Cayl – Page 4

Overview The elements are what your house deals with day-in and day-out, and what challenges your house during extreme conditions. Pretty much all houses have the basics down: keep water out, keep the inside relatively cool or warm depending on the season, and let light and air into the rooms we live in. However, if you're designing a new house it help's to consider beyond the basics. Different regions have variations between them in climate, sunlight, winds, storms, flooding, and fire. It's good to consider these things so that you can adapt your design to these elements. The Elements The elements are essentially what mother nature throws at us or makes available to us. Let's take a look at these. Sun The sun is a daily part of our lives, especially since without it we wouldn't be here. The sun rises in the east and sets in the west. Though knowing where these occur during the season is important, its the sun's path across the sky during the day that's important. Let's take a look at these. Sunrise and Sunset Let's start with when the sun rises and sets. As we're all aware, the sun doesn't rise and set at the same place each day. It moves to the north or south depending on the season. The movement also varies depending on how far north or south of the equator you're at (latitude). The position of sunrise and sunset is given in degrees, where north is 0 degrees, east is 90, south is 180 and west is 270. The directional position of sunrise and sunset is often given, with ENE (east-northeast) being where the summer sun rises, ESE (east-southeast) being where the winter sun rises, WNW (west-northwest) being where the summer sun sets, and WSW (west-southwest) being where the winter sun sets. The other aspect is time, as the sun sets earlier and rises later during the winter months compared with summer, but varies with latitude. For example, Chicago daylight on the summer solstice lasts 6 hours and 7 minutes longer than on the winter solstice, whereas in New Orleans it's 3 hours and 31 minutes longer. In Chicago the summer solstice sunrise is at 5:15 am rising from 57 degrees ENE and sunset is at 8:29 setting at 303 degrees WNW. In New Orleans on the summer solstice sunrise is at 5:59 am rising at 62 degrees ENE and sunset is at 8:04 pm setting at 298 degrees WNW. Solar Path The path across the sky will also vary. In summer the highest angle of the sun (solar noon) from south is higher than in winter. This means the sun's path across the sky in winter is shallower/lower in the sky than in summer, which will be higher. In the southern hemisphere the sun's path runs across the northern portion of the sky. In Chicago on the winter solstice the sun rises to 25 degrees above the southern horizon, while in summer it's 72 degrees above. In New Orleans on the winter solstice the sun rises to 37 degrees above the southern horizon, while in summer it's 83 degrees above. This understanding will give you a sense of how sunlight can impact your design through the year. In cooler northern climates you get more direct light into your house during the day because the sun's path is lower than in the warmer southern climates. This is especially beneficial in the colder months. Glare The sun's path also influences glare. Glare is unwanted reflection of light that is uncomfortable to look at. If you have a large light-color concrete patio outside your living space facing to the south, you can get uncomfortable glare when the sun is d reflecting off of it. Glare also occurs off bodies of water such as lakes or the ocean. Orientation of Your House For your house design, your house's orientation can impact how the sun affects your house. For your primary living space, a southern orientation is beneficial in northern climates as you can get more light throughout the year, but you need to be aware of glare when you select where hard and light-color surfaces are located. Photo by Mark McCammon. In warmer southern climates you might want your living space facing north so that you don't have the sun heating up your house in the summer and you minimize the potential for glare. Facing northeast would allow for some sunlight in the summer mornings before things get hot. Avoid facing your living spaces to the southwest if possible (northwest in the southern hemisphere), especially in warmer climates. In summer, as the day warms, you'll get the greatest intensity of heat in the afternoon when you least want it. If you want to utilize the sun for heating, a southeast orientation (northeast in the southern hemisphere) gets you more light early in the day, and therefore greater solar benefit. Other Considerations All this said, you'll need to take into account other aspects of your site as well when considering orientation. Potential views or the orientation of smaller urban or suburban lots can limit your options. Summer light can be controlled through the use of broad roof overhangs, architectural projections over windows, or the use of porches, loggias, verandas, and lanais (all of these are regional variations of the same thing). Wind Wind can be gentle or strong, and viscous during storms. Wind can vary in direction, though most regions have a prominent direction from which most winds blow. Wind can also vary in season. Strong winds from storm fronts or winds around a low pressure system can change the predominant wind direction for short periods of time. Seasonal winds can also impact the performance of your house. Cold winds challenge your house to maintain heat if its not well insulated or you have poorly performing windows. Strong winds can also damage your house. Seasonal winds such as derechos from squall lines, or regional winds such as the Santa Ana winds of southern California can be extremely intense. Roofs are especially susceptible to intense winds. Lighter-weight roofing material such as asphalt shingles can be easily torn off. Eaves that aren't attached strongly to the walls can lift the whole roof structure. Making sure you select roofing materials and construction methods that can perform during high and regional winds is important. Sand Storms Sand storms are rather unique features of dryer environments around the world. In the U.S. the deserts of Arizona and the semi-arid regions of the southern great plains of Texas are very susceptible to these storms. Photo by Corporal Alicia M. Garcia, U.S. Marine Corps. Though not a particular challenge for houses, you just need to make sure your house is effectively sealed so that you don't get bits of sand floating around the house. Courtyards enclosed on three sides with the open side oriented to the direction these storms come from can cause small mounds of sand to build up in the corners, similar to small snow drifts. Wildfire Wildfire is one of the most feared challenges for homes in the countryside, especially in dryer environments and regions with dry seasons. Even suburban homes near the forest or prairie can be vulnerable due to blowing embers igniting roofs or entering attic vents. Photo by Sippakorn Yamksikorn. Selecting fire-resistant materials is important. Masonry or stucco walls, clad or metal windows, metal eaves, and metal, slate, or clay-tile roofing go a long way to minimize the chance of your house going up in flame. However, no house is completely safe from wildfire. Below are different types of fire to consider. Forest Fire Forest fires are the best known of the wildfires. Forest fires can spread quickly in dry seasons with hot temperatures and strong winds. The magnitude of the flames is hard to comprehend. It's almost impossible for any home it's path to be saved from such a fire. Even homes not in the forest but near its edge can be affected. Many neighborhoods and communities have been decimated by nearby forest fires mainly due to embers being blown into neighborhoods. Even homes with fire resistant materials went up in flames because embers made there way into attics via roof vents. If you want your house to be built in the woods, keep in mind any potential for fire. Placing your house in an open meadow might mitigate the issue, but won't fully solve the problem. Prairie Fire Prairie fire, also known as brush fire or bush fire, can also be devastating. Wind is always a challenge with these fires as they can move and grow amazingly fast. These fires are common in dryer areas such as West Texas or parts of California. Again, fire resistant materials is very important, though no guarantee. If you're building in the country, keeping a wide band of non-combustible surfacing such as gravel around the perimeter of your house can be beneficial. Controlled Fire Controlled fire is used to manage undergrowth in forests or to burn away excess dry material from prairies. Prairies can benefit from occasional burning, allowing for healthy regeneration. If your building in the country, especially in more arid or heavily forested areas, keep in mind that fire may be controlled, but can also quickly become uncontained. Maintaining a band of gravel several feet wide at the perimeter of the house can assist in protection with controlled burns or a small easily-controlled fire. Rain and Storms Rain, rain, go away...this childhood nursery rhyme can be apt when water from rain storms becomes an issue. These present challenges that you'll need to consider. Let's review them. Rain Rain is a basic. Mostly gentle, rain can often become a deluge, challenging your house and overwhelming the ability of local drainage to keep up. When designing your house, be sure to keep in mind not just the typical rains, but the heaviest rains typically occurring in your region. Even arid and semi-arid areas can have intense rainfall for short periods, so be sure to account for it. The main things to consider are: Roof slopes to direct water off the house. This is especially important for "flat roof" designs, which still require thought on gentle pitches to get water to move off the roof.Gutters, downspouts, scuppers, or roof drains to take water from the roof to the ground.Correct detailing of exterior materials and components, with an intense focus where openings occur both on the roof and in the walls, where different materials intersect, and how flashing is best used.Allowing cavity walls for masonry or other cladding systems to rid of any moisture.Effective sloping of the project site to direct water away from the house and around it if on sloping land.Water capture systems if you'd like to take advantage of this water for other non-potable uses such as toilets or landscaping. Photo by Johannes Plenio. Lightning Lightning is a product of more intense storms and occurs most often from May through August in the U.S. In 2019 the Insurance Information Institute listed almost 77,000 claims against homeowner's insurance due to lightning losses. Florida, Texas, California, Georgia, and Louisiana led the pack of states with the highest number of claims. The force and intensity of lightning is amazing and can wreak havoc. Lightning can easily damage roofs and masonry, especially chimneys, along with windows and the electrical system of your home. Houses can be destroyed by fire directly from lightning or because of an adjacent strike such as to a tree next to the house that catches fire from the strike, spreading to the home. The best design methods to mitigate the damage is to use non-combustible roof material, keep trees away from the house, but especially to use a lightning protection system. A lightning protection system consists of rooftop (and chimney top) rods attached to guide cables that then connect to rods placed deep into the ground. Lightning is the connection of charged particles between the cloud and the ground. Lighting essentially seeks a path, which can often be via your roof. The lightning rod, being the highest element of the house, is used to provide that path to the ground, reducing the chance of it hitting the house itself. Hail Hail is another part of intense storms. Though most hail is small and falls without damaging a house, hail stones can grow as large as a grapefruit in the most intense storms. Large hail can damage roofs and break windows. Smaller-sized hailstones. Some storms can produce hail stones large enough to cover his palm!Photo by Bdahl. According to the Insurance Information Institute, there were almost 5,400 storms with hail 1 inch or larger in size in 2019, with Texas, Kansas, Nebraska, South Dakota, and Colorado leading the states. Though no home or material can fully resist hail damage from the largest stone sizes, the best protection from hail damage is impact- resistant roofing and storm shutters for the windows. Impact resistant roofing is made from materials such as cement or clay tiles, along with shingles made of plastic, molded polymer, or recycled resin or rubber. A clay tile roof that's withstood over 80 years of rain, hail, snow, and ice. Hurricanes Hurricanes are massive in size with high wind intensity and long-duration heavy rainfall that can lead to storm surges and flooding. NASA photo. Category 1 hurricanes, those of least force, have winds up to 95 miles per hour, while Category 4, the highest rating, can have wind up to 150+ miles per hour. In areas prone to hurricanes, house design should incorporate: Framed roofs constructed with hurricane straps to help keep the roof attached. Windows made with impact-resistant glass and/or have storm shutters. Exterior materials hardy enough to withstand debris impact.Houses raised above anticipated storm surge or flood levels. Concrete, when properly designed, is a good material to withstand the wind and water forces. Wood framing has good flexibility and can be used effectively when designed properly. Houses with a round or square shape are best at reducing wind pressure on any given side. Roofs with a 30-degree slope are good for wind deflection. Tornadoes Tornadoes are short-duration but intense storms that can do a large amount of damage in their path. The smallest tornadoes typically have wind speeds less than 70 miles per hour, causing little damage. The largest storms have winds over 200 miles per house. The largest of these storms had the most intense wind speed ever recorded at 318 miles per hour! National Weather Service photo. Tornado damage varies by storm size and proximity to its path. Light damage might include roof shingles being ripped off, windows being broken, or some trees being downed. Houses close to a strong tornado's path might have significant structural damage. Homes directly hit by large tornadoes have been fully wiped off of their slabs. The best protection to have is a basement, a storm cellar that can be accessed from in the house, or a safe room made of concrete. National Weather Service photo. There's no real tornado proof house - it would have to withstand not only the wind but debris weighing up to a ton being blown up to 150 miles per hour. Given that houses need windows, no window is going to survive that, much less any affordable material. Concrete or steel for the walls would have to be immensely strong and thick, which isn't cost effective. Besides a basement or safe room, the most recent concept in tornado resistant design was created by Q4 Architects as part of a design competition. The idea is to create a safety core for the house large enough for a kitchen, dining area, a bathroom, the utility equipment, and washer/dryer. This core would have thick concrete walls along with a few tornado resistant windows and doors. The rest of the house would be traditionally built around the core. If hit by a tornado, the house core would likely remain intact enough to keep living in it until the rest of the house is repaired or rebuilt. Flooding Flooding is one of the most challenging things to endure since you never know how deep the floodwater will get nor how long it'll last. Once your house gets flooded and the water recedes, you have to deal with the mess of the aftermath which can include mud and debris, soaked walls and floors that lead to mold growth, ruined furniture, and the loss of mementos. Photo by National Oceanic and Atmospheric Administration. The U.S. Government has studied areas prone to flooding and have determined a "100-year flood" based on local weather history and geography. They have maps available showing the potential flood areas and the flood elevation for the 100-year event. Understand that a 100-year flood is NOT the expected time frame between storms of this size. Rather, its the probability of an estimated extreme flood event that has a 1 percent chance of occurring within any given year. You can have more than one 100-year flood in a given year, and you can have multiple 100-year floods across several years. You also might not have a 100-year event in a hundred years. Seasonal The best design for flooding is to raise the house above flood stage - essentially put the house on stilts or design a lower level that isn't used for anything other than a garage. Many regions have seasonal flooding that's fairly consistent in maximum water depth over any given time. These areas are easy to design for since the extent is known. Unanticipated Flood Levels Areas with rapid suburban growth are shedding more and more water into creeks and rivers since hard surfaces don't absorb water. This has led to increasing flood levels and flood extents in many locations. An example of this is outside of Chicago. Mies Van der Rohe designed the Farnsworth house along the Fox River outside the small town of Plano, Illinois, in the late 1940's. He and the owner were aware of seasonal flooding, so he designed the house to be raised on stilts above the known flood levels. The Farnsworth House.Now not high enough.Library of Congress photo. However, by the 1990's suburban development had enveloped the Fox River basin upstream from the house's location. Flood levels on average have increased. Some minor flooding started with a few inches inside the house. In the 1990's storms started significant flooding of the house, with one storm's flood level reaching to an interior height of 5 feet! Tidal Surge Tidal surges are the result ocean storms and hurricanes pushing water inland along the coast. When storm strengths are fairly consistent over long periods of time a house can be raised to a reasonable level. This is common with the Tidewater design style of the American southeast. However, some storms are beyond what's normal, as we've seen with Hurricane Katrina in New Orleans and Superstorm Sandy in the northeastern U.S. These are the one's that are a challenge to anticipate. Flash Flooding Flash flooding can be deadly. Quick intense rainfall can send amazing amounts of water rushing down rivers and creeks at high rates of speed, inundating and often destroying anything in its path. In areas known for damaging flash flooding its best not to build near those waterways. A flash flood.Photo by B137.https://creativecommons.org/publicdomain/zero/1.0/deed.en Snow & Ice Snow and ice are inevitable in climates with cold winters and in high mountain locations . From a design standpoint you'll need to address the following: Orientation of the house: If you're not limited by smaller lots the orientation of your house should be considered carefully. Even on smaller lots, consider addressing winter conditions as best you can. Solar path: Take benefit of the solar path during the day to increase solar heating opportunities and light. Be careful as well of glare, especially with snow on the ground.Wind: Be aware of the directions of the wind throughout the season, especially during storms, so that you can create a design to minimize their impact.Snow loads: Snow is very heavy. Make sure your roof framing is sized appropriately. Sloped roofs shed snow loads more quickly and effectively than flat roofs, and broad roof eaves deposit the snow away from the exterior walls. Ice: Ice dams occur when a warmer attic space heats the roof surface causing the underside of the snow to melt. When that melt water reaches the colder eaves and gutters it freezes. The continuation of the process creates ice dams at the edges of the roof.Preventing ice damage: To minimize the potential damage, be sure your ceilings below the attic are well insulated to minimize the loss of heat into the attic. Also, be sure the attic is well ventilated from the eaves up through the attic by incorporating ventilation products into the roof or using mechanical ventilation systems.Roof underlayment: Using a water-proofing underlayment beneath the roof shingles or other roofing material assists in preventing leaks from any ice dams that do form.Gutters and downspouts: Electrical heat tracing of your gutters and downspouts is one option to ensure ice blockage doesn't happen in your roof drain system. Ground Water Ground water is moisture that stays in the ground even after soil has dried out after rains. The depth at which groundwater occurs is called the water table. The water table can vary in depth across locations and regions and over seasons. In some locations groundwater might not be a concern due to its lower depth, especially if slab construction is typical. The main concern with groundwater is potential damage to foundations and moisture penetrating the perimeter foundation walls and slabs in spaces below ground level. Mitigating the impact of ground water involves the following: Waterproofing foundation walls: Waterproofing the soil-side face keeps moisture away from the concrete or block foundation walls.Waterproofing basement slabs: This requires laying down a waterproof sheet, called a membrane, over the gravel bed on which the slab will rest.Installing foundation drainage: Foundation drainage consists of perforated pipes that run along the bottom of the foundation wall. Groundwater enters the pipes and then drains to an outlet below the foundation on sloped sites or to a basement sump-pump when an outlet is not viable. The pump lifts the water up to ground level for dispersion. Radon Radon is a natural radioactive gas formed when trace amounts of uranium found in most soils breaks down. This gas is colorless, odorless, and tasteless, and can cause health problems if enough of it gets inside the home. The presence of radon can be determined from soil tests. Additionally, many jurisdictions have construction and mediation requirements due to known radon presence in a region. A map of the U.S. showing estimated concentrations of homes that have radon exceeding the EPA's safe limits.Graphic from the Environmental Protection Agency. Radon is easily mitigated through the use of radon prevention and removal. Prevention involves ensuring your foundation walls and slabs are well sealed, including at sump pump wells and any pipe penetrations. Removal involves installing a mitigation system, the simplest of which involves a vertical vent pipe running from beneath the floor slabs to the roof for expulsion. Mechanical systems are also available. Check with your local codes for requirements. Taking Advantage of Mother Nature's Bounty In addition to preventing damage from the elements, try to take advantage of them when you can. Solar Design Solar energy is a free gift to us. Designing your house to take advantage of this can save you money in the long term. The most visible and known method is for electrical power generation through the use of solar panels on the roof. These panels have significantly improved in their efficiency and can be easily integrated into your roof system. It's important to properly orient roof surfaces to take advantage of this. Maybe the easiest method to take advantage of solar energy is passive design for solar heating of your house. This involves careful planning and design of your home to maximize its value. A house using passive solar design.Photo by Fips. Orientation of your daytime living spaces to maximize solar gain during colder months is important, as is the selection of flooring and wall materials that can receive, store, and then radiate the heat outward to warm the home. Effective materials can include various stones, tiles, masonry, and even polished concrete. The use of clerestory windows (bands of windows on top of tall solid walls or between roof levels) can assist by heating vertical surfaces as well as long as those surfaces are of an appropriate material. Such materials can include masonry and stone. You'll need to figure out shading during summer so that you don't overheat the house. This can include using broad overhangs or shading structures, high-performance glass, window coverings that reduce solar heat but allow in light, and the use of deciduous trees for shading in summer. These trees allow the sun into the house during the colder season after their leaves have fallen. The sun can also be used for heating water through the use of solar water heating systems. Wind Breezes have been used to cool houses for millennia. Designing your house to allow cross ventilation across rooms and through the house can draw out warmer air and provide a cooling breeze. Adding a means to draw air up and out of the house is also advantageous, using clerestories or cupolas (projecting structures with windows at the top of the roof) with operable windows to allow warm air to rise and exit the house. Wind generators use the flow of outside are to provide electricity. This can happen most easily in areas with consistent and stronger winds. The generator for a house typically uses a smaller-scale wind turbine. A small-scale wind turbine for electrical power generation.Photo by Anders Sandberg.https://creativecommons.org/licenses/by/2.0/deed.en Check with your local authority if this type of generation can be used. Some don't allow it due to potential noise impacts in neighborhoods. Some utility service agreements with communities might not allow it, though states have been pretty good at setting up utility power purchase of any excess power generation from houses. Rain Rain is another free benefit from nature. Rain can be captured and stored for later use. Uses can include lawn and garden water as well as non-potable (non-drinkable) water for uses such as toilets and laundry. A rainwater collection tank.Photo by SuSanA Secretariat, courtesy of the Sustainable Sanitation Alliance.https://creativecommons.org/licenses/by/2.0/deed.en Harvesting typically involves the use of cisterns, which are underground storage tanks, or ground-level collection tanks from which water can be drawn out into an independent plumbing system separate from the potable water plumbing system. Soil Soil is the fourth free gift of nature. Houses have been built into the ground to provide protection from winds for centuries. Building into the side of a hill, piling soil up to the roof of the house, or digging into the ground are options. Orientation of a house to balance wind protection with solar light and energy is important, or to reduce heat gain and glare in hot climates. Soil has also been used as a readily-available material to build walls. We'll discuss these systems later as part of the Building Mass Design section. Mud brick being fabricated on a construction site.Photo by Soare.https://creativecommons.org/licenses/by-sa/3.0/deed.en Soil as a building material is weak against lateral loads during earthquakes in seismic areas, so keep that in mind. Soil keeps air warmer or cooler than outside air when a space is fully below ground level, such as a basement or inner rooms of houses built into the sides of hills. You'll still need insulation and heating in colder months to maintain a comfortable temperature when using traditional construction methods. Soil actually has low insulation value (it can freeze in winter down to many feet of depth) so don't try to use it in lieu of insulation when placing soil against exterior walls or when building into soil. It can, though, act as a thermal mass when used as thick walls. Climates with hot days and cool nights are best. During the day walls built of soil soak up heat and then radiates the heat to the inside in the evening. The thickness of the wall is important in order to gain enough heat throughout the wall during the day that can then radiate into the house in the evening. Soil that's around 30 to 50 feet in depth starts to maintain a consistent temperature, generally the same as annual average air temperature of the region. This means soils at those depths are warmer than air temperature in winter and cooler than air temperature in summer. Soils at appropriate depths can be taken advantage of for heating and cooling. Tubes that extend from the house to those depths have a fluid circulated through a heat exchange system to take advantage of the temperature differences. Vernacular Design / Regional Design Vernacular design is a term for historic designs adapted to the materials and climate of a region. It's good to understand how materials were used in the region you're building as well as the designs they used to keep houses warm in winter and cool in summer. Vernacular house design using the Victorian style in central Texas.The deep wrap-around porches provide shade in the summer, with the large windows providing cross ventilation to cool the home.Photo from Library of Congress. You don't have to build an 'old house', though. Instead, learn from them so that you can apply the principles to your house design, especially in terms of natural heating and cooling. Today's materials and technologies can augment the historic materials and designs to allow you to create a unique and well-performing design based on historic precedents. Building Mass Design Building mass is the use of thick and heavy construction materials from the earth to augment or fully provide the heating and cooling needs of your house. Adobe Adobe is probably the best known of building mass design. This system uses mud bricks that are formed and dried on site, then stacked and covered with stucco. This creates a thermal mass that can transfer heat through the wall to warm the home in cooler months. An adobe house in Santa Fe, New Mexico.Photo by Laurianne Fiorentino.https://creativecommons.org/licenses/by-sa/4.0/deed.en Solar heating is often used to augment the thermal mass, using sunlight to directly heat interior surfaces. Cooling is accomplished primarily through shading of openings and natural ventilation. Rammed Earth Rammed earth construction.Photo by Nomidtr.https://creativecommons.org/licenses/by-sa/4.0/deed.en Another option is rammed earth construction. This is a process in which forms are created for the walls, then filled with soil and binding ingredients such as straw. The soil is tamped down to gain strength. The soil is covered with stucco or mud plaster for the final step. This otherwise acts similar to adobe in terms of performance. Masonry An additional option for building mass is masonry, specifically thick walls of solid brick or solid cement blocks. A mason building a mass wall.Photo by diamondmountain.https://creativecommons.org/licenses/by/2.0/deed.en Similar to soil, mass design utilizes the collection of solar heat during the day that transfers through the walls so that it can then radiate into the house to assist with heating during the evenings. Conversely, during warmer months the mass, if shaded, can assist in keeping hot air out during the day due to the lag time it takes for heat to transfer through the material. Since shaded mass doesn't get a lot of direct sunlight, the lag time will work such that any warmth in the wall will radiate back to the outside rather than into the house. Having lived in houses with masonry thermal mass in a climate with warm to hot summers and cold winters, the effect can be noticeable. However, the effectiveness can slow as the warmer and cooler seasons progress and the walls become ever more exposed to extreme outdoor temperatures. You'll need to balance this benefit with any need for insulation in a given region. Earthship Design Earthship design is a variant on using soil and thermal mass. It not only uses this natural material but also re-purposes and integrates man-made items that are typically thrown away as part of the design. The goal is to become self-reliant for heating, cooling, and electricity as much as possible, and to not have to burn fuel or wood for heating. The Brighton Earthship, Stanmer Park, Brighton, U.K.Photo by Gazzat5.https://creativecommons.org/licenses/by/3.0/deed.en The most common elements of earthship design is the use of tires as the "formwork" for walls. There are mountains of discarded tires throughout the world, and this design takes advantage of that. The tires are filled with dirt and compacted as the wall is built up. The wall is then covered in mud for the surface finish material. This creates a thermal mass wall. Tires being used to construct walls for an earthship house.Photo by Eugene Kim.https://creativecommons.org/licenses/by/2.0/deed.en The house is designed with these walls on three sides with the fourth side having a lot of glass oriented toward the sun . The sun is used to heat interior floor and wall surfaces built of materials that collect heat that can be radiated into the house during the day and evening. A variety of passive and geothermal cooling, on-site electrical generation, and water collection systems complete the self-contained design that is claimed to work for any climate. Strawbale Design Strawbale design is another variant on building mass design. This system uses bales of straw bound by wire and stacked to create a structural wall or to create an infill wall for timber framing. The bales are either stacked onto poles in the wall or between poles on either side of the bales. The straw is then covered in a thick layer of stucco or plaster. Strawbale construction within a wood-frame structure.Photo by Jonathan Cross. The stucco and plaster provide fire resistance as well as thermal mass for the interior surface. The straw provides significant insulation. This system can be combined with passive solar design to heat the house. Potential problems with this method of construction is moisture getting into the walls causing rot, and moisture also causing mold. The bales must be stacked on a foundation wall that's above the ground to assist with moisture issues, and must incorporate whats called a capillary break to prevent any moisture at the foundation wall from seeping up into the bales. These issues shouldn't become a problem if the wall is properly constructed and maintained. Straw bale construction methods must be adjusted to regional variations, and bracing must be integrated into the wall for seismic loads. Infill construction works best for colder climates and wet climates. Earth-Sheltered Design Earth-sheltered design utilizes soil to protect against the elements. Since it's built into the ground, this type of design must address potential groundwater, moisture in soil from rain and snow, and insulation that's needed for the house. These walls should be treated the same as basement walls. Light and ventilation are very important considerations. Such houses are typically oriented toward the sun in cooler climates, but often away from the sun in hot climates. A long glass wall is typically used for the fourth wall of the house to provide light and ventilation for the living spaces. Skylights might be used for light and ventilation for spaces toward the back of the house. There are a few variants on this method, which are reviewed below. Earth-sheltered house using bermed-earth design.Built by Peter Vetsch.Photo by Archi0780.https://creativecommons.org/licenses/by-sa/4.0/ Bermed-Earth A berm is sloped earth placed against a wall (or a long raised ridge in landscape design). Bermed-earth construction is more typical on flatter terrain. It can also be used for houses that will be partially in the ground. Vertical walls, typically of concrete or reinforced concrete block covered with waterproofing and insulated as needed, are then covered by earth piled up against them. The soil is sloped to fall away from the walls. Some designs, especially on sloped sites, will have the roof also covered with earth. A sub-variant is the penetrated bermed-earth design. In this design earth covers all sides of the house. Windows and doors penetrate through the berms where needed. Underground An underground house is completely dug into the ground with all rooms located off a central open atrium for light and air. This type of design typically happens on flatter terrain - think of Uncle Owen and Aunt Beru's house in Star Wars. A special consideration for this design has to do with water. The perimeter walls have the same issues as bermed-earth and basement designs, and so will require a perimeter drain system tied to a sump pit. Any rain water and snow melt in the atrium will need to be drained to this sump and be pumped up for drainage away from the house. Water from showers, sinks, washing machines, and floor drains will need to be collected for filtering and recycling if utilizing such systems. Such water will also be combined with toilet outflow to be ejected out via a sump pump to leach fields for sewage. Using passive solar design might be more challenging depending on the size of the atrium and how the spaces are arranged onto it. Historic image. As you can see, mother nature throws a lot of challenges at us but also provides a lot of opportunities for house design. Note: All images are by Cayl Hollis unless noted otherwise.