Don't tell Pat Tompkins that the stuff in her self-storage unit is junk.

Her hundreds of Beanie Babies? They're collectibles that could be worth a pretty penny.

Her holiday decorations, packed in orderly rows and towers of color-coordinated containers? They festoon her Wai'anae home each year.

The 33-year-old Ethan Allen canopy bed that belonged to her oldest daughter? Tompkins is saving it for that cute cottage she'll own someday. Maybe.

"I have issues," Tompkins said, laughing. "I just like stuff."

Tompkins, 55, isn't the only one who depends on rentable storage units to provide a home away from home for her excess "stuff." Growing numbers of Island residents are turning to rental space to store excess possessions, and it's leading to a boom in the development of self-storage facilities.

There are 33 self-storage facilities on O'ahu, up from 24 five years ago, and 18 more facilities have been proposed, said Stephen Stadlbauer of Lesher Chee Stadlbauer Inc., a real-estate appraisal and consulting firm.

The demand for rentable storage units stems from a host of reasons, from the practical to the psychological, said Dee Dee Lum, a professional organizer and owner of Maika'i Organizing in Kapolei.

Storage unit tenants include military families in need of temporary storage and families living in multigenerational homes. They also inevitably include some folks who might be better off learning to let go. Sometimes it's a little bit of both. And the attachment comes at a cost.

Renting a storage unit may cost $44 to $525 a month, Stadlbauer said. On average, it costs $170 a month to rent a 5-by-10-foot unit. That's $2,040 a year.

AN EXTRA 'GARAGE'

Susan Johnson's storage rental is packed with her husband's construction tools, scuba equipment, bicycles and coolers.

"We live in a townhouse complex, and we don't have a garage," said Johnson, 35, of Makakilo. "This is all typical stuff that people would store in their garage."

Johnson and her husband are paying about $200 a month for a 6-by-12-foot storage unit.

"We kind of don't have an option right now," she said. "As more units pop up, we're hoping the prices will get competitive."

Johnson's strategy is to monitor prices and to look for a better long-term solution.

"It's temporary until we get a house with a garage," she said.

Tompkins and her husband got a storage unit because they expected to take in a home-stay student. They have been renting a unit for nearly two years and have spent at least a couple of thousand dollars on storage.

"I could certainly better use that money elsewhere, but for now, it's working," she said.

Renting a self-storage unit was a temporary — albeit nearly eight-year — fix for Kehau Kali of Salt Lake.

At 29 years old, Kali decided to leave the Mainland and move back home to Hawai'i. That meant moving in with her parents and having to cram all her possessions into one bedroom.

She found the extra space that she needed at a self-storage facility two miles from her parents' house, which she found convenient. Johnson stored away a desk, twin beds, and boxes of books and winter clothing, among other things.

She already had winnowed out the possessions she felt she didn't need before coming back to Hawai'i and didn't want to part with the rest.

"It's nice to have my stuff and I didn't want to get rid of it," said Kali, now 37. "I got rid of a lot (when I moved back home) and it was nice to have the option to put stuff in a storage facility."

Kali kept her unit until she bought a home. While she kept the storage unit for nearly eight years and at the end was spending nearly $100 a month for it, Kali said it was "definitely" worth it to keep possessions valuable to her.

THE NEED TO COLLECT

Aside from practical reasons, often people need extra storage as a result of the compulsion to collect, said Lum, the professional organizer, who also has a master's degree in clinical psychology.

This doesn't mean the urge to have — and store — is necessarily pathological, though some do pile up possessions because they have a "pack-rat mentality," Lum said.

Others hang on to things because of a sentimental attachment or lack of organizational skills. There are also those who don't want to "waste" anything by throwing it away, or they think things will be valuable one day — " 'Antiques Roadshow' syndrome," as Lum calls it.

Whatever the reason for renting a storage space, Lum said, it should be a temporary fix, considering the monthly costs.

However, storage can be a first step to getting rid of things, Lum notes.

"If it's not in the house, it loses its power to trigger sentimental feelings," she said.

She suggests storage users visit their units periodically and sort through what's inside, getting rid of items that are no longer needed.

"It is easier to throw away things from a neutral space than from your home," she said.

Eventually, it may be possible to downsize out of storage altogether.

Tompkins, the Wai'anae resident, knows she eventually has to deal with all her stored belongings — from her grown daughter's childhood trophies to boxes of tax records.

"My New Year's resolution is to declutter, but I don't think I will get to the storage unit until next year," she said. "I'm having a hard enough time with the house."

Reach Zenaida Serrano at zserrano@honoluluadvertiser.com.