Civil Engineering Chapter 27 Homework The Following Instructions Are Intended For Stair

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Exercise 27 Stairs 111

CAUTION

111

Exercise 27

Stairs

OBJECTIVE

The objective of this exercise is to properly install butt

Follow manufacturer instructions when using

equipment. Use caution when cutting and

installing wall materials. Obtain assistance when

lifting wall materials.

TEXTBOOK REFERENCE

Information related to this activity can be found in the

INTRODUCTION

Movement from one level to another in the landscape is

typically accomplished through the use of stairs. Stairs

can be freestanding (placed on an embankment without

enclosing walls for support) or constructed as part of a

Interlocking Stair Installation

Interlocking stairs should be constructed as the wall is

shorter than the width of a single piece of wall mate-

rial. For wider stair treads additional material will be

required. If special solid blocks are available for stairs, or

if alternative tread materials are used, increase the num-

ber of wall blocks below the tread to match the dimen-

sion required.

Use the following steps to install interlocking stairs:

• Widen the granular base trench where the stair

material extending back from the front of the wall

alignment (Figure 27–1A).

• Fill this widened trench with base material and

compact.

• Place the first course of the wall.

• Place the material for the first step directly behind

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112 Exercise 27 Stairs

• Excavate a base trench behind the first step for

the second step. This trench should be 18 inches

wide (or the width of two pieces of wall material),

6 inches deep, and match the length of the first

stair trench. Fill the trench with base material

and compact. If a tile is present, fill over the tile

without disturbing its level. Smooth the base

material so that it is flush with the top of the

previous step.

with wall material. The cheek wall should be

perpendicular to the wall face. Trim block as

required to fit. If building the wall with wood

or stone, remember that the cheek wall must

interlock with the wall face and that alternate

courses of the cheek wall will run to the face of

the wall (Figure 27–1C).

opening.

Butt Stair Installation

While butt stairs are simpler to construct, they are not as

stable as interlocking stairs. Because butt stairs are not

interlocked into the cheek wall, they may move up or

down at a different rate than the walls next to them, caus-

ing unevenness or irregularity. The following instructions

are intended for stair tread widths that are slightly shorter

• Retaining walls and cheek walls can be

constructed prior to or concurrently with butt stair

installation. The cheek walls are perpendicular

to the retaining wall and must extend beyond

the back of the stairs. Leave an opening for stairs

when constructing the wall and verify that the wall

material on each side of the opening is level across

the opening. Adjusting the width of the opening

to match material dimensions is also desirable.

Use of a batter on cheek walls will require cutting

material to fit.

• Widen the granular base trench at the stair

12″

12″ 12″

Left edge

Base material

Rerouted

tile

Wall first

course

Extra wall

material

Left edge

of stairs

Step B

Center line

of stairs

First

tread

Third

tread

Cheek wall

Interlocked

corners

Figure 27–1 Interlocking stair construction for tie/timber walls.

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Exercise 27 Stairs 113

the length of the first stair trench. Fill the trench

with base material and compact. If a tile is present,

fill over the tile without disturbing its level.

Smooth the base material so that it is flush with

opening for the stairs. The second step should

overlap the back of the first tread enough to

create the desired tread width on the first step. If a

capstone is used for the tread, the overlap should

equal the wall material width minus the cap width

(Figure 27–2C).

• Backfill and compact behind the step.

• Repeat the preceding steps for each subsequent

PREREQUISITE EXERCISES

Students should have successfully completed Exercise 5,

Tool Operation and Construction Techniques, Exercise 6,

MATERIALS REQUIRED

• Proper clothing and safety gear

• Cutoff saw or wet masonry saw (prepared for

operation)

• Chain saw (prepared for operation)

• Vibratory plate compactor (prepared for

First step

riser

Rerouted

tile

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114 Exercise 27 Stairs

EXERCISE DESCRIPTION

To complete this exercise construct two short wall seg-

ments three courses high, one with a 4 foot wide set

Second riser Third riser

4′

Figure 27–3 Plan for stair construction installation.

together. The stairs should run from a flat area up a

gradual slope.

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