC piping run around the perimeter of the basement that helps channel water to a destination away from the foundation), a waterproofing or water repelling substance on the wall, gravel over the footer tile and footer (connecting the walls drainage to the footer tile) and a dirt backfill. Boy, was that simplified...

A poured wall functions basically the same, except concrete forms are used and the walls are made solid. There are benefits to both - HZG feels that if the block walls are done correctly, they are the best (another topic of discussion). For the purpose of wet basements, we'll use the block wall as the example due to the heavier percentage of them in existence.

Next Topic: A Dry Basement Part 2 - Water Issues

Actions to Control Relative Humidity

HZG recommends the following EASY actions to control moisture in the home.

To ADD moisture (if the air is dry)...
* Cook without lids; do not use stove exhaust fan
* Place bowls of water throughout the home
* Use exhaust fans only as long as necessary
* Add plants
* Hang clothes / towels to dry in the house
* Use a humidifier cautiously

To REMOVE moisture (if the air is wet)...
* Control basement moisture
* Cook with lids on pots and pans
* Take shorter showers
* Seal off laundry room
* Dry clothes outside
* Water plants less
* Move plants outdoors in the summer months
* Cover fish tanks
* Open windows, a crack at top and bottom when air outside has low relative humidity
* Use exhaust and ventilating fans to remove moisture
* Use a dehumidifier
* Use an air conditioner

These are all EASY things to do to aid in controlling the relative humidity in your home.

Next Topic: A Dry Basement - Part 1

Moisture Condensation Problems

Rocket science part 2 - moisture condenses on cold surfaces, such as windows and outside walls, due to a combination of relative humidity and temperature. As air cools, caused by its contact with cool surfaces, the relative humidity of the air increases until it reaches saturation. When that saturated air is cooled, some of its water vapor turns to liquid water and clings to the cold surfaces that cooled the air. Condensation occurs most frequently and plentifully on the room's coldest surfaces. Condensation increases as relative humidity increases and as surface temperatures decrease.

Effective strategies for reducing moisture condensation include:
1) Reducing relative humidity by reducing moisture sources.
2) Equalizing pressure between indoors and outdoors.
3) Installing or improving air and vapor barriers to prevent air leakage and vapor diffusion from transporting moisture into building cavities.
4) Ventilating with drier outdoor air to dilute the more humid indoor air.
5) Removing moisture from indoor air by cooling the air to below its dew point, with refrigerated air conditioning systems and dehumidifiers.
6) Adding insulation to the walls, floor and ceiling of a home to keep the indoor surfaces warmer and therefore more resistant to condensation. During cold weather, well-insulated homes can tolerate higher humidity, without causing condensation, than poorly insulated homes.

Next Topic: Actions to Control Relative Humidity

Setting Hot Water Termperature

High water temperatures waste energy and threaten occupants with scalding. High water temperatures also speed the buildup of calcium and magnesium deposits in the tank and pipes. These minerals become less soluble as water temperature increases, and precipitate out of the high temperature water. A high water temperature also speeds up corrosion, which is the death of many water heaters. Reducing water temperature to around 120 degrees F minimizes mineral buildup, protects residents from scalding, reduces corrosion and decreases energy consumption.

The storage temperature of a home's hot water is influenced by the presence or absence of a dishwasher. Most dishwashers have small water heaters inside that will boost the temperature about 20 degrees F or more. If the dishwasher has a booster, set the water-heater storage temperature to 120 degrees F. If the dishwasher doesn't have a booster, the setting should be between 130 - 140 degrees to get dishes clean.

Electric water heaters have a thermostat that is adjusted by turning a setscrew or knob. Gas and propane water heaters have a temperature dial located near the bottom of the tank on the gas valve. Marking the beginning temperature and adjusted temperature on the dial of the thermostat will provide a future reference. Several adjustments may be necessary before the water temperature is right.

Next Topic: Moisture Condensation Problems

Tank Insulation

Storage water heaters and other hot-water storage tanks rarely have an economically optimal level of insulation. The total R-value for any type of hot water storage tank should be R-15 to R-35, depending on the cost of fuel. If possible, the insulation should completely surround the tank. Usually the tank already has some insulation. Standard storage water heaters have a few inches of fiberglass between the tank and outer steel shell, amounting to R-3 to R-6. New standard models use foam insulation for higher R-values.

Technicians commonly use vinyl-faced fiberglass insulation (3 - 6 inches) to insulate storage water heaters. The insulation is often stapled and strapped to the outside of the tank, with the seams in the vinyl covering taped. The tape alone may not hold the insulation's weight permanently, so plastic straps are often used for support. The tops of gas fired storage water heaters should NOT be insulated, since the vinyl facing is combustible and the insulation might interfere with the draft diverter.

The payback on the water heater insulation installation ranges from 1-2 years. A GENERAL rule of thumb is if the water heater is less than 5 years old, don't insulate it. READ the water heater label - some specifically say DO NOT WRAP. Also, when wrapping, leave a flap for instructions on the tank to be read.

Next Topic: Setting Hot Water Temperature

Water Heaters - Energy Usage

The average household uses around 3500 kilowatt-hours of electricity or 230 therms of natural gas to heat water annually. Water heating consumes approximately 15% of the electricity and 25% of the natural gas used in residences. Water heating is the MOST variable class of energy consumption among families and varies according to water-heater capacity, climate, economic status, work schedule and age.

Water heaters use energy in 3 ways: demand, standby and distribution. Demand means energy is used for heating incoming cold water up to the temperature set point as hot water in the tank is used. Demand energy depends on water heater efficiency, occupant behavior, and consumption of fixtures like shower, clothes washer and dishwasher.

Standby energy accounts for heat lost through the storage tank's walls. Standby losses amount to 20% to 60% of the total water-heating energy. Households using less hot water have a higher percent of standby losses. Distribution losses consist of heat escaping through the pipes and fixtures. Pipes near the water heater lose heat even when water isn't flowing because hot water rises out of the tank, cools off in the nearby pipes, then falls back down into the tank.

Americans us 15-40 gallons of hot water per day per person. Water heating systems are designed for recovery capacities of 3-20 gallons per hour per resident. Most single-family homes have 40-gallon or 50-gallon storage tanks.

You can see that the "little old water-heater" is crucial to everyday living - and energy usage.

Next Topic: Tank Insulation

Appliances - Clothes Dryers

Are you ready for rocket science? Line-drying laundry is the most effective way to save energy on clothes drying. Wow...

Gas clothes dryers operate more economically than electric clothes dryers. At average prices for electricity and gas, electric clothes drying costs 30-40 cents per load versus 15-20 cents for gas per load.

Cleaning the dryer lint filter after each cycle minimizes drying time. Over time, lint collects in the vent, elements, and air passageways reducing airflow and increasing cycle time. Every few years, a dryer and its vent should be thoroughly cleaned.

Piping the dryer vent in smooth metal pipe, sealed at joints with silicon caulking, reduces drying time over piping with plastic flexible vents. Those crazy plastic vents cause approximately 13,000 fires per year. The reason smooth metal pipe works better is that the air has only to flow straight out of the pipe versus swirling around each coil. This makes the dryer work harder.

One more thing that you can do to improve your drying time is to use your WASHER more efficiently. Double-spin the clothing to extract additional water. If you don't believer HZG, then try it for yourself. Once your washer has completed the spin, place a bucket under the discharge and set the washer to spin again. You will get up to 3/4 of a bucket in some cases - depending on the size of your bucket. It's an absolute guarantee that you will get some excess water out - making your drying time reduced.

Next Topic: Water Heaters - Energy Usage

Fluorescent Lighting

The glow of a fluorescent tube is caused by electric current conducting through mercury gas. Fluorescent lighting is used mainly for indoor lighting. Fluorescent lights need controlling devices, called ballasts, for starting and circuit protection. Ballasts also consume energy.

Fluorescent lights are approximately three to four times as efficient as incandescents, and their lamp life is about ten times greater.

Compact fluorescents (CFLs) are the most significant recent lighting advance for homes. They combine the efficacy of fluorescent lighting with the convenience and universality of incandescent fixtures. Recent advances in CFL design also provide more natural color rendition and less flicker than older designs.

CFLs can replace incandescents roughly three to four times their wattage. When introduced in the early-to-mid 1980s, CFLs were bulky, heavy and too big for many incandescent fixtures. But newer models, with lighter electronic ballasts, are only slightly larger than the incandescents they replace. CFLs screw into incandescent fixtures and save up to 75% of the electricity used by incandescent lamps.

CFLs are continually evolving, however they cannot replace all lighting fixtures. Soon, though...

Next Topic: Appliances - Clothes Dryers

Incandescent Lighting

Incandescent lamps are the oldest, most common and most inexpensive lamps. Incandescent light is produced by a white hot coil of tungsten wire that glows when heated by electrical current. The type of glass enclosure surrounding this tungsten filament determines its light beam's characteristics.

Incandescent lamps have the shortest service life of the common lighting types. All incandescents are relatively inefficient compared to other lighting types. However, significant savings are possible - if you select the right incandescent lamp for its purpose.

Experts (including the modest HZG) say these lamps are the most common and the most inefficient light source available. Larger wattage bulbs are more efficient than smaller ones.

While fluorescent lighting is less expensive (energy wise, addressed next writing), HZG has found that the exterior flood lights do not last as long as advertised, making their price point too expensive. Maybe it's the climate; maybe it's a fluke. However, 3 bulbs have been tested fluorescent versus 3 bulbs incandescent, and the incandescents win.

Next Topic: Fluorescent Lighting

Duct Airflow Problems

It isn't unusual to find duct systems undersized for the heating output of the furnace. Undersizing means that the ducts' cross-sectional area is too small. A stubbornly high supply-air temperature or portions of the conditioned space that are uncomfortable may indicate a duct-sizing or duct restriction problem.

Ducts are often restricted by furniture placement, closed doors and dirt registers. A test involving opening the door to a furnace's blower compartment during operation can provide information about duct restriction. If opening the lower compartment door reduces supply temperature significantly, then improving return air will usually improve comfort and boost efficiency. Improvements to return air include:

1) Cutting off interior doors to allow air to return from rooms, which have no return register.
2) Installing vents in doors or through walls, or installing ducts in ceilings to allow air to return from rooms, which have no return register.
3) Installing a new return duct leading from a hard to heat area directly to the furnace cabinet.
4) Cleaning registers, blowers and air conditioning coils.

Without getting into major reconstruction, first check your house. HZG sees weekly supply registered covered by dressers, beds, drapes, etc. Be smart; let the air FLOW.

Next Topic: Types of Lighting - Incandescent

Changing Furnace Filters

This topic is almost brain-dead. Yet HZG sees this issue a minimum of 3 times per week. Changing furnace filters.

Clean air filters prevent dirt from collecting on the fan and heat exchanger of forced-air furnaces. Dirt reduces air movement and efficiency if it builds up on the filters, blower and heat exchanger.

The recommended frequency of filter changes depends on how much dirt is contained in the airstream and how long the furnace is running. Filters in some homes may last 6-months before needing replacement or cleaning, while other homes' filters may need to be cleaned or replace every month during a heating cycle.

Also, some furnace filters fit snugly in an enclosed spot of the furnace, while others are exposed. When we encounter an exposed filter, we use duct tape to cover the opening and show the homeowner. Reason? The exposed cavity invites in extra dirt, forcing a filter change to occur sooner than needed.

HZG's recommendation? In climates such as Ohio's, change the filter monthly during the heating cycle and every 3-months after.

Next Topic: Duct Airflow Problems

Programmable Thermostats

Programmable thermostats combine a clock with a thermostat and can save a significant amount of energy, especially during hours when the occupant is not home or asleep at night. Savings from an 8-hour, 10 degree setback will range from 5% to 15%. Two 8-hour, 10 degree setbacks will yield 10% to 20% savings. Milder climates receive a greater percentage of savings from night setback than more sever climates because their setback periods comprise a larger percent of run time in milder climates compared to setback periods in more severe climates.

The House-Zen Guy's wife controls our thermostat. She's got it set on workdays to be reduced from 7:30 AM to 5:00 PM, heating up for our arrival around 6:00 PM. She also has it set for reduction from 10:00 PM to 5:00 AM, a big 2 1/2 hour window of heat in the morning and 4 hours at night. On weekends, all bets are off.

Next Topic: Quickie - Changing Air Filters

Door Weatherstrips and Sweeps

Before beginning to weatherstrip a door, it is important to make sure the door is operating properly - tighten the screws in the hinges, door knob and strike plate.

The gap at the bottom of the door is usually the door's biggest air leak. Install a sweep to seal the door to its threshold. A sweep is easy to install, but it hangs below the door and may drag on the floor covering if the threshold is not high enough. Periodically, we have to adjust the height of the threshold.

The two most common types of door weatherstrip mount to the stop - sealing to the face of the door to the stop. Jamb-mounted weatherstrip seals to the edge of the door. Weatherstrip that installs to the jamb is a little more difficult to install but last longer because the door stop protects it from abrasion. Weatherstrip that attaches to the stop is easier to install, but is more prone to damage and must be designed to accommodate a door's seasonal movement. Wooden doors move considerably as they absorb and shed moisture with weather changes. Make sure you choose a weatherstrip that is flexible enough to follow the door as it moves.

Bottom line: Spend more money on weatherstripping and sweeps - they'll last longer and protect better.

Next Topic: Programmable Thermostats

Fiberglass Facings

Good evening all - it seems that some of the last few posts may have been rather mundane. You're correct - and this should only last a few more posts. Also, you may have noticed that I've changed from The Energy Guy to The House-Zen Guy. This is due to a separate post upcoming detailing the purchase and rehabilitation of homes. It's easier to go by one moniker - and the two sites will reference each other. With that being said...

Various facings are fastened to insulating materials during the manufacturing process. Fiberglass batt or blanket insulation is available with a variety of facings. Some common insulation facings are: kraft paper, aluminum foil, aluminum foil / kraft paper laminate and white vinyl sheeting. You've read my reference to white vinyl in previous posts.

Facings protect the insulation's surface, provide an air barrier and or vapor barrier, facilitate fastening and help to hold the insulation together. All of the common facings attached to fiberglass batts are air barriers and most are vapor barriers. However, their effectiveness as an air barrier depends on nearly flawless installation. Besides being an air and vapor barrier, aluminum foil is also a radiant barrier, retarding radiant heat flow when it faces an air gap.

When installing fiberglass facings in a home, the facing should always be facing the heating source. So if you are in a room remodel, the paper faces you. If you are in an attic, the paper faces downwards toward the living envelope.

Next Topic: Door Weatherstrips and Sweeps

Plumbing Penetrations

You can follow air leakage pathways in many homes by following plumbing. The bathroom, in particular, can create air leakage and attendant moisture problems. Problems include tubs sitting against unsheathed wall studs, gaping holes in the floor underneath bathtubs and plumbing walls with large holes in their top and bottom plates.

The main vertical drain pipe (the soil or "stink" stack) is often enclosed in a wall or in its own framed enclosure, which transports air between the basement and attic through leaks at penetrations in the floor and ceiling. We referenced this in a prior writing under Air Sealing - attic.

Again, you can following plumbing out the band joist as well - typically not air sealed or hidden.

Next Topic: Fiberglass Facings

Concrete Block Walls

We're back and up and running...

Concrete-block walls are not themselves air barriers. Since soil isn't an air barrier either, the block wall can transmit soil gases to the home. If the cores of the blocks are open at the wall's top, (where the sill plate resides), the concrete block wall can be one large thermal bypass. The cores of concrete blocks should be filled with insulation. If not, air travels unimpeded throughout the wall's area, since the mortar doesn't seal spaces inside the block. Convection within the cores also speeds heat transfer through the wall.

If you know of anyone in the profession that has an infra-red camera (and you live in a climate where there is a minimum 20% temperature difference from the inside of the home to the outside), you will see a glowing red (or white, if not in color) band where the exposed block is located. It's truly amazing the heat loss that occurs.

We touched in a prior writing on insulation foam - so let's touch again. Inexpensive and easy to install. Contact a contractor that provides "safe" foam.

Next Topic: Plumbing Penetrations

Pressures Driving Air Leakage

Morning all...the blog is still acting crazy and I hope to have it fixed soon. So if you can deal with not having bold copy, color or photos - just reading...I'll proceed on. No grammar or spelling chex either...

Pressures in a house contribute greatly to air leakage. Again, the more air leakage, the higher the energy bill and less comfort (both on your body and wallet).

The first type of pressure is called the Stack Effect. Cooler air is denser than warmer air, and this density difference creates a pressure that causes air to move. Hot air rises to the top and cooler air falls to the bottom. If the home has leaks, warm air leaves through higher openings and cool air enters through lower openings. This pattern of air leakage is called the stack effect because it resembles airflow in a chimney. The pressures created by the stack effect are greatest at the highest and lowest points in the building. Therefore, a hole in a basement or attic will allow more air infiltration than an equal-sized hole near the neutral pressure plane. This is why we focus on the basement and attic so much on our retro-fit jobs.

The second type of pressure is called Wind Pressure. The wind's speed is greater the higher from the ground you measure. As building height increases, wind's force against the building increases. Wind speed is affected by trees, fences, neighboring buildings and hills that block or divert it. Wind pressures push and pull air through holes in the shell - again causing air leakage.

Next pressure, Chimney & Exhaust Pressures. Chimneys, exhaust fans and clothes dryers create a slight vacuum indoors because they exhaust air out of the building. Replacement air, for air exiting exhaust devices, is called make-up air for exhaust fans or combustion air for combustion appliances. Make-up air and combustion air enter through air leaks, intentional openings, or ducts. Make-up air or combustion air may even come down a chimeny if negative pressures become too great - a dangerouse situation called backdrafting.

The last pressure is Duct Pressure. The furnace blower circulates air through the furnace and its supply and return ducts. Supply registers blow air into a room, pressurizing nearby areas of the room. Return registers suck air out of rooms, depressurizing areas near these registers. If the ducts are leaking, or return air is resticted, rooms may have high positive or negative pressures. These pressures are often large enough to double or triple the building shell's air leakage, compared to air leakage when the furnace blower is off.

Next Topic: Concrete Block Walls

Problem with the Blog

Hope to have back and running soon!

Unoccupied Basements and Crawl Spaces

Factors that are considered when determining if a crawl space is to included in the thermal envelope include climate, ground dampness, and the presence of ducts and pipes within the space.

The most important practical consideration affecting the decision to include or not include is the ease and cost of air sealing and insulating the floor versus air sealing and insulating the foundation walls. If there are many pipes and ducts that run under the floor, it is typically best to include the crawl space in the envelope. It is generally much easier to install perimeter insulation than floor insulation, unless the perimeter is not level and semi-smooth to work with.

Not currently approved for DOE grant money but on the rise is masonry block insulation. This process involves injecting 2-part foam into the masonry cores of block. It can be pushed up to 12 courses and expands to fill the empty core. An average 8" block can be brought from approximately an R2 to an R8. With at least 2 courses typically exposed above grade, this greatly keeps the temperatures out of the envelope.

Next Topic: Pressures Driving Air Leakage