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What’s the Best Way to Insulate Crawl Space Walls?

first_imgThe best route, Holladay says, is to use an air-impermeable insulation — either rigid foam with seams that have been carefully sealed or closed-cell spray foam.In theory, mineral wool and a clean cement surface shouldn’t support the growth of mold, adds Charlie Sullivan. “But if it’s a retrofit,” he adds, “there will probably be enough gunk there that you can’t clean off that it will still support mold growth.”He suggests that if the homeowner’s objection to rigid foam insulation is the global warming impact of the blowing agents used to manufacture it, choosing expanded polystyrene (EPS) over extruded polystyrene (XPS) is a good option. “But if the homeowner is philosophically opposed to petrochemicals,” he adds, “that doesn’t help.”Another option, Sullivan says, would be to use a product called Foamglas, described by its manufacturer as “cellular glass.”Sullivan’s tip has Chappell-Dick on the phone with the manufacturer, and at first blush Foamglas looks like a great alternative. It comes in 2-by-4-foot sheets, has an R-value of 3.4 per inch, and costs $1.20 per board foot.Fiberglass batts are not really an optionWriting from upstate New York, AJ Builder says the method typical in his area is to frame a wall 1 or 2 inches away from the concrete basement wall, insulate it with fiberglass batts and cover the wall with foil-faced insulation. “No mold issues,” AJ Builder writes.“I don’t know if you are being deliberately provocative, or whether you honestly think that this is the appropriate way to insulate a basement wall,” replies Holladay. “The technique you describe is about two or three decades out of date, and there are plenty of reports of failures resulting from this technique.”“I know it’s wrong,” AJ Builder says. “I also have never seen mold or moisture. We build in gravel and glacier moraine, and poured concrete here is quite water-resistant from my experience. Just telling it like it actually is. No [Rockwool] use, no foam, all batts of fiberglass, done. Thousands.”Be that as it may, Chappell-Dick says, “wood and fiberglass ain’t gonna happen.”What about adding a waterproof membrane to the assembly?If the risk of using an air-permeable insulation is that moisture will condense on the cold, inside surface of the foundation wall, what about keeping the moisture out of the wall assembly with some kind of a barrier?“I’m asking about putting the liner on the warm side of an R-10 or R-15 insulation on the CMU stem wall,” Chappell-Dick says. “I presume the dew point then will always be inside the insulation, and thus no condensation. And thus I can use [Rockwool]?”He adds: “Overall goal: to condition a crawl space without using foam.”Holladay finds three flaws with this approach. The first is that air between the fibers of the Rockwool insulation is warm, humid indoor air, “not magic dry air.” Second, daily changes in temperature will create a “pumping action” that provides an air exchange between basement air and the air within the insulation, so that eventually humidity finds its way into the wall assembly.“The third problem,” Holladay adds, “is that the concrete is damp, so that it’s possible for the area between the concrete and the membrane to get damp from that direction, too. The membrane traps moisture, leading to mold.”But lots of basements are insulated with fiberglassRichard Beyer is not understanding why a wall assembly that keeps moisture out of the mineral wool insulation with a waterproofing membrane is going to result in mold.“This proposed system will work providing a back-up dehumidifier and sump pit is added to ward off the unknown here and/or the potential freak storm which could change the drainage dynamics of this property,” Beyer writes. “Did I misunderstand something here?”Further, Beyer says, AJ Builder is correct: many homes in New England have fiberglass installed against raw cement walls with no mold issues.“Sometimes published building science is not always correct,” Beyer says. “Hence, why it’s consistently rewritten when failures occur, no different than our building codes. Most writings come from manufacturers who are selling product and who are filling the pocket’s of specifiers with $$$$.”Beyer wonders why Holladay is suggesting foam insulation when the homeowner doesn’t want the material in the house, adding, “I should also note there are many failures of foam out there, too.”Chappell-Dick also is curious about why a wall assembly in which the mineral wood is isolated from the crawl space wall by a membrane would be a problem.“The most important thing I have learned on this site is that while pure building science is exact and completely unarguable, applied building science is far more nuanced,” Chappell-Dick adds. “And, frustratingly arguable. It’s not so simple as ‘managing moisture.’ We’re managing risk and clients’ expectations, all at the lowest price possible while somehow extracting an income.”Also, says Beyer, building science has been in error many times over the years. For example, galvanized steel joist hangers were once specified in coastal locations, but it’s since been replaced by stainless steel. Why? Because galvanized steel corroded and failed.The membrane will trap moistureThe problem, Holladay replies, is that moisture can come from either direction. “If Andy followed your advice,” he writes to Beyer, “the waterproofing membrane would be chilled by the cold concrete, and would form a condensing surface for moisture in the interior air.”Holladay concedes that some installations using the method that Chappell-Dick proposes are successful. “The method is safer in warmer climates than in cold climates (because a concrete wall doesn’t get as cold in Alabama as it does in Vermont),” Holladay says, “and it is safer in a house with a very dry basement than a house with a damp basement.”But the bottom line is that any wall assembly including a waterproof membrane and batt insulation against a foundation wall is risky, Holladay says. This applies to walls with a layer of polyethylene plastic against the concrete, followed by fiberglass batts, as well as walls where the batts come first, followed by poly. Ditto for walls with two layers of poly and fiberglass in between.“What happens?” Holladay asks. “If you are lucky, and the soil around your house and the air in your basement are dry, these methods can work. In other cases — and plenty of remodelers have seen the failures, again and again — you end up with a moldy mess.“In other words, these sandwiches of fiberglass and polyethylene are risky. You are rolling the dice. But if you are feeling lucky, go ahead and roll the dice.”Our expert’s opinionHere’s how GBA technical director Peter Yost sees it:A crawl space foundation is just a short basement; you need the same three barriers that you need for any assembly — continuous air, water, and thermal barriers — as well as provisions for directional drying.Just as you would not insulate a basement before managing moisture, you need to manage moisture in the crawl space first, and then move on to insulation and air sealing. Check out this resource from Building Science Corporation.And if indeed crawls are just short basements, then check out these other BSC resources.Air-permeable insulations, including mineral wool, need a separate air barrier (and more than one of the BSC foundation details accomplishes this with a sealed rigid insulation layer between the masonry foundation and the air-permeable “cavity” insulation). Above-grade walls can have interior air barriers, like the Airtight Drywall Approach (ADA), but it is hard to consider ADA as appropriate for a crawl space or think of other interior sheathing that you could or would use as an interior crawl space air barrier.Insulating any building assembly on the interior makes the assembly colder; it’s just that masonry walls tend to care a lot less than framed walls, particularly ones sheltered below grade. For me, it’s that portion of the “below-grade” wall that is actually not below grade that is worrisome. And does it really matter if that condensation is only occurring in the portion of the wall above grade? It still represents a problem for any materials that can grow unintended biology.We tend to think of below-grade spaces as damp and cold because they are in contact with the soil and often aren’t moisture-managed. But if a crawl space is moisture-managed, you can air seal and insulate it just like a basement. Also bear in mind that any work to insulate and air seal the crawl space may have impact on levels of radon in the crawlspace and possibly the living spaces above.Using Foamglas is definitely a premium approach: the product has a good R-value, is inert, and is air-impermeable. With any other insulation approach, establish the three barriers and then check for directional drying potential. And frankly, if you can’t moisture-manage the crawl space, don’t insulate it. Andy Chappell-Dick is at work on a house in Climate Zone 5 where the task at hand is to upgrade a crawl space by adding insulation as well as a membrane to block the infiltration of moisture. The catch? The owners want to avoid the use of rigid foam insulation if at all possible.The floor of the crawl space is about a foot below grade, Chapell-Dick writes in a Q&A post at GreenBuildingAdvisor, and the area seems to be well drained. Foundation walls are made from concrete block (CMUs).He plans to foam in pieces of rigid extruded polystyrene in the rim joist area. To insulate the crawl space walls, Chappell-Dick wonders whether Rockwool Comfortboard 80, a rigid mineral wool insulation, would make a good substitute for rigid foam. Rockwool Comfortboard 80, according to the manufacturer, is non-combustible and chemically inert, and it’s made from natural and recycled materials, including rock. Rigid foam is a petrochemical.A second issue is how the waterproof membrane should be installed: should it be run up most of the crawl space wall, or can it be terminated at the base of the wall? And, Chappell-Dick wonders, does this detail have any bearing on the performance of insulation?That’s the backdrop for this Q&A Spotlight.This is not the place for RockwoolThe inherent air-permeance of mineral wool insulation makes it inappropriate for this application, writes GBA senior editor Martin Holladay.“The mineral wool can’t prevent humid interior air from contacting the cold crawl space walls,” he says. “The likely result will be moisture accumulation and mold.” RELATED ARTICLESHow to Insulate a Basement WallBuilding an Unvented Crawl SpaceFive Ways to Deal with Crawl Space Air From Building Science Corp: Conditioned Crawlspace Construction, Performance and Codes From the Canada Mortgage and Housing Corporation: Development and Assessment of Crawl Space Remediation StrategiesFrom Fine Homebuilding: Sealing a CrawlspaceCONSTRUCTION DETAILSInsulated and Conditioned Crawlspaceslast_img read more

Interview with Jignesh Mewani

first_imgOf the three young men who have galvanised Gujarat, ahead of the Assembly elections there, Dalit lawyer and activist Jignesh Mewani is perhaps the most articulate. In a recent interview in Ahmedabad, he talks to Smita Gupta about what Hardik Patel, Alpesh Thakore and he have achieved, analysing and anticipating problems while stressing that the first battle is to dislodge the BJP from power. Has anything changed in Gujarat since the last Assembly elections?The most evident change is that no one is talking about the Gujarat model: the Patidars, OBCs and Dalits are up in arms, but so are ASHA (Accredited Social Health Activist) workers, anganwadi workers, farmers, labourers, traders. The vikas (development) balloon has been punctured; the BJP can no longer use the Sabka Vikas slogan. The mood has changed: this kind of dissatisfaction has not been seen in 22 years. The ASHA workers threw bangles at (Prime Minister Narendra) Modi’s road show as he entered Vadodadra on October 22. In early October, angry residents of a municipal ward in Vadodara tied a BJP corporator to a tree and beat him up for failing to prevent demolition of their slum. Ever since chairs were thrown at (BJP president) Amit Shah at a rally in Surat last year by Patidars, he has been caged and the BJP has been on the backfoot. What are the reasons for this change in mood?(There has been) severe economic exploitation, agrarian distress, growing unemployment. For Dalits, apart from the economic problems, they are suffering from a sense of injustice.Immediately after four Dalits were publicly stripped and flogged in Una in the Gir Somnath district in July 2016, the community got activated. I was able to mobilise Dalits across Gujarat. I am picked up and arrested every time Narendra Modi lands in the state. The contradictions have sharpened. The Hindutva wave has worked three times (in 2002, 2007 and 2012), but if my child is still suffering from malnutrition, you can’t fool me any longer. Three youth faces — Hardik Patel, Alpesh Thakore and mine — have appeared. The three of us have come through agitations, we did not belong to any political party and therefore had no baggage. (It is only now that Alpesh has joined the Congress.) So caste is challenging Hindutva?A mobilisation on caste lines may not be a good thing but a deep analysis of what is happening now will show that the articulation of the caste-class reality is bound to happen in the absence of a progressive movement. What is happening has its roots in the current economic crisis. The promise of seven crore jobs in three and a half years by the BJP have not been fulfilled, the Rs 15 lakh in every bank account has not happened, the price of dal has shot up, farmers have not been given remunerative prices. The answer to everything is gaimata (the cow is the mother). And demonetisation and GST (the Goods and Services Tax) have already devastated people. Earlier, Mr. Modi was able to display a masculine larger than life image, using Goebbelsian rhetoric and the Hindutva wave. I have been to 16 States after Una, and I can tell you his graph is going down. Aren’t there social contradictions between Patidars, OBCs and Dalits — the three sections represented by Hardik Patel, Alpesh Thakore and you? How will you get around that? Of course, there are social and economic contradictions but the objective reality is that the biggest common enemy of the Patidars, OBCs and Dalits today is the BJP. Sooner or later, these contradictions will surface, but first, the battle against fascism must be fought and the BJP dislodged from power. That will provide interim relief. Fascism just can’t be defeated through electoral gains, it will require a long battle. How do you see your role in the coming elections?My role is to ensure that the over seven per cent Dalits in Gujarat don’t vote for the BJP. Currently of the 13 reserved seats, 10 are with BJP, but this time, the Congress will win 9 this time.Isn’t the BJP very strong still in urban Gujarat? Yes, we are yet to crack the urban areas, but the BJP will be wiped out from rural areas. There is an anti-BJP wave but no pro-Congress wave yet. Hindutva still works in urban areas. There is a refreshing innovative content that is coming from rural areas. A large chunk of Patels will come out strongly against BJP. Alpesh Thakore has mobilised his community. The BJP tried hard to woo the Dalits but the Ramnath Kovind card (making him President) did not work because of (the suicide of) Rohit Vemula, and (the attack on Dalits in) Saharanpur (in Uttar Pradesh) and Una. I have created consciousness among Dalit youth in rural areas, and have a slight influence among middle class Dalits. But because of class differences, the middle class Dalits may not yet join hands with working class youth.Will you form a political party? I have the soul of an activist; I don’t want to form a party. Some of Hardik Patel’s followers have left him.It has not affected his mass base. Alpesh’s base is solid. But because of the fragmentation of the Dalit movement, I will have to work harder. I now have support in Karnataka and Kerala, though, and after the Gujarat polls, I will campaign in Karnataka. Is there a possibility of a Dalit-Muslim platform? During the Una struggle, we were welcomed by Muslims and we are working for Dalit-Muslim unity in Gujarat. But the Muslim situation is much worse (than that of Dalits) — apart from having to be careful that they don’t become victims of the (sangh parivar’s) Love Jehad campaign, there is serious unemployment. (They are grappling with) existential issues. It is a battle for survival for them.last_img read more

Assam villagers donate land for elephant meal zones

first_imgA cluster of villages in central Assam’s Nagaon district has found a way of keeping crop-raiding elephants off their crops — by setting aside land to create a meal zone for them.Most farmers of 12 villages in the Ronghang-Hatikhuli area of central Assam’s Nagaon district do not have enough land to sustain their families. But they donated 203 bighas (roughly 33 hectares) of community land and took turns to plant paddy exclusively for the elephants that often come down the hills of the adjoining Karbi Anglong district.‘Jumbo kheti’The “jumbo kheti (cropland)” has been envisaged as the last line of mealy defence against some 350-400 elephants that have often paid for venturing too close to human habitations. Five of them were electrocuted by illegal electric fences in the last 16 months while half a dozen, injured by spears and arrows, died in the jungles up the hills.About 10 km from the paddy field, toward the hills, is an 8-hectare plantation of Napier grass that 35 reformed hunters have grown for the elephants. This plantation is on land belonging to a tea estate.The locals have also planted saplings of 2,000 outenga (elephant apple), 1,500 jackfruit and 25,000 banana plants on barren land between the paddy field and grass plantation. The three-step plantation has a common thread — environmentalist Binod Dulu Bora and the NGO Hatibondhu, meaning ‘friends of elephants’, he is associated with.“Growing paddy for elephants was the idea of Pradip Kumar Bhuyan, the director of our NGO. We had several meetings with the villagers and managed to convince them by saying they would be setting an example for the world to follow toward reducing man-animal conflicts,” Mr. Bora told The Hindu on Monday.Feeding patternOnce convinced that the experiment would save much of their crops, the villagers decided to donate land and labour to grow paddy for the elephants. Forest Department officials chipped in to provide solar electric fences around the crop area.“Work on the paddy field began less than two months ago. The fence will be withdrawn once the paddy ripens for the elephants to feed on. By mapping the area and studying the feeding pattern, we calculated that the elephants would take 20-22 days to finish the paddy in their demarcated zone,” Mr. Bora said.The nearest fields where the villagers have grown crops for themselves and for trade are 5 km away. “By the time the elephants finish the crop grown for them, we will have harvested much of our own. We think the elephants will turn back if they don’t find crop in our spaces,” said Dyansing Hanse, one of the two village headmen.The Ronghang-Hatikhuli area is inhabited by the Karbi and Adivasi communities.“The fruit trees will take time to grow. But the elephants can feed on the Napier grass, a tropical forage crop that grows fast, if they return to the hills. They have already partaken of the grass six times,” Mr Bora said, adding that 35 hunters who had given up hunting four years ago have been maintaining the grass plantation. ‘Unprecedented’Jiten Kro, the other headman said the villagers had been living in dread of the elephants for years. He hoped the experiment would go a long way in ensuring co-existence with the animals. “We are happy to have given back some space to the elephants through a project that I believe is unprecedented,” he said.last_img read more

South Korea keen to make a fresh start in Odisha

first_imgPutting behind the bitter experience of steel major POSCO’s unsuccessful bid to set up a plant in Odisha, South Korea has evinced keen interest in forging a new relationship in investment and business with the State.South Korean Ambassador Shin Bong-kil, who led a business delegation, met Chief Minister Naveen Patnaik and key functionaries of the industries department here on Monday.“Recognising the State’s potential in natural resources, POSCO had made $12 billion investment commitment in 2005 to set up a steel plant in the State — it was not only the single largest overseas investment by a South Korean company, but also the single largest foreign investment ever made in India,” said Mr. Shin.‘Fast-growing State’Observing that POSCO’s mega investment had faced many hurdles, he said: “I understand both sides have learnt from POSCO’s experience and now need to make a fresh start. Odisha is a State growing very fast.”The delegation included representatives of Samsung, Hyundai, Kia and LG. Commenting on the slowdown in the automobile sector, the Ambassador said: “I think the phenomenon is temporary. Things will improve shortly. Korean automakers, however, have been doing very well in India.”Addressing the delegation, Mr. Patnaik said, “The Republic of Korea and Odisha have many possibilities to collaborate across identified focus sectors. We are in the process of promulgating a strategy document, Vision 2030, to ensure that 50% of the primary metal produced in the State is value-added within the State.”“Odisha is also fast emerging as the petrochemicals and chemicals hub where Korea has natural strengths. We welcome Korean investments in these and other sectors,” said Mr. Patnaik.last_img read more