In some cases, stairs are too damaged to be renewed by a single painting. I used the following method twice : first stair was an old wooden one where most of the treads had been eaten by insects digging large and deep holes. The other one is the one pictured in this Instructable : a previously carpet covered chipboard stair. Remains of carpet and glue made a "Just paint it" solution inappropriate.

Step 1: Before Starting...

First of all, please forgive in advance any language faults, I'm french and english is not my mother language. Don't hesitate to point any eye bleeding horror in this article. The fact I'm french induce also metric system and Euro money.

Notes :

This method use laminate flooring and aluminum nosing to make a brand new stair from an old one. As you may guess, it wont transform a crumbling stair into a new one. The stair must be robust enough. We will work on its look, not on its structure.
On this stair, I covered both treads and risers but you can also paint the risers if they are clean enough and use the laminate flooring only on the treads. This second solution is easier and cheaper especially if the old treads have big nosing.
If you want to paint some parts of the stair (stringers, balustrade or risers), do it before starting. Laminate flooring will cover splashes. Yes, this hadn't been done here : pictured stair is my sister's one and she had no time to paint stingers before I came.
One great advantage of this method is that you can step on the stair immediately after one tread is finished. Your stair is still usable even during your work.

Time :

If you have a turning stair like the one pictured, expect to spend approx 45mn per tread/riser.

Step 2: Tools and Material

Tools :

A jigsaw with a special laminate floor blade (one with inverted teeth that cut when going down)
Square
measurement tape
caulk gun
Metal cutting saw or mini grinder to cut profiles.

Materials :

Neoprene glue cartridges for caulk gun (many. Depending on your stair, you could use one cartridge for 3 treads). Beware : use only neoprene based glue because this kind of glue stays soft when drying that allow it to keep gluing despite steps vibrations. Other ones that become rock hard are to be avoided.
Auto adhesive aluminum nosing : one per tread. (if one of the tread is too long for the nosing, you could use a remain of a shorter one.
Laminate flooring :
- If you want to cover the risers also, one plank per riser should be enough for a normally designed stair.
- For the treads, count 2 or 3 planks per tread. There's many angle cuts and therefore, many loss.

Step 3: Risers

If you want to cover both risers and treads, I strongly suggest you start by the bottommost riser and continue climbing to the top. Like that, risers hide irregularities of the tread flooring they are put on.

If you only want to cover the treads, you can start from wherever you want (yes, even in the middle of the stair). In this case, forget this step of the Instructable and just roll next steps until all treads are done.

First cut one flooring plank to the length of the riser. just take riser length measurement, trace a square line and cut the plank.
Put the riser cover in place against the riser and mark its back each end a little bellow tread surface
(first picture) (between 5mm and 1cm bellow). Cutting the riser cover a little shorter than the riser will ease above tread cover and the gap will be covered by the aluminum nosing.
Use a ruler to draw a line between your marks and cut.
After having verified that your plank has the correct dimensions by putting it in place without glue, glue it (pictures 2 and 3) making a spiral on the back of the plank. You could also try to glue the riser on the stair, but gluing a vertical surface is much harder.
put the riser cover in place and press it hard against the riser.

Step 4: Tread First Plank.

We are talking about a stair, so it must be robust. That's why, even if it's a little more complicated, the largest flooring plank must be the one on which the nosing will be glued.

Taking and reporting measurements.

I took pictures of the harder part of the stair : the part where it turns. To take correct measurements, we have to Find square angle where there's no one.

pic 1: Take the length of the tread
pic 2: Put a square on the tread to draw a line perpendicular to the riser on the end of the tread.
pic 3: On this perpendicular, draw a mark corresponding to your flooring planks width (20cm in my case).
pic 4: Measure the distance between the perpendicular and the real border of the tread.
pic 5 : report measured distance on the correct end of the plank.
pic 6 : at the other end, by sliding the tape and the square together find the measure where the plank becomes wider than the tread and thus, need to be cut. When you reach the position pictured, remove the measuring tape and use it to measure the distance between the leftest part of the ruler and the rightest end of the tread.
pic 7 : report this measure on the plank.
pic 8 and 9 : Take the measure of the other cuts to be done. I use a remain of a previously cut nosing as a tiny square
pic 10 : When all measures had been taken and drawn on the plank, cut it. Don't hesitate to trace larger that it really is. It's easier to recut some parts of the plank than to retrace all and loose the plank if your measures were shorter than reality.
pic 11 : put the first plank in place WITHOUT GLUING IT. Recut it if necessary...

... and go for next plank.

Step 5: Other Planks.

When dealing with the other planks, you use the same method than for the first one. There are 2 major differences :

You base your measure on the previously cut plank so be aware that it wont move when you measure.
Unlike the first plank where you have to consider its full width, next ones will assemble with previous and this assembly will "consume" a part of its width (in my case, clicker system make loose 5mm in the assembly).

Take the measures the same way you did for first plank using measuring tape and square.

Put everything in place together (again without gluing) recut if needed and go to last plank.

The last plank (if needed), can be very little. For this stair, I had to cut a triangle of 6cm width x 1,5cm eight. It's not a problem because it will be in the corner and no one will ever step on it.

Step 6: Gluing Tread Cover.

When all part gather perfectly without glue, just "clicked" together on the tread, You should raise your "tread floor" as whole part.

It's time to glue !

Let's say it's the critical path of the job.

For all the rest of the process. Before and after this very step, stairs could be still used with little method and appropriate tools management.

But at the very moment when you take the caulk gun, and for the next 10mn : "YOU SHALL NOT PASS !!!"

Clean or vacuum-clean the thread an put the glue on it.

I usually start by any corner of the tread to follow tread borders as a spiral to the center. If your tread surface is irregular don't hesitate to put more glue in the holes. That's not the case on the picture, the surface was regular, the gluing is -quite- regular.

Be aware that large treads floating on many glue should be instable during the first hour.

Too much is not better. Believe me, I tried.

If you put too much glue

Flooring may rip, when you work on the next tread, for example. It's like floating on the glue but only few centimeters in general. By ripping out, tread floor can also take down the already glued riser that was -eventually- put on it.

In that case, put everything back in place, starting by the riser (if any) then the tread floor. Clean any glue and just go easy on the tread keeping an eye on it for the next hour. After this long, it would be totally stuck.

Step 7: Auto Adhesive Aluminum Nosing

As you may have seen in 2nd picture of previous step, nosing is not quite clean when only flooring is in place. That's why I use the "magic bars !". It's from far the more expensive part of this kind of project (apart from time). Flooring is not so expensive neither is glue. Each nosing profile cost around 10€. At least 80% of final cost.

If you are a true one, this kind of profile can be bought in 4m long bars that you have to cut and glue by yourself. It's, of course, much cheaper.

By the way, cutting the profile is quite simple now that you defeated the level one boss "Flooring" !

Starting from one end of the profile and then use first end marks as a referential for other end has proven efficiency.

Again, taking measurements is about square angles. When at your second nosing, use square cuts of your remains of first profile to help measuring (pic 1). For first nosing, I'm afraid you'll need to take more measurements. You should also cut little part of not yet used profiles. In my experience, for 1,10m long profiles, I had a 30 cm standard loss. So, if you cut 10cm in one "future loss", it could greatly help you. Just check before your medium nosing length on the stair and compare it to your profiles length.

Put a square angle cut profile on the tread and push it down and front for it to be stuck on both thread and riser surfaces.

Measure the gap between square angle and real tread angle running on from profile. Report measure on profile and trace cut line. Don't hesitate to bring the profile in the stairs to check if your cutting marks seems coherent with tread shape. Mistakes cost much here so check twice.

By default, except if your stair is very strange, vertical part (the small wing od the "L") is always cut up/down vertical.

When first end is traced, checked and validated, measure far nose length. Best is to measure an invisible line at crossing of riser and tread plans. Just do your best. A 5mm gap is barely visible if dispatched on the 2 ends. A 1cm gap becomes hard to hide except in stair corners if any.

Report this measure on the profile between the point on the "L" corner at first end and a new mark on the "L" corner at other hand. This line on the profile will be the real nose of the tread, it will be our referential.

Now that we have our "point zero" on the other end of the profile, we can measure and trace second end by using same "gap to square angle measurement" technic, and same "square profile remain tool" (pictures 2 and 3).

Cut the ends using a metal saw or a miniature grinder and after a last check, remove adhesive protection and glue it strongly on tread. Beware, the glue on the adhesive is designed to be instant and very strong. Misplaced profile can't be easily unglued once in contact so be precise when approaching.

Step 8: Conclusion

Now that you know how to cover a full tread, continue until all are done and you'll have a beautiful stair.

This project has 2 main advantages

you can schedule it your way. A tread one evening, 3 or 4 on week end...
It's way much cheaper than stair renewal kits that you can find on internet. You spend time rather than money.

I think I said all that could be useful. If something is missing or unclear don't hesitate to ask.