Monthly Archives: October 2014

Caution Ahead: Brick Veneer and Spray Foam

There are a lot of different ways to build a wall. There’s standard 2×4 walls, 2×6 walls, ICFs, SIPs, concrete block and steel stud, to name the major ones. Then, there’s what to put on the outside the wall (siding, brick, stone, EIFS, etc.), inside the wall (<a title=”Simple Saver” href=”http://northstarcomfort pfizer viagra france.com/simple-saver/”>fiberglass, cellulose, spray foam, etc.), then the interior of the wall (what kind of sheetrock, paint, etc.). All of this is your wall system. Yes, the construction industry considers the wall system – not a living, breathing one – but a system nonetheless.

That said, the specific point of this entry is that caution needs to be used when using spray foam insulation & brick veneer in climate zone 4, which is where Wichita and Kansas City, to name a couple of cities, are located. Why? Well, it comes down to a few things:

  • Brick veneer can store huge amounts of water.
  • Most house wraps are also called a Weather Resistive Barrier, is very vapor permeable (as in water vapor goes through it very easily)
  • The sun will drive water vapor towards the inside of the house, through the house wrap and into the OSB.
  • The foam, open or closed cell, has such a low permeability that the water effective stops inside the OSB, as it has nowhere to go until it can evaporate back to the outside.

Unsurprisingly, this can lead to structural weakening of the OSB. So, what to do? The two main things to do involve tweaking common building practices slightly so that we can make longer lasting structure. Notice I’m not saying don’t do spray foam & brick veneer – I’m just saying that I would:

    • Use a weather resistive barrier with lower permeability. Permeability is rated in Perms. Standard WRBs are 35 or so. 10 Perms or less will keep enough water vapor out to help minimize the intrusion.
    • Change the way you build the veneer, to include more ventilation. Current practices on residential construction use only weep holes at the bottom of the brick at regular intervals. The research I’ve seen suggests that creating a more breathable brick veneer will keep moisture in the air moving & not heading in, towards your house.

Thanks to Lucas Hamilton at CertainTeed for doing all the heavily lifting with this. All I did was ask the question & thought I should pass along the information. And, again, this is just for Climate Zone 4 – and there are 6 across the U.S., so ask your builder, insulator, architect, energy auditor, what’s recommended for your area.

    -Jeff

 

Air Leakage

A blower door tests the tightness of the home’s envelope by pressurizing or depressurizing the structure and then measuring the amount of time for the entire air supply in the house be replaced with fresh air. For the NAHB’s Field Demonstration of Alternative Wall Insulation Products study, four builders insulated different houses with the various insulation materials. Their summary noted the following:

  1. Better caulking, window foam and other air barrier improvements generated the most improvement in the building envelope – in fact, a large measured difference between batt insulated houses was found, when one used improved air sealing techniques and the other did not.
  2. Neither the Blow-in-Blanket System (R14 alternative viagra avis.7) nor cellulose (R12.6) measurably reduced air leakage but
  3. While foam in place (R12.6) had the lowest air leakage, the results were variable when uncoupled from air sealing techniques.

So, where does that leave us? The most important thing is that whatever insulation you use, the details are the most important thing. Paying attention to where air can come into the home is the easiest way to create a more comfortable home – or create headaches later if you don’t. The other important thing to remember is that every insulation system can stop uncontrolled air. Just as the house is a system, your insulation is one too.

Building Science Part 3: Moisture Flow

Controlling moisture flow in a building has significant impacts on occupant health and safety, comfort, building durability and energy efficiency. This section will cover the basics of moisture and its effects on the house system. It will also discuss how geographic location and house type can affect choices of moisture control strategies.

Applied building science is concerned with four different moisture transport mechanisms and the effects of that moisture flow:

  • Bulk water movement (rain, snow, or groundwater)
  • Capillary action (capillarity)
  • Air transported moisture

 

Source: https://basc.pnnl.gov/information/building-science-introduction-moisture-flow 

Building Science Part 5: Conclusion

Over the past few months, we’ve discussed some of the main factors in creating a comfortable and safe home. The end of most of these articles contained a note about reducing risk and increasing tolerance. Let’s talk about how these ideas fit together. In the last 50 years, home building has changed dramatically – increased insulation, tighter homes, smaller chimneys, more efficient HVAC, reduction of good flashing details, cementitious siding, power attic ventilators, to name a few. All of these things are designed to create more comfortable homes. If you simply throw one idea in without regard to how they fit together, you’re increasing your risk. 

Risk is inherent in building a house. The homeowner may not like the wall color that you had agreed upon. The plumber may forget to run a pipe and no one notices until after the wall has been sheet-rocked. The weather may put your schedule 3 costly weeks behind. And then there’s the more long-term risks, like mold, houses that won’t heat or cool properly, polluted indoor air and lawsuits. Why make building riskier than it already is? The Environments for Living program, from where most of this information has come, lists 7 steps to risk reduction:

  1. Airtight
  2. Provided with fresh air (mechanical ventilation)
  3. Insulated right
  4. Equipped with properly sized and installed HVAC
  5. Pressure balanced
  6. Moisture managed
  7. Combustion safe

Every home is an interactive system that needs to have all of the above in place to function properly. One thing out of whack can contribute to failure of the entire system ou acheter viagra generique. When building for durability, energy efficiency and health and comfort of occupants, it is important to remember that the comfort of a house is in the building envelope. If you start with this in mind, you have the the basis for a low risk, high tolerance and, most importantly, happy customer.

Building Science Part 4: Indoor Air Quality

Indoor Air Quality 

 

 

 

 

 

 

 

 

Anyone can smell the air and tell if there are indoor air quality problems. However, many air problems may not stink now but will cause one later.

There are five types of pollutants in houses:

1. Volatile Organic Compounds (VOCs) – cleaning products, aerosols, pest killers, furniture finishes, fabricsand building materials

2. Particulates – pet dander, dust mites, mold spores,
dust, smoke and pollen

3. Soil Gases – Insecticides, liquid fertilizers, septic gases and, of course, radon

4. Moisture-Borne Pollutants – Moisture in the air is a vehicle for dust mites, mold, etc., although the moisture itself is NOT a pollutant

5. Carbon Monoxide (CO) – Comes from gas appliances, fireplaces, wood stoves, unvented kerosene heater, cars parked in attached garages, and from outside air So sources both outside and inside the home can affect our quality of air. So how do we control these things?

  • Eliminate pollutants from the home. A great idea in theory, but in reality, the next 2 steps are more likely.
  • Reduce the amount of pollutants.
  • Separating pollutants from the living space. Detached garages, for instance.
  • Filtration. Your furnace filter is a great place to start but testing shows that standard fiberglass filters remove.
  • less than 20% of all particulates.
  • Ventilation. There are 2 kinds of ventilation. Passive ventilation occurs in leaky houses and when the windows are open. Therefore, in today’s tight houses, we need active ventilation, such as kitchen exhausts (@100 CFM intermittent), bathroom exhausts (@ 50 CFM intermittent or 20 CFM continuous) and heat-recovery ventilators (HRVs) or energy-recovery ventilators(ERVs). A minimum rate of 7.5 CFM per person plus .01 CFM per square foot of conditioned floor area is needed to bring in sufficient fresh air.
  • Controlling pressure.

NFRC and Window Films

If you glance at a window film manufacturer’s list of statistics and your eyes may glaze over due to the sheer volume of data. All of this information is and has always been tested, verified and provided by the manufacturer itself. But third party verification is now on the horizon. Enter the NFRC: the National Fenestration Rating Council. The NFRC is a 30-year-old organization that administers the only uniform, independent rating system for windows, doors, etc. All new windows come with this sticker on it. Solar Heat Gain Coefficient (SHGC) (upper right) relates to how much heat the glass cuts down, U-factor (upper left) relates to heat loss. Window film, on the other hand, does not use this system. 

All film uses Total Solar Energy Rejected or Heat Gain Reduction as the means of measuring heat rejection. You can figure an SHGC but you would still be using the manufacturer’s numbers. Thus, comes the NFRC certification, to add credibility to the manufacturer’s numbers. Plus, it will make sure that the playing field is level between manufacturers. Furthermore, entry into the ENERGY STAR program is a possibility now for window films. While the NFRC board approved procedures for film in early 2005, everything should be in place by mid-2006. Certified energy ratings for window film will be soon upon us, which is good news for both window film installers, like us, and anyone else who wants better performance out of their glass.

Attic Ventilation

 

Attic Ventilation 

The International Residential Code specifies a 1 to 150 ratio of total net free ventilating area to area of space to be ventilated when it comes to ventilating attics. So, what exactly does this mean and why is it important to ventilate attics in the first place? We’ll start with the second part of the question. Ventilation provides the conditions that allow air to move, obviously. Efficient ventilation systems provide a steady, high volume of air movement. At this point, we should note that simply cutting a 6” hole somewhere in the attic is not creating an efficient ventilation system. The air movement we are discussing needs to be controlled and balanced. The amount of air coming in must be equal to the amount going out, otherwise, the attic will start sucking air from the house or stagnate due to insufficient free vents.

The purpose of ventilation is twofold:

1. During warmer months, it keeps attic air moving and, by extension, make the house easier to cool. Basic physics tells us that hot air rises and cold air falls. By circulating the air in the attic, all the really hot air that would build up in there is pushed up and out. Also, We should note that during really hot months, an unventilated attic seldom loses enough heat overnight to compensate for heat gained during the day.

2. During cooler months, it reduces moisture to keep attics dry & helps prevent ice dams. The warm inside air can hold more moisture than the cool air outside (and in the attic) and as this warm, moist air hits the cold, dry air, it can condense. So, now we’re at the stage to get some practical information. Let’s take a house with an attic with 2000 square feet. Now we’ll divide this by 150 to find the total net free ventilating area, 13.3 square feet. To make sure that the system is balanced, we then divide this number in half because half the vents will be lower and half will be higher. This means that 6.6 square feet (or 950 square inches) of ventilation is required at both the bottom and top of the attic.

 

Insulating Pipes and Wires

 

Insulating Pipes and Wires: Right vs Wrong 

What comprises a good insulation job? What should it look like? Where are the most common errors? We’ll take the next few months to look at some common installation issues.

Insulating Pipes & Wires

Let’s start with a sample job: Most of the insulation near the electric box is pressed to the side of it, with little or none behind the box. As a result, there is part of this cavity with no insulation and another with compressed insulation.

Here’s another installation scenario: The installer has taken the time to cut the batt and adequately insulate behind the box. By insulating this way, compression of the batt beside the box is also avoided. Of course, the Blow-in-Blanket System fills voids and gaps around pipes and wires completely. BIBS also increases the wall insulation R-value to R15 in 2×4 walls. However, a good batt installation is possible – it just requires attention to the details.

Insulating Pipes Insulation Wire Insulation Wichita Northstar Pipes Wires

The Easy Way to get R-15 Sidewalls

This month’s installment of the Building Science overview – Indoor Air Quality

In the June issue of the WABA Digest, two separate columns discussed some of the proposed changes to the International Energy Conservation Code (IECC), particularly in reference to wall insulation. As a reminder, the proposed changes are from R-13 to R-15 in 2×4 walls and from R-19 to R-21 in 2×6 walls. I have no intention of debating the merits of this change. Instead, I would like to point out that the easiest way to achieve higher R-values without switching to high-density batts or adding exterior sheathing: Certainteed’s Optima insulation, designed for use in the Blow-in-Blanket System, achieves an R-15 in 2×4 framing and an R-23 in 2×6 construction. The advantages of using Optima are numerous – no gaps or voids, no settling, plus it goes in the wall cavity completely dry. It also contains no chemicals that create noxious odors nor is it a source of food for insects or animals. One of the main concerns about raising the wall insulation R-values is about adding cost and using Optima does cost more than normal batt installations. But given estimates of changing to high-density batts or from 2×4 framing to 2×6 adding around $1,000 to the cost of an average new home, upgrading to the BIBS system with Optima adds less than half that. Plus, you still get all the benefits of having a better insulation job than just thicker batts can give you. Regardless of energy codes now or in the future, Optima may be a better choice to keep your customers’ homes more comfortable.

Building Science, Part 2: Heat Flow

Last month we discussed air flow and its causes. This month, we delve into heat flow. First, let’s cover the basics. Conduction, convection, and radiation are the three mechanisms by which heat moves. Conduction occurs between objects that touch each other, such as when your warm hand touches a cold window during winter. Convection is the movement of hot air upwards and cold air downwards. Radiation is the movement of heat across open space. So, how do we affect heat flow in a home? There are four main steps to avoid thermal related issues.

  1. Framing must protect insulation
  2. Insulation must be installed correctly
  3. Enhanced air sealing
  4. High-performance windows (installed correctly)

An important note here is that the comfort of a house is in the building envelope. While activity, clothing, relative humidity, air velocity, temperature and radiant surface temperatures all affect comfort, the building envelope will dictate how much these factors alter the comfort of the occupants. An inadequate envelope will result in a home that never functions quite right peut on se procurer du viagra. The first step to controlling heat flow is to reduce convection. An effective air barrier that separates the inside, conditioned air from the outside air begins with framing. It is extremely beneficial to explicitly label the air barrier on the house plans. Enhanced air sealing, when coupled with air barrier framing, is the second part of reducing convection. Good air sealing requires significant attention to detail. Insulation problems generally include gaps, voids, compression or insulation/air barrier misalignment, all of which add to conduction. While the insulator can be at fault for these issues, often they are merely ‘playing the hand they’ve been dealt’ by the subcontractors before them. Certain insulation systems, such as the Blow-in- Blanket System, can reduce the occurrence of these problems. Helping you reduce risk and increase tolerance in any given home is the driving force behind building science and part of our mission. Next month – Moisture Flow.