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Here we explain how to Correct Improper or Inadequate Attic or Under-Roof Ventilation in buildings, part of our series of articles about ATTIC CONDENSATION CAUSE & CURE. This article series describes inspection methods and clues to detect roof venting deficiencies, insulation defects, and attic condensation problems in buildings. It describes proper roof ventilation placement, amounts, and other details.

These recommendations are based on a survey of building science literature combined with 35 years of building inspections, on the observation of the locations of moisture, mold, ice dams, condensation stains, and other clues in buildings, and on the correlation of these clues with the roof venting conditions at those properties.We have measured very large changes in airflow, temperature, and moisture before and after installing roof venting. We include references to building and industry experts as well.

See CATHEDRAL CEILING VENTILATION, and also see VENTILATION in buildings and INSULATION LOCATION - WHERE TO PUT IT. And see COOLING LOAD REDUCTION by ROOF VENTS.

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Roof Ventilation - Best Practices

As explained in Best Practices Guide to Residential Construction, chapter on BEST ROOFING PRACTICES:

All residential building codes require some form of roof ventilation. These rules were first developed in the 1940s, when attic spaces first started to develop problems with mold and mildew due to excess moisture. (See Inspect Attics for Moisture or Mold for details.)

With the growing use of plywood, asphalt shingles, insulation, and better doors and windows, houses were being built tighter. The tighter spaces retained more of the normal household moisture generated by cooking, bathing, household plants, crawlspaces, and exposed basement slabs. As the stack effect drove this moisture up into attic spaces, problems ensued.

Building Code Requirements for Roof Ventilation

The rules of ventilation developed by researchers in the 1940s were adopted first by the Federal Housing Administration (FHA) and later by all the major residential building codes, including the 2003 IRC, with few changes. Most asphalt shingle manufacturers will void their warranties if these rules are not followed. They require:

• 1 square foot of net free vent area (NFVA) per 150 feet of attic floor.
• 1 square foot of NFVA per 300 square feet of attic floor if a vapor barrier is installed on the ceiling below.
• The IRC adds that the NFVA ratio can also be reduced to 1:300 if 50% to 80% of the required ventilation is located in the upper portion of the attic (or cathedral ceiling) and the rest is located at the eaves, with the upper vents at least 3 feet above the lower.
• See Roof Venting: Intake - Outlet Area Ratios for details.
  

-- Adapted with permission from Best Practices Guide to Residential Construction.

How to Correct Improper or Inadequate Attic or Under-Roof Ventilation in buildings

Home inspectors and building owners should be especially concerned about insulation placed directly under the roof sheathing such as between the rafters. This can trap heat and moisture and damage sub-roofing as well as roofing shingles.

Also, cathedral ceilings without vents in the soffit and up at the ridge or without adequate air path between the roof insulation and the underside of the roof sheathing can lead to major condensation problems, rot, insect damage, and severe structural damage in just a few years.

Do look for those dark rafter lines and don't underestimate the damage that can exist. See Inspect the Soffit Vent System from the Attic for details.

The best "fix" for cathedral ceilings and un vented roof cavities is to assure that there is an air path into the attic up the under side of the roof along the building eaves.

If insulation blocks the soffit intake venting, it is corrected simply by installing soffit vent baffles at the house eaves between every rafter pair (cardboard or Styrofoam pieces made for that purpose and sold at most lumber yards) and adding vents if not in place. See Inspect Attics for Blocked Soffit Intake Vent for details.

Watch out: when correcting insulation-blocked soffit intake venting, don't just pull back insulation into the attic, or you risk creating a cold spot over the interior ceilings near building exterior walls, increasing heat loss, and making ice dam problems worse. Also see Insulation Air & Heat Leaks.

Un-Vented "Hot Roof" Designs Risk Costly Hidden Damage

An alternative un-vented "hot roof" design (the right-hand cathedral ceiling structure shown at the right in Carson Dunlop's sketch) is touted by some building experts who argue that under-roof venting is not needed whatsoever.

Roof surface temperature affects the life of the roof covering. Studies in Florida confirmed that asphalt roof shingle surface temperature varies more as a function of shingle color than as a function of whether or not the under-roof cavity is ventilated.

Mark Cramer informs us that an insulated roof is only 7 deg. F. hotter than an un-insulated roof. By this view roof life may not be reduced significantly by an un-vented design. But here are some concerns that the "hot roof" design leaves incompletely addressed:

Details about hot roof designs are found at HOT ROOF DESIGNS: Un-Vented Roof Solutions.

• Hidden leak damage: If insulation is placed between the roof rafters, especially using some water resistant foam insulation products, leaks into the roof cavity from outside are likely to cause significant and costly structural damage (and possibly mold infection) before the leak is discovered.
• Higher heating/cooling costs: A sloped, insulated roof has a larger radiating surface area than an insulated attic floor, increasing building cooling or heating costs. The conversion of the attic space to a "conditioned" space (by placing insulation between roof rafters) is a bonus in some buildings if the space is to be used, but a cost in buildings where it is not to be occupied.
• Lack of moisture damage resistance: A building with an interior moisture problem that results in moisture movement up through the building to the roof underside is more likely to suffer mold and rot problems if that moisture is trapped in an un-vented attic or roof cavity. Good building management includes identification and correction of leaks or other sources of un-wanted moisture. But good building design takes into account "real world" conditions that actually occur in the field, not just optimal conditions that describe what people should do.

Leaks and moisture problems are common on buildings in most climates and these conditions are likely to occur over the life of a building. Good building design resists water damage. Readers who have hot roof designs or hard-to-vent roof cavities should also see HOT ROOF DESIGNS: Un-Vented Roof Solutions and CATHEDRAL CEILING VENTILATION.

Use of Gable End Vents with Soffit and Ridge Venting?

Question: should I add gable end vents to my attic space?

I will be siding my house in the near future. I currently have soffit vents along with a ridge vent.

Will adding gable vents to the two sides of the house add or hinder the air flow? - Mike Martino

Reply:

We recommend against adding gable end vents where a continuous ridge and soffit vent system is installed. Adding gable end vents will prevent proper roof ventilation so long as you have un-blocked soffit intakes and ridge outlet openings. When warm air in the attic moves upwards by natural convection and exits at the ridge, cooler drier air is drawn into the attic or under-roof space at the building eaves or soffits.

We want that incoming air to treat the entire under-roof surface, from the lower edges or eaves up to the ridge, by flowing along the underside of the roof deck and out at the ridge.

If you were to add gable end vents, some of the draft created by air exiting at the ridge will be satisfied by incoming air at the gable ends, as the gable vents are naturally closer to the ridge at either end of the building than are the soffit intake vents.

As a result, less air flow will be provided for the lower center portions of the roof, and the benefit of cooling and drying the entire roof underside surface will be impeded.

This attic air movement theory can often be confirmed in practice by careful observation. Home inspectors sometimes observe the combination of soffit vents, ridge vent, and gable end vents on a home where they also find that the more serious condensation and least effective under-roof ventilation is apparent at the lower center portions of the roof slopes, while on a similar home with similar interior moisture conditions, materials, age, construction, but using only soffit and ridge venting, having omitted or blocked off the gable end vents does not suffer the same problem.

In fact during an under-roof ventilation retrofit in which continuous soffit and ridge vents are being added to a building, if there are existing gable-end vents installed we recommend that after the new vents are provided the old gable-end vents should be closed off.

Details are at Roof Venting: Proper Locations.

Attic Roof Vent Configuration Designs, Alternatives & Advice

No intake nor exhaust venting: best advice is to add continuous soffit intake and ridge line outlet venting, with an air path up the under-side of the roof decking in an attic or cathedral ceiling

Soffit vents only: limited effectiveness as a roof venting, varying with wind direction. Best to add continuous ridge venting.

Ridge vents only: a bad idea, this condition will increase heat loss from the building and increase building heating costs. Add continuous soffit vents at the eaves. Also see Insulation Air & Heat Leaks.

Gable vents only: traditional design, better attic venting is achieved with continuous soffit intake and ridge outlet venting; after these are installed, close off the gable end vents for best venting performance as discussed above. Just stapling plastic over gable end vents from inside the attic should be sufficient. Details are at Roof Venting: Proper Locations.

Roof Turbine vents or Spot vents: this is a more complex venting pattern. Often builders install soffit and ridge vents but leave the turbine vents in place. Probably ok. Turbine vents are also used as "spot vents" to try to ventilate difficult roof structures, but beware: if you do not provide a source of outdoor air to satisfy the exhaust effects of the turbine vent(s), building heating costs may be increased in some cases.

Attic Ventilation Details - Best Practices

As discussed in Best Practices Guide to Residential Construction, chapter on BEST ROOFING PRACTICES:

Ridge & Soffit Vents - Importance of Balanced Roof Ventilation

For both attics and cathedral ceilings, roof ventilation works best when it is balanced between high and low to take advantage of natural convection (Figure 2-55 at left). This configuration also tends to evenly wash the entire underside of the roof surface with ventilation air. That's why we insist that soffit intake venting and ridge outlet venting on buildings should be continuous rather than intermittent or "spot" vents or intermittent louvered soffit inlet vents. Ridge vents should either have external or internal baffles to minimize infiltration of windblown rain and snow. Watch out: Do not use ridge vents or other rooftop vents without low vents to provide makeup air. The suction created could help pull moist household air into the attic. And do not install ridge vents nor any other roof venting outlet without providing adequate outside inlets to the roof cavity at soffits or eaves. Making that mistake will draw conditioned (heated or cooled) air out of the building and thus will increase building heating or cooling costs as well. Ridge Vent Alternatives Where ridge vents are not an option, combine any type of upper vent such as gable-end vents, roof vents, or turbines, with soffit vents. Where soffit vents are not possible, use gable-end vents on both ends of the roof, which will ventilate adequately under wind pressure. Avoid high ridge vents alone: you'll increase building heating and cooling costs as we explained above. .

Ratio of Soffit Intake Vent to Ridge Outlet Vent Area

The soffit-vent intake area should be larger than the ridge-vent area. As we explain at Roof Venting: Intake - Outlet Area Ratios, many builders use a 2:1 inlet to outlet ratio. Having a bit more soffit inlet than ridge outlet vent area assures that the building never satisfies the outlet convection air current draw by pulling air out of the conditioned spaces of the home - drawing such air from outdoors and moving it up under the roof surface is what we want. Use insulation baffles or modified framing to make sure that the ceiling insulation does not block airflow at the eaves (Figure 2-56 shown at above left.) The sketch at left is provided courtesy Steven Bliss & J Wiley & Sons [4] Details of soffit intake to ridge vent outlet ratios are at Roof Venting: Intake - Outlet Area Ratios.

Cathedral Ceiling Ventilation Details

Cathedral ceilings require the same continuous air barriers, and balanced soffit and ridge vents, as attics. Both air sealing and ventilation are more critical, however, since any trapped moisture in the roof cavity will remain longer and potentially cause greater damage than in an open attic. Also, since there is little or no communication from bay to bay, an effective ventilation system must reach every bay (Figure 2-57 at left). Details about cathedral ceiling ventilation are at CATHEDRAL CEILING VENTILATION. Also see CATHEDRAL CEILING INSULATION.

Hips and Valleys: Roof Ventilation Details

Ventilating hips and valleys can be challenging with a cathedral ceiling. One approach is to use a double or triple hip or valley rafter one size smaller than the common or jack rafters. This will create a vent space along the top of the hip or valley rafter that can be used to supply ventilation air to the jack rafters (Figure 2-58 at left).

Roof Ventilation Details at Skylights to Provide an Air Path - Eaves to Ridge

Localized hot spots such as skylights can also lead to ice dams below, due to blocked ventilation as well as melt water from skylight heat loss. Notching the rafters on either side of the skylight will help maintain airflow above the skylight (Figure 2-59 at left). If icing on your skylight window interior surface in winter is still a problem, add an interior storm window to reduce heat loss through the glass in cold weather.

As a backup to prevent leaks at skylights, during skylight installation and even though modern skylights are usually provided with a factory-built flashing and counterflashing, it is always a good idea to seal the skylight curb and surrounding roof area with a bituminous membrane (see Figure 2-5 at left). Also see SKYLIGHT LEAK DIAGNOSIS & REPAIR and see Skylight Glass Breakage. The sketch at left is provided courtesy Steven Bliss & J Wiley & Sons [4]

Also see Ice Dam Protection for Skylights for cases where under-roof venting is not provided around a skylight.

-- Adapted with permission from Best Practices Guide to Residential Construction.

Questions & Answers regarding this article

Questions & answers about ways to correct or improve under-roof ventilation including at special problem cases where there is no roof overhang or where eaves-trough gutters are installed

Question: what type of intake venting will work best at the eaves or soffits of a steep pitched roof with no horizontal soffit covering?

I am currently constructing the roof on a small timber frame cabin. The roof has a 1:1 pitch and has a cathedral type ceiling. I plan to have a continuous ridge vent installed at the top. I will also install continuous soffit vents on the bottom sides of both eaves, running the length of the building.

The eaves are a boxed cornice type with the soffits attached to the bottom of the extended rafters. Therefore the soffits are sloped up at a 45 degree angle. I asked a prominent manufacturer of continuous soffit vents if having the soffit vents angled up at a 45 degree angle made any difference. They said they would not recommend that because they thought it might compromise the flow of air to the ridge vent.

I am wondering how that can be. Maybe louvers in the vent will be angled in the wrong direction and thus impede air from flowing in. Most continuous soffit vents have directional louvers in them. Does this mean that one should only construct a soffit which is horizontal so that the louvers in the vent will be angled the right way? Certainly there must be continuous soffit vents which are functional when placed in sloped soffits? Can you suggest any such product to me?

Reply: continuous perforated vent strips are ok, complete perforated soffit covering is more effective; be sure there's a ridge vent; close off any gable end vents; special problems occur if there are eaves troughs or no roof overhang.

Tom I'd sure like to hear some specific reasoning from the manufacturer you spoke with. Either I don't understand the question and mfg's comment, or else what you report sounds like arm-waving and speculation. Look at the vent strips in this horizontal soffit (photo at left). Can anyone really suggest the vent openings change if the vent openings are placed on an angle rather than horizontal as shown? Do the little holes know which way they are facing? A.V.'s response about "short circuiting" the roof venting seems stuck on a misunderstanding that you were adding venting at the gable ends, not the eaves of the home. Maybe because you talked about a sloped surface?

Your angled roof overhang at the house eaves is a very common design (sketch at left). As long as the air path up under the roof is not blocked by insulation, perforated soffit panels on the under-roof side of that overhang will work just fine. In more than 30 years of inspecting the exterior and interior of buildings for under-roof ventilation and related problems I have seen (nor read about) no evidence whatsoever that there is a measured difference in the effectiveness of roof ventilation between a horizontal soffit intake and an angled soffit air intake except as I note next. Incidentally in both designs, when wind is blowing towards the walls of the house where there is roof overhang, airflow increases inwards at that soffit. I speculate that an angled soffit of the same square-feet in area will catch and move more air up under the roof space than a horizontal soffit of the same square-foot area, for the same wind conditions. Just be sure you provide adequate air flow space below the entire roof, from soffit to ridge, or the venting will be ineffective. Finally, I have not found any soffit intake vent product that differentiates between horizontal soffit intakes and angled soffit intakes. I prefer to cover the entire soffit with perforated panels to maximize the air inflow, though vent strips can be adequate in many cases.

Follow-Up comments from Roof Vent Manufacturers

This is the response I got back from Air Vent Inc.

"We have no testing on installing soffit vents up the rake, but it has been our long standing opinion that this would or could short circuit the ridge vent or whatever form of exhaust at the ridge. You may want to consider an alternate form of intake, like the Edge vent at the bottom of your roof. There is no difference performance wise from the plastic or metal soffit vent." [1]

Because they stated, "up the rake", I thought they might have misunderstood that I meant to put the vents along the eave, just with the eave sloped up. But when I questioned them again, they reconfirmed their initial response. Their response caused me to make multiple inquiries.

This is what the National Roofing Contractors Association had to say:

"Soffit vents are designed with louvers that should have the fins facing out away from the structure when installed. If installed on an angle they will not trap the air flow as well as on the horizontal, but they will function. Louvered vent are the most efficient, but there are many non louvered open hole soffit panels that are part of a metal panel soffit system. Louvered or open hole continuous panels should function in an angled installation." [2]

Here is what another manufacturer had to say:

"As long as the intake air flow is entering the soffit/attic space and directed towards the ridge/peak of the roof, with no other “escape routes” it should serve as effective intake ventilation and it should balance out with the exhaust ventilation of the ridge vent."

My sense is that installing louvered metal continuous eave vents will be functional and will work. It just won't have the louvers angled in the optimum direction. Since I have multiple layers of 6 mil plastic vapor barrier over the ceiling boards and will have 2 inches of free airspace between the roof sheathing and cross members (2x4s) between the 2x6 rafters (2 1/2 inches between sheathing and insulation), I think the angled vents will be adequate.

Reply from InspectAPedia: what's the diff between gable end, rake, eaves and soffit?

Now that we're getting clear on distinguishing between "rake" or gable-end venting and soffit or eaves venting (photo at left), I completely agree with Air Vent on this.

By "rake" they are referring to the edges of the roof that run parallel to the roof slope and seen at the building (usually triangular) gable ends of the building, not the lower roof edges or eaves that run parallel to the lower roof edges. [For a key to a sketch of various house parts including soffit, ridge, rake, gable end, see Home Inspection Definitions & Terms].

I agree that we do NOT want intake venting under the rake nor at gable end walls once there are a soffit and ridge vent system installed. And I agree that leaving gable end venting in place would short circuit airflow just as Air Vent described.

Using the same reasoning I want to close off gable-end vents on older homes (the traditional "roof venting" method) when we install soffit intake and ridge outlet venting. Otherwise I've seen, tested, and visually demonstrated (using smoke) that the air exiting at the ridge vent pulls incoming air at the nearby gable end vents (or rake venting) and stops pulling as much air in from the lower roof edges, eaves, or soffits.

What we agree we want is continuous incoming airflow along the lower roof edge, between EVERY rafter pair, and continuing up to an exit at the ridge - that's how we avoid ice dams and how we dry the entire roof underside. Our photo (left) of a horizontal soffit covering on an older home shows ice dam leak stains - why? Because this is what we call "faux venting" - the builder installed perforated vent panels but over solid plywood or wood soffit enclosing material - there was actually no air flow under this roof.

Edge Vent™ and products like the Hicks starter vent™ and Smart Vent™[3] are products that can give an alternative air intake path at the lower roof edges by replacing the lower few inches of roof decking with a vented strip for air intake under the shingles.

If yours is a conventional (though steep) gable with modern roof framing and rafter design that provides air space clearance between the underside of the roof deck and the top of the wall top plate, you don't need those products.

But for buildings whose soffits or eaves are "blocked" by an eaves trough roof design - a starter vent may not fit nor work in that situation both because the eaves trough is in the way and because in my experience on pre-1900 homes there is often a solid beam sitting atop the house walls with rafters butting into the beam on the attic side and lookout rafters tacked on on the outer side of the house wall to support the roof extension and eaves trough. Details are at Roof Venting: Eaves Intake if no Overhang

And finally, I agree that if you are using louvered rather than simple flat perforated vent openings at a soffit, the louvers will pick up more air if their openings face outwards, away from the house walls - presuming there is a breeze blowing in that direction. No breeze, no difference.

Questions & Answers regarding this article

Questions & answers about ways to correct or improve under-roof ventilation including at special problem cases where there is no roof overhang or where eaves-trough gutters are installed

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ATTIC LEAKS, CONDENSATION & ATTIC MOLD
  Air Bypass Leaks, Thermal Tracking
  Blocked Soffit Intake Vents
  CATHEDRAL CEILING INSULATION
  CATHEDRAL CEILING VENTILATION
  Comparing Two Houses
  Heat Tapes: Use on Roofs for Ice
  HEAT TAPES & CABLES on Roofs for Ice Dams
  HOT ROOF DESIGNS: Un-Vented Roof Solutions
  HOUSEWRAP AIR & VAPOR BARRIERS
  HUMIDITY LEVEL TARGET
  ICE DAM PREVENTION
  ICE DAM CURE: Comparing Two Houses
  Inspect Attics for Moisture or Mold
  Inspect Attics for Blocked Soffit Intake Vents
  Inspect Basements for Moisture or Mold
  Cold Pour Joint Leaks
  Form Tie Leaks
  Wall Crack Leaks
  Floor-Wall Joint Leaks
  Inspect Building Exterior - Roof Venting
  Inspect the Ridge Vent System from the Attic
  Inspect the Soffit Vent System from the Attic
  ROOF VENTILATION SPECIFICATIONS
  Roof Venting: Intake - Outlet Area Ratios
  Roof Venting: Proper Locations
  Roof Venting: Both Ridge & Eaves Venting Needed
  Roof Venting: Eaves Intake if no Overhang
  Roof Venting: Soffit Intake Vent-Continuous
  Roof Venting: Un-Vented Hot Roof Solutions
  ROOF VENTING ENERGY SAVING DETAILS
  ROOF VENTING NEEDED?
  SKYLIGHT VENTILATION DETAILS
  Soffit Ventilation

ATTIC VENTILATION

• Carson Dunlop, Associates, 120 Carlton Street Suite 407, Toronto ON M5A 4K2Toronto. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
• Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
• "Unvented Roofs, Hot- Humid Climates, and Asphalt Roofing Shingles Research Report - 0306 Feb-2003 Building Science Corporation", Building Science Corporation, 30 Forest Street, Somerville, MA 02143
  Quoting from the article abstract: "When constructing unvented roofs with asphalt shingles in hot-humid climates, a vapor barrier must be installed between the asphalt shingles and the roof deck." - Web Search 5/21/2010
• Thanks to reader - Mike Martino for discussing attic ventilation retrofit ideas - August 2010
• [1] Air Vent, Inc., Tel: 1-800-247-8368, Email: ventilation@gibraltar1.com, web search 08/11/11,
• [2] National Roofing Contractors Association, NRCA, 10255 W. Higgins Road Suite 600 Rosemont, IL 60018-5607 Telephone: (847) 299-9070, web search 08/11/11,
• [3] Hicks Starter Vent, and Smart Vent, see Roof Venting: Eaves Intake if no Overhang
• [4] Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education. Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com.

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

• Building Research Council, BRC, nee Small Homes Council, SHC, School of Architecture, University of Illinois at Urbana-Champaign, brc.arch.uiuc.edu. "The Small Homes Council (our original name) was organized in 1944 during the war at the request of the President of the University of Illinois to consider the role of the university in meeting the demand for housing in the United States. Soldiers would be coming home after the war and would be needing good low-cost housing. ...  In 1993, the Council became part of the School of Architecture, and since then has been known as the School of Architecture-Building Research Council. ... The Council's researchers answered many critical questions that would affect the quality of the nation's housing stock.
  • How could homes be designed and built more efficiently?
  • What kinds of construction and production techniques worked well and which did not?
  • How did people use different kinds of spaces in their homes?
  • What roles did community planning, zoning, and interior design play in how neighborhoods work
• "Energy Savers: Whole-House Supply Ventilation Systems [copy on file as /interiors/Energy_Savers_Whole-House_Supply_Vent.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11880?print
• "Energy Savers: Whole-House Exhaust Ventilation Systems [copy on file as /interiors/Energy_Savers_Whole-House_Exhaust.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11870
• "Energy Savers: Ventilation [copy on file as /interiors/Energy_Savers_Ventilation.pdf ] - ", U.S. Department of Energy
• "Energy Savers: Natural Ventilation [copy on file as /interiors/Energy_Savers_Natural_Ventilation.pdf ] - ", U.S. Department of Energy
• "Energy Savers: Energy Recovery Ventilation Systems [copy on file as /interiors/Energy_Savers_Energy_Recovery_Venting.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11900
• "Energy Savers: Detecting Air Leaks [copy on file as /interiors/Energy_Savers_Detect_Air_Leaks.pdf ] - ", U.S. Department of Energy
• "Energy Savers: Air Sealing [copy on file as /interiors/Energy_Savers_Air_Sealing_1.pdf ] - ", U.S. Department of Energy
• Humidity: What indoor humidity should we maintain in order to avoid a mold problem?
• The Stairway Manufacturers' Association, (877) 500-5759, provides a pictorial guide to the stair and railing portion of the International Residential Code. [copy on file as http://www.stairways.org/pdf/2006%20Stair%20IRC%20SCREEN.pdf ] -
• What Mold and Allergens Look Like: mold identification photos to help identify mold - choosing what to sample in buildings
• How to Clean Moldy Wood Framing & Sheathing How to clean/seal mold from/on exposed lumber or plywood subfloor or roof sheathing indoors - some suggestions based on our field and laboratory research
• Mold spores in the Home - a Photo ID Library for detection and identification of mold allergens.
• How to Find and Test For Mold in buildings A "how to" photo and text primer on finding and choosing the right spots to test for mold in buildings
• Stuff that is not mold but is often mistaken for it - things you may not want to test. Also, not all "black mold" is toxic - here are examples of harmless black mold.
• Simple Adhesive Tape Sampling of Moldy Surfaces - how to send a mold sample to our lab
• Mold Sampling Methods in the Indoor Environment - In-depth article: detailed critique of popular mold testing methods - Is your mold test kit worth the bother?
• Mold-Resistant Building Practices, advice from an expert on how to prevent mold after a building flood and how to prevent mold growth in buildings by selection of building materials and by anti-mold construction details.
• "Weather-Resistive Barriers [copy on file as /interiors/Weather_Resistant_Barriers_DOE.pdf ] - ", how to select and install housewrap and other types of weather resistive barriers, U.S. DOE
• What Style Is It?: A Guide to American Architecture, Rev., John C. Poppeliers, S. Allen Chambers, Wiley; Rev Sub edition (October 6, 2003), ISBN-10: 0471250368, ISBN-13: 978-0471250364
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