Entries Tagged 'Insulation' ↓

With that in mind and venting aside, lets talk about what works. Lets say you have a brick home that is over 60 years old. Then lets say that the walls you have on the inside are plaster-on-brick (with exception to most interior walls). You have an insulation value in that wall of less than 1 (remember, neither plaster or drywall, not even brick, are good insulators and you should always rate them at an R-value of less than 1). I know what you are thinking. You are thinking “this guy is full of it, my house has 15″ thick brick walls – that has gotta be insulating”, and/or  “less than 1 R-value, but my house is ;ike 3 feet from my neighbors and I couldn’t hear them running a jackhammer through my brick walls”, which is insulation – but not the heat/cold (thermal) kind – that is sound (acoustical) insulation.

You might think to say that 3-wythes of brick (in masonry, courses are vertical stacks and wythes are the measure of horizontal rows) thick, how much air can get through? Well, a lot is the answer. Imagine that brick is like a very hard cotton ball. Air still gets through it (called air infiltration) whether you realize it or not. Now, with good tuckpointing, and with a good interior plaster coat with a painted surface, that air leakage can be reduced but still exists.

Brick or masonry walls  do not insulate for temperature much better than – say – siding. Or even better…stone. Brick is of course man-made, but it shares several properties similar to that of stone. And when it comes to stone, have you ever been to Cold-Stone Creamery? They take a large slab of stone and set it on top of cooling tubes (refrigeration lines) because it transmits the cold so well and is great for slowing the melting of ice-cream as it is violently forced to coexist with various toppings. (It really is a beautiful process if you like ice cream). So stone is great for creamerying (??? what do they actually call that- toppinging?), but not so great as an insulator.

So you want insulation on those masonry walls? There are two common ways to achieve it. 1 is to use furring strips (1/2″ to 1″ thick strips of lumber that are on average 1.5″ wide) and try to use pieces of rigid (board insulation) to insulate. The insulation board is expensive but also it is on average R6 per inch. That is 2x better R-per-inch than fiberglass or cellulose can offer (see building insulation types post).

This method has its place but is not my preference if the situation allows me to do full-furring. Full furring is basically framing a 2×4 wall on the interior side and up against the brick wall. You can get at least R13 insulation in the cavities, there is plenty of room for electrical and plumbing lines to be installed, and you can even buy yourself some structural earthquake safety. See part 3 for that revelation….

Okay, I need to vent. In St. Louis County, insulation is paramount to all things construction (in residential), at least since the “green” movement hit the consumer masses. In St. Louis City, it is not. These are different regions functioning on different plans. In the county, the inspection divisions have such a large tax-base, that the inspectors can actually inspect each job based on CODE and good common construction sense. In the City, the line gets a bit more blurry as the tax base is smaller and and any improvement over plaster-on-brick construction is an improvement whether it follows energy-efficiency or not. The inspectors know their business in both cases, but the city inspectors are left with the conundrum of whether to enforce the codes and the common sense, or risk potentially pricing people out of city living.

If you are buying a city or a county home over 20 yrs old, there will be costs to maintaining it, period. In the codes enforced by the City, there is no rule that states that one MUST insulate in their project unless it is new construction or an attic. Let’s clear this up, ALL insulation is good insulation! Drywall does not count as insulation nor does an “air-space” when talking about weather-sealing insulation. R13 is better than R>1 (just drywall) or plaster-on-brick, or the same with drywall over that, or drywall on studs can offer.  But, no insulation in furred walls over masonry is still code-legal for walls in most historic and older-urban situations where one is remodeling and already starting from the zero insulation number.

For the purpose of evaluating the benefits and drawbacks of different types of insulation, we are going to use fiberglass-batt insulation as our base product as it is the most commonly used and available. Before we discuss each type in detail, we need to discuss sizing and efficiency per building unit needed to attain good efficiency. So let’s look at what can help you by first looking at the requirements and terminologies relative to the insulation most often used in residential remodeling. After you have read the notes below, you can refer to the chart below to start exploring which insulation is best for your application.

First and most common for the past thirty years is fiberglass wool spun and woven into batts of various thicknesses. A batt is a strip of the insulation cut to a certain width to match the joist or stud spacing into which it is to be installed. Fiberglass batts are available in R-value ratings from R3 to R49. The most commonly available values are R11, R13, R19, and R30.

• If we are assuming that we are in the climate zone associated with Saint Louis, then anything below a value of R13 should be used only for non-conditioned areas, sound insulation, or in locations where achieveing a minimum 3.5″ depth for the insulation is not possible. We often use R11 to insulate interior ceilings between conditioned floors to quiet down the sound transfer and assist split HVAC systems in maintaining the temperature continuity between floors. Exterior walls in this climate require a minimum insulation value of R13. Remember-I said minimum-you can install as much insulation as you want. More is always better when it comes to insulating the habitable core of the home.
• Certain locations demand a value of R19 although this is usually in special situations such as vaulted ceilings that have only 6″ deep framing allowing only enough room for R19 insulation. Have you done the math yet? I show in the chart below that fiberglass has an average of 2.9 of R value per inch of thickness, but to make sure there is no mistake or variation in the manufacturing, we will use three as our multiplier. If I call a fiberglass batt “R19″, you can take that number (19) and divide it by three to find out what the average thickness is. Your equation is 19/3=6.33 inches, which is pretty close to most R19 fiberglass insulation types, the average I have seen is 6″ of thickness.
• The next important insulation R value is R30. This is currently the enforced code amount in many areas for attics/crawlspaces and is the largest of the fiberglass batt insulation currently available in home stores. However, while any insulation is good insulation, you should always consult the U.S. Department of Energy recommendations for your climate region. They have made this an easy task with an interactive website using your zipcode to begin the process of determining your recommended insulation values (http://www.ornl.gov/~roofs/Zip/ZipHome.html). With that in hand, the recommended insulation value for attics and crawlspaces in Saint Louis is R49. While batt manufacturers are currently advertising that this insulation is in production and available, you will likely have to go to a specialty supplier or perhaps your local home store can order it, but it is probably not worth the cost they charge when there are other insulation types that you can apply to the thickness of your choosing for a very affordable price. These R49 batts will likely be available in stores someday soon as the codes will alter to the USDE recommendations as the drive toward fuel efficiency and energy conservation continues.

The chart below is a basic comparison of the insulation that we use or have used and its different properties. This chart is for review only and is not intended to recommend one insulation over another for a specific project as regional and other factors also may play a role.