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Posted by rh on January 22, 2007, 10:19 am
tbasc@bellsouth.net schrieb:
> Richard wrote:
> > I put the technical data at the end of this email.
> > I'll give you the Blah, Blah, Blah first.
> >
> > I tore out the old interior staircase from the
> > 1st to 2nd floor in my house. The old staircase
> > had 2 stringers.
> >
> > I cut 3 stringers and when I put the middle
> > stringer in it severly limits the head clearance
> > when I go down the basement.
> > Because of this, I would like to omit the middle
> > stringer.
> >
> > I'm about to screw and glue and I've
> > asked everyone I know what to do and
> > I get conflicting opinions. If some of my
> > advisors wouldn't throw in comments
> > about the decreased weight capacity
> > of the staircase, that 3rd stringer would
> > already be in the coal stove.
> >
> > Location: Interior 1st to 2nd floor
> > Stringer Length: 14 feet
> > Stringer Lumber: 2x12 pine
> > Tread Thickness: 1 inch
> > Tread width: 31 inch
> > Tread Depth: 10 inch
> > Building Inspection: No
> >
> >
> > Is this a bad idea? Is 2 stingers enough for a
> > stairway 31 inches wide?
>
> Double stringer each side.
> Glue and nail or screw the paired stringers.
> Load test a tread for the 31 inch span.
> It should pass the test.
> TB
Hallo, Richard ,
Stringer Lumber: 2x12 pine
The Stringer Length: 14 feet has much more influence on the necessary
dimensions of the stringers than the tread with, if You only make the
treads thick enough.
Tread Thickness: 1 inch by Tread Depth: 10 inch will carry most
people. To my feeling, an educated guess based on a rather similar
stairs in my house, the deformation of the tread could be enough to
produce a noise a the joints when You use the stairs. A bit thicker,
1.5 Inches or at least 1.25 would be welcome.
With Tread Thickness 1.5 Inches I am rather inclined to take only 2
stringers, but they need to be thick enough. A cursory calculation
affirmed this by far. NO GUARANTEES! I have no inclination to end in
front of an American court.
There is however another problem: Beams that are much higher ( 12 '' )
than thick ( 2 '' ) want to lay on the side. You have to make sure that
the stringers remain in the upright position. In several old houses I
have seen the screwed to the adjacing wall.
But do not inhibit the deformation due to seasonal changes in moisture.
Invent a sort of clamp or drill bigger holes into the stringers than
the bolts would need and use washers.
To make it real clear or just for the fun of it: mail me at
tips-01@ideenschmiede-rh.ch
Greetings and good luck rh ,
a long time ago engineer
for mechanical resistance (stress and strain)
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