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# Round or Octaganol Deck Steps

#1
09-16-02, 07:33 PM
castrong
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Round or Octaganol Deck Steps

My son has asked his Dad to help build octagonal steps off the face of his (trex) deck (3 steps needed). Although my husband has built other deck stairs with basic stringers and treads, this latest request is stumping him. If anyone knows where we can obtain directions, it would really minimize additional gray hair and also further our son's apparent belief that his Dad knows how to do everything!! :-)

#2
09-16-02, 10:15 PM
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Join Date: Mar 2000
Location: Arlington, WA
Posts: 9,238
I'm not following what the problem is. If Dad can figure out how he would build these steps out of wood, that is exactly how he will do them with Trex, with only 2 differences.

1.) Trex is used ONLY for the treads, NOT for the structural portions of the steps (the stringers).

2.) Most 2X woods that are used for decking can be spanned 24". Trex has a maximum span (residential) of 20" and can only span 16" in commercial applications. So he may have to add an additional stringer.

#3
09-16-02, 10:24 PM
josh1
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lefty i think its the "octagon" thats got him?

Since its steps im thinking he really wants a "half octagon" up to the level of the deck?

The only difference will be the back of the stringers will be cut at an angle. An octagon is really just a squared up circle. Divide 360 degrees or 180 if its half octagon by 16 or 8. Each corner is 45 degrees so you need 22.5 cut on the stringer where it contacts the bottom and the rim joist most likely. Id draw some scale drawings on graph paper to get a good idea. Math isnt so bad!

How you go about attatching the stringers is varied alot of ways. One way is to cut an "extra" tread and riser and this goes behind the rim joist and can be screwed nailed to the joists or blocking if its perpindicular.

Havent built the octagonal stairs but really its just the matter of cutting on an angle when he cuts out the stringers.

Hope this helps-Josh

#4
09-16-02, 10:26 PM
josh1
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PS id cut the stringers in two stages. one with the saw at the 22.5 ( probably) angle for the risers and one with it at 90 for treads . Otherwise youll have some tilted treads! -Josh

#5
09-16-02, 10:40 PM
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Join Date: Mar 2000
Location: Arlington, WA
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OK Josh, I am following your thoughts. But, if it were me, I would simply attach my stringers squarely to each of the 8 faces of the octagon, and cut the treads of the steps at the 22-1/2 degrees to form the intesecting angles. Let the treads cantilever past the stringer.

#6
09-17-02, 12:55 PM
castrong
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Thanks for the replies! I guess my original post was a bit confusing. Sorry. My husband says that the steps are actually hexagonal but the concept was still pretty much the same. Lefty's reply to let the "treads cantilever past the stringer" is one of the solutions that he's already considered but he is worried that the cantilevered TREX won't be able to adequately support weight.

#7
09-17-02, 05:29 PM
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Join Date: Mar 2000
Location: Arlington, WA
Posts: 9,238
Your husband is correct in being concerned about too much cantilever, especially with Trex. One solution would be to install a diagonal brace under the cantilevered portion of the tread back to the stair stringer, or possibly a vertical leg under it to a small pad of concrete below. Another possibility would be to install a stringer (or a pair of stringers sistered together) to catch the ends of the treads in the corner where they meet.

#8
09-17-02, 06:25 PM
castrong
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Thanks again!!

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