San Diego’s nearly $5 billion infrastructure funding shortfall would be about $1 billion higher if the city included hundreds of maintenance projects that officials are delaying and ignoring, a city audit says.

Delaying those projects, which include roof patches and minor repairs to air conditioning systems, will increase long-term costs, forcing the city to replace entire buildings sooner than necessary, according to the 57-page audit.

“While delaying maintenance may save money in the short term, delaying maintenance results in higher future costs and can harm city services, worker morale and the city’s overall reputation,” the audit says.

It can also deprive city leaders of an accurate picture of how far behind they are on infrastructure projects. The audit says deferred maintenance should be included in future assessments of the city’s infrastructure deficit.

If included, it will likely represent the second largest deficit, behind only stormwater. In last winter’s assessmentthe stormwater deficit was $1.6 billion, the streets deficit was $989 million, and the parks deficit was $801 million.

The audit says the roughly $25 million San Diego spends annually on facility maintenance represents only 8 percent to 18 percent of what the city should be spending.

This is based on National Research Council recommendations that cities should spend 2% to 4% of their asset replacement value on routine facility maintenance each year.

San Diego’s 1,600 buildings and facilities have an estimated net value — or replacement value — of $7.2 billion, which would require annual expenditures of between $143 million and $287 million for routine maintenance.

The audit also says the city is spending those limited resources the wrong way.

It says best practices dictate that government agencies should spend 30 percent of their facility maintenance money on repairs and 70 percent on preventive maintenance projects.

By contrast, San Diego spends 87 percent of its facility maintenance money on repairs and only 13 percent on preventive maintenance.

“We found that continued underfunding of facility maintenance has also resulted in the Facilities Services Division having to take a reactive approach to maintenance, meaning the city repairs facility components as they fail and postpones repairs until there is time and funding needed for staff,” the audit says. “This model has created a substantial amount of deferred maintenance and limits Facilities Services’ ability to perform preventive maintenance.”

To help solve that problem, the audit said the city should develop a facility management plan to track and report maintenance needs and decide how to address them and how much money is needed for each project.

The audit also recommends the city use that plan to create a long-term funding strategy that addresses both annual maintenance needs and deferred maintenance.

A third recommendation is that the City establish a goal for the percentage of the total replacement value of the facility that the City plans to spend annually on facility maintenance. The city now spends 0.4 percent of the facility’s $7.2 billion replacement value — well below the recommended 2 percent to 4 percent.

In the city’s defense, the audit says San Diego is far from alone in putting off maintenance, because it’s one way cities make ends meet — spending money on immediate priorities and putting off less immediate ones.

“The National Research Council says that underfunding maintenance and repairs is such a widespread practice in the public sector that it has become a de facto policy that makes the problem worse every year as the number of maintenance needs increases,” the audit says.

City officials agreed with all of the audit’s recommendations, but pointed out that complying with them would require more money.

“A significant investment is needed in the Facilities Services Division to correct underfunding issues and to be able to take the necessary steps for ongoing maintenance to protect the city’s investment in its facilities,” wrote two officials — Comptroller Rolando Charvel and Director of General Services Musheerah Little – in writing. a letter to City Auditor Andy Hanau.