A reinforced concrete slab is a common construction project, but a simple drawing can serve as an invaluable communication tool. The drawing is used as the basis for the contractor’s estimate, and establishes the parameters of the work. It’s not necessary to be an accomplished draftsman to produce a clear drawing of the intent. A plan view, showing the slab from above, and section view, to provide more information about the materials and dimension, and accompanying notes, is usually sufficient for basic construction. Familiarize yourself with drafting symbols, and draw to scale, but use notes liberally.
Tape paper to the table or board to keep it from shifting. Place the T-square on the edge of the table for horizontal lines, and support the triangle on the T-square for vertical lines.
Choose a scale for the slab layout that allows a plan view, a section drawing at a larger scale, and room for a title block and notes. Keep the drawing inside a border 1/2 inch from the edge of the paper.
Draw a horizontal line with the T-square, and a vertical line with the triangle, for the plan view, staying inside the border. Find the length and width of the slab to the selected scale. Finish the other two sides of the square or rectangle shape of the slab. Draw the lines firmly, using a dark pencil, and keeping it sharp with the knife or mechanical sharpener.
Apply the concrete symbol in the corners and scattered inside the square or rectangle. Draw the location for the construction and control joints, labeling them at the right of the drawing, connecting the note and the object with an arrow. Label the slab with a note below, or in the center of the slab, adding the area size, such as "Reinforced Concrete Slab, 16 feet by 24 feet."
Select a larger scale for a section drawing, to show the construction materials in a vertical cross section, placing it to the side of the plan view. Choose a point of connection, such as where reinforced steel bar dowels into a wall.
Draw the vertical information to scale, including the concrete, subgrade material and part of the original soil. Use a break line for the horizontal part of the slab,
Draw the concrete at the required depth, adding the symbol for welded wire mesh. Continue to the sub-grade material, differentiating symbols for compacted subgrade, and undisturbed soil.
Label the materials, adding notes for the size, spacing, and required concrete depth -- cover -- over the steel. Title the plan view and section view, at the bottom of each drawing. Add the scale at the bottom of each title.
Note the project title, address, drawing title, date, and your name and phone number, at the bottom left, staying within the border. Add general notes above the title block, including such information as the concrete strength, and additional information essential to the project.
Photocopy the drawing, or take it to a professional printing service. Revise the drawing as necessary, making sure to date the revisions. Remove outdated copies from circulation.