Planning a remodel or new build in West Lake Hills? One of the first hurdles you may hit is impervious cover. It shapes everything from your driveway width to whether that pool and patio will fit. If you understand how it works, you can design smarter, avoid delays, and protect resale value. This guide breaks down what counts, how to check your numbers, and practical ways to stay compliant. Let’s dive in.
What impervious cover means
Impervious cover is the part of your lot that does not let rain soak into the ground. Common examples include building footprints, roofs, driveways, concrete or asphalt patios and walkways, pool shells and surrounding decks, and compacted gravel. Some codes also treat heavily compacted soil as impervious.
Pervious areas allow water to infiltrate. Grass, native soil, and engineered permeable pavements fall into this category when they meet the city’s standards. The crucial detail is that acceptance varies by jurisdiction. In some places, an open-graded paver system with the right base counts as pervious. In others, it does not. Always verify what West Lake Hills recognizes before you finalize plans.
Why West Lake Hills regulates it
West Lake Hills sits on steep, sensitive terrain where runoff and erosion can escalate quickly. Impervious limits help manage stormwater, reduce downstream flooding, protect creeks and reservoirs, and preserve hillside stability. These limits also influence neighborhood scale and site planning, which is why they show up early in the design process for homes, driveways, pools, and outdoor living areas.
Where the rules live
You will find the authoritative standards in the City of West Lake Hills Land Development Code and related zoning rules. Development Services or Planning staff can confirm definitions, required submittals, and how the city measures coverage on your lot. County and FEMA floodplain maps may also affect what you can build, and state water-quality standards can apply to larger projects.
The key point: confirm the current code for your zoning district and lot size. Limits, definitions, and exemptions can change over time, and they are often different for various zones or hillside overlays.
What usually counts (and what might not)
Every city writes its own definitions. Here is how features are commonly treated so you know what to ask when you verify with West Lake Hills:
- Roofs and building footprints usually count. Overhangs can be handled differently.
- Driveways and parking areas typically count. Narrower layouts or recognized permeable systems may reduce the counted area if the code allows it.
- Patios and terraces count if paved or compacted. Open-grate or boardwalk-style decking may be treated differently.
- Pools are often counted, including the shell and surrounding deck. Some codes also count the water surface; some do not.
- Retaining walls and terraces can trigger review if they alter drainage. The surface treatment influences whether they count.
- Small paths and narrow linear features may be exempt up to a threshold. Always check the definitions section and any de minimis provisions.
How the city measures coverage
Most municipalities use a percentage of lot area. They divide the total impervious square footage by the lot size to get a percentage. Some places distinguish between “impervious cover” and “building coverage.” Building coverage might only count the house footprint, while impervious cover includes all non-permeable surfaces. West Lake Hills will specify which definitions apply and the method you must use for calculations.
Practical impacts on your project
Impervious limits influence layout, footprint, and features. If the allowable coverage is tight, you may choose a second-story addition instead of expanding the ground-level footprint. Driveway design becomes strategic. Pools, large patios, and extensive hardscape are common reasons projects exceed the cap.
On sloped lots, long or wide driveways add area quickly. Outdoor living areas can still be generous if you use materials the city recognizes as pervious. Rain gardens and other stormwater features may be required or used voluntarily to offset impacts, depending on what the code allows.
Smart design strategies to stay compliant
A thoughtful plan can protect both function and compliance. Consider these tactics as you shape your site plan:
Reduce counted area
- Use accepted permeable paving for driveways and patios where the city allows it.
- Narrow or shorten the driveway and consolidate parking.
- Replace traditional concrete paths with stabilized gravel or open-joint pavers that meet code specifications.
Manage runoff on-site
- Add rain gardens, bioswales, infiltration trenches, or dry wells if recognized by the code for credits or mitigation.
- Consider rainwater harvesting cisterns and, where appropriate, green roof strategies if the city recognizes them.
- Incorporate detention or retention features if required to offset increases.
Reconfigure the layout
- Build up instead of out when the lot footprint is constrained.
- Place hardscape in flatter areas and preserve native ground cover to reduce erosion and keep natural infiltration.
Step-by-step: check your coverage
Before you commit to design or a purchase, run a simple check to estimate where you stand. You will confirm the final numbers with a survey and city-reviewed site plan, but this early step helps set expectations.
- Step 1: Get your lot area from a survey. Example: 0.5 acre equals 21,780 square feet.
- Step 2: Measure existing impervious surfaces. Hypothetical example: roof 2,800 square feet; driveway 1,200; patio 400; pool deck 600. Total impervious equals 5,000 square feet.
- Step 3: Calculate percent impervious. 5,000 divided by 21,780 equals about 23.0 percent.
- Step 4: Compare to the allowed limit for your zoning in the West Lake Hills code. If the limit is 30 percent in this example, the remaining capacity would be about 1,524 square feet. Your actual limit and rounding rules must come from the current city code.
This quick math helps you see whether a pool, larger patio, or additional parking will fit within allowable coverage or if you will need mitigation or a variance.
Permits, plans, and professionals
Any increase in impervious area typically triggers a building permit and, for larger scopes, a site development permit. Expect to submit a site plan, current survey and topographic survey, drainage details, and tree protection plans. A civil engineer or landscape architect often prepares drainage calculations. During construction, erosion controls are inspected, and the final site is checked to ensure it matches the approved plan.
A pre-application conversation with West Lake Hills Planning or Development Services can save time. They will outline submittals, how they count specific materials, and whether any mitigation will be required.
Variances and exceptions
If your design exceeds the limit, you have options. You can redesign to reduce hardscape, propose on-site mitigation the city recognizes, or apply for a variance. Variances require a clear hardship, minimal community impact, and a plan that represents the least modification necessary. If granted, they often come with conditions like enhanced stormwater controls or landscaping. Administrative relief may be possible for smaller adjustments, depending on project specifics and city standards.
Buyer checklist: evaluate before you write an offer
Protect your plans by verifying what is buildable on a lot in West Lake Hills. Start with these items:
Request documents
- As-built site plan and recorded plat.
- Permit history and certificate of occupancy for current improvements.
- Recent boundary and topographic survey.
- Tree survey and any protected tree notes.
- HOA or deed restrictions if applicable.
- FEMA and local floodplain designations.
Do early due diligence
- Estimate current impervious percentage using the step-by-step method above.
- Ask about any unpermitted work that could count against the limit.
- Schedule a pre-application conversation with Planning/Development Services.
- Budget for site design and civil engineering if mitigation is likely.
Seller checklist: plan improvements wisely
If you want to boost value before listing, focus on upgrades that deliver market impact without pushing coverage over the limit.
Low-impact, high-ROI ideas
- Interior updates, lighting, and fixtures.
- Second-story additions rather than footprint expansions when feasible.
- Pervious landscaping, small decks that may be treated as pervious, and curb-appeal refreshes.
For bigger projects
- Start the entitlement process early.
- Be ready to document pervious systems and propose mitigation like rain gardens or cisterns if needed.
- Keep all approvals and as-built documents organized for buyers.
Common pitfalls and consequences
Working past the limit without approval can lead to stop-work orders, fines, and costly removals or retrofit work. At resale, title or lender concerns may surface if unpermitted work is discovered. A property that is already at its impervious cap offers less flexibility for future additions, which can influence buyer interest and pricing. The safest path is to verify early and build a clean paper trail.
A local, construction-literate approach
In West Lake Hills, the right plan starts with a clear read on your lot’s capacity and the city’s definitions. A construction-informed strategy helps you balance lifestyle goals with compliance. When you align your driveway, outdoor living, and pool ideas with accepted materials and runoff management, you protect both your budget and your resale story.
Ready to map out a compliant plan or evaluate a property’s potential? Reach out to Jenny Walker for a practical, construction-literate perspective tailored to West Lake Hills.
FAQs
What is impervious cover for a West Lake Hills home?
- It is the total area on your lot that does not let water infiltrate, such as roofs, driveways, concrete patios, pool shells, and compacted gravel, as defined by the city code.
How do I find my lot’s impervious limit in West Lake Hills?
- Check the West Lake Hills Land Development Code for your zoning and lot size, then confirm with Development Services or Planning, ideally through a pre-application meeting.
Do gravel driveways count toward impervious cover in West Lake Hills?
- It depends on the city’s definition. Some jurisdictions count compacted gravel as impervious; verify with West Lake Hills whether a specific permeable base and installation are required.
Does a pool count against my impervious limit?
- Often yes. Many codes count the pool shell and surrounding deck, while treatment of the water surface varies. Confirm the city’s definitions before design.
Can permeable pavers reduce my counted coverage?
- Possibly, if West Lake Hills recognizes the system as pervious and it is installed to specification with proper base and maintenance documentation.
What if my planned remodel exceeds the permitted impervious area?
- You can redesign to reduce hardscape, add on-site mitigation if accepted, or apply for a variance that demonstrates hardship and minimal impact.
