Masonry walls are generally highly durable. However, when masonry walls in cold climates stay too wet for too long, freeze-thaw damage can occur. This issue has particular relevance for energy efficiency retrofits, because the addition of interior insulation causes the masonry to stay colder and have a lower drying potential.
The following documents present details of BSC’s research and experience regarding the prevention of freeze-thaw damage in retrofit projects. Technical topics such as the critical degree of saturation (Scrit) are discussed, and case studies and recommendations are provided.
The American Foursquare, a Sears, Roebuck & Co. kit home, was a staple of small American towns between 1908 and 1940. More than 100,000 of them were built in America. Homes built prior to 1980 make up 80% of the housing stock in the United States, and are responsible for a majority of the residential energy use in the country. All of the renovations used systems engineering principles to ensure good indoor air quality and longterm durability while providing deep energy reductions. This posting is permission of ASHRAE. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAE's prior written permission.
An edited version of this Insight first appeared in the ASHRAE Journal. You have got to love salesmen. They figure things out way before physicists, usually before engineers and certainly before greenie weenies. They found, what we should all know, that it is much more cost effective to fix the enclosure so that the actual system that you need is small and therefore does not cost much to install and does not cost much to operate. Oh, by the way, this approach also saves energy. Who knew?
Moisture accumulates when the rate of moisture entry into an assembly exceeds the rate of moisture removal. When moisture accumulation exceeds the ability of the assembly materials to store the moisture without significantly degrading performance or long-term service life, moisture problems result.
This digest will begin with a brief description of the system and materials, review moisture problems in buildings, and summarize how moisture control should be dealt with in strawbale buildings.
An edited version of this Insight first appeared in the ASHRAE Journal. So what do you do when you have an old building and the walls aren't doing their job? What do you do when the walls look bad, leak and are falling apart? You give them a face-lift.
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.
An edited version of this article was first published in the ASHRAE Journal.
I have loved bourbon for a long time. I like the history. And I like the independent spirit of the folks who make it, their sense of tradition, and their willingness to continue to experiment. Even now after two hundred years of history, they experiment mostly by trial and error rather than by computer simulations. I have often thought that if engineers were in the liquor business, bourbon would be the liquor they would make.
The primary function of a housewrap or building paper is rain penetration control. It is not air infiltration despite what the manufacturers say.
An edited version of this Insight first appeared in the ASHRAE Journal. Ever wonder how we can build a 50 story glass tower that doesn’t leak, but we can’t seem to build a two-story house that doesn’t leak? The answer is a little bit of counter intuitive thinking.
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.
Stucco and EIFS are common cladding systems that appear similar from the exterior. These systems have very different attributes however. This Digest explains the reasons why face-sealed EIFS are fundamentally flawed as cladding systems for most applications, and describes how drained EIFS can be used successfully in almost all climate zones and exposures. Cracks, lamina deterioration, and movement joints are also discussed.
This digest reviews the moisture control principles that must be followed for a successful insulated retrofit of a solid load-bearing masonry wall. Two possible approaches to retrofitting such walls are presented and compared.
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.
Providing thermal comfort without excess space conditioning costs is one of the primary requirements of buildings. Therefore, thermal control is an important aspect in almost all buildings. Understanding heat transfer and the temperature distribution through building materials and assemblies is also important for assessing energy use, thermal comfort, thermal movements, durability, and the potential for moisture problems.
Heat flow occurs through the building enclosure via opaque enclosure elements, is directly transferred into the building by solar radiation through windows, is carried along with air across the enclosure by unintentional leakage and ventilation, and can be generated within the building by occupants and their activities.
The control of heat flow in buildings requires insulation layers compromised with few thermal bridges, an effective air barrier system, good control of solar radiation, and management of interior heat generation.
We learn our lessons from disaster. Hurricane Andrew taught us about wind. Hurricanes Charley, Frances and Jeanne taught us about rain. The Red River of the North Basin taught us about floods. Hurricane Katrina had it all: wind, rain and flood. That we will rebuild, and rebuild in the same place, is not in doubt. This is what we do – for better or worse. If we are to rebuild and if we are to rebuild in the same place how should we rebuild?
The function of a vapor barrier is to retard the migration of water vapor. Where it is located in an assembly and its permeability is a function of climate, the characteristics of the materials that comprise the assembly and the interior conditions. Vapor barriers are not typically intended to retard the migration of air. That is the function of air barriers.
Moisture is involved in most building problems. The most serious tend to be structural damage due to wood decay, unhealthy fungal growth, corrosion, freeze-thaw, and damage to moisture sensitive interior finishes. Avoiding these problems requires an understanding of moisture, the nature of materials, and how it interacts with materials. This digest deals with these fundamentals.
This paper examines methods of using hygrothermal models, primarily WUFI, to assess the impact of energy efficient enclosure upgrades on the durability of historical buildings. Means of producing and choosing input data for the hygrothermal simulation are discussed. Methods for using the hourly results from the simulations to generate a corrosion index and a freeze-thaw count are developed. An example wall is used to demonstrate the type of output that can be expected and how this can be used in making retrofit design decisions.
Exposure to sunlight (ultraviolet radiation) and moisture are the major factors affecting the durability of paint coatings and the durability of the substrate.
