The Perfect Wall, Roof, and Slab — Building Science Podcast

first_imgRELATED MULTIMEDIA Video: Superinsulating a Home with Rigid FoamA Home Energy AuditGreen Builder Won’t Compromise on the Envelope GREEN PRODUCT GUIDE Insulation Blown Insulation Batt Insulation Board Insulation Foam InsulationThe most important factors are often not considered in design, construction, and regulation; and the unimportant ones tend to have an overly enthusiastic and detailed amount of specs associated with them. The Perfect Wall has all of the structure to the interior and all of the control functions to the exterior. Let’s start at the outside of the perfect wall with the cladding. Cladding provides three functions: 1. Aesthetics, 2. Protection from UV light 3. Physical, mechanical protection of the other control layers. Aesthetics matter because people don’t take care of ugly things. Ugliness is not sustainable. The longer something is around, the more resources it consumes, so the more resource efficient it is, and the fewer resources it uses over its lifetime. We want a beautiful building that lasts a long time and is ultra-efficient. Claddings should be completely open — we want air circulation behind the cladding system. The more air circulation, the better the system works. Sealants are purely aesthetic, they’re not functional. If the sealants fail, the primary air, thermal, vapor and rain control elements are not affected. If we take the perfect wall and lean it, we get the perfect roof. From the inside to the outside, the control layers are:StructureVapor control membraneInsulationCladdingSome of the old-timers will recognize this type of roof as an IRMA — Inverted Roof Membrane system. If you replace the ballast with dirt, grass, and a goat, you would get a green roof. (That was a joke.) Flip the roof and you get the perfect slab:Dirt and stonesInsulationVaporConcrete (structure)The physics of a foundation, wall and roof are the same (this is an Ah-Ha! moment). When we look at a section of the perfect roof, wall, and slab, and we get the other Ah-Ha! moment — the important parts are the corners. You have to connect the rain control element of the foundation to the rain control element of the walls, the air control element of the foundation to the air control element of the walls, the vapor control element of the foundation to the vapor control element of the walls, the thermal control element of the foundation to the thermal control element of the walls… Pretty fundamental stuff. Most failures occur where roofs connect to walls _Tip: Buy multi-colored pens_ Whenever we do design reviews in our office, we tell the youngsters to take a colored pen and trace the rain control layer around the building enclosure. If the pen has to leave the paper, they’ve identified a discontinuity that needs to be addressed. Use a different colored pen for each of the control layers. Whenever the pen leaves the paper, you’ve identified a flaw. It’s as simple as that. We find that the flaws are concentrated at the connecting elements. Windows complicate the perfect wall Now these are pretty easy, but it gets complicated. In the real world, someone pokes a hole in the building and we call that a window. Windows have to do everything that a wall does, and more. It has to control water, air, heat, and vapor; you want to be able to see through it, and every so often someone is going to want to open it too. Windows can actually do all of that stuff, which is pretty amazing. No wonder they’re so expensive. All we have to do is connect the rain control element of the window to the rain control element of the wall, the air control element of the window to the air control element of the wall, the vapor control element of the window to the vapor control element of the wall, the thermal control element of the window to the thermal control element of the wall. The reason we’ve been having so much trouble with window-to-wall connections is because we’ve been relying on one person to do all of this: His name is “By-Others.” Mr. By-Others shows up on all of these specs and you have to make sure he is not going to be responsible for all of these connections. Someone has to be responsible. The window industry doesn’t do us any favors either — they don’t tell us in their window system which part of these windows systems are responsible for controlling water, air, vapor and heat. In the absence of guidance, we have to assume that the innermost component of the window is where all four of those functions collapse. So we wrap the window openings and make the connection at the back — so that if the window should fail, the water will go to the outside. That’s how you design a building: water continuity, air continuity, vapor continuity, thermal continuity. It can’t be that simple, right? Well, the answer is, “Yes it is.” Podcasts: Podcast:Air Barriers vs. Vapor BarriersHow Heat Moves Through HomesEfflorescence = Water Damage Insulation Retrofits on Old Masonry BuildingsHow Air Affects a House RELATED ARTICLES Insulation Overview Insulating Roofs, Walls, and Floors Installing Fiberglass Right” Insulation Choices Can Foam Insulation Be Too Thick? The Global Warming Impact of Insulation CONSTRUCTION DETAILS Building Plans for the Energy Star Thermal Bypass Checklist Energy Star checklist details Insulating behind tub with rigid foam Air sealing behind tub Foundation/Floor Intersections Roof/Wall Intersections Wall/Floor Intersections _This podcast series is excerpted from a two-day class called_ Building Science Fundamentals _with Drs. Joe Lstiburek and John Straube of Building Science Corporation. For information on attending a live class, go to BuildingScienceseminars.com This week Dr. Joe talks about enclosure design principles of energy efficient buildings_ _______________________________Let’s start with smart things The building enclosure has four functions. In order of importance, they are: 1. Rain control 2. Air control 3. Vapor control 4. Thermal control Thermal control is the easiest to specify, calculate, and measure, so that’s what codes focus on. Codes typically ignore the most important layers because they’re the most difficult to specify. The vapor control layer is easier to specify than the air control layer, so codes obsess over specifying the vapor control layer and ignoring the air control layer. Video:last_img read more

Modi discriminating against Punjab govt., says Amarinder

first_imgPunjab Chief Minister Amarinder Singh on Monday accused Prime Minister Narendra Modi of discrimination against the Congress government in Punjab on matters of religious importance, as part of his and his party’s divisive agenda.Capt. Amarinder in a statement asked why the Prime Minister had not pointed fingers at the Akali Dal leaders, including the Badals, for failing to attend the Central government function to commemorate the centenary of the Jallianwala Bagh massacre.“Neither Parkash Singh Badal nor Sukhbir Badal, nor Harsimrat Badal, who happens to be a Minister in Modi’s own Cabinet, deemed it fit to pay their homage to the martyrs at the historic Jallianwala Bagh,” said the Chief Minister, pointing out that Mr. Modi himself chose to keep away from the occasion of national importance but had criticised him (Amarinder) even though he had been part of a series of events at the Jallianwala Bagh national memorial. “Why was Mr. Modi not present at this major event? Why did the Badals fail to turn up, and why did the Prime Minister choose to conveniently ignore their absence,” asked the Chief Minister. ‘PM exposed’Capt. Amarinder said by holding a parallel event to mark the Jallianwala Bagh centenary, instead of supporting the State government’s commemorative programmes, the Prime Minister had exposed his true intent.He added that there was a clear pattern in the Prime Minister’s attack on him on the Jallianwala Bagh issue, which the Central government had been trying to politicise to woo the Punjabi community and further the BJP’’s political ambitions.last_img read more