Field notes / Homeowner guide
Grading, drainage and foundation planning before layout and pricing
Earthwork, site water and foundations are three views of one problem: how the house meets the ground. Each finding on the site raises a question for a specific professional, may change a specific document or scope, and should be decided before anyone prices the work. This guide organizes those handoffs. It contains no engineering values or design solutions.
Written · KB Remodeling
The short answer
Treat grading, drainage and foundations as one coordination sequence: survey and geotechnical findings come first, the civil and structural engineers turn them into grading, drainage and foundation design, and the building authority reviews what its rules require. In the City of Los Angeles, LADBS says a soils and/or geology report is usually required for its Grading Division's technical review before grading permits issue.
Who this applies to
Owners planning a new or replacement house, a large addition or an ADU where earthwork, site water or foundation choices may matter. Whether a parcel needs a grading permit, retaining walls, stormwater measures or a particular foundation depends on the authority's rules and the engineers' design for that parcel, not on a hillside label.
01 · When it applies
One sequence, three questions
Who reviews site work depends on where the parcel is: a City department within an incorporated city, or LA County Public Works for unincorporated County land, which lists retaining walls among its trade permit types. In the City of Los Angeles, LADBS's Grading Division reviews soils and geology reports and inspects grading work.
The owner's job is not to choose a foundation or a drainage method. It is to make sure the right evidence exists, that each question has a named professional, and that the answers reach the drawings and the estimate in the same revision.
Ask yourself
- Which authority reviews grading, drainage and foundation drawings for this parcel?
- Which professional on the team owns each of the three questions?
Source for this section
02 · The decision
Grading, earthwork and access
Grading questions start with the topographic survey and the planned floor levels: how much the ground changes, where excavated material goes, how equipment reaches the work and whether walls hold back soil. LADBS describes grading permits as required for grading work in its designated hillside grading area and in other defined circumstances; read the authority's current criteria for your parcel rather than assuming either way.
Access shapes earthwork as much as volume does. A narrow street, a shared driveway or a steep approach can limit equipment and hauling, and may raise questions about haul routes or staging that the authority or neighbors care about.
| Site finding | Question for | Possible affected document or scope | Decision before pricing |
|---|---|---|---|
| Planned floor well above or below existing grade | Architect and civil engineer | Grading plan; retaining walls; stairs and driveway | Set floor levels and accept the earthwork they imply |
| Excavated material must leave the site | Civil engineer; authority | Export quantities; haul route conditions | Confirm whether haul-route review applies |
| Limited equipment access | Contractor; civil engineer | Staging, equipment and sequence | Agree access assumptions to price against |
| Walls retaining soil near property lines | Structural and geotechnical engineers | Wall design; permits; neighbor coordination | Confirm wall scope is in the drawings, not an allowance guess |
Source for this section
03 · The decision
Drainage, stormwater and site water
Water moves across and through a site before and after construction. The questions are where it comes from, where it goes today, how the new house and paving change that, and what the authority requires. The City of Los Angeles expanded its stormwater mitigation requirements with a Low Impact Development ordinance applied to projects requiring building permits, and LA Sanitation publishes an LID handbook; whether and how those requirements apply to your project is for the civil engineer and the City to confirm.
Keep drainage decisions in the layout phase. Moving the house, the driveway or a patio after drainage is designed can change the design, and drainage elements may need space, access or easements.
| Site finding | Question for | Possible affected document or scope | Decision before pricing |
|---|---|---|---|
| Water flows onto the lot from uphill or a neighbor | Civil engineer | Grading and drainage plan | Agree how existing flow is to be handled in the design |
| New roof and paving add hard surface | Civil engineer; authority | Stormwater measures on the site plan | Confirm which local requirements apply |
| No obvious place for water to go | Civil engineer; public works | Drainage route; easement or connection questions | Resolve the outlet question before final layout |
| Groundwater or seepage noted in the geotechnical report | Geotechnical and structural engineers | Foundation and below-grade waterproofing scope | Carry the finding into foundation decisions |
Source for this section
04 · The decision
Foundations as an interface
A foundation is where site evidence, structural design and construction scope meet. The geotechnical report supplies findings and recommendations; the structural engineer designs the foundation using them and the house's loads; the contractor prices and builds what the drawings show, often with the geotechnical engineer observing parts of the work. A neighbor's foundation type is not evidence for yours.
For the owner, the useful questions are whether the drawings and the geotechnical recommendations are the same revision, which items are left for field decision, and who observes them.
| Site finding | Question for | Possible affected document or scope | Decision before pricing |
|---|---|---|---|
| Geotechnical recommendations depend on the final footprint | Geotechnical engineer | Report addendum | Freeze the footprint, then confirm the report covers it |
| Structural drawings issued before the latest report | Structural engineer | Foundation drawings | Reconcile both to one revision |
| Construction observation items listed | Geotechnical engineer; contractor | Inspection and observation schedule | Include observation in budget and schedule |
| Existing foundation to be reused or removed | Structural engineer; contractor | Demolition, repair or new foundation scope | Decide reuse or replacement before bids |
05 · An example
Fictitious scenario: a sloping replacement lot
A generalized, fictitious owner replaces a house on a sloping lot. The survey shows the street lower than the rear yard, the geotechnical report notes seepage, and the architect wants a lower-level garage. The three matrices turn that into decisions: floor levels and export questions for grading, an outlet question for drainage, and a foundation and waterproofing scope tied to the report. Bidders receive one drawing revision with those items shown, and site work is priced as separate lines rather than a single allowance. No cost or duration is assumed here.
Ask yourself
- Which site decisions are still open in the drawings you plan to price?
Who resolves which question
| Question | Resolved by | May be reviewed by |
|---|---|---|
| Existing ground and boundaries | Land surveyor | Building authority (as part of plans) |
| Subsurface conditions | Geotechnical engineer / engineering geologist | Building authority's grading or geotechnical review |
| Grading and drainage design | Civil engineer | Building authority; public works |
| Foundation and retaining-wall design | Structural engineer, using geotechnical recommendations | Building authority |
| Pricing and sequence | Contractor, from the issued drawings | Owner |
A scenario to consider
Fictitious, generalized scenario: two bids differ widely because one assumed retaining walls and the other did not. The owner asks the engineers to show the wall scope in the drawings and rebids both on the same revision.
Planning scenario
Bring this to your conversation
- Confirm the authority that reviews grading, drainage and foundations
- Get the survey and geotechnical report before fixing floor levels
- Assign grading, drainage and foundation questions to named engineers
- Resolve the drainage outlet before final layout
- Reconcile foundation drawings and geotechnical report to one revision
- Price site work as separate lines from the issued drawings
One more question
Does a hillside lot always need a grading permit or a special foundation?
Not necessarily. That depends on the authority's rules for the parcel and on the engineers' design. A hillside label is a reason to ask, not an answer.
Official references
Research the property · Web resource · English source
LADBS — Grading permitsUse this for: Read the City of Los Angeles grading-permit criteria for your parcel before assuming either way.
Research the property · Web resource · English source
LADBS — Grading Division and inspectionsUse this for: Understand how the LADBS Grading Division reviews soils and geology reports.
Research the property · Web resource · English source
LA Sanitation — Low Impact Development handbookUse this for: Background on City stormwater (LID) requirements; your civil engineer and the City confirm what applies.
Research the property · Web resource · English source
LA County Public Works — Building and Safety permitsUse this for: Confirm whether LA County Public Works issues your permits (unincorporated areas) and which trade permits apply.
For requirements specific to your property, consult the local reviewing authority.
About this guide
Published by KB Remodeling from the official sources cited. It is not attributed to an individual author and does not claim review by an architect, engineer or attorney. We receive remodel, ADU, new-home and rebuild inquiries; scope, licensing and location are reviewed before any next step.