Construction lag

Key Takeaways

• Construction lag is the time between deciding a project should exist and finishing it, and it is measured in months or years, not weeks.
• Because new supply cannot arrive quickly, a jump in demand shows up first as higher prices and only later as more homes.
• Permit review is part of the lag. Washington gives a local government 65, 100, or 170 days to issue a final decision under RCW 36.70B.080, depending on whether public notice and a hearing are required.
• Land availability, zoning limits, and infrastructure capacity stretch the lag well past the physical build time.

What It Means

Construction lag is the stretch of time between the moment someone decides a building should exist and the moment a buyer can move into it. Land has to be found and bought, a design drawn, financing arranged, permits pulled, and utilities connected. Only then does framing start. For housing that whole sequence commonly runs more than a year, and for a large project several years.

That delay is the reason housing supply answers a change in demand so slowly. If buyers flood a county this spring, the only homes for sale are the ones already finished or nearly finished. Nothing new can appear before summer. Price moves first and quantity moves later, which is what economists mean when they call short-run housing supply inelastic. The mechanics of that pressure are worked through in our guide to buyer and seller markets.

The lag is not only about pouring concrete. Zoning decides what may be built and where, the Comprehensive Plan decides where a jurisdiction directs growth at all, and permit review takes its own months on top. Every one of those steps sits between demand and delivery, which is why a hot market and a housing shortage can sit side by side for years without resolving.

How It Works in Washington

Washington puts real numbers on part of the lag, which makes part of it something a broker can forecast. Under RCW 36.70A.110 every county planning under the Growth Management Act must designate urban growth areas within which urban growth is encouraged and outside of which growth can occur only if it is not urban in nature, so builders cannot simply move outward to cheaper land. Permit timing then comes from RCW 36.70B.080, which caps how long a final decision may take once an application is complete: 65 days for a project permit that needs no public notice, 100 days when public notice is required, and 170 days when public notice and a public hearing are both required. Those clocks stop while the applicant is gathering requested information, while an environmental impact statement is prepared under chapter 43.21C RCW, and while an administrative appeal runs, which is why a real permit often takes far longer than the headline number.

The legislature has also pushed on the supply side. RCW 36.70A.635 now requires larger cities to authorize middle housing on lots zoned predominantly for residential use, and RCW 36.70A.635(6)(c) makes a city apply the same permit and environmental review process to middle housing that it applies to a detached house. Lag does not disappear, it shortens. And it is not uniform across the state, as our look at how different Washington markets really are lays out.

Example

Cedar Ridge Homes buys a 4.2 acre parcel in Marysville in March 2024 for $1,150,000, planning 18 townhouses. Design and engineering run through September. The city deems the Subdivision application complete on October 1, and because the plat needs public notice and a hearing, RCW 36.70B.080 allows 170 days, which puts the decision in March 2025. Two rounds of requested corrections stop the clock for another eleven weeks. Site work starts in June 2025, framing in September, and the first four units close in April 2026. That is 25 months from purchase to first closing. Over those same two years the local median price climbed from $640,000 to $712,000. Cedar Ridge captured the Appreciation, but the 18 homes did nothing to cool 2024 prices, because in 2024 they did not exist.

Common Mistakes and Exam Traps

• Construction lag explains inelastic supply in the short run. It is not a description of demand, and it is not a price theory.
• The lag starts at conception, not at groundbreaking. Land assembly, design, financing, and permit review all sit inside it.
• A shortage plus rising prices does not mean builders are idle. It usually means the homes now going up were started when demand looked very different.
• Do not confuse construction lag with a construction loan or a construction lien. Those are financing and security concepts, not a timing concept.