Ice Dams 
Build up of ice which occurs when snow piles up on the roof of a house, melts and runs down the roof, freezing just about the time it reaches the eaves. Gradually the ice forms a dam which blocks the water behind it so that it can't run off and eventually seeps under the shingles and building paper, soaking through the wood and runs down into the house, causing water damage. 

Idle 
1. To operate with gears disengaged. 
2. Transmitting power but not operating. 
3. To cause to be inactive or unemployed. 

Igneous Rock 
Rock formed by volcanic action or intense heat, as rocks solidified from molten magma, which is liquid or molten rock deep in the earth. Granite and basalt are two types used in construction. 

Ignite 
To set on fire.

Illiquid 
An investment that cannot be quickly sold or converted to cash without incurring a significant loss. Real estate is generally an illiquid investment. 

Illiquidity 
1. Inadequate cash to meet obligations. Real estate is an illiquid asset because of the time and effort required to convert it to cash. 
2. A characteristic of an investment indicating an inability to sell or convert to cash in a short period. 

Illuminate 
1. To light up. To brighten. 
2. To explain or make clear. 

Impact Noise Rating 
Rating system to indicate how much noise is transferred through a ceiling or floor when walking or moving furniture. 

Impact Resistance 
Ability to ward off damage that occurs from a sudden force. 

Impact Wrench 
Powered wrench, which drives a socket fitted over a bolt and exerts an adjustable amount of torque to the fastener with rotary impact blows. 

Impaired Credit 
Decline in the credit status of a prospective borrower. 

Impact Fees
Fees that must be paid by developers of new homes and subdivisions to pay for town facilities such as schools and parks. 

Impedance 
Total opposition to the current flow in an AC electrical circuit, which is equal to the square root of the sum of the squares of resistance and reaction in the circuit. The circuit voltage divided by the circuit impedance and the flow of current in an AC circuit are equal. 

Impeller 
Used most often when pressure is needed in a system or fluid must be moved upward, it consists of a rotating wheel with vanes, inside a casing, for example a centrifugal pump. The fluid that goes into the center of the spinning impeller is flung to the outer edges by use of centrifugal force, which gives velocity to the fluid due to the rotational speed of the impeller. The flow of the fluid is directed through the pump casing discharge outlet by the casing around the impeller. An impeller can be used with a number of fluids. 

Imperial Gallon 
Liquid measure which equals 1 ¼ U.S. gallons or 160 ounces. 

Impermeability
Ability to stop fluids from passing through. For example, certain materials, such as plastic sheeting, resist penetration by water. 

Impervious 
1. Incapable of having things passed through to penetrate. 
2. Not being affected by something. 

Implement 
1. Any article or device used in any given activity; tools, instruments, utensils, etc. 
2. To provide the means for carrying out an act or to use. 

Implied 
Something that is inferred but is not explicitly stated and may be deducted from relevant information. 

Implied Condition 
A provision not explicitly stated in an agreement but considered an important item. 

Implied Contract 
An agreement created by actions of the parties involved but not written or spoken. 

Implied Easement 
Property that is used consistently for many years without challenge by the actual owner. 

Implied Warranty 
Under law, there is an express warranty that real estate sold is appropriate for sale and is in proper condition even if not stated. 

Implied Warranty of Habitability 
Legal Doctrine: all new homes are assumed to meet all building codes and are fit for habitation. 

Implosion 
Bursting inward. 

Impost 
1. A column that supports the end of an arch. 
2. Load bearing portion of a wall. 

Impound Account 
A fund set aside for future needs. 

Impounds
That portion of a monthly mortgage payment which is placed in an account to be used to pay for property taxes, private mortgage insurance and insurance. 

Impregnate 
To fill or saturate all of the spaces of any item with another substance. 

Impression 
1. A mark, imprint, dent or something made by physical pressure. 
2. An imitation of the behavior of someone else. 

Improved Land 
Land that has been developed for use and has had installation of such utilities as water, sewer, roads and building structures. These improvements make the raw land increase its usability, thereby increasing the market value. 

Improvement 
Change to a house that adds value, prolongs its use or adapts it to different use. 

Impulse Resistance Welding 
Electric resistance welding with the use of electric current pulses.