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 CONCRETE-STAIRS

CON-TEC VENTURES LTD  



25mm=1" ...metric conversion


CONCRETE STAIRS

LAYOUT CONCRETE STAIR
CONCRETE STAIR LAYOUT

Open  concrete stair way
Set up temporary walls to actual size and on this wall:
Sketch out actual stair false work ..measure and mark lines as follows

 1) top concrete-stair landing risers 6 x rise of 190 = 1140 off of finished floor
(make sure floor is level) snap a level line 800 long at this elevation this
represents top of concrete landing

2)now go to floor and duplicate this same line on floor and add to it the
run of the stairs use 6 run x250 (1500) and mark the floor
(your total length 800+1500=2300)  from this point on the floor snap
a line to the top of the landing were the stairs begin... this gives you your nosing
 line for stairs

3) now on this nosing line ... starting at  the floor mark out your bridge measurement
(rise..190 squared plus run..250 squared = x the square root of x is your bridge
 measurement)314 mark it on the nosing line 6 times going upwards to edge of landing
.. this indicates the nosing edge of each stair

4)mark a  plumb line down 190 from each nosing point.. this gives you bottom of riser

5) mark a level line which represents the tread... from the nosing point past the bottom
of each riser by 25 then join this mark to the nosing of riser above this gives each stair
 its nosing

6) now snap a line from the bottom of first riser to the bottom of the six riser this gives you
top of concrete-stair throat

7)measure and mark from two points on throat line ..the depth of the throat 150 at ninety degrees
from throat line ... these two points represent the bottom of the throat...
 snap a line from the floor to the landing... this line is the top of your 19 plywood soffit

8) measure down 19 for plywood snap another parallel line ..indicating bottom of soffit plywood
and top of you2x4 stringer measure down 89 (3.5")and snap another line..giving you
bottom of stringer

9) mark out bottom of landing 150 below first landing line..gives bottom of concrete
measure down 19 snap line ..gives bottom of plywood soffit
measure down 89 snap line gives you bottom of landing joists


Stand back and look ... all your angles and measurements for the concrete-stairs are there on the wall



Cutting schedule using wall patterns see above blueprints for matching cuts:

Joists 38x89
 A...4 soffit stair stringer joist see wall pattern
B...6 joists for landing              "     "      "
C...2 supporting joists for soffit  "     "      "


Posts 38x89
D... eight for landing
E...four for mid stair

Soffit 19 plywood
F...stairs
G...landing

Side 19 plywood
H...side stair
I...side landing

Inverted stair stringer 19 plywood
J ... to wall pattern three times left, right,centre


38x89 plates and kickers
K...stiffeners for form sides
L... plates for form sides
M... kicker plate re edge of soffit to nail braces to

19 plywood
N...Gussets 8pcs
O...braces 4pcs
P...Post braces
CONCRETE FORM STAIR RISER
BRACE TEMPORARY WALL AND NAIL ALL GUSSETS THOROUGHLY CONCRETE WEIGHT
CAN DESTROY THINGS IN THE BLINK OF AN EYE

BRACE BOTTOM RISER TO FLOOR IN THEORY IT CARRIES ALL THE WEIGHT OF THE CONCRETE-STAIR THROAT

DO NOT FORGET THAT CENTRE STRINGER IT KEEPS THE RISERS FROM BENDING

USE 15M STEEL @ 12 INCH CENTRES BOTH WAYS

POUR FROM TOP OF STAIR AND VIBRATE DOWN TO FILL ALL AIR POCKETS... ONCE POURED HAMMER TAP RISERS THEN FINISH

DO NOT TROWEL STAIRS LEAVE WITH A BRUSHED OR FLOATED SWIRL NONE SLIP FINISH

CURVED RISERS WITH NOSINGS MUST BE CUT IN AN ARC SO THAT WHEN THEY ARE BENT AROUND THE CURVE  THEY STRAIGHTEN OUT.... I HAVE ONLY DONE A FEW CURVED STAIRS WITH THE STANDARD 1" NOSING THE ARC IS .O255 TIMES LENGTH OF THE RISER EXAMPLE A SIX FOOT LONG STAIR WIDTH WOULD HAVE AN ARC OF 6'X .O255 X12"=1.836"
THIS IS THE DISTANCE FROM THE CHORD OF ARC TO CIRCUMFERENCE
concrete stairs forms

strong backs concrete stairs

concrete stringer
FORMING STAIR STRINGER
INVERTED CONCRETE STRINGER
CONCRETE STAIRS HOW TO USE BRIDGE MEASUREMENTS
CUT LINES FOR CONCRETE STAIR
CONCRETE STAIR NOSINGS

CRANED IN PRECAST STAIRS FORM WORK

FORMING PRECAST CRANE IN STAIRS
PRE CASTING CONCRETESTAIRS
PICTURE 1 SHOWS
LAYING OUT A BASE OF 4X6 INCH TIMBERS AT  ONE FOOT CENTRES...
 LAY A 21 INCH  STRIP OF PLYWOOD DOWN THE CENTRE AND NAIL ONE NAIL PER TIMBER ON EACH SIDE OF PLYWOOD
...CUT 2X4 WALER STRONGBACKS TO RUN FROM GROUND TO TOP OF STAIR WIDTH (VARIES WITH STAIR WIDTH
...NAIL WALERS TOGETHER WITH SPACERS
... SPIKE TIGHT TO PLYWOOD... THRU TO 4X6 TIMBERS
.... BRACE BACK AT ABOUT TWO FOOT LEVEL THESE BRACES WILL PICKUP A WALER AS YOU CONTINUE TO BUILD
CONCRETE STAIR DETAIL
AS FLOWN CONCRETE STAIRS
REVERSE CUT STRINGERS
START THIS STEP BY:
...by nailing paper face forming plywood to  2x4 strong backs at twelve inch centres
...stand this up against vertical strong back walers and spike off
...cut the reverse stringers as described above and nail in place to plywood panel
... picture below shows the 2x7 (7 is rise) lumber nailed to plywood sheathing and also to reverse stringers
... these will be have to be special cuts depending on stair rise and run
...this strengthens form work and gives nailing surface for plywood tread and risers


CONCRETE STAIRS


POURING CONCRETE PRECASTS
PICTURE FIVE
... rip risers( plus plywood 5/8s) required rise
..note a 7 degree angle bottom  will make these fit nicely against stringer
...cut top of rip  at 45 degree angle will support tread paper side of form plywood sharp side of angle
...to close each stair, tread is ripped at desired width
...note bottom riser has return to meet bottom of stair throat
...top riser is shorten to fit into landing.. you will have to think this through to make it work perfectly
...remember to undercut tread to allow for drainage slope ...see risers above
...use silicone in seams to ensure a solid clean fit ... make sure silicone is cleaned from paper face as it will wreck finish



NAIL SECURELY
CLOSE UP PANEL
...close up as shown pay attention to the returns at top and bottom use extra 2x backing as required
...throat is as required by designer
...temporary spreaders should be used at top and pulled at end of pour
CLOSE UP WALERS
...close up panel should be pre built with plywood and walers nailed together before  closing
... nail bottom plate in position with duplex nails to hold close up panel in place
TAPER TIES TOP AND BOTTOM
....taper ties placed under and over form work as dry ties
...oil forms well to ensure multiple uses
POURED READY TO STRIP 





DIVISION CON-TEC VENTURES LTD.
Please note: verify all sizes and specifications
with your local building codes.
copyright Samuel Roy Chambers
CONTACT 250 510 4831

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