Introduction to garden planning and design session 2 slides no safety content 2020 zoom
- 1. Introduction to Garden Planning and Design Week 2 – Surveying and plan drawing
- 2. Learning objectives • Describe how to carry out basic linear surveying techniques, including the use of tapes, offsets and triangulation • Describe the methods used for recording surveying data. • Produce a simple scale plan using data obtained from survey (homework).
- 3. Equipment needed for basic surveying •‘Chain’ – a 100ft (30m aprox.) long tape on a reel. •A metal tape measure or folding rule •Wooden pegs •A set square •A compass •A string line (with as little stretch as possible) •A clip board, paper and pen •A spirit level (if surveying slopes)
- 4. Surveying Basics • All measurements are taken from known fixed points – this could be from a building, or from points along a tape (a chain line) that is fixed and does not move throughout the process. • Tapes are kept taut and straight. • Data is recorded clearly. • Large areas are broken down into manageable sections; usually triangular. • Plan how you will survey the area before starting. Use a sketch like this…
- 5. Surveying Process – part 1 • Sketch the area to be surveyed, including all significant features (but not any features that will definitely be removed).
- 6. Survey Process – part 2 • Divide the area to be surveyed into triangular sub-areas, using ‘chains’ (30m tapes that are not moved during the survey). You could use string lines. • Record the position of these on your sketch plan (so you can remember how they relate to each other). • Note the deviation from North of each chain line. Note the total length of each chain. • Now you are ready to start measuring.
- 7. How to orient your survey to North • Using a magnetic compass –the app on your phone will do – stand at the start point on your chain (‘A’ on the A-B chain, etc.) or facing out from the building. • Point the ‘direction of travel’ arrow down the chain or straight out in front of you. Read the bearing on the bezel of the compass – see the diagram. • Note the number of degrees off North for each chain.
- 8. Surveying techniques Running measurements– used to plot the house outline and features Offset measurements from a fixed base line – used to plot curves and features less than 8m from the base line. Triangulation from two points on a fixed base line – used for points in a larger area (more than 8m from the base line).
- 10. Offset Measurements Line of feature
- 11. Triangulation – from house
- 12. Recording your measurements •Two options – a sketch plan or using ‘booking sheets’ (one for each chain line). •Sketches are best for small, simple surveys. •More complex surveys need booking sheets.
- 13. A Booking Sheet
- 14. Drawing to Scale How to draw a scale plan of your design area.
- 15. Drawing to scale This method ensures that the distances on the ground are accurately represented in the correct proportions on the plan. Enables features and areas to be designed to scale – making sure they fit the site and are a useful size. Using a scale and the right size of paper means that the entire site can be seen from above on the plan..
- 16. Drawing to scale • A scale ruler makes the conversion easy. A scale of 1:1 is actual size, 1:50 means that each centimetre on the plan is 50cm on the ground etc. • The scale chosen should be large enough to show sufficient detail but not so large as make the plan unmanageable. For most gardens 1:100 or 1:50 is appropriate
- 17. Drawing the plan 1 Plot the building first taking the information from your survey notes. If there is no building, then draw on your base line in light pencil to scale. Plot the building or base line at the appropriate deviation from North (North is at the top of the page – use a protractor to measure the degrees). Think about where on the page you need to start; with a smallish garden at 1:100 on A3 paper you could centre the garden in the middle of the paper. There may be some ‘trial and error’ in deciding where to start drawing at first.
- 18. Drawing the plan 2 • Work out from the building or base line once drawn. To plot triangulated points use your ruler to make several marks at the right distance and make an arc. • Where the two arcs of a triangulation cross is the point of the feature recorded. • To plot offset points use a set square and ruler. • Join the dots!
- 19. Learning outcomes Describe how to carry out basic linear surveying techniques, including the use of tapes, offsets and triangulation Describe the methods used for recording surveying data. Produce a simple scale plan using data from survey (homework).
Editor's Notes
- #16: A4 paper will be too small, A3 is better, anything larger may need a board