Greetings,
(repost since I'm locked out of the first one trying to get the photos uploaded. Just posted links to the photos-mods delete the other one if you will...)
I've done a few laminate and hardwood floor DIY projects in the past but looking for ideas on how to finish off with trim against stairs that end with a curve.
First problem-curved last step:
I understand the need to leave an expansion gap between the hardwood floor and the wall so when it comes to a curved step that will be carpeted any advice on how to finish that gap? (note- the carpet is old and will be replaced in a few months after the floor goes down)
First idea: leave the expansion gap and when the carpet is replaced, add some luan along the rise to build it out so when the carpet is replaced it will overhang that expansion gap
Second idea: cut away the carpet and add a molding such as below then 1/4 round off that. Then the new carpet can run up against that molding. https://www.homedepot.com/p/Alexandria- ... /302681059
(main concern is will it bend enough)

https://imgur.com/4tefgaY]

Second problem-stair railing trim work
Next problem is part of the stair railing goes straight down and how to trim that out.
First idea: is to cut out the trim/stair 2x10 so that the hardwood can float under it. Similar to cutting out the trim at the base of a door so the floor can slide under it.
Second idea: 1/4 the hell out of it. (I just think this would be prone to catching toes coming down/turning around the stairs.

https://imgur.com/BqpHUrX

https://imgur.com/8OkcPaH


General trim question-In the past I have done laminate and hardwood in an enclosed room. What I did was pull the trim (repaint) and install the flooring first then drop the trim on top to cover the expansion gap. First time I'll be doing with room transitions where dropping the trim on top would cause an uneven trim transition between flooring types. Is it best to put the trim on first (replacing the trim), hardwood up against the trim + expansion then 1/4 round it?

The easiest way to lay flooring around a curved step is to undercut it. This will leave room for expansion underneath. Cut the carpet back and slide a saw along the top of a board for the correct height before building paper is put down.
No need to ever use quarter round for floor trim. if necessary use base shoe. Quarter round is the last resort if you can not find the right trim.
If you can undercut the skirt board without cutting completely through it will still support the treads.
An electric under cut saw really make for easier work. It could be used for undercutting a fireplace hearth if it is raised, too, with a diamond blade.

thanks
so I can assume it's just some kind of plywood under the carpet on the stair rise and cut that out till i hit the 2x4 framing and call it good to just slight tuck it under that. And when they redo the carpet they'll just carpet down to the hardwood?
My dad has one of those vibrating multitool cutters for that so I can just borrow that.

I'm just going to drop the new trim on top of the hardwood and maybe some shoe molding if there are gaps under the trim due to uneven flooring. I hate 1/4 round.

Just pull the carpet up/off the bottom riser. Do the undercut with your father's oscillating multitool. trim the excess carpet and reattach with a narrow crown stapler until you replace the carpet. When the carpet is replaced it will cover the riser and meet the new flooring.
Where there is a flooring height change rip the bottom off the baseboard so it sits flush on both flooring heights and the top of the baseboard is the straight.