If your Kuna yard has a slope to hold back, or a fence line where the neighbor’s lot sits higher, Meridian Retaining Walls can help with retaining wall installation in Kuna, Idaho. Start with the height. The city’s subdivision code says any lot with a slope exceeding 6 feet in height “shall include a retaining wall with drainage designed by an Idaho registered Professional Engineer”.
Kuna keeps adding homes. The regional planning agency counted 1,252 new residential units permitted here in 2025, up from 912 the year before. New lot or old yard, call us with the slope’s height, the wall’s length and a few photos and we can talk it through.
- Slope rule
- Over 6 ft in height: a wall with drainage designed by an Idaho engineer
- Wall and fence cap
- 72 inches
- Building permit
- Over 4 ft, including footing
- Fence permit
- $25 submittal plus $65 inspection
Retaining wall installation in Kuna: slope, fence-line and backyard walls
Retaining wall for a slope over 6 feet
If your lot falls under the rule quoted above, the engineer’s design is part of the job. See engineered retaining walls.
Fence-line wall where the neighbor sits higher
When your lot and the one next door sit at different grades, check the fence height along with the wall. The zoning code treats walls as fences with a height cap, and allows a waiver only where the lots differ by 2 feet or more and only for the lower lot’s owner. Start from retaining wall installation.
Terraced walls for a sloped backyard
Good for a back slope close to the city’s grading cap for a finished lot. Tiered retaining walls split the height, but they take room: under the block industry’s guideline, a pair of 4 foot walls needs more than 8 feet between faces to count as two.
Holding back a slope in Kuna?
Have the measurements handy and give us a call.
The 6-foot slope rule for retaining walls in Kuna subdivisions
The subdivision code caps final lot grades at 1 to 4 at the rear and 1 to 3 on the sides. Once a lot has a slope exceeding 6 feet in height, the sentence quoted at the top of this page takes over.
Good to know That sentence can be read two ways: the engineer designs the wall and its drainage, or the drainage only. Confirm with the city which applies to your lot.
Until the Building Department tells you, budget as if the engineer designs both. It’s the safer guess. Their number is (208) 922-5546.
Idaho’s engineering board says plans the code requires from a design professional must be prepared by an Idaho licensee, and owning the property doesn’t change that. So where the rule applies, your own sketch won’t do.
What does a retaining wall or fence permit cost in Kuna?
These are the city’s fees, not the price of the wall.
| Fee | Amount | Source |
|---|---|---|
| Small-structure permit, work valued up to $2,000 | $65 | Small-structure permit table. |
| Each additional $1,000 of value, up to $25,000 | $11.35 | Small-structure permit table. |
| Worked example: wall valued at $8,000 | $133.10, before plan review | Worked from that table. |
| Residential submittal fee | $70 | Building Department fee schedule. |
| Residential structural plan review | $65 per hour, 1 hour minimum | Building Department fee schedule. |
| Fence permit submittal | $25 | Fence permit form, July 2026. |
| Fence permit inspection | $65 | Fence permit form, July 2026. |
Source: City of Kuna Building Department fee schedules; fence permit form, July 2026.
Which of these apply to one wall, and whether they stack, is the Building Department’s call. Ask before you budget. The wall itself is a contractor’s price. Call us with the slope’s height and the wall’s length, and we’ll help you find one who works in Kuna.
Call (208) 445-1999 to talk it throughor request a quote online
How long does a Kuna wall permit take, and how do you apply?
Kuna works through applications in the order they come in, so ask the Building Department for the current wait when you apply.
You apply by email. Residential applications go in as PDFs, not through a portal. The Building Department is in City Hall at 751 W. 4th Street, open Monday to Friday, 8 to 5. Ask for an inspection before 4 pm and you get the next business day.
Which walls need the building permit? Those over 4 feet in height, “including footing”, in the city’s words, and its permit FAQ measures from the bottom of the footing. That matters more than it sounds, because the footing is buried and the lawn is not where the count begins. If your wall is planned anywhere near 4 feet, ask the Building Department how it will be measured before the design is settled. The statewide rule is on the retaining wall permits page.
Walls count as fences in Kuna: the 72 inch cap and the lower-lot waiver
| Rule | What the code or form says |
|---|---|
| Walls as fences | Walls are treated as fences needing a permit and capped at 72 inches. |
| Height waiver | Only where adjoining lots differ in grade by 2 feet or more, and only for the owner of the lower lot. |
| Site plan | The fence permit’s site plan must show existing and proposed retaining walls. |
| Easements | 10 feet along front lot lines, 5 feet along sides, at least 10 feet along the rear. |
If your lot is the higher one, the waiver isn’t yours to ask for.
Want to check a Kuna rule first?
Tell us what you are weighing and we will talk it through.
Kuna and the lava field: rock under a retaining wall
State geological mapping puts the city at the edge of the Mountain Home-Kuna lava field, an extensive field of Quaternary basalt southeast of the Boise River valley.
A map can’t tell you how deep the rock sits under your yard. So ask up front what happens to the price if the trench hits it.
What to look for in a Kuna retaining wall quote
- The slope’s height in feet The slope rule turns on that number. Ask who measured it and how.
- The engineer’s design, where the slope rule applies It should be its own line on the quote, with an Idaho licensee behind it.
- Drainage on the drawing Under block manufacturer guidance, a wall over 4 feet gets a drain pipe, and so does any wall in silty or clay soil.
- Which permit the wall falls under Building permit, fence permit, both or neither.
- A price for rock Get it in writing before anyone starts digging.
Kuna retaining wall questions
Do I need a permit for a retaining wall in Kuna?
Yes, if it’s over 4 feet in height including footing. The city lists that among work needing a residential permit. Under that line you may still need one, because the zoning code treats walls as fences needing a permit.
Can a retaining wall be on the property line?
Maybe not. The subdivision code sets easements of 5 feet along side lot lines, 10 feet along the front and at least 10 feet along the rear, so a wall on the line would sit in that strip. What’s allowed there is the city’s decision, so take a site plan to the Building Department and ask.
How steep can my backyard be?
Final lot grades are capped at 1 to 4 at the rear and 1 to 3 on the sides. Once the slope exceeds 6 feet in height, the engineer rule quoted at the top applies.
Can I put a 6 foot fence on top of a retaining wall?
Walls are treated as fences and capped at 72 inches. Ask the city how it measures a fence standing on a wall before you order panels. A block manufacturer’s rule of thumb is that a fence should sit at least 3 feet behind a wall.
Don't see your question? Call (208) 445-1999.
Sources and review date
Reviewed October 2026. Sources: City of Kuna Building Department pages, permit FAQ, fee schedules and fence permit form; Kuna subdivision and zoning code; Idaho engineering board guidance; state geological mapping; regional planning agency development report; block industry guidelines.