Open stairs - glue and screw, or just screw?


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Old 07-30-22, 12:10 PM
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Open stairs - glue and screw, or just screw?

I'm making a set of open tread stairs, and am going to mill a 1/4" pocket for each step. I'll use heavy duty FlatLok screws on the side for aesthetics and to hold the step in the pocket (I like the look of the flat washer head on the riser). Do I need to use a construction adhesive (ie, not liquid nails, but rather PL premium or something like that without moisture) or are screws sufficient? I'd like to keep my options open if I ever decide to relocate the stair or repurpose it. I suppose there may be creaks if I don't use any adhesive.

Thanks!
 
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Old 07-30-22, 03:46 PM
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Open stairs typically aren't allowed any longer by code. (4" sphere rule) . But we don't know your code so can't say for sure.
 
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Old 07-30-22, 04:59 PM
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Code not withstanding, I would use the glue or mastic in addition to the screws. Is this inside or outside?
I can't believe open tread stairways are not allowed since so many style and types including spirals would not fit a closed style decor. They are not banned or against code!

The 4" spherical rules refers to an open stair case without walled side. Or another words railing with vertical support where there are no walls to support a rail.

Is that what you're refering to or do you mean an open tread without a backing?
 
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Old 07-30-22, 06:39 PM
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Here is an example of the code I am referring to. FYI, open tread means no riser... or an opening between adjacent treads. Spiral staircases are covered under exceptions.

R311.7.5.1 Risers.

The riser height shall be not more than 73/4 inches (196 mm). The riser shall be measured vertically between leading edges of the adjacent treads. The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm). Risers shall be vertical or sloped from the underside of the nosing of the tread above at an angle not more than 30 degrees (0.51 rad) from the vertical. Open risers are permitted provided that the openings located more than 30 inches (762 mm), as measured vertically, to the floor or grade below do not permit the passage of a 4-inch-diameter (102 mm) sphere.

Exceptions:
  1. 1.The opening between adjacent treads is not limited on spiral stairways.
  2. 2.The riser height of spiral stairways shall be in accordance with Section R311.7.10.1.
❖ The code establishes that the maximum riser height is 73/4 inches (197 mm). The provisions specify how the riser height is to be measured [see Commentary [url=https://codes.iccsafe.org/s/IRC2015/chapter-3-building-planning/IRC2015-Pt03-Ch03-SecR311.7.5#IRC2015_Pt03_Ch03_SecR311.7.5.1_FigR311.7.5.1_1]Figure R311.7.5.1(1)]. The uniformity of risers and treads is a safety factor in any flight of stairs. The section of a stairway leading from one landing to the next is defined as a flight of stairs. This is important because variations in excess of the 3/8-inch (9.5 mm) tolerance could interfere with the rhythm of the stair user. It is true that adequate attention to the use of the stair can compensate for substantial variations in risers and treads; however, the stair user does not always give the necessary attention.

To obtain the best uniformity possible in a flight of stairs, the maximum variation between the highest and lowest risers is limited to 3/8 inch (9.5 mm). This tolerance is not to be used as a design variation, but its inclusion is in recognition that normal construction practices give rise to variables that make it impossible to get exactly identical riser heights and tread dimensions in constructing a stairway. Therefore, the code allows the variation indicated in Commentary Figure R311.7.5.1(2).

The risers must be vertical or slope back, effectively providing a wider overall tread depth. The code does not require solid risers, but riser openings that are located more than 30 inches above the floor or grade below must not allow the passage of a 4-inch-diameter sphere. This is consistent with the guard provisions of Section R312, where a 4-inch (102 mm) sphere is used to determine compliance.

For spiral stairways, the openings between adjacent treads are not limited and riser heights are regulated by Section R311.7.10.1.
 
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Old 07-30-22, 06:44 PM
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To make them code compliant I am putting a horizontal rod between the steps, fyi.
 
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Old 07-30-22, 06:49 PM
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Perfect.
 
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Old 07-30-22, 06:55 PM
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​​​​​Code not withstanding, I would use the glue or mastic in addition to the screws. Is this inside or outside?
These are indoor stairs, to a loft.

What will the adhesive do that the screws won't? The screws are unlikely to work themselves out - I'm using heavy-duty timber screws:

https://www.fastenmaster.com/products/headlok

Additionally, my treads are 2" thick - while cracking could be a possibility, it's unlikely multiple treads would crack, so the treads above and below the cracked tread would keep it in place.

I guess - well here's the thing - I'm a belt and suspenders type of person... so my normal mode is glue+screw but for these stairs I'm concerned I may want to disassemble them one day. Will adhesive stiffen the tread? Prevent squeaks?
 
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Old 07-30-22, 07:29 PM
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open tread means no riser... or an opening between adjacent treads.
And that is exacty what the OP posted and is exactly what I was refering to.
All the tech talk and specs are great but the bottom line is that OPEN tread means no backing. Open stair case means no suporting side on one or both sides.
My question was one of clarification.
All construction has specifications of some sort and codes that should be followed that allow up to or including openeings, size, weight , ect...
So if I understand the OP's other posts, the treads are open and he will add some type of blocking (horizontal rods) and one or both sides are not against a solid wall. I don't believe (without actual measurement's that those rods are needed, but that is OP's choice).
You ask the question and I offered the glue as an answer. But a lot depends on how often they will be used and what type of traffic they will see. I also will always look at the possibilty to remove or relocate a building product or process, but a set stairs most likely will never be moved. Although I did in one case do exacly that. So you never know.
 
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Old 07-31-22, 04:27 PM
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You ask the question and I offered the glue as an answer. But a lot depends on how often they will be used and what type of traffic they will see. I also will always look at the possibilty to remove or relocate a building product or process, but a set stairs most likely will never be moved. Although I did in one case do exacly that. So you never know.
Used by one person, stairs are in an outbuilding / workshop space. Maybe see traffic once a day (up+down)? I don't quite know, honestly, as I'm putting in a second floor at the same time and so as I finish the second floor space it might get used more often (especially since I work from home most of the week).
 
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Old 07-31-22, 04:43 PM
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If you want to keep your options open to remove it without destroying it, you cannot glue it. So that is completely up to you. Glue makes the stairs as strong as possible by limiting movement. If they are permanent it's a no brainer. Glue it. If you want to take them apart someday, don't. Yes, it might creak a little.
 
 

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