Notched stringer, top stair tread not wide enough

[pm634]

I have installed new oak stair treads in place of the original pine planks. Due to the stringer being notched and the top stair having the structure of the top floor directly behind it, I couldn't slide it in from the back like the other stairs. I installed it at and angle and with a little encouragement got it in there eventually. There isn't much overlap in the notch underneath and in the progress of cramming the tread in there, there is really nothing to wedge it up against. My question is what the best way to resolve this is?

Can I just cut a piece of wood (say a 2x6) and sister it to ther stringer for only this step using some 16D nails? Is there a better, more appropriate repair? I don't think I did, but I'm crossing my fingers I haven't done irrepairable damage to the stringer and need to have it replaced

 

[hokie66]

A sketch of what you have done would help. Doesn't sound good.

 

[pm634]

Hope this helps...

 

[msquared48]

Other than the stair tread falling through due to a possible lack of bearing, I do not see much of a problem. If you are concerned about this, a 2X block under the tread should handle that.

You have not altered the stair jack from what it was as far as I can determine, and the stair tread of concern is at the top of the jack span. So where is the perceived problem?

Mike McCann
MMC Engineering

 

[dhengr]

That’s called a “housed stringer” system of stair building. I understand the new tread is still o.k. but you don’t have much bearing in the routed housing dado, because of the way you had to trim the end of the tread to get it in there. You want to be careful not to have spread the stringers apart in doing what you did. I would cut triangles from a 2x6, or whatever, grain orientation to match the stringers, maybe a 3/4" pcs. of plywd., to fit against the lower riser, and match the slope of the wedge shaped bottom of the dado. Glue and screw these triangles, in place and to the stringers, and then use a wider wedge which will engage both the stringer dado and your added triangular blocking.

 

[pm634]

Great, since I did not touch the bottom part of the dado or eat into the thickness of the stringer I did not think I did anything too bad. Thanks for re-iterating.

msquared48, My concern is precisely what you suggest. I am moving out of the house and just did the work about 6 months ago and haven't had a problem, but need to get it inspected to make it 100% legal before I list the house.

dhengr, The stringer is secured on both sides to structural walls. I'm not worried about having spread the stringers apart.

The wedges that were put into dados extend out a little. I can use a little dremel saw to cut it out if needed. I put a little sketch of what I intend on doing attached (excuse my crude word drawings). Let me know if I misunderstood your explanations at all. The 2x would be flush against the stair tread and the riser for stair below. The plywood and 2x should be glued together and screwed to the stringer or glue them all together? What type of screws should be used?

 

[dhengr]

I meant the 2x6 ..OR.. the 3/4" plywd. triangular blocking, not both together; and that it should be cut approx. to match the stringer triangle, back of the riser, sloped wedge surface (plane) and bottom slope of the stringer. But, the important thing would be for the blocking top surface to match the wedge plane. Then glue and screw the blocking to the stringer, to rebuild and widen the wedge plane. And then, use a wider wedge to engage both the dado and the new blocking to increase the bearing width.

I’m not quite sure what I expected to see, but your second sketch is kind of a mess. What good do the wedges do now, if you don’t have anything to drive the tread up into or under, and the tread is cut too short. Given what you show, I’d just use 2x triangular bearing blocks, or a couple layers of 3/4" plywd. all glued and screwed together and to the stringer; set at the horiz. elevation of the underside of that tread and nail the tread down to the blocks. I don’t know how you are going to fill all the chiseled/cut out gaps.

 

[pm634]

Yeah, I realized I overanalyzed your response. I somewhat exagerated the sketch to get the point across. I ended up cutting 2x lumber to the size of the triangle underneath the tread. It is flush with the bottom of the tread and the wedge for the riser on the step below. I drove 2 nails through each side of the tread to secure it to the new support and filled in the holes with some wood filler to make it look much less offensive.

As a far as gap created where the top part of the dado used to be, as I said it is somewhat exagerated and at this point doesn't serve much of a functional purpose so it just needs to be filled. Probably need to apply a few coats of compound to fill it, smooth it out and should be good to go.

Thanks for your reponses!