1:5:10:365 EcoTip Blog

April 20, 2008

:111 Fill a Bag – Checking HVAC Flow

 Welcome to today’s 1:5:10:365 Tip for becoming a better steward for our home and planet.

1:5:10:111 EcoTip: In order for central air conditioning systems to function efficiently, it is necessary for them to be free of significant leaks and be balanced. This means that the air supply is flowing somewhat equally throughout the system. In an unbalanced system you might have too much air going to one area and not enough in others. There are sophisticated duct balancing systems that can be used to professionally perform these checks, but an inexpensive simple do-it-yourself method was developed by the Canadian Mortgage and Housing Administration using a plastic garbage bag, coat hanger, duct-tape and a timer.

image credit: Lawrence Berkeley National Laboratory

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Additional Information

Suggested Review – :110

The CMHC says to use a Glad 66 cm x 91 cm garbage bag. Which is about 2ft X 3ft when it is laid out flat. The coat hanger is bent into a circle, shape that will fit all the way around the heating and cooling supply registers you have in your home. You may need to reshape it for different openings. Tape the edge of the plastic bag to the coat hanger.

To test your duct system – turn your HVAC fan unit to on. It is not necessary to have it actually heating or cooling  –  just blowing. Place the completely deflated garbage bag over a supply register and time how long it takes the bag to inflate completely. Record this time for all the supply registers. Now place the fully inflated garbage bag over each return register record how long it takes for the bag to deflate.

The total inflation time for the supply registers should equal the total deflation time for the return registers. If there is only one return register, you may find it deflates too quickly to measure accurately. In this case you might try using two bags simultaneously over the return register.

If it takes 2 seconds for bag to inflate that is approximately 75 cubic feet of air per minute coming into the room. This is pretty good for a standard size room. Same size rooms should have approximately the same amount of air delivered to them. Half size rooms should have about half the air. Serious deviations should be checked. A duct may have come loose or the system may not have been designed properly.

The following table from CHMC shows ratio between inflation times and airflow rates.


Time to inflate a plastic trash bag (66 cm x 91 cm [26 in. x 36 in.]

Airflow

Approximate time to inflate bag

5 L/s (10 cfm)

13 seconds

10 L/s (20 cfm)

8 seconds

15 L/s (30 cfm)

5 seconds

25 L/s (50 cfm)

3 seconds

If more air is required, adjust the grille openings at the supply register in the room. Keep in mind that bedrooms require more fresh air when occupied by more than one person. http://www.oee.nrcan.gc.ca/Publications/infosource/Pub/hrv/hrvsystem.cfm?text=N&printview=N#airflow

 

 

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April 19, 2008

:110 Upgrade Furnace Filters

Welcome to today’s 1:5:10:365 Tip for becoming a better steward for our home and planet.

1:5:10:110  EcoTip: Pleated filters are available that do a much better job than standard HVAC filters. Hot weather is coming so it is time to start thinking about making sure your air conditioning system can run as efficiently as possible.

When you change your filter – upgrade to a higher efficiency pleated filter. They fit in the same slot as a standard fibrous furnace filter but are much more effective in removing dust and small particles like mold spores. 

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 Additional Information

Suggested Review – none

The Filtrete pleated filter by 3M has a MERV 11 rating which means it will do a pretty good job of removing mold spores, pollens and other small particles and it fits in a standard system slot.

Lawrence Berkeley research laboratory has excellent additional information of furnace system retrofits and includes information on filters at: http://ducts.lbl.gov/HVACRetrofitguide.html

 

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April 18, 2008

:109 Stucco care

Filed under: :109 Stucco Care — Tags: , , , — John Banta @ 5:23 am
Welcome to today’s 1:5:10:365 Tip for becoming a better steward for our home and planet.

1:5:10:109 EcoTip: Homes with stucco exteriors require some special care to help insure durability. Clean, inspect and maintain stucco exterior homes at least once every year.

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 Additional Information

Suggested Review – :075, :076, :105, :106, :107, :108

 
Stucco Cracks should be monitored and filled when they exceed 1/8 inch. Don’t use caulk on cracks, it is important they be filled with an appropriate stucco filler. In 1:5:10:075 I mentioned photographing cracks to be able to monitor if they are changing. If cracking exceeds that from normal settling, it is important to find out why and correct the condition. Your home may be on expansive soil (1:5:10:076).

Don’t penetrate the stucco in order to attach planters, patios, sunscreens, fasteners or other items to the home. This may damage the drainage plane and create a pathway for excess water to enter the wall cavities creating expensive damage. Any such changes should be left to professionals that warrent their work.

Caulk windows, doors, dryer vents, electrical boxes and other penetrations every year with a 25 year silicon caulk.

Historic stucco is very different from today’s applications. For older stucco buildings the National Parks Service has prepared Preservation Brief 22 with some great information.

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April 17, 2008

:108 Clear Weep Screed

Filed under: :108 Clear weep screed — Tags: , , , , , , , — John Banta @ 12:05 am

Welcome to today’s 1:5:10:365 Tip for becoming a better steward for our home and planet.

1:5:10:108 EcoTip: The weep screed needs to be clear to allow drainage of any water that unavoidably enters. There are many ways the weep screed can become clogged. I have seen some houses where the stucco was never cleared after it was installed. Plants growing too close to the house may grow up into the holes. Even the careless application of caulking material can block the holes.

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 Additional Information

Suggested Review – :105, :106, :107

 To clear the holes you will need a mirror and a piece of coat hanger or other thin stiff wire and a stiff putty knife. If the original plaster is covering the holes, you can usually run a putty knife along the bottom edge which will knock off the plaster. Any holes that are blocked can then be cleared by carefully using the wire to remove the blockage. Don’t ream it around inside the wall cavity or you may damage the open cell foam insulation that is present.

Once the weep screed is clear, do your best to maintain it that way by following tips :105, :106, :107

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April 16, 2008

:107 Insect Exclusion

Filed under: :107 Excluding Insects — Tags: , , , , , , , , — John Banta @ 1:01 am

Welcome to today’s 1:5:10:365 Tip for becoming a better steward for our home and planet.

1:5:10:107 EcoTip: Stucco weep screeds frequently leave gaps between the foundation and the screed. This can permit insect entry.

A properly installed weep screed will allow moisture to drain but exclude insects.

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Additional Information

Suggested Review – :106

The weep screed should be sealed to the foundation so that the only openings are the weep holes that permit water to drain. These weep holes are designed to help exclude insect. What needs to be sealed is the gap that may be present between the weed screed and the foundation or stem wall of your home. I’ve seen these openings be large enough to insert ones fingers (scary thought). The sealant should be a silicone elastic caulk material that can expand and contract as conditions change. It should be checked every year to be sure it remains in good condition. This is usually best accomplished by using a mirror to give you a better observation angle.

When applying the sealant, it may be helpful to apply painters tape to cover and protect the weep holes from becoming clogged with sealant. Once the sealant has been applied the tape is removed to uncover the holes.

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April 15, 2008

:106 Debris Around Foundation

Filed under: :106 Foundation Debris — Tags: , , , , , , — John Banta @ 12:01 am

Welcome to today’s 1:5:10:365 Tip for becoming a better steward for our home and planet.

1:5:10:106 EcoTip: It is important that dirt, leaves, mulch and other types of debris be kept well below the weep screed and the building’s walls. Allowing the weep screed to become covered or blocked can lead to moisture being trapped in the walls and deterioration.

The entire perimeter of the foundation should be checked several times a year to be sure that the weep screed is exposed to allow drainage and air circulation for drying.

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Additional Information

Suggested Review – :105

 

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April 14, 2008

:105 Weep Screeds

Filed under: :105 Weep Screeds — Tags: , , , , , , , — John Banta @ 12:01 am

Welcome to today’s 1:5:10:365 Tip for becoming a better steward for our home and planet.

1:5:10:105 EcoTip: The weep screed is a type of metal material that is typically installed at the bottom of a home’s stucco or some types of siding that allows any water that get past the outer finsh coat or material to drain away and exit. It is important that there be a minimum 4 inch clearance between the bottom of the weep screed and the soil or landscaped surface of the yard. 

If sidewalks, driveways, patios or other concrete or hard surfacees are installed next to the builidng there needs to be a minimum of 2 inches of clearance between the weep screed and that surface.

image credit: City of Long Beach, CA

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April 13, 2008

:104 Roof Types

Welcome to today’s 1:5:10:365 Tip for becoming a better steward for our home and planet.

1:5:10:104 EcoTip: A well anchored basic roof is less likely to suffer damage than a complex roof. Hip roofs seem to hold up better than gable roofs.

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Hip Type RoofGable Type Roof

image credit: Restoration Consultants

Additional Information

Suggested Review – :098, :099, :100, :101, :102, :103

Intricate roofs or those with numerous valleys and changes in pitch are more likely to leak when wind-driven rain forces the water under the flashing or roofing materials or when roofing shingles are blown off. The roofing shingles near the roof edge, which faces the worst winds, should be set in special mastic during construction or re-shingling. Don’t run a solid line of mastic, use dabs so if water does get under the shingles, it will be able to drain back out. Try to eliminate or minimize penetrations through the roof with special louvered storm vents instead of the standard types of ventilation vents. Roof overhangs help protect walls against water intrusion much better than zero clearance overhangs.
 

Climate change isn”t only about warming. In my book- Extreme Weather Hits Home: Protecting Your Building From Climate Change, I discuss how to prepare your home for many extreme weather conditions such as high winds.

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April 12, 2008

:103 Wall Ties

Welcome to today’s 1:5:10:365 Tip for becoming a better steward for our home and planet.

1:5:10:103 EcoTip: Wall anchors can help create a “continuous load path” that helps reinforce the building. By improving the strength of the structure the durability can be substantially increased.

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Additional Information

Suggested Review – :098, :099, :100, :101, :102

Credit: Simpson StrongTie Co., Inc.

Whole-house strapping is made up of metal fasteners that are important for tying the building together. The ties should be installed at stress points for load-bearing walls. Securing non-load-bearing walls adds extra expense without significantly improving the durability of the home. Experience has demonstrated that many of the homes with the greatest damage weren’t fastened at the critical junctions between the roof and the walls, the upper and lower floors and the walls to the foundation.

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April 11, 2008

:102 Roof Slope

Filed under: :102 Roof Slope — Tags: , , , , , , , , , , , , — John Banta @ 12:01 am

Welcome to today’s 1:5:10:365 Tip for becoming a better steward for our home and planet.

1:5:10:102 EcoTip: Roof slope makes a great deal of difference in the uplift force exerted as wind flows over the top. The steeper the slope the less chance the roof will fly away.

Credit: Simpson-StrongTie Co., Inc.

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Additional Information

Suggested Review – :098, :099, :100, :101

 The following excerpt is from my book – Extreme Weather Hits Home:

The same forces that allow airplanes to fly are exerted on roofs exposed to strong winds. The angle of your roof can make a great difference to whether your roof will stay intact or sail away like the wings of a plane. Research conducted by Clemson University at their wind load test facility has demonstrated that a category 5 hurricane can develop uplift as much as 100 pounds per square foot. This is typically enough to lift a house right off its foundation. The lifting force is greatest for flat or low-slope roofs. As the angle of the roof increases the force drops. A roof slope between 4.5 and 6.5 seems to be the least aerodynamic. A gable roof will act more like the wings of a plane than a hip roof which slopes down on all sides, helping to cancel lift forces from all directions (Clemson).

The lifting force of wind is tremendous. When airplanes taxi for takeoff they achieve speeds in the 50 to 150 mph range, which is about the same as those speeds found in damaging winds. The roof of your home has a much greater lifting surface area than most airplane wings, allowing the entire roof to be lifted off the house. Once the roof is gone the walls will easily collapse. The lifting force for a roof — just like an airplane wing — is caused by the Bernoulli effect of air passing over the top of the roof creating lift. Some people have advised keeping your windows open to help neutralize the interior building pressure but this doesn’t really work and will let in lots of water causing additional damage to the interior. The best way to keep homes intact when exposed to strong winds is to keep them in one piece and securely fixed to the foundation.

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