[Vafa]

I am gluing up 8 pieces of 1 3/8" x 3 1/2" x 39 1/2" SYP to make a treads for my mono stringer stair(a mono look by covering or filling the 6" space between two stringer). I have a plan to cover it with hardwood in future when I accrue some experience and tools for veneering.
I did make one tread with regular wood glue 6 month ago and it's was on good shape until I left it outside of my garage, screwed to mockup stringer and it ruined by rain
The tread is not suppose to be out side and it gonna live in an air conditioned house. So no worry about more rain.
Because it's tread and it's gong to be under human weight, I was worry about long term durability/reliability on those glued up pieces. The stringer is going to touch 7 pices 100%, and and 1/3 of nosing piece.
The treads going to hold down by a lag screw to the stringer from bottom of stringer. (probably 4 long hole have to dig in stringer to bring lag screw close to treads).
Should I just use regular wood glue or there is a different/better application for such a abuse?
Based on my plan to bleach the wood, What finish you suggest for this application? I found some mate/non slippery polyurethane for treads, Dose it bring yellow color back to SYP in future?


Thank in advance for you advices.

This is the design:

 

[DrRobert]

Any wood glue is fine. I usually use TiteBond 2 for general ww’ing.

Polyurethane generally yellows a little, shouldn’t look bad on SYP.

How are you going to fasten treads to risers?

 

[Steve Neul]

I would use any wood glue since it's for interior use.

 

[Vafa]

How are you going to fasten treads to risers?

I mentioned already:

The treads going to hold down by a lag screw to the stringer from bottom of stringer. (probably 4 long hole have to dig in stringer to bring lag screw close to treads).

I got the idea from builders reply to comments under this video. He also mentioned that he made the stringer 1/3 width of the treads.
Still not sure about size of the screw. What I tried was 3 1/2 deck screw and it was acceptable but I probably going with something like this.

 

[builtinbkyn2]

Boring holes from the bottom of the stringers to accommodate the washer head of these screws will weaken the stringers and probably make the whole run of stairs "bouncy". His design is vastly different from your design. I would guess he lag bolted thru the top of the treads into the stringer and then covered the bolt holes with more material. His treads look like a sandwich with a layer of hardwood on top. Also, in your design, the tread will act like a lever when a person stands off-center of the stringer. This will pull up on the threads of your screw which will then want to pull out from the wood. Not a good design in my opinion. I'd rethink how you are going to go about this.

 

[kwoodhands]

I am gluing up 8 pieces of 1 3/8" x 3 1/2" x 39 1/2" SYP to make a treads for my mono stringer stair(a mono look by covering or filling the 6" space between two stringer). I have a plan to cover it with hardwood in future when I accrue some experience and tools for veneering.
I did make one tread with regular wood glue 6 month ago and it's was on good shape until I left it outside of my garage, screwed to mockup stringer and it ruined by rain
The tread is not suppose to be out side and it gonna live in an air conditioned house. So no worry about more rain.
Because it's tread and it's gong to be under human weight, I was worry about long term durability/reliability on those glued up pieces. The stringer is going to touch 7 pices 100%, and and 1/3 of nosing piece.
The treads going to hold down by a lag screw to the stringer from bottom of stringer. (probably 4 long hole have to dig in stringer to bring lag screw close to treads).
Should I just use regular wood glue or there is a different/better application for such a abuse?
Based on my plan to bleach the wood, What finish you suggest for this application? I found some mate/non slippery polyurethane for treads, Dose it bring yellow color back to SYP in future?


Thank in advance for you advices.

This is the design:


View attachment 444693
View attachment 444694

The dimensions indicate a 13-3/4" overhang each end. I would widen the stringers so the overhang is 3" or less.
Your design does not show risers. I haven't worked at the trade for a while as i am retired, from what I recall risers are required inside a home. Check with building inspector about this.
Titebond 1 is fine for the glue. Simpson angles and lag screws to fasten the treads to stringers. Risers hide the angles.
mike

 

[B Coll]

I am gluing up 8 pieces of 1 3/8" x 3 1/2" x 39 1/2" SYP to make a treads for my mono stringer stair(a mono look by covering or filling the 6" space between two stringer). I have a plan to cover it with hardwood in future when I accrue some experience and tools for veneering.
I did make one tread with regular wood glue 6 month ago and it's was on good shape until I left it outside of my garage, screwed to mockup stringer and it ruined by rain
The tread is not suppose to be out side and it gonna live in an air conditioned house. So no worry about more rain.
Because it's tread and it's gong to be under human weight, I was worry about long term durability/reliability on those glued up pieces. The stringer is going to touch 7 pices 100%, and and 1/3 of nosing piece.
The treads going to hold down by a lag screw to the stringer from bottom of stringer. (probably 4 long hole have to dig in stringer to bring lag screw close to treads).
Should I just use regular wood glue or there is a different/better application for such a abuse?
Based on my plan to bleach the wood, What finish you suggest for this application? I found some mate/non slippery polyurethane for treads, Dose it bring yellow color back to SYP in future?


Thank in advance for you advices.

This is the design:


View attachment 444693
View attachment 444694

That is a lot of laminations you have to do. Have you considered using a Glulam beam?

 

[Vafa]

Boring holes from the bottom of the stringers to accommodate the washer head of these screws will weaken the stringers and probably make the whole run of stairs "bouncy". His design is vastly different from your design. I would guess he lag bolted thru the top of the treads into the stringer and then covered the bolt holes with more material. His treads look like a sandwich with a layer of hardwood on top. Also, in your design, the tread will act like a lever when a person stands off-center of the stringer. This will pull up on the threads of your screw which will then want to pull out from the wood. Not a good design in my opinion. I'd rethink how you are going to go about this.

I am not worry about those two weakened stringers with 3/8 holes all along because I have 7 or maybe 8 more stringer all joined together between them to make the mono stringer.
As I said, He mentioned in comments that he bore a hole from buttom and used a lag screw.
I think screwing from top or bottom doesn't make any difference. the buttom has a advantage of not having to cover the holes or just dry-plug it and make the treads fully maintanable.

That is a lot of laminations you have to do. Have you considered using a Glulam beam?

Each of this tread that I'm making, cost me $17 wood which is 1/4 cost of the beam. It was taking me 2 hours to build one of this treads and 30 minutes planing and sanding it. 16 to go.

The dimensions indicate a 13-3/4" overhang each end. I would widen the stringers so the overhang is 3" or less.
Your design does not show risers. I haven't worked at the trade for a while as i am retired, from what I recall risers are required inside a home. Check with building inspector about this.
Titebond 1 is fine for the glue. Simpson angles and lag screws to fasten the treads to stringers. Risers hide the angles.
mike

We want something minimal so widening the stringer are against the design. I had a same concern and build myself a mockup and tried it before actual build.
International building code allows stairs without riser if the opening between treads not execs 4". That's why I'm building 3.5" treads.

 

[Vafa]

Boring holes from the bottom of the stringers to accommodate the washer head of these screws will weaken the stringers and probably make the whole run of stairs "bouncy".

I took your advise and revising the treads connection to stringer. It's just making it easier to do and less problematic if I don't bore those 12 inches 5/8 hole all along the width of treads. Instead I'm making a pocket hole jig with 5/8" hole to bore a hole from side of stringer and drive this 4" long screw:

I am still joining one 2x6 to each stringer.

 

[Vafa]

Just some update,
Things going very slow.
The kiln dried lumbers was bought last year and air dried in my garage as well. No way to pass them trough the 6" delta jointer and just couple of pass with electric hand planer and not impressed with the result!
Planed and they are pretty straight. Cut on miter-saw and hand saw.

I made the attachment for my Kreg jig with brass bushing.

It was making a perfect hole until I start doing it on the actual stringer and it failed on forth hole!

It was several parameter involving the failure, Including but not limited to the low quality augur bit and the glue.

I just gave up on the 5/8" lag screw and switching to 2 1/2 Kreg screw and adding one extra screw on each side.

Also got advice from structure engineer regard the stringer connections to headers and making sure every thing is code compline.

The live and dead load together are less than 300lb on each tread so any force can be handled by 3 screw on each side, total of 6 for each tread which based on my calculation with considering lever action of the treads on stringer, SYP specification and this force test results on cedar, can hold up to 2255lb of uplift. The 300lb dead and live load will make uplift force on 857lb. I did not considered/compared my wider 12" joint anywhere in my calculations I saw in post test just to be in safer side.

I am gonna lightly painted with white latex paint to give the wood less orange look and put the water based poly on top. Will sand between coats. Under 50F temperature here in Texas didn't let me do any glue up or finish work.

Will glue/screw the supports to the stringer tonight and will start with making a proper post for landing header which it need a drywall removal and installation, texture and paint all over the area.
Making the tread and finish and install them will be the last thing before starting the railing 🤦‍♂️. Too much to do ha?

 

[Half Fast Eddie]

I give you credit for trying something different. But i would not walk on those treads, except exactly in the middle. Looks like a hazard.

 

[builtinbkyn2]

Thru bolts may be the only way this isn't a hazard, and even then I don't believe this is a good idea. Sorry to say that, but you're utilizing soft wood vs hardwood and that totally changes the soundness of the design you are trying to mimic. Ask your engineer if they will put their seal on this. That will give you your answer. Hate to be a downer, but you would hate to have someone seriously hurt in a failure. This design can be accomplished, but it requires the proper design, materials and fastening components. You haven't mentioned handrails. That's a local code issue you will also need to address.

 

[Olwoodguy]

I can say this. I have built stair cases with 4"×48" treads. Larger wood moves more. For strength I adopted angle iron into the design. 1/4"×3"×11". 1 on each side. Painted galvanized 3/8" bolts satin black and the angle iron satin black. I like the look of iron and pine. Classic. Used acorn nuts on the bottom. Looked really nice and the added extra support from the bottom helped it have longevity.
Anyhows that is how I dealt with it. Doing stairs can be a place to really accent a room. I always used titebond 2-3. And usually varathane brand polyurethane. But on steps that would be difficult to repair. Deft brand laquer only requires a light sanding and topcoat. Just how I handled it

 

[Vafa]

Thru bolts may be the only way this isn't a hazard, and even then I don't believe this is a good idea. Sorry to say that, but you're utilizing soft wood vs hardwood and that totally changes the soundness of the design you are trying to mimic. Ask your engineer if they will put their seal on this. That will give you your answer. Hate to be a downer, but you would hate to have someone seriously hurt in a failure. This design can be accomplished, but it requires the proper design, materials and fastening components. You haven't mentioned handrails. That's a local code issue you will also need to address.

One of the reason that I'm sharing this with you is to hear your different idea and this was very helpful on finding my weakness. So don't feel bad by sharing your thought.
He's design was my reference only in term of using wood for this kind of stair, Other that that I used engineer to make sure about structure and connection because there are difference in the project, He had a post and I have a landing. I liked to use his way of connecting treads to stringer because it was something to not leave any track of fastener on treads, But I took your advice on not making hole all along the width of stringer and I went with pocket hole and change the design. The lag screw as my calculation say is gonna be over design and 2 1/2" pocket hole screw giving me enough strength. I still have several option to strengths up the treads if something big is missed in my calculations. So not much element left from his design on mine.
The pocket hole screw that I use is designed for softwood. Carpenters use same wood and nail to do the same job with the differences that I'm thinking I am compensating.

It will be a code compline hand rail with wooden posts and 3/8 cable only on open side. I will follow International Building Code for the height and maximum opening.

 

[Half Fast Eddie]

Other that that I used engineer to make sure about structure and connection because there are difference in the project,

The lag screw as my calculation say is gonna be over design

It will be a code compline hand rail with wooden posts and 3/8 cable only on open side. I will follow International Building Code for the height and maximum opening.

If you used an engineer for part of the design, you should have him work out all the details. The lag screw comment bothers me.

Cable rails are not compliant. And you can't have open risers.

 

[Vafa]

There are facts for each of my decisions i mentioned in this threads. That's make me comfortable building it and walk on it.
The 2.5 in pocket hole screw is in same category with the lag screws. I'm inviting you to look at the numbers on this official test.
Building code doesn't force what material use for railing. All concerns is about opening and gaps that cable fill that out. I may confused you on cable and railing, The hand rail is not gonna be ⅜ cable, it's gonna be ~3" wood. I didn't mention but I have an architect in-house(my spouse) for this kind of details