Deck builders in Algonquin, IL

The median home in Algonquin was built around 1993. A deck built with a house of that age is now about 33 years old — the stage where first-generation pressure-treated decks commonly need major repair or replacement.

Decks built before 2004 were very likely made with CCA-treated lumber, which was phased out of most residential uses at the end of 2003. That doesn't make an existing deck unsafe, but old boards shouldn't be burned, and demolition debris should be disposed of according to local rules.

That makes Algonquin's housing 4 years newer than McHenry County as a whole, where the median home was built in 1989. Statewide, the median Illinois home was built in 1971. Among the 102 covered Illinois communities with Census data, Algonquin ranks #97 for oldest housing. In this ZIP code, 11% of homes were built before 1960, 13% between 1960 and 1979, 49% between 1980 and 1999, and 27% since 2000 — the single largest group dates to the 1990s.

The nearest NOAA climate station with 1991–2020 normals is Elgin, about 7 miles away. It records an average of 139 days a year with a low at or below 32°F — a substantial freezing season. On roughly 90 of those days the temperature climbs back above freezing, so water in wood, soil and gaps between boards repeatedly freezes and thaws.

For Algonquin, that means footings must bear below the locally required frost depth to avoid heaving, and wood surfaces should be kept sealed so absorbed water doesn't split boards over winter. Synthetic decking tolerates freeze-thaw well but still needs the manufacturer's expansion gaps.

Average snowfall near Algonquin is about 32.1 inches a year (Elgin). That's enough that shoveling and ice-melt choices affect deck surfaces, and stair treads benefit from good texture and drainage.

Precipitation averages about 39.9 inches a year, falling on about 74 days with 0.1 inch or more — wet enough that drainage and flashing still matter, but dry spells also let wood surfaces dry out and check in the sun.

Average summer highs reach about 82°F, and around 15 days a year top 90°F. On a deck with full afternoon sun, dark composite can get uncomfortable on those days, so test samples in the sun before choosing a color.

Budget, upkeep tolerance and sun exposure on your particular lot still decide the final choice between these options.

Algonquin has about 12,113 housing units across its covered ZIP code. 76% are single-family detached homes, 16% are attached homes such as townhouses and rowhouses, and about 8% are in buildings with two or more units. Roughly 88% of occupied homes are owner-occupied.

Detached single-family homes dominate in Algonquin, so most decks are backyard decks attached to the rear of the house. That gives more freedom on size, layout and stairs, and makes a well-planned deck one of the most-used rooms of the home.

• Replacement and major repair: about 7,201 homes (59%) were built between 1970 and 1999, the age group whose original or early add-on decks are most likely to have worn-out framing, connectors and boards.
• Retrofit decks on older homes: about 1,612 homes (13%) predate 1970. Here the priority is confirming that add-on decks are properly attached — or rebuilding them freestanding — before any cosmetic work.
• Upgrades and expansions: about 1,004 homes (8%) were built since 2010. Their decks are usually sound but small or builder-grade, so enlarging the deck, adding stairs and switching to composite or upgraded railings are common.

Algonquin has a defined building season. Spring and early fall offer the most comfortable working weather; winter is a good time to settle the design and apply for permits. Stains and sealers generally need dry weather and moderate temperatures, so plan wood finishing for late spring or early fall.

For Algonquin, IL, ask the permit office whether your deck needs a permit based on its size, height and attachment to the house, which drawings and inspections are required. Statewide code background for Illinois is on our state page; local rules change, so the building department remains the authority.

The closest covered area is Barrington, about 7.6 miles from the center of Algonquin's covered ZIPs. Its median home was built in 1982, 11 years earlier than in Algonquin. The two have a similar share of detached single-family homes (76% vs. 79%). Owner-occupancy is 88% in Algonquin compared with 87% in Barrington. Algonquin's covered ZIP code span about 15.8 square miles of land with roughly 12,113 homes — about 767 per square mile, a low density that usually allows larger decks and freestanding designs.