House Framing
There are several interesting details in the construction of this 1800’s house worth noting. 

26. Mortise and Tenon Joints
A close examination of the framing reveals that the house was framed using “mortise and tenon” joints instead of nails.  In this method, mortises, sockets or slots, were hand-hewn in framing members for the insertion of tenons.  Although entirely replaced in modern construction by nails and other metal connectors, this method produced a strong solid frame. 

27. Framing members
If you look at the wall studs and floor joists you’ll notice that they are much larger than their modern equivalents.  The larger size of these members can probably be accounted for, at least in part, by the availability of inexpensive, abundant wood.  With increased costs in the modern era, engineers who helped develop building codes concluded that the strength of wood in current sizes was adequate to carry normal loads. 

28. Old/New/Repaired Wood
The design team made the decision early on to re-use as much original wood as possible in the renovation of the building.  All around the house there are examples of darker old wood, lighter and smaller new wood and in some places old wood that has been filled with an epoxy resin.  In deciding what of the original wood could be used in the renovation, engineers evaluated the strength of the existing timbers for appropriate re-use.  Where wood was water damaged, rotten or otherwise deemed unusable, one of three options was selected.  In cases where a timber that was mostly usable, but had a small bad section, it was made re-usable by injecting a plastic epoxy into the bad section to restore its strength.  In instances where old wood that had a damaged section too large to epoxy, a section of new wood attached to it in a process called “sistering”.  As a last resort, in cases where the wood was too damaged to use the member was replaced with new wood. 
 
 

Floors  A most outstanding example of the re-use of wood in the house is in the magnificent old heart pine floors.  At the beginning of the renovation the existing tongue and groove floors were removed and stored.  In the final phase of construction, the reusable pieces of the original floor were replaced and refinished.  New flooring, lighter in color, can be seen on the staircase and in the side rooms on the first and second floors.

29. Shear Walls
As originally built the frame of the house was covered by wood siding.  The siding served to stiffen the framing, providing resistance to twisting, or “shear”, if the house were subjected to severe forces associated with earthquakes or hurricanes.  Modern construction practices call for the addition of “shear walls” in most structures.  The plywood sheets you see covering the wall studs on houses under construction form the "shear walls".  Brick veneer or wood siding is then added to finish the home’s exterior. 

Adding shear walls to the outside of the house was rejected as an option in this project for two reasons.  One, to do so would require removing the existing siding, a labor intensive and costly process.  Two, over a hundred years, individual planks had molded themselves to the minute contours of the framing.  Once removed, replacing them, if it could be done at all, would require numbering the individual planks and replacing them exactly in their original positions.  The solution was adding the capacity of the house to resist shear forces to the interior walls with plywood.  Plywood sub-flooring connects to the shear walls to further stiffen the building.  Another contribution to the shear capacity of the building comes from the wood “blocking” between the floor joists.  The blocking helps the structure to move uniformly when subjected to twisting or lateral forces.

30. Enka drain
The dark brown material between the wall studs is a product called “Enka Drain”.  It is a plastic, spongy fabric-like material designed to catch condensing moisture vapor entering the house through small gaps and seams in the siding.  Its purpose is to provide a space between the siding and insulation in which moisture can collect and evaporate before entering the house.  It helps the house to “breathe”.  It is not a protection against wind driven rain likely to be encountered in heavy rain and wind events. 
 
 
 
 

Earthquake Bolts  Visitors to Charleston often ask about the “bolts” they see on masonry houses in the historic district.  The bolts were placed in these buildings as an earthquake retrofit, to help prevent their collapse.  Some people have asked why these bolts aren’t present in this house.  First, the bolts were only used in masonry houses.  These houses were originally built so wooden floor joists were simply inserted into pockets in the brick walls.  In an earthquake, without the bolts, the brick walls shook, expanded outward and the floor joists slipped out causing the floors to collapse.  Bolts were added to hold the walls together, keeping the floor joists in place.  Wood frame houses such as this did not need bolts because the floor joists are connected to the house framing with mortise and tenon joints or in modern times, with nails.

31. Window connections
In areas, like Charleston, subject to high winds from hurricanes, it is not only important to protect windows with storm coverings, like the ones shown in this house, it is also important reinforce the connection of the window unit (glazing and frame) itself to the structure of the house.  Notice that each window in this house is connected to the framing with metal straps.  Without this precaution, in extremely high winds, even a storm-protected window unit could literally be sucked out of the window opening leaving a gaping hole in the wall. 

32. Lighting
 The kinds of light bulbs, fixtures and controls used in homes contribute to energy efficiency.  In this house two types of light switches have been used.  The first are the usual wall switches. The second are automatic switches that turn lights on in response to motion.  These are in common use in outdoor lighting applications for security and porch lights.  Because these switches only turn lights on when they are needed and turn them off again when they are not, they are highly energy efficient.  The South Carolina Energy Office uses a slogan which says it succinctly - “when not in use, turn off the juice”.  The most commonly known motion sensor is infrared.  The other type uses low intensity, inaudible sound waves.

The kind of light bulb used also contributes to energy efficiency.  In the past, incandescent light bulbs were most commonly used in the home.  They use electricity to heat a filament until it glows, giving off  light. In fluorescent light bulbs, electricity is passed through inert gas, reacting with a chemical coating on the interior of the bulb causing it to give off light.  Fluorescent light is more efficient and the bulbs last longer.  In the past, fluorescent light tubes were most often used in office and commercial settings.  In the home, they have been used mostly in kitchens, basements and garages.  Many people found the light from fluorescent lights harsh and unpleasant and they didn’t fit into existing fixtures and lamps.  Today, compact fluorescent light bulbs have been engineered to give off a more pleasing light and may be used in many standard incandescent fixtures.  A 15-watt compact fluorescent bulb will generate approximately the same light output as will a 60-watt incandescent bulb while consuming only 25% of the energy.  The rated average life of compact fluorescent is 8,000+ hours while the life of the incandescent is approximately 750 hours. 

At 113 Calhoun St., 120-watt flood lamps have been replaced with 18-watt compact fluorescent lamps with a magnifying lens that produces the equivalent light output of the 120-watt incandescent bulbs.  In addition to the energy saved directly, compact fluorescent bulbs generate very little heat, which significantly reduces the cooling load requirements of the air conditioning system.  Halogen lamps, yet another type of light, are also more energy efficient than incandescent flood lamps.  In the Center’s offices, 65-watt task lamps have been replaced with 45-watt halogen lamps, thus reducing their energy consumption by approximately 30%.

On the second floor videos, take a look at how we have "sistered" old wood (by adding a new piece next to an old one) to strengthen weak old wood, and note the use of epoxy to stabilize other old pieces.  Step out onto the piazza to take a look at some Lexan shutters.

 
1. Enter, East Wall (568 KB)
2. 2nd floor Piazza (536 KB)
3. Head Upstairs (119 KB)
 

Finally, let's go up to the Third Floor.