F1 - Lay out buildings Flashcards
What is one of the first steps in the construction of a building?
To properly lay out corner locations for the building and determine elevations.
When the layout is tight to the allowable lot line setbacks, or if the layout is complex due to building design or other reasons, what is the solution?
A registered surveyor is hired to pin the building corners.
Pins are steel rods driven in AFTER excavations but before footings are constructed.
What is the best way to ensure a square?
Check the measurements of the sides, then compare diagonals
What does NG and FG stand for?
NG = Natural Grade
FG = Finished Grade
What does a site survey often include?
Taking elevations over the entire building and digging soil tests
What would an 11% grade be?
A slope with an elevation change of 11 ft over a span of 100 ft
How are grade stakes used?
Driven into the ground along grid lines & marked with the amount of cut or fill needed at each stake. Normally measured from the top of the stake.
What are the 3 methods for laying out over a sloped area.
1) Measure level then plumb down
2) Use Pythagoras theorem, to measure a long the slope
3) Using trig and measuring along the slope
If the layout is square, the diagonals will be:
Exactly equal or within 1 or 2 mm
The larger the triangle used in the 3-4-5 method, the more _____
The more precise your layout will be.
As part of the site survey, test pits are dug, what exactly was done in that process?
A test pit is dug to the full depth of excavation to determine the water table heights and what type of soil will be encountered during the excavation.
Do you immediately fill in a test pit after digging?
Leave the test pit open for several hours to find out if any water has seeped into the pit
What are the two meanings of the term Grade?
1) Surface of the ground on the job site. (EX NG or FG)
2) Grade also means slope - a 2% grade means that the earth drops 200 mm vertically for every 100 M traveled horizontally.
A 2% grade can be called what?
A 2% fall as well
Grading elevations are often established how?
By referencing them to a benchmark on or near the building site.
On large projects such as industrial sites and shopping centers, most grading takes place when?
Most grading takes place BEFORE excavation and a small amount of finish grading occurs AFTER the building is complete
Grade stakes located at the corners of excavations indicate what?
The depths of cut
Grade stakes are driven into the ground where?
At the intersection of the gridlines
The purpose of a grade stake is what?
To determine where soil must be added or removed
What does a very tall grade stake usually mean?
If considerable earth cutting and removal is required
What is a screed stake used for?
To set the elevation of the top of the concrete
For narrow slabs, what forms the screed usually?
The formwork usually forms the screed for narrow slabs
For wider slabs of concrete, what screed application is needed?
Intermediate screeds in addition to the formwork
What are screeds made from?
Wood or metal (usually pipe)
When are the screeds and wooden stakes removed?
After the strike-off
What is the usual spacing for screed stakes?
Between 6 ft and 12 ft OC
How are screed stakes placed?
They are placed in a grid pattern similar to the way grade stakes are placed
Stakes are either driven in or cut off such that the top of the stakes are even with the _________ of the top of the slab
Elevation
What tool is used to determine that the tape is being held close to level using the “Plumb down” method”
A string line level or an optical level
How to find the depth of slope?
COA = Adj divided by COS angle = depth (hypotenuse)
