http://www.buildingscience.com daily 1 2010-01-26T02:05:02Z http://www.buildingscience.com/documents/digests/bsd-013-rain-control-in-buildings Moisture is one of the most important agents leading to building enclosure deterioration. Understanding and predicting moisture movement within and through the enclosure istherefore of fundamental importance to predicting and improving building enclosure performance, particularly durability. Since driving rain deposition on walls and roofs is quantitatively the largest single source of moisture for most walls and roofs, it is no surprise that controlling rain penetration is one of the most important parts of a successful moisture control strategy. In fact, failure to control rain is likely the oldest and most common serious building enclosure performance problem. Commentators as long as Vitruvius (70 BC) bemoaned the challenges of controlling rain penetration. This document will consider rain control from a general to a specific level. The following sections will cover: basic moisture control principles that should be employed in the design of above-grade building enclosures; driving rain as a moisture load on walls; a classification system of the various rain control strategies available for walls; and finally, good design practises for walls. The rain control of roofs will be covered in more detail in another BSD. No publisher John Straube Building Science Digests are information articles intended for professionals. The author and the publisher of this article have used their best efforts to provide accurate and authoritative information in regard to the subject matter covered. The author and publisher make no warranty of any kind, expressed or implied, with regard to the information contained in this article. The information presented in this article must be used with care by professionals who understand the implications of what they are doing. If professional advice or other expert assistance is required, the services of a competent professional shall be sought. The author and publisher shall not be liable in the event of incidental or consequential damages in connection with, or arising from, the use of the information contained within this Building Science Digest. vapor permeance moisture-Drainage plane type-high-rise deflection type-institutional moisture-Flashing/Deflection driving rain drying radiation enclosure-Foundation assembly residential ventilation guidance-Roof design enclosure-Roof assembly flashing comp-roofs moisture-Driving rain enclosure-Wall assembly rain screen guidance-Below-grade enclosure moisture-Vapor Permeance rain guidance-Wall design moisture-Drying guidance-Enclosure design principles airflow-Indoor Air Quality comp-walls rain control type-low-rise doc-Digest drainage 2013-04-03T00:05:40Z BSC Article http://www.buildingscience.com/documents/digests/bsd-018-the-building-enclosure_revised That part of any building that physically separates the exterior environment from the interior environment(s) is called the building enclosure or building envelope. Environmental separator is another term used to describe the enclosure, but note that this generic term also applies to separators of two different interior environments. The term building enclosure is preferred to the term building envelope largely because it is considered both more general and more precise. Also note that the building enclosure may contain, but is not the same as, the so-called thermal envelope, a term that is used to refer to the thermal insulation within the enclosure. The enclosure, the loadings it must resist, and its functions are addressed in this digest. No publisher John Straube guidance-Enclosure design principles durability guidance-Below-grade enclosure radiation ASHRAE doc-Digest residential ventilation relative humidity 2013-04-02T03:41:06Z BSC Article http://www.buildingscience.com/documents/digests/bsd-103-understanding-basements Buildings used to be constructed over cellars. Cellars were dank, dark places where coal was stored. People never intended to live in cellars. Now we have things called basements that have pool tables, media centers and play rooms. Cellars were easy to construct – rubble, stone, bricks and sometimes block. If they got wet or were damp so what? Basements are different. They are not easy to construct if we intend to live in them. They need to be dry, comfortable and keep contaminants out. Over the last 50 years there has been a notable expansion of living space. The useful conditioned space of building enclosures is expanding to the outer edge of the building skin (Figure 1). Attics, crawlspaces, garages and basements are valuable real estate that are being used to live in or used for storage or places to locate mechanical systems. Basements are viewed by many as cheap space that can easily be incorporated into a home. Keeping basements dry, comfortable and contaminant free is proving to be anything but simple. No publisher Joseph Lstiburek Building Science Digests are information articles intended for professionals. The author and the publisher of this article have used their best efforts to provide accurate and authoritative information in regard to the subject matter covered. The author and publisher make no warranty of any kind, expressed or implied, with regard to the information contained in this article. The information presented in this article must be used with care by professionals who understand the implications of what they are doing. If professional advice or other expert assistance is required, the services of a competent professional shall be sought. The author and publisher shall not be liable in the event of incidental or consequential damages in connection with, or arising from, the use of the information contained within this Building Science Digest. moisture-Diffusion/Vapor Pressure airflow-Indoor Air Quality thermal-Insulation guidance-Below-grade enclosure moisture-Vapor Permeance resources-technical comp-below-grade doc-Digest enclosure-Foundation assembly moisture-Interstitial Condensation vapor barrier resources-homeowner resources-mold 2013-03-21T18:21:45Z BSC Article http://www.buildingscience.com/documents/digests/bsd-105-understanding-drainage-planes Controlling rain is the single most important factor in the design and construction of durable buildings and in the control of mold. Drainage planes are used in the design and construction of building enclosures to control rain. All exterior claddings pass some rainwater. Siding leaks, brick leaks, stucco leaks, stone leaks, etc. As such, some control of this penetrating rainwater is required. In most walls, this penetrating rainwater is controlled by the drainage plane that directs the penetrating water downwards and outwards. No publisher Joseph Lstiburek Building Science Digests are information articles intended for professionals. The author and the publisher of this article have used their best efforts to provide accurate and authoritative information in regard to the subject matter covered. The author and publisher make no warranty of any kind, expressed or implied, with regard to the information contained in this article. The information presented in this article must be used with care by professionals who understand the implications of what they are doing. If professional advice or other expert assistance is required, the services of a competent professional shall be sought. The author and publisher shall not be liable in the event of incidental or consequential damages in connection with, or arising from, the use of the information contained within this Building Science Digest. enclosure-Wall assembly guidance-Enclosure design principles moisture-Roofs comp-walls moisture-Drainage plane resources-technical radiation comp-below-grade moisture-Flashing/Deflection doc-Digest guidance-Roof design enclosure-Roof assembly guidance-Wall design enclosure-Wall assembly-insulation comp-roofs 2013-03-27T15:06:24Z BSC Article http://www.buildingscience.com/documents/digests/bsd-109-pressures-in-buildings Air flow in buildings is one of the major factors that governs the interaction of the building structure with the mechanical system, climate and occupants. If the air flow at any point within a building or building assembly can be determined or predicted, the temperature and moisture (hygrothermal or pyschometric) conditions can also be determined or predicted. If the hygrothermal conditions of the building or building assembly are known, the performance of materials can also be determined or predicted No publisher Joseph Lstiburek Building Science Digests are information articles intended for professionals. The author and the publisher of this article have used their best efforts to provide accurate and authoritative information in regard to the subject matter covered. The author and publisher make no warranty of any kind, expressed or implied, with regard to the information contained in this article. The information presented in this article must be used with care by professionals who understand the implications of what they are doing. If professional advice or other expert assistance is required, the services of a competent professional shall be sought. The author and publisher shall not be liable in the event of incidental or consequential damages in connection with, or arising from, the use of the information contained within this Building Science Digest. enclosure-Wall assembly guidance-Enclosure design principles condensation subsystems-HVAC airflow-Indoor Air Quality moisture-Diffusion/Vapor Pressure doc-Digest guidance-Building systems/HVAC guidance-Below-grade enclosure type-high-rise moisture-Vapor Permeance ASHRAE airflow-HVAC interactions analysis-Testing moisture-Interstitial Condensation guidance-Wall design airflow-Airtightness/Air barrier airflow-Driving forces/stack effect subsystems-HVAC-ducts resources-mold 2013-03-02T02:39:22Z BSC Article http://www.buildingscience.com/documents/digests/bsd-144-increasing-the-durability-of-building-constructions The current building industry focus on durability is in part a reaction to the current perceived lack of it. Warranty claims and callbacks are viewed as increasing. Litigation and insurance costs are felt to be rising as a result. Another reason for the current focus on durability is the recognition that sustainability is not possible without durability. If you double the life of a building and you use the same amount of resources to construct it, the building is twice as resource efficient. Therefore durability is a key component of sustainability. It seems that one thing that both the development community and the environmental community can agree on is that durability is a good thing. What do we know about durability and how do we know it? The lessons of durability have come principally out of failure. Engineering is an iterative process of design by failure. Buildings are constructed. Problems are experienced. Designs and processes are changed. Better buildings are constructed. The building industry is in essence a reactive industry, not a proactive industry. It can be argued that the industry continues to do things until they become intolerably bad and then the industry changes. Examining failures gives us guidance on increasing the durability of building constructions. No publisher Joseph Lstiburek Building Science Digests are information articles intended for professionals. The author and the publisher of this article have used their best efforts to provide accurate and authoritative information in regard to the subject matter covered. The author and publisher make no warranty of any kind, expressed or implied, with regard to the information contained in this article. guidance-Enclosure design principles moisture-Diffusion/Vapor Pressure moisture-Drainage plane guidance-Below-grade enclosure type-high-rise radiation ASHRAE type-institutional doc-Digest moisture-Convection/Air barriers analysis-Material Properties residential ventilation type-low-rise 2013-04-02T03:49:12Z BSC Article http://www.buildingscience.com/documents/insights/bsi-003-concrete-floor-problems An edited version of this Insight first appeared in the ASHRAE Journal. Perhaps it was the drug culture of the 60’s that turned brains into coleslaw but it is hard to understand the lunatic practice of placing a layer of sand over the top of a plastic ground cover under a concrete slab in California. No publisher Joseph Lstiburek moisture-Capillary break guidance-Below-grade enclosure doc-Insight resources-technical moisture-Moisture storage ASHRAE airflow-Airtightness/Air barrier resources-homeowner 2013-03-01T03:23:45Z BSC Article http://www.buildingscience.com/documents/insights/bsi-009-new-light-in-crawlspaces An edited version of this Insight first appeared in the ASHRAE Journal. Think of the good old days—the Civil War, WWI, the Great Depression, WWII—crawlspaces were uninsulated. They were ventilated and they didn’t have ground covers—and they didn’t have problems. Why? No publisher Joseph Lstiburek moisture-Diffusion/Vapor Pressure resources-homeowner guidance-Below-grade enclosure airflow-Physics of Air Movement doc-Insight moisture-Vapor Permeance thermal-Physics of Thermal Control resources-technical relative humidity moisture-Physics of Moisture Control climate-Building design and climate resources-mold 2012-12-05T02:41:25Z BSC Article http://www.buildingscience.com/documents/insights/bsi-011-capillarity-small-sacrifices An edited version of this Insight first appeared in the ASHRAE Journal. Water causes enough trouble by itself, but when we add salt we go to a whole different level, especially where porous materials are concerned. What is the deal with porous materials? Simple, porous materials are capable of wicking water large distances due to capillary suction. And when water can move large distances only bad things can happen. No publisher Joseph Lstiburek guidance-Enclosure design principles moisture-Diffusion/Vapor Pressure guidance-Below-grade enclosure doc-Insight resources-technical analysis-Material Properties ASHRAE moisture-Physics of Moisture Control climate-Building design and climate 2013-04-13T03:46:02Z BSC Article http://www.buildingscience.com/documents/insights/bsi-041-rubble-foundations An edited version of this Insight first appeared in the ASHRAE Journal. It’s pretty easy to deal with new basements. If you want a challenge try dealing with century old houses sitting on top of rubble foundations. These houses are not going away and sooner or later we are going to have to fix them and insulate them. No publisher Joseph Lstiburek guidance-Below-grade enclosure doc-Insight enclosure-Foundation assembly drainage Retrofit 2012-04-06T16:40:33Z BSC Article http://www.buildingscience.com/documents/insights/bsi-059-slab-happy An edited version of this Insight first appeared in the ASHRAE Journal. How hard can it be to insulate a flat sheet of concrete? I mean you only have three choices – on the top, on the bottom, or on the edge. OK, you might have some combination of the three as well. No publisher Joseph Lstiburek high-R foundation guidance-Below-grade enclosure doc-Insight comp-below-grade enclosure-Foundation assembly ASHRAE moisture-Physics of Moisture Control 2013-02-27T00:59:45Z BSC Article http://www.buildingscience.com/documents/published-articles/pa-built-wrong-from-start Top ten blunders that rot your house, waste your money, and make you sick. Reprinted with permission from Fine Homebuilding Magazine, April/May 2004, pages 52-56. No publisher Joseph Lstiburek guidance-Windows subsystems-HVAC guidance-Building systems/HVAC guidance-Below-grade enclosure doc-PublishedArticle thermal-Convective/air movement guidance-Wall design vapor barrier resources-homeowner 2013-04-05T18:31:13Z BSC File http://www.buildingscience.com/documents/case-studies/ma-westford-national-grid-deep-energy-retrofit-westford-modern-colonial-retrofit There are many suburban neighborhoods built within the last 20 years that have similar houses. This project demonstrates the potential for significant energy savings for these newer homes. No publisher Building Science Corporation enclosure-Wall assembly ERV resources-homeowner guidance-Building systems/HVAC guidance-Below-grade enclosure deep energy retrofit guidance-Windows doc-CaseStudy climate-zone-cold enclosure-Foundation assembly guidance-Roof design enclosure-Roof assembly guidance-Wall design renovation Retrofit 2013-04-02T17:06:58Z BSC Article http://www.buildingscience.com/documents/case-studies/cold-climate-national-grid-deep-energy-retrofit-millbury-cape This Cape Cod style house was built in 1953. While the owners had made interior improvements and necessary repairs in the 25 years since they purchased the house, they now wanted to do some exterior upgrades and at the same time tighten up the house in keeping with their long-standing goal of becoming energy efficient and reducing their impact on the environment. No publisher Building Science Corporation enclosure-Wall assembly guidance-Enclosure design principles climate-Building design and climate guidance-Building systems/HVAC deep energy retrofit doc-CaseStudy resources-low-energy climate-zone-cold enclosure-Foundation assembly Building America enclosure-Roof assembly resources-homeowner Retrofit doc-DesignsThatWork 2013-04-02T16:53:18Z BSC Article http://www.buildingscience.com/documents/case-studies/cs-ma-gloucester-cold-climate-national-grid-deep-energy-retrofit-gloucester-coastal-cottage In 1920, when this house was built on the bank of a coastal cove, it served as a summer cottage complete with a boat dock. Over the years, the house has been remodeled, added to, and converted to a year-round residence. Now, as part of the latest renovation, it has undergone a deep energy retrofit. No publisher Building Science Corporation enclosure-Wall assembly subsystems-HVAC enclosure-Wall assembly-sheathing deep energy retrofit enclosure-Wall assembly-siding doc-CaseStudy climate-zone-cold enclosure-Foundation assembly Building America enclosure-Roof assembly resources-homeowner enclosure-Wall assembly-insulation guidance-Construction details Retrofit doc-DesignsThatWork 2013-04-02T17:05:41Z BSC Article