Designing the Terrain Plan

We’ve been fortunate to have a local Architectural firm, H2A Architects, provide its professional and experienced insights as design consultants for our Grandview Home Design Project.

High on our list of priorities for the project have been sorting out our sloped lot’s drainage and ensuring that the structure sits on the lot properly. To accomplish this, considerations need to be made in optimizing site excavation to limit engineering requirements and dirt removal from the site.

We sat down with our consultants to review the preliminary concept for the house’s footprint, and made good progress brainstorming and understanding how to address the terrain.

Preliminary Terrain Plan

Because of the length of the house and the desire to have backyard space, a large volume of ground will need to be excavated. Once removed, retaining walls will need to be added to shore up the edges of the excavations. In our area, retaining walls lower than 4’ tall do not require an engineering stamp, so the concept of the process was made to include multiple terraced retaining walls, approximately 4’ high and at least 5’ of green area on top before the next step in the terrace. This method also lends itself aesthetically to the property and will allow for nice steps between levels and plus a pleasant water feature.

Once we had the general understanding of the terrain, we began looking at numbers to identify the approximate amount of ground to be removed to achieve the correct elevations for the structure. We used the Primary Terrain Contours from our plan and discussed the location of the floor for the house. The terrain retaining walls and elevations were sketched onto a piece of vellum overlaying our print.

Terrian Sketch on Vellum

We were able to identify two areas to limit our total cut:

  1. We decided to move the entire house forward 11 feet. This will reduce the total amount of soil to be removed from the backside of the hill and allow us to use some of the cut soil as fill for the front pad of the house, and it will create flat areas for a small front yard and driveway pad. This approach also means that less soil overall will need to be removed from the site, further reducing costs.
  2. We will keep grade at the back corners of the house a few feet above the floor platform. In order to achieve this without creating a stepped wall inside the house, due to the differing thicknesses of the framed wall and concrete stem wall, the Architects introduced us to a foundation wall assembly that is a clever and graceful approach. In concept, a 6” concrete retaining wall is constructed from crawlspace footing depth to the top of grade. It has an extra wide footing offset to the interior of the house. A framed load bearing wall is built on the footing to crawlspace height; this supports the platform. The result is a pair of walls with the outer concrete wall shorter and capped 6” above grade, with the framed wall extending the full height to the roof. View the CAD detail

Our changes to the terrain design will add retaining walls in the front and sweep the driveway forward on the lot.  The lot has an approximate 22 degree slope; any lot over 18 degrees requires a storm water management plan stamped by an engineer or landscape architect.  We will be using a firm to complete this requirement before submitting the site plan to the building department.

Revised Terrain Plan
Revised Terrain Plan

Have experience with a sloped or interesting lot to share? – post on our comments.

4 Things We Considered When Purchasing the Grandview Land

Purchasing land for a new home requires a lot of decision-making and research. It’s important to take into consideration every aspect of the land before purchasing. Here are 4 things we considered when purchasing our residential lot for the Grandview project:

  1. Capitalization & Hookup fees

Capitalization Fees or “cap fees” may be required when hooking up to infrastructure items like sewer or water. While searching for land in a well-developed neighborhood, we identified two great properties. We found that the sewer cap fee had already been paid ($7,500) on one of the properties which influenced our final purchase.  We also took into consideration the cost of utilities.  All utilities are available at the lot, so we called each utility to confirm the hookup fees to avoid any surprises.

  1. Easements & Setbacks

Our local building department let us know that the lot had two setbacks in the front, a minimum and a maximum. The maximum setback was to protect the view for the houses on the street above.   The easements from the city and the utility did not have an impact on our decision.  The city has a drainage easement and the utility for power, cable and telephone.

  1. Neighborhood & Location

We wanted land with a view and close to town. We had the chance to talk to the neighbors before purchasing, which ended up giving us insight into the neighborhood, what others have encountered during the building process and who they used to build their homes.

  1. Building Code Requirements and CC&Rs

One of the neighbors mentioned that an owner of a newly purchased lot nearby was frustrated when they learned that the local building code requirements stated a driveway could not exceed a 12-degree slope when they submitted their site plan. To avoid surprises, we called the building department and then read the building requirements outlined by the county. Further, we also reviewed the homeowner association CC&Rs for specific building requirements above and beyond the county.

Comment with additional considerations when buying land and your experiences.

Beginning with the Site Plan

Why create a site plan?

Our city of Coeur d’Alene requires a site plan prior to submitting for building permits. This plan is an illustration of the site perimeter, existing trees, and the proposed residence location. This information helps the city reviewers to determine whether the proposed plan meets setback and other requirements.

Where to begin?

Here are the two avenues we explored as we began developing our site plan.

1. Parcel Map

Setbacks

  • Through our Local County Assessor’s database, we were able to obtain a parcel map of our lot. This was helpful as an evaluation before purchasing the lot. We then saved this information as an image file, imported it into Chief Architect Software and then traced over it creating a 3D site plan.

Watch how we imported our parcel map to create the 3D site plan

2. Surveyor Data

Survey PDF1

  • To obtain more detailed information, we hired a local surveying company to mark the property boundary, elevation data, and major trees. Choosing the right company took a little work. We requested a couple of bids, references, and example DWG files to review. This allowed us to make sure the DWG file was formatted correctly with easy to identify layers. We were then able to easily convert it to a 3D plot plan with Chief Architect Software.

Watch how we imported the surveyor’s DWG file to create a 3D site plan

What’s Next?

Now that we have our site plan, we’ll use it to determine our residence location and landscape layout and begin the design process!