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INTERIORS of BUILDINGS ACOUSTICAL SEALANTS AGE of a BUILDING - how to determine AIR BYPASS LEAKS AIR LEAK DETECTION TOOLS AIR LEAK MINIMIZATION AIR SEALING STRATEGIES ANIMAL ALLERGENS ASBESTOS IDENTIFICATION IN BUILDINGS ATTIC LEAKS, CONDENSATION & ATTIC MOLD ATTIC VENTILATION BASEMENT HEAT LOSS BASEMENT LEAKS Moisture or Mold BASEMENT WATERPROOFING BATHROOM VENTILATION BLOWER DOORS & AIR INFILTRATION BRICK LINED WALLS BUCKLED FOUNDATIONS due to INSULATION? CATHEDRAL CEILING INSULATION CHIMNEY INSPECTION DIAGNOSIS & REPAIR COMBUSTION AIR for TIGHT BUILDINGS CRAWL SPACES DEW POINT CALCULATION for WALLS DEW POINT TABLE - CONDENSATION POINT GUIDE ELECTRICAL INSPECTION, DIAGNOSIS, REPAIR ENVIRONMENTAL HAZARDS FIBERGLASS INSULATION FIREPLACE Damage & Unsafe Hearths - Settlement FLAT ROOF MOISTURE & CONDENSATION FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP FLOODS IN BUILDINGS-mold FLOORING TYPES & DEFECTS FOUNDATION WATERPROOFING FREEZE-PROOF A BUILDING HEAT LOSS in BUILDINGS HEAT LOSS DETECTION TOOLS HEAT LOSS INDICATORS HEAT LOSS R U & K VALUE CALCULATION Heat Tapes: Use on Roofs for Ice HEATING COST SAVINGS METHODS HOUSEWRAP AIR & VAPOR BARRIERS HUMIDITY LEVEL TARGET ICE DAM PREVENTION Ice Dams: Comparing Two Houses INSULATION IDENTIFICATION GUIDE INSULATION LOCATION for BASEMENTS INSULATION LOCATION for CAPES, CRAWLSPACES INSULATION R-Values & Properties INSULATION & VENTILATION INSPECTION & IMPROVEMENT ATTIC CONDENSATION CAUSE & CURE Air Bypass Leaks, Thermal Tracking Blocked Soffit Intake Vents BRICK VENEER WALL INSULATION CATHEDRAL CEILING INSULATION ENERGY SAVINGS in BUILDINGS ENERGY SAVINGS PRIORITIES ENERGY SAVINGS RETROFIT CASE STUDY ENERGY SAVINGS RETROFIT LEAK SEALING GUIDE ENERGY SAVINGS RETROFIT OPTIONS FRAMING DETAILS for BETTER INSULATION FRAMING DETAILS for DOUBLE WALL HOUSES Inspect Attics for Moisture or Mold Inspect Basements for Moisture or Mold Inspect Building Exterior Inspect the Ridge Vent System from the Attic Inspect the Soffit Vent System from the Attic Insulation Air & Heat Leaks INSULATION R-Values & Properties Insulation Values of Log Home Walls POLYISOCYANURATE FOAM INSULATION POLYSTYRENE FOAM INSULATION RADIANT BARRIERS RIGID FOAM USE INDOORS Urea Formaldehyde Foam Insulation UFFI URETHANE FOAM Deterioration, Outgassing Vermiculite Insulation LOG HOME GUIDE MOBILE HOME INSPECTIONS MOISTURE CONTROL in BUILDINGS MOLD INFORMATION CENTER ODORS & SMELLS DIAGNOSIS & CURE PAINT FALURE, DIAGNOSIS, CURE, PREVENTION PLASTER & BEAVERBOARD & DRYWALL RADIANT BARRIERS RADIANT HEAT RADIANT HEAT Floor Mistakes to Avoid RADIANT SLAB FLOORING CHOICES RADIANT SLAB TUBING & FLUID CHOICES ROOF VENTILATION SPECIFICATIONS Inspect the Ridge Vent System from the Attic Inspect the Soffit Vent System from the Attic Insulation Air & Heat Leaks 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 Roof Solutions ROOF VENTING ENERGY SAVING DETAILS ROOF VENTING NEEDED? Soffit Ventilation ROT, FUNGUS, TERMITES TERMITE SHIELDS vs TERMITICIDE ROT, TIMBER FRAME SAFETY HAZARDS & INSPECTIONS SEARS KIT HOUSES SOLAR ENERGY SYSTEMS PASSIVE SOLAR DESIGN METHOD PASSIVE SOLAR HEAT PERFORMANCE PHOTOVOLTAIC POWER SYSTEMS SLAB INSULATION, PASSIVE SOLAR SOLAR COLLECTOR AIR or GAS COLLECTION SOLAR COLLECTOR FILMS SOLAR COLLECTOR WOOD HOUSINGS SOLAR HEATING SYSTEMS SOLAR HOT WATER HEATERS SOLAR HOUSE EVALUATION SOUND CONTROL in BUILDINGS STAIN DIAGNOSIS STAIRS, RAILINGS, LANDINGS, RAMPS STUCCO OVER FOAM INSULATION STRUCTURAL INSPECTIONS & DEFECTS SUMP PUMPS GUIDE THERMAL EXPANSION of MATERIALS THERMAL MASS in BUILDINGS THERMAL MASS in UPSTAIRS THERMAL TRACKING Indicates Heat Loss VAPOR BARRIERS & AIR SEALING at BAND JOISTS VAPOR BARRIERS & CONDENSATION in BUILDINGS VAPOR BARRIERS & HOUSEWRAP VAPOR CONDENSATION & BUILDING SHEATHING VENTILATION in BUILDINGS Air Bypass Leaks, Thermal Tracking ATTIC CONDENSATION CAUSE & CURE BATHROOM VENTILATION Blocked Soffit Intake Vents BLOWER DOORS & AIR INFILTRATION BRICK VENEER WALL INSULATION CATHEDRAL CEILING INSULATION CRAWL SPACE VENTING & Dryout Procedures HEAT LOSS: How to Calculate Heat Loss in a Building HOUSEWRAP AIR & VAPOR BARRIERS HUMIDITY LEVEL TARGET ICE DAM PREVENTION Inspect Attics for Moisture or Mold Inspect Basements for Moisture or Mold Inspect Building Exterior for Moisture Problems Inspect the Ridge Vent System from the Attic Inspect the Soffit Vent System from the Attic Insulation Air & Heat Leaks MOISTURE CONTROL in BUILDINGS MOISTURE CALCULATIONS MOISTURE PROBLEMS: CAUSE & CURE 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 Roof Solutions ROOF VENTING ENERGY SAVING DETAILS ROOF VENTING NEEDED? Soffit Ventilation VENTILATION DESIGN PROBLEMS & SOLUTIONS WHOLE HOUSE VENTILATION Strategies WATER ENTRY in BUILDINGS WIND TURBINES WINDOWS & DOORS SKYLIGHT LEAK DIAGNOSIS & REPAIR SITE BUILT DOUBLE GLAZED WINDOWS SLOPED GLAZING DETAILS VERTICAL GLAZING DETAILS WINDOW / DOOR ENERGY EFFICIENT, DOE WINDOW LEAKS INTO BASEMENT WINTERIZE A BUILDING WOOD Burning Heaters Fireplaces Stoves More Information InspectAPedia Blog - News Updates Air Conditioning & Heat Pumps Bookstore Electrical Environment Exteriors Heating Home Inspection Insulate Ventilate Interiors Mold Inspect/Test Plumbing Water Septic Roofing Structure Accuracy & Bias Pledge Contact Us |
This is "Un-Vented Roof Solutions: how to avoid condensation, leaks, attic mold, & structural damage when roof venting is not possible", part of our discussion of "Attic Condensation". Also see CATHEDRAL CEILING INSULATION and see our "hot roof design concerns" described at Correcting Roof Ventilation and see Heat Tapes: Use on Roofs for Ice. This article describes inspection methods and clues to detect roof venting deficiencies, insulation defects, and attic condensation problems in buildings. © Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website. Un-Vented Roof Solutions: how to avoid condensation, leaks, damage when roof venting is not possibleAt Correcting Roof Ventilation we argued that while some experts like the "hot roof" design that omits attic or under-roof ventilation entirely, that approach risks surprise rot, mold, or insect damage on buildings where leaks and moisture are trapped in building cavities and remain un-noticed. Some buildings, by their shape or design, simply don't make it easy to install continuous intake venting at the eaves or lower roof edge, or continuous outlet venting along a ridge. For example, a house which has no roof overhang at all makes intake venting at the eaves difficult. A house with a pyramid roof shape or complex roof shapes makes outlet venting at a ridge difficult. Problems with Partial Roof VentingOn these roofs, partial venting can be worse than no venting. For example, adding a ridge vent, or several roof "spot vents" or roof turbine vents on a few roof slopes, typically mid-slope or in the upper third of the slope on roof surfaces not visible from the front of the building, may please the installer, but they are worse than ineffective. Placing an outlet vent on a roof without adequate inlet venting (see Roof Vent Area Ratios) works against the interests of the building and its occupants. As convection currents and heat loss into the roof space or attic vent out through these vents, the intake air needed to satisfy the exhausted air leaving the building will be drawn from the building interior - increasing building heating costs and possibly increasing particle movement from basements or crawl spaces (if there is a mold concern in the building). If you can't provide enough intake venting it is probably better to not vent at all in these conditions. What are some solutions for un-vented roofs if we want to avoid cold-climate ice dam leaks?Our photo (below left) shows an ice-dam prone roof on a tall building with a slate roof.
Worries about the "hot roof" un-vented Cathedral Ceiling DesignsAs explained in our "hot roof" discussion at Correcting Roof Ventilation, I don't have confidence in the long term durability of "hot roof designs" because any future roof leak into this cavity produces trapped moisture and rot. We call this a "hot roof" design because failing to vent the roof from below not only misses a chance to avoid ice dam leaks and condensation damage in cold climates. In hot climates the roof temperature will be much higher on an un-vented roof, resulting in much shorter shingle life. This is less of a concern for slate and similar product roofs. In buildings where there is no roof venting anyway, an un-vented, well insulated "hot roof" is a second-best alternative to preventing ice dam related leaks in cold climates. Be sure to inspect the roof surface from outside for leaks and damage every year and to fix any damage quickly. ... Technical Reviewers & References
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website. INTERIORS of BUILDINGS |
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INTERIORS of BUILDINGS AIR BYPASS LEAKS AIR LEAK DETECTION TOOLS AIR LEAK MINIMIZATION AIR SEALING STRATEGIES BATHROOM VENTILATION BASEMENT WATERPROOFING BLOWER DOORS & AIR INFILTRATION BRICK LINED WALLS BUCKLED FOUNDATIONS due to INSULATION? CATHEDRAL CEILING INSULATION CRAWL SPACE VENTING & Dryout Procedures MOISTURE, MOLD, ICE DAM LEAKS in ATTICS & ROOFS ATTIC CONDENSATION CAUSE & CURE HEAT LOSS: How to Calculate Heat Loss in a Building HOUSEWRAP AIR & VAPOR BARRIERS HUMIDITY LEVEL TARGET HOUSEWRAP AIR & VAPOR BARRIERS ICE DAM PREVENTION INSULATION INSPECTION & IMPROVEMENT More Information InspectAPedia ® Home & Site Map Air Conditioning & Heat Pumps Bookstore Electrical Environment Exteriors Heating Home Inspection Insulate Ventilate Interiors Mold Inspect/Test Plumbing Water Septic Roofing Structure More Information Accuracy & Bias Pledge Contact Us |
More Information on Building Diagnostic Inspections and RepairsMore Reading about Dealing with Attic Mold, Identifying, Removing, and Preventing Mold in AtticsBe sure to review HOW TO FIND MOLD: How to Inspect Homes and Other Buildings for Mold - the Basics of How to Find Problem Mold Indoors in our Mold Action Guide. Here are other articles that will be helpful in evaluating attic mold presence, causes, and cures:
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10/14/2009 - 06/02/1990 - InspectAPedia.com/interiors/atticcond8htm - © 2009 - 1988 Copyright Daniel Friedman All Rights Reserved - InspectAPedia® is a Registered U.S. Trademark