Cutting custom stair stringers-- what about the rise??
#8
  
Looking to replace the stairs at my church to a landing at the front door-- current stairs are rotting and not used, nor were they built to code--very awkward to step on.

I've watched some videos, as well as downloaded trex installation documents.  (I replaced the porch area with trex a few years back, and want the stairs to match).  In some of the videos, they talk about making the "run" of the stringers 9.75".  In the trex documents, they show a minimum of 11".  Considering the trex 1x6 boards are actually 5.5", I would think a little over 11", to have a little overhang.  
The one thing no one seems to account for is the riser boards.  In the trex documents, they seem to call for a 1x8 board--which the only 1x8's I can find are for fascia, and are about 1/2" thick.  Seems some like to put the treads on first, jammed all the way up against the rise of the stringer, where others seem to have the rise put on first-- is this just a preference thing?  Should I be adding a 1/2" to the run to account for the thickness of the riser?  No one seems to say anything about this.

   

Colin
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#9
  Re: Cutting custom stair stringers-- what about the rise?? by Cdshakes (Looking to replace t...)
Risers, I believe, are highly optional. They don't add structure.  So I think the material choice is yours.  1/4" thick might be enough.

The only thing I know for sure about stairs is that all the risers including the first and the last have to be exactly the same height.

https://www.google.com/search?q=stairs+w...66&bih=662
No animals were injured or killed in the production of this post.
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#10
  Re: RE: Cutting custom stair stringers-- what about the rise?? by Cooler (Risers, I believe, a...)
(11-14-2017, 01:11 PM)Cooler Wrote: Risers, I believe, are highly optional. They don't add structure.  So I think the material choice is yours.  1/4" thick might be enough.

The only thing I know for sure about stairs is that all the risers including the first and the last have to be exactly the same height.

https://www.google.com/search?q=stairs+w...66&bih=662

That is wrong.  Risers do add structure.  They help transfer loads across the stringers much better then just a tread as the riser is vertical.  Think of an I beam.

Also, since you will be kicking them with your toes the statement for 1/4" thickness is also poorly thought out.

They also do not have to be exactly the same height.  The code allows for up to 3/8" between the tallest and shortest riser... though you should aim to make them uniform.

Finally, for commercial use like a church they are not optional... they are mandatory by code.  Open risers are not permitted.

I've rebuilt decks for many people and added risers where they had been open and every one of the home owners were amazed at how solid and stiff the stairs now felt.  

I like to install the risers first and then the treads leaving an 1/8" gap to shed water.   For treated lumber decks I buy 1x treated wood and if I have to I will rip straight edges on them and use two butted to make a full riser.   Use adhesive to gain the structural effect.

As far as altering the tread depth I don't bother because all the added risers displace all the treads equally so the treads width ends up being the same (except for the top most where you have to compensate for riser thickness if joining directly to a deck)

Stairs are much safer with risers also. You can slip and jamb your foot into the open space.

regarded the OP's use of Trex.  I've made trex risers by using one full trex board and one ripped.  Butt them together and place the ripped edge on the bottom facing downward.
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#11
  Re: RE: Cutting custom stair stringers-- what about the rise?? by Splinter Puller ([quote='Cooler' pid=...)
(11-14-2017, 01:49 PM)Splinter Puller Wrote: As far as altering the tread depth I don't bother because all the added risers displace all the treads equally so the treads width ends up being the same (except for the top most where you have to compensate for riser thickness if joining directly to a deck)


Doesn't this affect the overhang of the front board over the riser?  I would think you need to consider this in the sizing of the run to include the thickness of the riser of the step below..?
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#12
  Re: RE: Cutting custom stair stringers-- what about the rise?? by Cdshakes ([quote='Splinter Pul...)
(11-14-2017, 03:53 PM)Cdshakes Wrote: Doesn't this affect the overhang of the front board over the riser?  I would think you need to consider this in the sizing of the run to include the thickness of the riser of the step below..?

No, The riser on the top step makes the stringer run length 3/4" shorter, but the riser on the 2nd from the top makes the run 3/4" longer again.  Make sure to add a riser on the bottom step. 
As an aside  wrt the bottom step.  The tread on the first step will add the thickness of the tread to the rise.  Make sure to trim the stringer bottom by that thickness to conform to uniform riser height.

Also, Think about where the top and bottom terminate.  I have seen stringers attached to a structure with an eight foot deep foundation and footer  terminate on a floating pad.  When we had an extended period of sub-zero temperatures the ground heaved enough to bend a couple of nails at the top and split a stringer.  (P.S- No longer code to just toenail and nail from the back. You need structural support for the stringers... Actually I don't think it was ever code, but I saw a number done that way.)



Edit:  Aha! are you attaching to a concrete landing with no overhang?  If so, then yes, add the thickness of the riser to the top tread  or alternately trim the top vertical part of the stringer adjacent to the pad the same thickness as the riser, just as you did for the bottom step. But you must also account for the thickness of the ledger board if you are attaching to one.
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#13
  Re: RE: Cutting custom stair stringers-- what about the rise?? by Splinter Puller ([quote='Cooler' pid=...)
(11-14-2017, 01:49 PM)Splinter Puller Wrote: That is wrong.  Risers do add structure.  They help transfer loads across the stringers much better then just a tread as the riser is vertical.  Think of an I beam.
I worded that poorly.  The risers are not part of the code consideration when calculating the structure.  So the stairs have to be to code with or without the riser in place.  That requires the correctly sized and spaced risers and the appropriate thickness of the tread for the width of the stairs.
So once the stairs are to code, adding the riser will add strength but strength that is not required by the building code.

As far as commercial buildings not allowing open risers, in the eastern USA that is not the case.  I used to travel with my dog, who for reasons I never understood, refused to ever walk up a open riser stairway.  In the hotels that had those open risers I had to take him to the room in the elevator even if it was just one flight up.

NOTE: This was a long time ago. When I look on line I'm not seeing any commercial buildings with open risers.
No animals were injured or killed in the production of this post.
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#14
  Re: Cutting custom stair stringers-- what about the rise?? by Cdshakes (Looking to replace t...)
(11-14-2017, 12:50 PM)Cdshakes Wrote: Looking to replace the stairs at my church to a landing at the front door-- current stairs are rotting and not used, nor were they built to code--very awkward to step on.

I've watched some videos, as well as downloaded trex installation documents.  (I replaced the porch area with trex a few years back, and want the stairs to match).  In some of the videos, they talk about making the "run" of the stringers 9.75".  In the trex documents, they show a minimum of 11".  Considering the trex 1x6 boards are actually 5.5", I would think a little over 11", to have a little overhang.  
The one thing no one seems to account for is the riser boards.  In the trex documents, they seem to call for a 1x8 board--which the only 1x8's I can find are for fascia, and are about 1/2" thick.  Seems some like to put the treads on first, jammed all the way up against the rise of the stringer, where others seem to have the rise put on first-- is this just a preference thing?  Should I be adding a 1/2" to the run to account for the thickness of the riser?  No one seems to say anything about this.



Colin

I install the risers first. Treads are installed with subfloor adhesive and 16d galvanized casing nails, hand driven with pilot holes. Risers are then nailed into the back edge of the treads with the riser flush with the top of the stringer. If you install the riser first you will gain 3/4" for the nosing. You can get 3/4" stock ,wood suitable for exterior or a Pvc product . Yes you add 3/4" to the run or whatever the riser thickness is.
I usually make the overhang 1-3/8", this may be too much for Trex, not sure as I have not used Trex for stair treads.
If you use PVC for the risers , note that Lowes sells Atez and HD sells a less expensive PVC trim that appears to be the same as Atez. 
mike
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