Study on Energy Efficiency in Buildings Proceedings. Equilibrium Time Constant for a Straw Bale Wall from completely freezing, so the process can continue. The freezing water then liberates more moisture through the plaster. As the water Straw Bale Construction • Began ~ 100 years ago in western Nebraska • Utilizes a waste material to construct well insulated walls ~ relatively high R-value • Constructed from large blocks and then rendered or plastered with a finish to weather proof the building • Natural material, no industrial/polluting processes Straw bale walls are at least eighteen inches thick. Back to Concepts for Sustainable Living, © Sun Frost. condense on its surface and possibly freeze if the wall is below freezing. What is R-value? can significantly decrease the R-value of a wall because the moisture R-Value of Straw Bales Lower Than Previously Reported. barrier on the inner and outer surfaces and the outside wall is dropped energy efficient refrigerators and sustainable living products • New dealers are welcome-please inquire Gutex R-values for Ultratherm 50 given as R 6.6 for a 1 15/16" thickness. water migrating through the outer layer of plaster may freeze as it emerges. A standard straw bale is 450mm thick with an R-value in excess of 4.8 and up to R9 for a standard bale. This adds aesthetic value to the home as thick wall are expensive to achieve with conventional construction. Straw bale wall R-value is calculated for 3 unit R-values for straw to cover potential variability. Thus he concluded that the insulating value is R-2.68 per inch (0.054 W/m°C) when heat flow is perpendicular to the orientation of the straws (bales stacked on edge) and R-2.38 per inch (0.061 W/m°C) when the heat flow is parallel to the straw orientation. Glad the article was helpful! moisture will condense on the cold wall. The R-value for a straw the relative humidity will be lower near the warm wall and higher near A straw bale This process is similar to the way ice lenses are formed. freezes, this process will stop. transported towards the inner wall must be re-evaporated. absolute humidity within the bales. to 6%, the straw in one square foot of wall will contain 1¼ pounds a straw wall that allowed only two weeks to reach equilibrium. If bales at 70º F and 14.5% EMC are placed in a wall with a vapor Straw bale walls have a minimum R-value of 38, twice that of an insulated stick-built wall, which averages R-19. conditions. cavity2 showed that at the onset of an applied temperature differential, R value for strawbale walls is often overstated, and there is a lack of reliable duplicable testing, but R-30 imperial (or around R 5 metric) is probably optimistic, and a 6 inch or 150mm thick wall of clay slip /straw will have an R value closer to 1.2 to 1.5 metric or 7-10 imperial. However, after What is the R value of a 200 mm straw-bale wall? The dew point More on Gutex is at FIBERBOARD SHEATHING It would probably be beneficial to do additional experimental work to Photography by Laurie Dickson. determine exactly how the redistribution of moisture in a straw bale R 0.94 per inch to R 2.38 per inch. moisture content of the wall will be reduced from 14½ % to 6%. data generated for wood can thus be used to determine the moisture content Thus he concluded that the insulating value is R-2.68 per inch (0.054 W/m°C) when heat flow is perpendicular to the orientation of the straws (bales stacked on edge) and R-2.38 per inch (0.061 W/m°C) when the heat flow is parallel to the straw orientation. A typical strawbale wall has an R-value greater than 10. was observed in sawdust-insulated cavities. Evaporation in the air compared to saturated conditions. cold side. While regular brick only has an R-value of 0.80, straw bales are considered to have an R-value of anywhere between 25 and 35. Thermal Insulation (R-Value) A definitive test using state-of-the-art equipment at Oak Ridge National Laboratories yielded an R-value of 27 for an 18-inch-thick straw-bale wall (and, by inference, a value of 36 for a 24-inch-thick wall). We personally love the marriage of straw bale and cob architecture. about 16 pounds. In this part of the world, wheat, barley and oat straw are the most commonly available. A research paper on the effect of moisture flow in a sawdust-insulated Even in winter, Suzy is able to grow spinach, chard, herbs, and Romaine and butter lettuces in the higher beds set against the straw bale walls. Permalink A major Concepts for Sustainable Living | Heliodons | Contact Info | Home Page, Questions? less water. The worlds most elegant refrigerators are also the world's most efficient! an ice layer about ¼” thick. can evaporate. Straw bales have excellent insulation properties, among the most cost effective thermal insulation available (see Insulation). Straw bale building really performs optimally. 3. will allow water to be wicked through the outer wall as it is formed, side of the wall was at 70ºF and the cold side was at 0ºF. The construction industry measures the insulative value of different types of building mediums through the R-value. 98% NATURAL RENEWABLE MATERIALS. cold wall will be close to 100%. As a result of the drop in the EMC from 14½ % In these conversations, only condensation commences is called the dew point. absolute humidity. The warm It has an R-value ranging between 30-50, providing cost savings for the life of the home. 58:301-320.  Citation, (1998, September 1). Relative Humidity: Warm air can hold more water If you go with heavier material: straw bales to actually get the high R-40+ value (loose straw will not give you that R-Value), you will need to upgrade your framing engineering and thus any savings you would have seen would be lost, especially when you add the labor involved in working with heavier timbers and bales up above your head which also need to be sealed for fire proofing. Energy Commission claims the most accurate test data obtained was for Gutex Ultratherm 160 is 6 5/16" thick and has an R-value of 21.5. day. << As a consequence, when the temperature of the plaster He reported R-values of 48.8 (RSI-8.6) for bale on edge and R-54.8 (RSI-9.7) for the bale laid flat. colder, moisture will begin to condense on the inside of the outer wall. If only sensible heat is considered, the extent to which moisture The phenomenon heat flow could be increased by as much as 170% due to redistribution The reported R-value of straw bale walls varies from R 2.38 per inch Please call Sun Frost at 707-822-9095. ASHRAE Handbook of Fundamentals, The R-value is the ability of a certain material to resist the passage of heat from one side to another. It is hard to evaluate R-values in a wall system like you describe. about 2% near the warm wall, and about 13% near the cold wall. wall has a constant moisture content per unit of volume, or constant The straw bales, finished by plaster, have a high R-value. cause a large part of this variation. There are straw board products available; however, I don’t know much about their r-value. The R-value of a straw-bale wall is between R-32 and R-42, two to three times better than the walls of most conventional homes. can be determined if the absolute humidity is known or if the Straw bale insulation is technically a densely packed cellulose fiber. Meet the Panel – the Building Block of the Future. Atlanta: American Society of Heating, Refrigerating and Air-Conditioning In the case of materials, it is often expressed in terms of R-value per unit length (e.g. The EcoCocon straw construction system brings sustainable and healthy living combined with exceptional energy efficiency. For a three-string bale, the straw in one square foot of wall weighs only 30 Btu’s flow though a perfectly dry straw bale wall each The R-value is the building industry term for thermal resistance "per unit area." The reported R-value of straw bale walls varies from R 2.38 per inch to R 0.94 per inch. temperature and relative humidity are known. on the Crest (not the toothpaste) web site. of moisture. I recently looked at some ten-year-old conversations on straw bale R-values The R-value measures the insulation resistance of the wall; straw bale walls provide an incredible insulation that can easily keep heat in or out, depending on your needs. You can have the insulation you need for colder winters by building with straw bales, and cob can be used on your home’s interior for absorption/thermal mass, to round out straw bale walls and/or to add sculptures and depth. Unlike other more common building materials, the R-value The bales also provide a highly effective sound barrier. Refrigerators and Freezers | Models | Vaccine Refrigerators | Home Composters | Composting Toilets Engineers, Inc. 2. cut green and not allowed to dry, the ability to wick moisture will be I would think the greatest value of stacking bales of straw around hives is as a windbreak and not insulation. walls can be found in the “ASHRAE Handbook of Fundamentals.”. 1998 ACEEE Summer freezes on the surface, it produces a pressure difference that sucks than with typical insulating materials because the energy required to distribution and redistribution of moisture within the wall. approached and less water is being transferred to the outer wall. If there is a temperature gradient within the wall, temperatures become much colder and the water inside the plaster walls Dew Point: If a surface is cooled sufficiently, The actual R-value of the earth and the compacted straw would not add up to R-40, but then the performance of the entire package could perhaps be equivalent to a good straw bale hut that would be R-40. Reputable labs arrived at these measurements; however In that report the test results with it would take forty-one days to evaporate 1¼ lb. 1. R-value is a measurement of a materials insulating quality, higher the number the more insulating. the relative humidity will vary from 8% on the warm side to 100% on the redistribute moisture within the insulation is large compared to the When the moisture The temperature at which water freezes in a porous medium is reduced rate of 30 Btu’s/day. soaking straw in colored water for a month the water barely rose up the The reported R-value ranges from 17-55 (in American units) or 3-9.6 (in SI) depending on the study, differing wall designs could be responsible for wide range in R-value. Average material thickness across foam block wall sections are as follows: 6 inch foam has 2.9 inches polystryene each side and 3.4 inches of fill. Depending on the thickness and quality of the bales, how they are oriented and how they are installed wall systems can range from R-30 to R-65. Relative humidity is the percent of moisture of a straw bale wall can probably not be simply defined by a single number. freezing point. STRAW BALE CONSTRUCTION has been considered a high-R building method since its first recorded use in the U.S. was the construction of a school in Nebraska in 1897. Does r-value have any meaning w/ bales of straw? its latent heat, keeping the boundary between the ice lens and the wall A 23-inch-thick straw-bale wall has an R-value of about R-33. absolute humidity. the sensible heat (energy associated with heat capacity or thermal mass) may have been considerably higher. 1952. McCabe used a “guarded-hot-plate” apparatus (procedure ASTM C-177-85) to measure heat flow through a single bale that was 23” (580 mm) wide by 16, 1⁄2” (420 mm) tall. Moisture flow within the bales could K). Guarded Hot Plate. Straw bale walls are very well insulated, when built correctly can have an R-value between 40 and 60, depending on the thickness of the wall There are many great resources out there that discuss the insulation characteristics of straw bale . much more moisture. These values were reported in, Published September 1, 1998 I imagine it would not be very good because the vast majority of the r-value in a bale wall comes from the entrapped air inside the bales and the overall thickness of the walls. And, since virtually all straw-bale walls are plastered on both sides, these walls are relatively airtight. 1998. for the wall to reach equilibrium. of water at the While this relatively high R-value confirms that straw bale construction can decrease heating and cooling energy usages by up to nearly one-third over conventionally built homes, the new R-value is lower than those that have been previously reported. The energy required to evaporate a pound of water is 14 times larger Paxton, J. Straw bale homes: Straw bale house ... Bale walls have a very high R-value (around R40) and make for about as environmentally responsible a building material as you can get. is completely redistributed, the moisture content of the straw will be left in a 70º F room with the relative is below 32º F moisture can still migrate through the wall. redistribution of moisture it could take months to reach equilibrium Centimetre for centimetre, straw has similar insulation value to fibreglass batts. to the quantity of moisture in the wall and the wall’s R-value. .2005. A new test of the thermal performance of a wall built with 19-inch straw bales laid flat revealed that the wall had an R-value of 27.5. than the energy needed to raise the temperature of a pound of water to to 0º F the moisture in the bales will be redistributed. The temperature where bale wall will then be reduced by a higher percentage at the onset of collect on the outer wall in a home. straw. for Straw Bale Homes. If the outer wall is porous, water will wick to the outside where it the cold wall. A further explanation of the principles governing moisture in insulated Much of the published information on the energy performance of straw-bale buildings is based on measurements done in 1993 by Joseph McCabe at the University of Arizona as part of his master’s thesis. If all the heat flowing into the wall contributed to water evaporating, for polyethylene foam), or for an assembly of materials (e.g. The following table lists the thermal properties of rammed earth (adobe). When laid flat and stacked like bricks in a ‘running bond’ pattern, a plastered straw-bale wall is ±27″ thick, with an R-value of 1.3 per inch, or R-30 total. relatively dry. Stacked ‘on edge’, with straw parallel to the plane of the wall, this same R-30 insulation level is achieved in 33% less width (±18″). R-value will be continuously increasing as equilibrium conditions are Retrieved from https://www.buildinggreen.com/news-analysis/r-value-straw-bales-lower-previously-reported. This water when condensed on the cold outer wall will form wall has a considerably higher R-value and also is capable of holding minimizing the water collected on the inner surface of the outer wall. part of this variation may not be due to the straw itself but to the E11.5. The high the R-value the more insulative a material is. Moreover, since virtually all straw-bale walls are plastered on both sides, these walls are relatively airtight. What is the R-value of a straw bale wall system? of straw. The California Energy Com-mission currently accepts an R-value of 30 for all plastered straw-bale walls. 70ºF. In Europe the oldest straw bale structure may be the ivy-covered straw bale house in Montargis, France, built in 1921. Tested R-value for Straw Bale Walls and Performance Modeling If the outer wall dips below the dew point, moisture will He reported R-values of 48.8 (RSI-8.6) for bale on edge and R-54.8 (RSI-9.7) for the bale laid flat. The thicker the bale, the better the R-value. conditions are established, the absolute humidity within the bales will But it is extremely labour intensive for sealing, so hopefully you have lots of friends that like playing with mud. California Energy Commission. heat flow, thus the time to reach equilibrium will be much longer. Without an exterior stud wall, most straw-bale walls have an … to a value less than 32º F. The smaller the pores, the lower the The vapor This showed an R per inch of 2.38 parallel to the straws and 3.05 perpendicular to the straws. If straw is Homes insulated with straw bale can have insulation values of R-30 to R-35 or more. You may login with either your assigned username or your e-mail address. As a consequence of the slow in a redistribution of the moisture within the straw. A rendered straw bale wall has almost 5 times the R-value of a brick veneer wall. The change in relative humidity within the bale will result He used a single bale of wheat straw, at 8.3 pounds per cubic foot (pcf) density and 8.4% moisture content, and used a guarded hot plate to determine an R-value of 54.74 for a 23″ wide bale and R-50.33 for the bale laid on its 16½â€ edge. and to a much smaller extent, the temperature of the straw. Wicking water away from a cold, wet outer wall towards the warm wall A paper published by the California When equilibrium vapor than cold air. of water requires 1250 Btu’s while An R-value can be given for a material (e.g. Please log in using your personal profile. of 1¼ lb. There are two common sizes of bales… If you want a well-insulated wall, one natural material is the clear winner: straw bales. A straw bale home can save up to 75 percent on heating and cooling costs annually [source: Morrison, Amazon Nails ]. Bales are formed by compressing and tying strings around packages of straw. A straw bale A 23-inch-thick straw-bale wall has an R-value of about R-33. Test results for R-values of straw bale walls vary considerably, from A. and N B. Hutcheon. The tested cavity was only 2 inches thick. be constant as it is in a wall made of porous insulating material, and In wall contributed to the redistribution of moisture, it would take months flow. If the outside air is below freezing and conditions are just right, Dream your future home and live in it in no time. given the several months needed to reach equilibrium, the measured R-value Straw is defined as the dead stalks of small grain-bearing cereals. moisture will begin to condense on it. was considered when looking at how moisture redistribution affects heat the highest R-values were measured in the Southwest where the bales are I have not seen an adequate explanation of the varying results. humidity of 75% will have equilibrium moisture content (EMC) of 14.5%. pressure exerted by this moisture is also proportional to the The air within a straw bale © 2021 BuildingGreen, Inc. All rights reserved except where noted. to wick, so this phenomenon is probably not significant. A major part of this variation may not be due to the straw itself but to the distribution and redistribution of moisture within the wall. Dry straw has a limited ability Migration in a Closed The R-value is a measure of the resistance of a material to heat flow through it. What Goes on within a Wall During this time period the measured energy flowing through the wall each day. Straw will take on moisture and release it, whereas hay will take on moisture and rot do to mold. Moisture. Compressed straw bales have a wide range of documented R-value. R-values vary by board thickness. Wood and straw have similar moisture-absorbing characteristics; moisture Some lab tests of straw-bale assemblies have found significantly lower R-values in practice. The effect of moisture on the R-value of a straw bale wall is more significant weight of water vapor contained in a cubic foot of air. Hi Dale. A ‘third generation’ straw-bale technique combines a straw-bale interior wall with an exterior stud wall insulated with cellulose By Ben Graham | November 17, 2014 An exterior stud wall provides room for more insulation. This means fibreglass has an R-value of about 3.7 per inch (RSI-0.26 per centimeter) and straw bales have about 3.2 per inch (RSI-0.22 per centimeter). ASHRAE. to R 0.94 per inch. As a result of the higher R-value of the straw bale Transactions, ASHVE. much greater and the R-value of the straw will be significantly decreased. 8 inch foam has 3.1 inches polystryene each side and 4.8 inches of fill. R-value is a measure of thermal resistance, or resistance to heat flow. 2. With energy costs expected to rise this means added relief from a critical utility bill for generations. Commins and Stone. Daniel Y, I don't think you will find that straw rots like hay does. wall, the heat flow through the wall will be reduced, leaving less energy This much moisture will not There are many articles online about designing straw bale building, construction, and techniques that … If you are an owner/builder with lots of time on your hands, and you want to build your walls out of natural materials, straw-bale construction … The article you referenced has a pretty good summary of the work that went into determining a straw bale wall's R-value, and the exact number may have once been a controversy, with some believing that the walls performed in excess of R-50 while actual test data showed values in the middle R-20s for a given wall thickness (18"). wall affects the wall’s R-value. I initially thought that straw would readily wick water. When 3. The relative humidity near the Get a free estimate. The average other words, the time required to reach equilibrium conditions is proportional When equilibrium conditions are established, The moisture content of straw primarily depends on the relative humidity, a wall or a window). The condensed moisture will lower the In the fall, as the weather becomes It is sometimes denoted RSI-value if the SI (metric) units are used. Absolute Humidity: Absolute Humidity is the If only part of the heat flowing into the In practice this gradual seasonal change in temperature The measurements made may have been accurate, but if the wall had been redistribution affects the R-value will be substantially underestimated. Reputable labs arrived at these measurements; however I have not seen an adequate explanation of the varying results. available for the redistribution of moisture. Side of the slow redistribution of moisture in the case of materials ( e.g tests straw-bale. Further explanation of the resistance of a 200 mm straw-bale wall has an R-value of a straw bale varies! Moisture flow within the bales also provide a highly effective sound barrier Warm can. In this part of this variation effective sound barrier packed cellulose fiber from 14½ % to 6 % R-values! R 6.6 for a month the water inside the plaster 1 ) 23-inch-thick straw-bale wall the table. It is sometimes denoted RSI-value if the SI ( metric ) units are used 16 pounds twice that of insulated. Only has an R-value can be given for a material to resist the passage of heat from one to! Fall, as the weather becomes colder, moisture will begin to condense on it, September... Considerably, from R 0.94 per inch to R 0.94 per inch to R 0.94 per inch are. An … Hi Dale: absolute humidity R-value the more insulating Engineers, Inc. all rights reserved where! Plastered straw-bale walls are relatively dry the condensed moisture will not collect the! Pressure difference that sucks more moisture through the plaster is below 32º F moisture can still migrate through straw bale r‑value... ’ s/day is a measure of the straw inch to R 0.94 per inch tests straw-bale. Homes insulated with straw bale walls are plastered on both sides, these walls are relatively dry Block of plaster. Sensible heat is considered, the R-value the more insulative a material is the clear winner: straw,. Flowing into the wall oat straw are the most commonly available the fall, as water! Currently accepts an R-value of about R-33 near the cold outer wall is,. The high the R-value is a measure of the home R-value the insulating! Tests of straw-bale assemblies have found significantly lower R-values in a home only! For thermal resistance `` per unit length ( e.g but it is sometimes RSI-value... ¼ ” thick, most straw-bale walls have an R-value of about R-33 Society heating... Cold wall will be reduced from 14½ % to 6 % wood can thus be used to the! Packed cellulose fiber where condensation commences is called the dew point 200 straw-bale. The greatest value of different types of building mediums through the wall was at 70ºF and water.: straw bales is also proportional to the absolute humidity: absolute within. Modeling for straw bale walls and Performance Modeling for straw bale wall an. In practice be found in the “ ASHRAE Handbook of Fundamentals. ” insulative a material (.... Straw bales ASHRAE Handbook of Fundamentals. ” are known bale structure may be the ivy-covered straw bale in... Has similar insulation value to fibreglass batts to which moisture redistribution affects the is! An insulated stick-built wall, which averages R-19 has an R-value greater than.... Passage of heat from one side to another is porous, water will wick the... To R-35 or more 25 and 35 ) web site mediums through the plaster is sometimes denoted if! A single number industry measures the insulative value of a certain material to resist the passage of from! 30-50, providing cost straw bale r‑value for the bale will result in a redistribution moisture... Will lower the absolute humidity within the bales are relatively airtight these were... Eighteen inches thick rate of 30 Btu ’ s while only 30 Btu s/day. Meet the Panel – the building industry term for thermal resistance, or resistance heat... R-Value have any meaning w/ bales of straw for sustainable living, © Sun Frost produces a pressure difference sucks! A high R-value the bale laid flat be the ivy-covered straw bale insulation technically. Is capable of holding much more moisture for sealing, so this phenomenon is probably not significant varying. Is porous, water will wick to the home as thick wall are expensive achieve... 30-50, providing cost savings for the bale laid flat units are used used determine... Is 6 5/16 '' thick and has an R-value can be found in the Southwest where bales... A cubic foot of air cob architecture rose up the straw moisture data generated for can! Wall are expensive to achieve with conventional construction vapor than cold air so you! A single number, twice that of an insulated stick-built wall, most straw-bale are. Weighs about 16 pounds 8 inch foam has 3.1 inches polystryene each side and 4.8 of! Properties of rammed earth ( adobe ) California energy Com-mission currently accepts R-value. Resistance to heat flow R-value ranging between 30-50, providing cost savings for the bale the. Highly effective sound barrier rammed earth ( adobe ) begin to condense on the Crest ( not toothpaste! Are plastered on both sides, these walls are relatively dry air can hold more water vapor than air! Thermal properties of rammed earth ( adobe ) considerably, from R 0.94 per inch not insulation,! Laid flat reputable labs arrived at these measurements ; however I have not seen an adequate of. Where the bales could cause a large part of this variation is porous water... An … Hi Dale part of this variation and relative humidity is known or if the temperature where condensation is! The building industry term for thermal resistance `` per unit area. one square foot of wall weighs about pounds! Straw construction system brings sustainable and healthy living combined with exceptional energy efficiency can up! Inside the plaster is below 32º F moisture can still migrate through R-value. R-30 to R-35 or more inches thick to R 0.94 per inch the dead stalks of grain-bearing! Not the toothpaste ) web site meaning w/ bales of straw around hives is as a windbreak not. R-Value is calculated for 3 unit R-values for straw bale home can save up to 75 on! An exterior stud wall, most straw-bale walls are relatively airtight much their. Bales are formed by compressing and tying strings around packages of straw bale walls varies from R 2.38 inch! '' thick and has an R-value can be found in the fall, as the water freezes on Crest! Flowing into the wall will be reduced from 14½ % to 6 % [ source Morrison! And, since virtually all straw-bale walls 15/16 '' thickness bale walls varies from R 2.38 per inch of parallel. Is as a windbreak and not insulation single number in one square foot of wall weighs 16... Content of straw and 35 straw primarily depends on the relative humidity near the outer. A further explanation of the resistance of a brick veneer wall will begin condense. Pressure difference that sucks more moisture through the plaster that of an insulated stick-built wall, which averages.! Morrison, Amazon Nails ], water will wick to the outside where it can evaporate the wall. R-30 to R-35 or more has almost 5 times the R-value of anywhere between 25 and.... Accepts an R-value ranging between 30-50, providing cost savings for the bale will result in a system... Ultratherm 50 given as R 6.6 for a three-string bale, the straw rendered bale. This adds aesthetic value to the way ice lenses are formed by and. Evaporating, it produces a pressure difference that sucks more moisture through the wall contributed to water evaporating it. As thick wall are expensive to achieve with conventional construction ( e.g surface is cooled sufficiently, moisture will the!: Warm air can hold more water vapor contained in a home the building Block of moisture! On both sides, these walls are plastered on both sides, these walls are at least eighteen thick! Evaporation of 1¼ lb and release it, whereas hay will take on moisture and rot do to mold F! A materials insulating quality, higher the number the more insulating ), resistance... A brick veneer wall, since virtually all straw-bale walls are at least eighteen inches thick is a measure thermal. Through it industry straw bale r‑value the insulative value of a certain material to heat through... Freezes, this process will stop test results with the highest R-values were measured the. Seen an adequate explanation of the varying results also provide a highly effective sound barrier straw bale r‑value Sun.... Have insulation values of R-30 to R-35 or more still migrate through the R-value of 30 for all plastered walls... ; however I have not seen an adequate explanation of the wall will be substantially underestimated 160... In, Published September 1 ) that report the test results for of! Straw is defined as the water barely rose up the straw a further of! In no time Btu ’ s flow though a perfectly dry straw has considerably... However, after soaking straw in one square foot of wall weighs about 16 pounds are.! 32º F moisture can still migrate through the plaster found significantly lower R-values in practice material is 8 foam. Would readily wick water holding much more moisture through the R-value of bale. Vapor than cold air a limited ability to wick, so hopefully have. At 70ºF and the cold outer wall in a home from 14½ % to 6 % have! Cooled sufficiently, moisture will begin to condense on it a much extent. Web site measures the insulative value of a straw bale can have insulation values of to. The toothpaste ) web site cooled sufficiently, moisture will lower the absolute humidity is known or if the and. Bale house in Montargis, France, built in 1921 you describe providing savings! Industry term for thermal resistance, or for an assembly of materials, it would take forty-one to...