Okay, to discuss insulation in the old house, we must first understand the different insulating methods and materials that were commonly used when the home was built, during the period leading up to the present, and those currently being used. As per usual, we are going to assume that the house we are talking about is masonry construction with either a framed flat roof or a framed third-floor and encased by a gable roof above the masonry line. Also, we will be discussing two important factors relating to specifying insulation types and grades. First, we need to know how well we can insulate a specific area of the home and what insulator will work the best for the application. The “how well” and “what with” in regards to any insulation project is usually determined by local availability of the different types of insulation, accessibility of the area to be insulated, most insulating value per inch thickness of the insulating material, and of course the cost of the insulation material and installation labor.
Now this is where I am going to recommend that you reboot your mental archive of what you think when you hear the word “insulation”. And with that, please understand that I don’t have any personal issues with any of the different types of insulation, or with professional insulation installers. Bear in mind, I work on historic houses and unusual projects the majority of the time. Also remember this blog is designed for residential applications – I AM NOT MAKING THESE RECOMMENDATIONS FOR COMMERCIAL CONSTRUCTION! And while you are rebooting, consider that there are rarely cases when the historic home can be perfectly insulated. In fact, I can’t think of a single case I have come across where it has been even hypothetically possible to perfectly insulate and seal a historic home. I am all about green and and energy efficiency, but first you must start with the concept that any insulating is better than leaving it alone. Just don’t drive yourself crazy (as I repeatedly do trying to hermetically seal my home just to prove if it is possible) fighting an uphill battle that my not even prove worthwhile (I will qualify these statements as I move through this, bear with me).
The basics;
- The insulating value of the material to be used is rated in “R-Value”. The “R Value” is a measurement that rates heat/cooling transfer through an insulating project and its resistance to that transfer. The number is a compounding multiplier – the higher the number, the better the insulating job a product will do. Drywall for example is a poor insulator having at best an R value or 1 or less per inch of thickness whereas fiberglass batting has an average R value of 3.3 per inch of thickness.
- The second factor of a good insulating job is the air or vapor permeability. Think of this as how much draft or wind the insulation can stop. This is not directly affected by or relative to many types of actual insulation, but it does affect the insulated value of the home (see building envelope post).
- Cost is the third factor we should discuss. I would love to use closed-cell foam insulation in my home. It has a high R-Value-per-inch rating (average is around 7) and it acts as and air barrier sealing out drafts. But it is the most expensive of the methods available at this time. Fortunately, it is no longer only available to professional installers with $50-100K spray rigs to install. Now there are DIY kits available to homeowners and non-installers alike. These kits are pretty fantastic too as they are not propelled by CFCs or pollutants. Even with that, the cost average is what we have to weigh out. I will go into this in the chart that follows later.
- Accessibility: this should be pretty straighforward but there are a few notable items. You can insulate closed cavities with blown-in cellulose or some foam products by cutting a small hole or two and filling them in. You cannot insulate closed walls or floors with batt insulation (woven or spun fiberglass/wool/etc.) although I continually find people that try. There is still this absolutely ignorant and foolish concept in this industry that if you “stuff” the batt insulation into closed cavities from an open end, you will get an unbelievable insulatory effect. It is unbelievable. Don’ believe it, it is absolutely false. This method of insulating is called “dense-packing” and works only with some forms of cellulose and like types of insulation. It does not work with the “pink-stuff”! Basically, the better the access, the better an insulating job you’ll end up with in most DIY applications.
- Availability of insulating materials; this is a pet peeve of mine. You can get dry-application blown cellulose (with a free blower machine rental) at any Lowes or Home Depot. The stores sell what is essentially the same product, but the blower they give you at Lowes is much better that the one at the Depot, the Depot one takes a lot longer and jambs constantly. You can get the “pink-stuff” or fiberglass batt insulation and also rigid foam board insulation at anyplace that sells home improvement products. And finally, most spray foam products have to be ordered and shipped to you. I would mention Ultratouch Cotton Batt insulation manufactured by Bonded Logic, but I don’t know if it can be ordered by anyone. The nearest dealer is in Chicago and doesn’t have any interest in cost-effectively shipping to St. Louis. When I contacted Bonded Logic to find a local dealer, there isn’t one. Then I tried to get set up as a dealer…..I have had a faster response and better customer service from Charter Communications. I would love to market their product to the area. I would even be happy to buy it from a local distributor. I can’t even get an email response or a callback. But as they say, you can lead a horse to water……
So you may be wondering, “what about insulating my house?”
Most of the houses built at the turn of the century had little, if any insulation. If there was any insulation, it was likely rock-wool type insulation tossed as loose fill in the attic space. Sometimes, over the years, people have stuffed newspaper remnants, cotton, cloth, socks (yes I actually found a man’s dress sock stuffed in a loose brick gap once), or anything else that could be stuffed into openings where the insulating is poor. This can serve to decrease the permeability but has little affect on the insulating value as the items used are often too thin or have too poor an R value to actually offer any insulating value. Plus, the location needing insulation was often determined by the cold or hot breeze blowing through that alerted the occupant/improviser to attack that particular spot. These improvised solutions are most commonly found around window and door openings. Remove them and go back with expanding foam, they are not helping you any.
In the next post, I will show you how to choose your insulation and get your feet wet with the install.
