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Stringer connection for outside concrete stairwell

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Aug 19, 2013, 03:14 PM
kal72
Stringer connection for outside concrete stairwell
We are replacing the exterior steps to our basement entry (8' concrete stairwell). The previous stairs were supported by three 2x10 stringers for a 4' wide tread. The 2 side stringers screwed to the sides of the stairwell AND into a ledger at the top with hangers along with the center stringer. Mid way up the stairs, there was also a support structure of 4x4 posts holding up the stringers.

1. Do I need to have the side stringers connected to the sidewalls, or can they just hang off the ledger at the top? i.e. the ledger connection should be all the strength they need? Maybe tapconing them to the sides just gave them lateral stability?
2. Do I need the mid-support structure that was there before? I assume three stringers for a 7-8 foot total rise should be fine with just the ledger connection?
3. Would I consider using 2x12s instead of 2x10s?
4. Can I get pre-cut stringers or is are those for when you have a little more flexibility on the rise and run and location of the bottom tread.
Aug 19, 2013, 05:57 PM
Jaybee
quote:
Originally posted by kal72:
We are replacing the exterior steps to our basement entry (8' concrete stairwell). The previous stairs were supported by three 2x10 stringers for a 4' wide tread. The 2 side stringers screwed to the sides of the stairwell AND into a ledger at the top with hangers along with the center stringer. Mid way up the stairs, there was also a support structure of 4x4 posts holding up the stringers.

1. Do I need to have the side stringers connected to the sidewalls, or can they just hang off the ledger at the top? i.e. the ledger connection should be all the strength they need? Maybe tapconing them to the sides just gave them lateral stability?

The stringers will be stronger if the end stringers can be fully attached to a solid wall on the sides. Frankly, if that wall is to remain then there is no reason not to use it so make a really strong stairway. However, for an 8' run three stringers can support a stair if built correctly and strongly supported at each end.
2. Do I need the mid-support structure that was there before? I assume three stringers for a 7-8 foot total rise should be fine with just the ledger connection?

You will need at least three stringers for a 4' wide set of stairs.
3. Would I consider using 2x12s instead of 2x10s?

Always use 2x12, never anything smaller. The cut-in points on material smaller than 2x12 is just too small to have any strength. Only if your stringers are also a ledger fully attached to the sides (like your existing stair) can you get by with lighter lumber for the stringers.
4. Can I get pre-cut stringers or is are those for when you have a little more flexibility on the rise and run and location of the bottom tread.

Forget pre-cut, you'll never find them in that size. Pre-cuts are only for an open stair where actual rise and run doesn't matter. As long as you are leaving from one fixed point at the bottom and going to another fixed level point at the top, you will need to make your own stringers.



Jaybee
Aug 20, 2013, 07:09 AM
kal72
What I meant in Question 2, was do I need support underneath the stringers midway up the stairs. There was a structure of double 2x4s that were used to hold stringers up mid way up the stairs. I guess to support the middle stringer that wasn't connected to the wall.

Also, if I attach the side stringers to the concrete wall, can I use tapcons? For a 10' long stringer would I have 2 tapcons every 2 feet or so?

This message has been edited. Last edited by: kal72,
Aug 20, 2013, 09:28 PM
Jaybee
If your old stringers were made from 2x10's, then that was the reason for the central support. If you make that center stringer out of 2x12, then you will not need the center support.

TapCons will work fine for attaching the two side stringers to the walls. I'd do a minimum of one under each step.


Jaybee
Aug 21, 2013, 07:43 AM
kal72
Thanks Jaybee.