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Mobile View EXTERIORS of BUILDINGS AGE of a BUILDING - how to determine ALGAE, FUNGUS, LICHENS, MOSS ATTIC CONDENSATION BASEMENT WATERPROOFING BOOKSTORE - EXTERIORS CHIMNEY INSPECTION DIAGNOSIS REPAIR DECK & PORCH CONSTRUCTION DECK COLLAPSE Case Study DECK FLASHING LEAKS, ROT Case Study EARTHQUAKE DAMAGED FOUNDATIONS ENERGY SAVINGS in BUILDINGS ENERGY SAVINGS PRIORITIES ENERGY SAVINGS RETROFIT CASE STUDY ENERGY SAVINGS RETROFIT LEAK SEALING GUIDE ENERGY SAVINGS RETROFIT OPTIONS ENVIRO HAZARDS FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP FRAMING DETAILS for BETTER INSULATION FRAMING DETAILS for DOUBLE WALL HOUSES FOUNDATION WATERPROOFING HEAT TAPES & CABLES on Roofs for Ice Dams HOUSEWRAP AIR & VAPOR BARRIERS LEAD POISONING HAZARDS GUIDE LEAD TEST KIT for HOME USE LOG HOME GUIDE LIGHTNING PROTECTION MOISTURE CONTROL in BUILDINGS MOLD DETECTION & INSPECTION GUIDE MVOCs & MOLDY MUSTY ODORS ODORS & SMELLS DIAGNOSIS & CURE PAINT & STAIN GUIDE, EXTERIOR PAINT FALURE, DIAGNOSIS, CURE, PREVENTION PAINT FAILURE CHECKLIST PORCHES & Sunrooms ROOFING DIAGNOSIS INSPECTION & REPAIR SEPTIC SYSTEMS SHEATHING, Gypsum board SHEATHING Homasote & Other Board SHEATHING, OSB SHEATHING, Plywood SHEATHING, FOIL FACED - VENTS SIDING, ASBESTOS CEMENT SHINGLES SIDING EIFS STUCCO SIDING HARDBOARD SIDING VINYL VINYL CHLORIDE HEALTH INFO SIDING WOOD STAIN DIAGNOSIS on Building Exteriors STAIN DIAGNOSIS on Indoor Surfaces STAIRS, RAILINGS, LANDINGS, RAMPS STUCCO OVER FOAM INSULATION TERMITES, ROT THERMAL EXPANSION of MATERIALS THERMAL MASS in BUILDINGS THERMAL MASS in UPSTAIRS VAPOR BARRIERS & AIR SEALING at BAND JOISTS VAPOR BARRIERS & CONDENSATION in BUILDINGS VAPOR BARRIERS & HOUSEWRAP VAPOR CONDENSATION & BUILDING SHEATHING VENTILATION in BUILDINGS WATER ENTRY in BUILDINGS WINDOWS & DOORS SKYLIGHT LEAK DIAGNOSIS & REPAIR Diagnose & Repair Skylight Leaks Rooftop Skylight Leaks Water Testing Skylights Repairing Skylight Leaks Avoiding or Preventing Skylight Leaks SITE BUILT DOUBLE GLAZED WINDOWS SLOPED GLAZING DETAILS Seals, sealants & leaks Sloped Glazing Design Temperature effects on windows Sealants & Gaskets Sealant Joint Depth & Width Sealed Window Joint Failures Avoid Joint Depth Sealant Failures Avoid Adhesion Window Sealant Failures Using Window Glazing Tapes Using Window Glazing Gaskets Using Window Setting Blocks Choosing Skylight Glass Skylight Glass Breakage Window Glass Seal Failures Stopless Window Glazing VERTICAL GLAZING DETAILS WINDOW / DOOR ENERGY EFFICIENT, DOE WINDOW LEAKS INTO BASEMENT WINTERIZE A BUILDING 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 & Privacy Policies Contact Us |
This article discusses design details for site-built double-glazed windows, including which window pane should be sealed most carefully, venting the space between window panes, the amount of space that should separate window panes, and comparing the cost of factory-built windows with site-built windows. Accompanying text is reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss. Our photograph (left) shows an interesting sloped window installation on the roof of a barn silo that had been converted to living space. Conventional wood-frame double-hung windows were set into the sloped silo roof - this was not a successful installation and the windows rapidly rotted, leaked, and disintegrated. Readers who are building their own windows or who are installing factory-built windows should also see SLOPED GLAZING DETAILS and VERTICAL GLAZING DETAILS. For suggestions about how to diagnose and repair leaks in existing skylights, see SKYLIGHT LEAK DIAGNOSIS & REPAIR. © 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. Site-Built Double Pane WindowsThe link to the original Q&A article in PDF form immediately below is followed by an expanded/updated online version of this article.
The question-and-answer article below paraphrases, quotes-from, updates, and comments an original article, (see links just above) from Solar Age Magazine and written by Steven Bliss. Topic: ways to construct site-built double-pane windows.Question: I have heard of various ways to construct site-built, double-pane windows. One way is to seal the inner pane airtight, then to fit the outer window pane somewhat loose. Other ways are similar, involving small holes to let the inner air space "breathe". What do you recommend? Also, what maximum spacing do you recommend between panes of fixed glass in a double-glazed window? - David Lile, Santa Cruz, CA Answer: Since it is virtually impossible to achieve a hermetic seal in site-built windows (except with exotic hot melt window construction systems used sometimes in commercial window retrofits), we agree with your suggestions. Inner window pane: Keep the inside window pane as airtight as possible to keep moist household air out of the window unit. In sealing window glass it is essential that proper allowances are made for contraction and expansion of materials over the expected temperature range -see THERMAL EXPANSION of MATERIALS. Outer window pane: provide a moisture escape route to the outdoors once moisture does enter the space between the two window panes. A few 3/8-inch weep holes, drilled through the sill and stuffed with fiberglass or screening (to keep bugs out) is one detail we've seen. This seems preferable to a "loose" outer window pane. Watch Out for Leaks at Drain Holes Drilled in Wood Window FramesDJF Note: but beware: drilling through wood window frame components, if they are not properly protected from the weather and from leaks, can lead to serious window frame rot. Recommended Space Between Window Panes in Double-Glazed Window ConstructionAs for the recommended spacing distance between panes of glass in a multi-glazed window, beyond 3/4-inch there is no gain in thermal performance. A one-inch double glass window unit is rated at about R-2 versus about R-1.8 for a 5/8-inch spaced window glass unit. [Specific research citations needed here.] Window glass panes too far apart?DJF Note: other studies have shown that if the space between window panes becomes too great, even if the window is a factory-sealed unit, thermal convection can cause air movement inside the window, increasing building heat loss during cold weather. For an explanation of convection currents and how they can cause even sealed building cavities to act as heat loss conductors. As we detail at Convective Loops & Thermal Bypass Leaks, stack effects in buildings chill the interior walls - increasing conduction (heat) losses through them. Sealing in the home's interior will reduce infiltration, but it won't stop partitions and plumbing or electrical chases that are open to the attic from filling with cold air. A window whose glass panes are set too far apart can create these same effects, turning a window into a heat pump, sending indoor heat outdoors. Window glass panes too close together?DJF Note: other studies have shown that if the space between window panes is too small, even if the window is a factory-sealed unit, radiation losses from the warm inner window surface across the air space between the panes and onto the cold outer window pane will significantly reduce the window's R-value. Stick with the common window pane spacings used by window manufacturers, typically 3/16" to 3/4" between glass panes. [Specific research citations needed here.] Window Cost Comparison: Site-Built versus Factory Made Double-Pane WindowsIncidentally, in standard window sizes, factory-sealed double-glazed window units cost about the same as two individual lites of glass you would buy to build your own site-built double-glazed windows. So unless you are retrofitting windows of odd sizes, or require extra thick windows, factory-sealed window units may be your best bet. |
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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.
EXTERIORS of BUILDINGS
AGE of a BUILDING - how to determine
ALGAE, FUNGUS, LICHENS, MOSS
ATTIC CONDENSATION
BASEMENT WATERPROOFING
BOOKSTORE - EXTERIORS
CHIMNEY INSPECTION DIAGNOSIS REPAIR
DECK & PORCH CONSTRUCTION
DECK COLLAPSE Case Study
DECK FLASHING LEAKS, ROT Case Study
EARTHQUAKE DAMAGED FOUNDATIONS
ENERGY SAVINGS in BUILDINGS
ENVIRO HAZARDS
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FRAMING DETAILS for BETTER INSULATION
FRAMING DETAILS for DOUBLE WALL HOUSES
FOUNDATION WATERPROOFING
HEAT TAPES & CABLES on Roofs for Ice Dams
HOUSEWRAP AIR & VAPOR BARRIERS
LEAD POISONING HAZARDS GUIDE
LEAD TEST KIT for HOME USE
LOG HOME GUIDE
LIGHTNING PROTECTION
MOISTURE CONTROL in BUILDINGS
MOLD DETECTION & INSPECTION GUIDE
MVOCs & MOLDY MUSTY ODORS
ODORS & SMELLS DIAGNOSIS & CURE
PAINT & STAIN GUIDE, EXTERIOR
PAINT FALURE, DIAGNOSIS, CURE, PREVENTION
PAINT FAILURE CHECKLIST
PORCHES & Sunrooms
ROOFING DIAGNOSIS INSPECTION & REPAIR
SEPTIC SYSTEMS
SHEATHING, Gypsum board
SHEATHING Homasote & Other Board
SHEATHING, OSB
SHEATHING, Plywood
SHEATHING, FOIL FACED - VENTS
SIDING, ASBESTOS CEMENT SHINGLES
SIDING EIFS STUCCO
SIDING HARDBOARD
SIDING VINYL
VINYL CHLORIDE HEALTH INFO
SIDING WOOD
STAIN DIAGNOSIS on Building Exteriors
STAIN DIAGNOSIS on Indoor Surfaces
STAIRS, RAILINGS, LANDINGS, RAMPS
STUCCO OVER FOAM INSULATION
TERMITES, ROT
THERMAL EXPANSION of MATERIALS
THERMAL MASS in BUILDINGS
THERMAL MASS in UPSTAIRS
VAPOR BARRIERS & AIR SEALING at BAND JOISTS
VAPOR BARRIERS & CONDENSATION in BUILDINGS
VAPOR BARRIERS & HOUSEWRAP
VAPOR CONDENSATION & BUILDING SHEATHING
VENTILATION in BUILDINGS
WATER ENTRY in BUILDINGS
WINDOWS & DOORS
SKYLIGHT LEAK DIAGNOSIS & REPAIR
Diagnose & Repair Skylight Leaks
Rooftop Skylight Leaks
Water Testing Skylights
Repairing Skylight Leaks
Avoiding or Preventing Skylight Leaks
SITE BUILT DOUBLE GLAZED WINDOWS
SLOPED GLAZING DETAILS
Seals, sealants & leaks
Sloped Glazing Design
Temperature effects on windows
Sealants & Gaskets
Sealant Joint Depth & Width
Sealed Window Joint Failures
Avoid Joint Depth Sealant Failures
Avoid Adhesion Window Sealant Failures
Using Window Glazing Tapes
Using Window Glazing Gaskets
Using Window Setting Blocks
Choosing Skylight Glass
Skylight Glass Breakage
Window Glass Seal Failures
Stopless Window Glazing
VERTICAL GLAZING DETAILS
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10/01/2009 - 03/01/1984 - InspectAPedia.com/Energy/Windows_Site_Built.htm - © 2009 - 1988 Copyright Daniel Friedman All Rights Reserved - InspectAPedia® is a Registered U.S. Trademark