Glossary of Construction Terms

Do you ever feel as if your contractor is selling you polyisocyanurate foam when what you really needed was a setback thermostat? Here is a handy guide to common (and not so common) construction terms. Scroll through the glossary below or sort by the letter that starts the word you're looking for. For example, to find polyisocyanurate foam, select P and click Submit.

A (7) | B (6) | C (18) | D (8) | E (9) | F (8) | G (2) | H (4) | I (1) | J (1) | L (4) | M (3) | O (2) | P (11) | R (10) | S (19) | T (7) | U (1) | V (1) | W (4) | Z (2)
Title Definition
Radiant Heat

Our sun produces radiant heat. Its light energy converts to heat when it strikes a solid object. For cooling purposes we need to block the sun's rays. For heating, we use the principles of radiant heat in systems like gas fireplaces and hydronic (hot water) heating. Most of the heating in such system occurs when the radiant heat reaches the person or object to be heated.

See also: Topics: Air Conditioning

Radiant Heat Panels

These are metal panels that fit into the joist space under a floor. A pipe with hot water fits into the panel radiating the heat to the floor above.

George's TipsThis type of a system can provide some very even and comfortable heat. When properly installed it allows for excellent distribution and control of the heat and great energy efficiency.

Wirsbo Joist Track Radiant Heat Panel

A Wirsbo Joist Track Radiant Heat Panel available from our sponsor


A naturally-occurring radio active gas common in many parts of the country e.g. very high levels are found in portions of Pennsylvania and New Jersey and very low levels are found in most portions of western Washington. Radon gas exposure is associated with lung cancer. Mitigation measures may involve crawl space and basement venting and various forms of vapor barriers.


The framing member which directly supports the roof sheathing. A rafter usually follows the angle of the roof, and may be a part of a roof truss (see diagram).


See also: Topics: Roof, Q&A: Roofs, Q&A: Framing

Rain Screens

A siding installation system designed to allow moisture to drain our from behind the siding and help prevent damage to the structure of the house. In such systems, a space is created between the sheathing and the siding material. This space promotes air circulation and the safe drainage for any water that might have penetrated behind the siding.

Rain screen siding application systems are recommended in areas with hight moisture and rain levels and for structures with limited roof overhangs.


See, "Concrete"

Relative Humidity

The amount of moisture in a volume of air as a percentage of the maximum amount of moisture which can be held in that air at a certain temperature - cold air can't hold as much moisture as warm air.


The upright section of a stair. The board between one stair tread and the next.

R Value

A measure of insulation. For example, typical new home's walls are usually insulated with 6" of batt insulation with an R value of R-19, and a ceiling insulation of R-28.

See also: Q&A: Leveling and Insulating A Basement Floor, Q&A: Insulation and Energy

Roof Certification

A written opinion by a roofing professional (contractor or inspector) regarding the expected remaining useful life of a roof system (roofing, venting, flashing, etc). Under certain circumstances a financial institution may request a "roof cert" for a property prior to the issuance of a mortgage. Not to be confused with a roofing material or workmanship guarantee, or warrantee.

See also: Topics: Roof