Home Building and Remodeling Glossary

Plain-language definitions of the building terms that come up on our estimates, on this site and in conversation with homeowners.

Terms, A to Z

Air barrier

A continuous layer that stops air from moving through the walls, roof and floor of a house. Air leaks carry heat and moisture, so a good air barrier matters as much as insulation.

Air sealing

Closing the gaps where air leaks in and out of a house, especially at the attic floor, the top of the walls, around chimneys and wiring holes, and at the rim joist.

Aluminum coil wrap (trim capping)

Sheet aluminum bent on site to cover wood window, door and fascia trim so it no longer needs paint.

Blower door test

A test that uses a powerful fan mounted in a doorway to depressurize the house and measure how leaky it is. It also makes leaks easy to find.

Board sheathing

Solid wood boards nailed across the wall framing, common on older New Hampshire houses before plywood and OSB became standard.

Climate zone 5

The energy code divides the country into climate zones. In New Hampshire, Cheshire, Hillsborough, Merrimack, Rockingham and Strafford counties are climate zone 5, and Belknap, Carroll, Coos, Grafton and Sullivan counties are the colder climate zone 6, which calls for more wall insulation.

Clapboard

Long, narrow, overlapping wood boards used as siding. Vinyl and fiber cement lap siding imitate the look.

Continuous exterior insulation

Insulation boards installed over the outside of the sheathing, without breaks at the studs, which reduces heat loss through the framing.

Fiber cement siding

Siding made of cement, sand and wood fibers. It is heavier and more rigid than vinyl and is painted.

Flashing

Metal or membrane pieces that direct water out and away at windows, doors, roof edges and wall intersections.

Frost footing

A footing that goes down below the depth the ground freezes, so frost cannot heave it.

Housewrap

A water-resistive barrier installed over the sheathing and under the siding. It sheds water that gets behind the siding while letting the wall dry. It is not a vapor barrier.

Ice dam

A ridge of ice at the roof edge that traps meltwater behind it. Ice dams are usually caused by heat escaping into the attic.

IRC

The International Residential Code, the model building code for one- and two-family homes. New Hampshire moved to the 2024 edition on July 1, 2026.

IECC

The International Energy Conservation Code. New Hampshire kept the 2018 edition when it adopted the 2024 IRC.

J-channel

A J-shaped vinyl trim piece that holds the cut ends of siding around windows, doors and roof lines.

Ledger board

The board that attaches a deck to the house. It needs proper fasteners and flashing so water does not rot the wall behind it.

LVP

Vinyl plank flooring: waterproof planks that click together and float over most subfloors.

R-value

A measure of how well insulation resists heat flow. Higher numbers insulate better.

Rainscreen

A small air gap behind siding that lets water drain and the wall dry.

Replacement window insert

A new window set into the existing frame after the old sashes are removed, without disturbing the interior trim.

RRP rule

The EPA Renovation, Repair and Painting rule. It requires lead-safe work practices by a certified firm when paid work disturbs painted surfaces in homes built before 1978.

Sheathing

The layer of boards, plywood or OSB nailed to the outside of the wall framing, under the housewrap and siding.

Sill pan

A formed or flashed tray under a door or window threshold that catches water and directs it out.

Soffit and fascia

The soffit is the underside of the roof overhang; the fascia is the board along the roof edge. Both are usually covered when siding is replaced.

Starter strip

The first piece installed at the bottom of a wall that locks in the first course of vinyl siding.

Vapor barrier

A layer that blocks water vapor. In above-grade walls, Atlas uses housewrap only and never adds a vapor barrier behind the siding.

Waterproofing membrane

A sheet or liquid-applied layer behind shower tile that keeps water out of the wall. Backer board alone is not waterproof.

Want to see these ideas in practice? Read our articles or the resources page.