Planning Your Insulation Upgrade

Start in the attic and the basement
. Insulating the attic prevents warm air from escaping and also substantially cuts down on the amount of solar heat gain you will experience in the summer, substantially reducing the cooling load. If the attic is accessible you can add more batts between or on top of the joints, 12 inches in the NYC climate zone, or if it's a small crawl space you can use blown-in insulation. If you have a brownstone that has no attic space because the top floor room ceilings butt up against the under-side of the roof, then consider adding rigid insulation from the top side of the roof (see Roof Insulation below). In the basement you can attach insulation to the underside of ceiling/ floor joists of the floor above.

Wall insulation can be achieved through a combination of cavity insulation and insulated sheathing. Remember, gaps in insulation lead to convection heat loss – leaks – so be sure it is installed properly with no gaps. If you are not removing interior walls you will need to have insulation blown into the walls, and special care needs to be taken to reach every nook and cranny. This can be a particular challenge, and possibly unfeasible, in brownstones and other old housing with plaster-and-lathe walls because, when the wall does not have a huge uninsulated gap as noted above, you often have essentially no gap because the lathe may simply be attached to the exterior wall furring strips, leaving no space into which insulation can be blown. See the discussion below regarding factors to consider when choosing insulation (density, loose fills may sag etc.). 

Don't be discouraged if you've got an older house that has no, or inadequate, gaps for blowing in wall insulation. Convection heat loss – leaks— usually account for the greatest amount of heat loss. Wall insulation primarily addresses radiation heat loss. Therefore, if it is not practical or is outside your budget to peel off your interior walls in order to add wall insulation, then simply removing your floor shoe molding and/or baseboard and caulking and sealing all the joints between floor and wall will reduce or eliminate leaks (convection heat loss) and make a positive difference in your energy consumption and heating bills.

Roof insulation  If the top floor of your brownstone has no attic or crawl space allowing for traditional methods of insulation then you can apply methods used to insulate cathedral ceilings. One method is to install a layer of rigid foam insulation in the ceiling, from inside the room, between the joists (this means you'll have to take down your ceiling) leaving a small air space between the foam and the roof. Another option is to use structural insulating panels (SIPs), usually composed of a foamboard core sheathed on both sides with plywood, that are applied on top of the roof over your existing roofing material. SIPs can be obtained with a nailable side so that a waterproof membrane and roofing finish materials may be nailed to it. SIPs are a good alternative because they reduce the need for structural lumber and cut down on air leaks. SIPs, by the way, are also available with drywall sheathing for use as walls and SIPs also provide sound insulation.

Other roof heat loss/gain issues: Flat roofs, typical on brownstones, act like solar collectors. Cover your roof with a reflective surface, white or metallic finish, to reduce solar heat gain.

Adding an extension to your brownstone? You're lucky in more ways than one. Starting with a clean slate enables you achieve maximum efficiency with sustainable products. If you are planning on brick to match your brownstone facing then Concrete Masonry Unit (CMU) with high fly ash content (a by-product of burning coal) are an excellent alternative to cinder blocks (which uses Portland cement, the product of an extremely energy-consuming manufacturing process) for building the structure and has good insulating value. Incorporating SIPs can cut down on the lumber you need for framing and provide insulation and sound proofing. You also have completely open walls enabling you to use spray foam insulation which is an ideal insulation because it insulate against both convective and conductive heat loss.

Don't forget the small things: only use insulated recessed lighting cans, outlets and wall switches.

Types of Insulation

Insulation comes in a variety of forms. Be sure to read the Health/Indoor Air Quality section below and avoid certain types of insulation give off harmful VOCss; it is possible to get insulation made from cotton, cellulose and fiberglass that is free from formaldehyde.

Batt and Blanket Roll Insulation is typically made from mineral fiber (fiberglass or rock wool) and is now also available in "green" substances like recycled cotton.  It is manufactured in blankets of various sizes and thicknesses. Batt insulation is typically fitted between studs, joists, and beams and should fill the wall, floor, or ceiling cavity without any gaps, voids, or compression.

Blown-in, Loose Fill Insulation is blown into wall cavities through holes and is typically made from fiberglass or cellulose, or the latest green products derived from soy and denim, and is literally blown into the walls and attic through a large hose. Blown-in insulation should completely fill the wall cavities and be an even thickness and density throughout the cavity otherwise it will sag over time and create gaps. The R-value of a particular kind of blown-in insulation will depend on how densely packed it is so follow the manufacturer's instructions.

Sprayed or Injected Foam Products are typically injected or sprayed into cavities where they expand to the desired thickness. Spray foam insulations are excellent because they make a continuous air tight barrier and a sealed thermal envelope and, as such, address both convection and conduction heat loss. Typically spray foam insulation is either open cell or closed cellOpen cell foam insulation is soft, like packing material molded around an object, and is "open" because the cell walls, meaning the walls around the air bubbles created when the foam expands upon installation, are broken.  Closed cell foam is rigid (degree varies between manufacturers) because the cell walls are not broken, has a higher R-value per square inch than open cell foam and provides some structural support to the building.  Both stop airflow and heat transfer but open cell foam allows some vapor penetration (so use of a vapor barrier is necessary) and should not be used in exterior applications or below ground.  However, being more dense means that closed cell foam is more expensive per square inch of R-value than open cell foam. 

Research these carefully, however, because traditionally foams were/are made from petrochemiclas and contain toxic chemicals that emit VOCs and may contain CFCs and HCFCs in the propellant. Biobase is a green alternative. It is made from soy bean oil (an annually renewable resource, grown in US), is inert and antimicrobial (will not support mold growth or be food source for insects). It is sprayed in as tiny particles that expand to 100x their original size so it's easier for these tiny particles to make it into nooks and crannies and fill every void when expanded. Spray-in insulation also reduces noise pollution. Biobase also claims to maintain structural integrity (will not sag to allow for air leaks).

Rigid Insulation is typically made from polystyrene, polyurethane, or polyisocyanurate foam, which is expanded or formed into large sheets. Rigid insulation can be used to provide a continuous thermal barrier in basements, crawlspaces, and on exterior walls, and can be used in conjunction with blown-in or batt insulation.