20 Onsite and Offsite Factors You Should Consider for Site Analysis

Site planning is the art of arranging structures on a land and shaping the space in between them. Site analysis is a technique which is part of site planning that helps us understand the various factors at play.

What is the need for site analysis?

To learn the strengths and weaknesses of the site.
To understand the site and derive the form and function of the building based on the factors.
To fix issues on the site, if any.
To try and predict the potential future changes in or around the site and design the building accordingly.

The major site factors can be divided into onsite and offsite factors in the book ‘Site Analysis’ by Edward White.

Onsite factors Checklist for Site Analysis

They refer to the factors present on the site.

The major ones are-

Location
Size
Topography
Vegetation
Drainage
Groundwater
Soil
Danger signals
Man-made features
Legal factors
Utilities
Right of way
Circulation
Microclimate
Sensory

Offsite factors Checklist for Site Analysis

These refer to the features around the site.

Some of them are-

Climate
Access
Neighborhood
Culture
Views

Onsite factors

1. Location

Coordinates
Area of the site
Names of the adjacent road
Landmarks
Nearest services like hospitals, airports, schools, stores etc.

2. Size

The length and breadth of the land should be noted.
The total buildable area after subtracting the area for setbacks and easements should also be calculated.

3. Vegetation

Includes the trees, shrubs and groundcover on site.
They affect the wind pattern and drainage of the site.
Weeds and ground cover can be removed while trees should be retained.
The building can be designed to use them as buffer or shading devices.

4. Topography

Refers to the features of the surface of the land.
Contour, high points, low points, ridges, valleys and flat land should be documented.
Flat surface is best used for intensive activities.
Steep slopes are hard to construct and move on.
Buildings can be constructed between 1:6 and 1:12 slope.

5. Drainage

This depends on the contour of the land.

6. Groundwater

Refers to the water below the surface level.
Construction should be done considering the depth of the water table.

7. Soil

The soil should be tested to determine its soil-bearing capacity.
Depending on the type of soil, the foundation is chosen.

8. Danger signals are exhibited by some features like

Rocks lying close to the surface
High water table
Underground stream
Loose clay or fine sand

They call for expert analysis and special construction.

9. Man-made features include

Walls
Fences
Hydrants
Power poles
Pavements

10. Legal factors include

Ownership of land
Setbacks- minimum open space around a building
FSI (floor space index)- total built area/total plot area
Height restrictions
Allowed uses of the site

All buildings should be constructed with respect to the development control regulations.

11. Utilities

Includes services like water, sewage, electricity, gas.
Can be under or above ground level.
The distance of these facilities from the site should be noted.
Some services like HTL (high tension lines) passing through the site can make it hazardous.

12. Right of way

A part of the site can be used to provide access to another piece of land.

13. Circulation on site is of two types

Pedestrian
Vehicular

14. Microclimate

Apart from the general climate of the surrounding area, the site can have a microclimate determined by the following factors-

Location of structures
Vegetation
Surface materials
Topography
Water bodies
Surrounding buildings

15. Sensory factors are

Visual views from the site.
Olfactory- the smell from surrounding vegetation and buildings.
Audible- sounds from roads and neighboring areas.
Tactile- wind influenced by vegetation and buildings.

Offsite factors

1. Climate includes

Rainfall
Wind direction
Sun path
Humidity
Temperature

The variations in these factors throughout the day and year and possible natural calamities like floods or tsunamis should also be considered.

The shading and ventilation of the building depends on these factors.

2. Access refers to

The different ways of approaching the site.
The roads around the site.
Location of site with respect to the roads,
Usage and traffic on these roads.

3. Neighborhood includes

Existing buildings.
Open spaces in the vicinity.
Buildings with historical context.
Vernacular context of the area.
Possible hazardous waste disposal areas.

4. Cultural factors are

Population density
Age distribution
Income and employment
Family structures
Crime patterns

These help in the zoning of the site.

5. Views include

Positive and negative views.
How the site looks from different points and how these might change with distance or time.

What is the importance of thorough site analysis?

To have greater efficiency while designing.
To discover the interrelationship between site factors.
To maximize data triggers for design conceptualization.
To avoid legal implications

Hence it becomes necessary to carefully understand and record the above-mentioned factors while analyzing the site so as to use it to the best of its abilities.