Deck builders in Mount Prospect, IL

The median home in Mount Prospect dates to about 1969, roughly 57 years ago. Most homes from that era were built without a deck; the decks you see now were usually added in later decades, sometimes by previous owners with little documentation.

That history matters: retrofit decks are where missing ledger flashing, undersized footings and nailed-rather-than-bolted connections are most common. Before resurfacing or extending an add-on deck, it is worth confirming how it was framed and attached.

That makes Mount Prospect's housing 8 years newer than Cook County as a whole, where the median home was built in 1961. Statewide, the median Illinois home was built in 1971. Among the 102 covered Illinois communities with Census data, Mount Prospect ranks #39 for oldest housing. In this ZIP code, 26% of homes were built before 1960, 49% between 1960 and 1979, 19% between 1980 and 1999, and 6% since 2000 — the single largest group dates to the 1960s.

The nearest NOAA climate station with 1991–2020 normals is Chicago Palwaukee AP, about 4 miles away. It records an average of 122 days a year with a low at or below 32°F — a substantial freezing season. On roughly 79 of those days the temperature climbs back above freezing, so water in wood, soil and gaps between boards repeatedly freezes and thaws.

For Mount Prospect, 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 Mount Prospect is about 38.4 inches a year (Chicago Ohare Intl. AP). That's enough that shoveling and ice-melt choices affect deck surfaces, and stair treads benefit from good texture and drainage.

Precipitation averages about 32.3 inches a year, falling on about 63 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 17 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.

On Mount Prospect's many older homes, a wood-look capped composite or a stained cedar deck usually suits the architecture better than high-gloss boards.

Mount Prospect has about 22,676 housing units across its covered ZIP code. 57% are single-family detached homes, 3% are attached homes such as townhouses and rowhouses, and about 40% are in buildings with two or more units. Roughly 69% of occupied homes are owner-occupied.

The mix of detached homes and attached or multi-unit housing in Mount Prospect means deck projects range from large backyard decks to compact rear decks on narrow lots. Lot size, neighbors' sightlines and any association rules shape the right design.

• Retrofit decks on older homes: about 11,729 homes (52%) predate 1970. Here the priority is confirming that add-on decks are properly attached — or rebuilding them freestanding — before any cosmetic work.
• Replacement and major repair: about 9,649 homes (43%) 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.
• Upgrades and expansions: about 766 homes (3%) 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.

Mount Prospect 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 Mount Prospect, 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 Prospect Heights, about 2.7 miles from the center of Mount Prospect's covered ZIPs. Its median home was built in 1976, 7 years later than in Mount Prospect. Mount Prospect has 20 percentage points more detached single-family homes (57% vs. 36%), which changes how many projects are backyard decks versus compact townhouse decks. Owner-occupancy is 69% in Mount Prospect compared with 67% in Prospect Heights. Mount Prospect's covered ZIP code span about 10.9 square miles of land with roughly 22,676 homes — about 2,080 per square mile, a typical suburban density where most homes have usable backyards.