Every word a contractor will say in your basement.

Annual fuel utilization efficiency. The share of gas you pay for that becomes heat in the house. 80% vents up the chimney; 96% is a condensing furnace that vents out the wall and needs a drain.

Microscopic bubbles mixed into concrete so freezing water has room to expand. Without it the surface scales off in the first winter. Should be named on the estimate.

The strip of driveway between the sidewalk and the curb. It belongs to the Village, follows the Village construction detail, and needs its own inspection.

A valve on the sewer lateral that closes when the street sewer surcharges, so it cannot back up into the basement. The least protective of the three Village-reimbursed flood-control options.

Crushed stone under a slab, four to six inches, compacted in lifts. It drains water and spreads load. The most important line on a concrete estimate and the one you cannot see afterward.

The fan inside the furnace that moves air through the ducts all year, for heating and cooling. Variable-speed (ECM) blowers run quieter and even out temperatures.

British thermal unit, the unit of heating capacity. A furnace is rated in BTU per hour of input; output is input times AFUE. One ton of cooling is 12,000 BTU per hour.

The shutoff on your water service near the sidewalk. The Village owns the water line from the main to the buffalo box; you own it from there into the house.

A video camera run through a sewer lateral or down a chimney flue. The evidence for any estimate. Ask to watch it and to keep the file.

A cement mix poured around a form inside a chimney flue, lining and stabilizing it at once. Used for fireplace flues and deteriorated stacks.

In a dual-fuel system, the outdoor temperature at which heating switches from the heat pump to the gas furnace. It decides your gas bill and should be written on the estimate.

A heat pump rated to keep useful heating capacity well below freezing, typically to around 5°F or lower. Ask for the capacity at 5°F, not the nameplate tonnage.

The outdoor unit with the fan. It dumps the heat pulled out of the house into the yard. Rated as a matched pair with the indoor coil.

A 90%+ furnace that extracts so much heat the exhaust is cool enough for PVC venting and produces acidic condensate. Installing one leaves the water heater alone in the chimney.

A groove cut or tooled into a slab so that shrinkage cracks happen there, in a straight line, instead of randomly. Every 8 to 12 feet on a four-inch slab.

Sheet metal let into the chimney's mortar joints that laps over the step flashing. Most chimney leaks are flashing. It should be replaced, not caulked.

The slab that seals the top of the chimney masonry around the flues. Poured concrete with a drip edge lasts decades; a mortar wash cracks in two winters.

A resin-saturated liner inverted into a sewer pipe and cured in place, creating a new pipe inside the old one without a trench. Needs a mostly intact host pipe.

A breaker and wire serving one appliance only. Required for a heat pump, and by the Village basement program for the sump pump.

Perforated pipe in gravel laid in a trench along the inside of the basement floor at the footing, running to a sump. Manages water that has already reached the wall; does not stop it entering.

A heat pump paired with a gas furnace. The heat pump heats most of the winter; the furnace takes over below the changeover temperature. The normal setup in River Forest.

A sealed pit and pump that lifts basement plumbing waste up to the sewer, used in an overhead sewer conversion. The Village spec is at least 18 by 30 inches with a half-horsepower pump.

A joint with compressible filler where a slab meets a fixed structure: the house, the garage, the public walk. Lets the slab move without pushing.

The board along the roof edge that gutters hang from. Ninety years of leaking gutters leave sections soft; it should be inspected and priced before new gutters go on.

A passage inside a chimney carrying exhaust from one appliance. Most River Forest chimneys hold two or three. Flues are on the Village permit list.

Heating seasonal performance factor, the winter efficiency rating of a heat pump under the current federal test. Higher is better; compare on the same scale.

The original 1905 to 1940 wiring: single conductors on ceramic knobs, no ground, cloth insulation. Cannot be buried in insulation or extended, and many insurers will not cover it live.

The pipe from your house to the sewer main in the street. You own all of it, including the part under the parkway and street. Village program reimburses street-portion repairs.

The federal Renovation, Repair and Painting rule. Contractors disturbing paint on pre-1978 houses, most houses here, must be EPA certified and contain, control and clean up dust.

Mortar with lime as the main binder, softer than old brick and breathable. Correct for 1900 to 1940 River Forest brick. Standard Portland mixes are harder and spall the brick face.

The two copper tubes carrying refrigerant between the indoor coil and the outdoor unit. New, flushed or reused: the estimate should say which.

A stainless steel pipe dropped down a flue, sized to the appliance and ideally insulated. The fix when a 96% furnace leaves the water heater alone in a coal-era flue.

The steel angle above a window carrying the brick over the opening. It rusts, expands and cracks the mortar above in a stair-step pattern. The most common structural item on a masonry estimate.

The engineering method for sizing heating and cooling to a specific house. Also, in electrical, the calculation of how many amps a house needs. Ask whether the size came from one.

An outdoor condenser and indoor coil tested and rated together. The efficiency number and often the warranty hold only for the rated pair.

Equipment that adjusts output continuously instead of running full-on or off. Most comfortable, most expensive, and the largest price spread between two estimates that both say furnace and AC.

Rerouting the basement plumbing to an ejector pit and raising the house's sewer connection above the street sewer, so it cannot back up. The most protective Village-reimbursed flood-control option.

The breaker box. Its main breaker sets the amperage ceiling for the whole house. 60 was normal in 1950, 100 in 1975, 200 today.

The strip between the sidewalk and the curb. Village property. Parkway trees belong to the Village; work under the parkway needs a right-of-way permit.

Village approval before work starts, with inspections. Most of the twelve projects need one. Work started without one is stopped, surcharged and can be ordered removed.

What the rest of the country calls tuckpointing: grinding out failed mortar and packing new mortar in.

Seasonal energy efficiency ratio under the current federal test. Reads slightly lower than the older SEER for comparable equipment, so compare estimates on the same scale.

Increasing the amperage coming into the house: new panel, meter socket, service entrance cable and mast, plus ComEd replacing their drop. More than a panel change.

The face of a brick popping off, usually from freeze-thaw stress concentrated by mortar that is harder than the brick. Visible on many 1990s tuckpointing jobs.

How many output levels equipment has. Longer, gentler cycles from two-stage and variable equipment even out a warm second floor.

Individual pieces of sheet metal woven into the shingles where the roof meets the chimney, under the counter flashing.

The pump in a pit that lifts collected water out of the basement. Half-horsepower cast iron on a dedicated circuit is the baseline; a battery backup keeps it running when the storm takes the power.

12,000 BTU per hour of cooling capacity. Residential systems here run two to five tons, in half-ton steps.

Grinding failed mortar out of brick joints to a set depth and packing new mortar in, in layers, tooled to match. The grind depth and the mortar type are the whole job.

The pipe and hood where ComEd's overhead wire attaches to the house. Part of a service upgrade; owned by you, not ComEd.