I am installing composite decking stair and I found there are two ways to do it:

One inch overhang:

enter image description here

Flush and show fascia edges:

enter image description here

What are the pros and cons of each method? I tend to go with the second one for the fact that I have a bunch of groove decking boards. I don't want to show the groove at the edges so having fascia boards to cover is nice. Of course, I could buy the non-groove ones but that's taking more time to order / delivery and shipping cost.



I just measured the height of the step (with the decking board below) and it varies. Since the length is like 20 feet, I see it's ranging from 6.25" to 6.75". That means I have to cut the fascia board regardless of which method anyways. For the overhand method (Option 1), it might be better looking to hide larger gap below the overhang I guess.

  • This is really more of an opinion as both have value. I like the overhang because it reduces toe kick damage on the face boards, I usually will use a router to shape the overhang. A nice carbide bit with a bearing then a spacer board held in place makes a very nice rounded edge. The con of this method a heavy load on a dolly pulled up or going down can cause more damage because of the overhang.
    – Ed Beal
    Jul 25, 2016 at 8:17
  • I'm pretty sure that there are "weighty" opinions supporting bull-nose/overhang as being less likely to cause falls, but I can't immediately recall where I've read that - but I have. I've also experienced just how uncomfortable "flush" stairs can be.
    – Ecnerwal
    Jul 25, 2016 at 14:34
  • Overhanging treads allow a deeper tread for a given run. This gives folks with bigger feet a bigger target. In this case, if there's just one rise, or if extra-deep (three-board) treads are used, it's not a concern.
    – isherwood
    Jul 25, 2016 at 14:49

1 Answer 1


Either method is fine so it becomes a matter of taste and skill.

The first method is the overhang bullnose style, which is the most common. I believe you are using the Trex style grooved decking that utilizes the invisible clips. The grooved boards are definitely not what you want to use for the bullnose or any outside edge, as the grooves will show. You need the standard radius edge boards for those exposed pieces. They may be in stock at your supplier. One major advantage is that two pieces usually makes a perfect 11 inch tread and installation is very easy and any mitered corners fit well together. Don't forget to use some glue and thin SS finish screws to keep corners tight.

The second method of flush mitered edges is very difficult to build correctly. All edges of the treads and risers should be rip mitered. Exposed ripped edges look terrible. If you have ever tried to rip long lengths of Trex, you will find it is a lot more difficult than it looks. Cut edges of Trex can be very rough if you don't use a sharp 60 to 80 tooth blade, not at all like cutting wood with an 80 tooth blade to get a smooth edge. Trex is unforgiving if you wobble a little or pause during the feed through the saw. Trex does not sand well at all, so any imperfections cannot easily be sanded out without harming the sheen or texture of the finished, exposed side of the Trex. Long mitered edges can be very difficult to make fit tightly. You will have to glue and use lots of finish nails to keep the joint tight and free of gaps. Another consideration is that because Trex is fairly soft, mitered corners are susceptible to chipping and denting.

I think you are seeing that my opinion is to use the bullnose method over the flush method when using Trex or any composite, flexible decking.

  • Good answer, but I'm confused about where and why "rip miter" joints are needed. Everything I see in that second photo is done with crosscut miters. Please clarify.
    – isherwood
    Jul 25, 2016 at 14:48
  • OK, sorry for the confusion. When I first looked at the top pic, I thought it was a more detailed photo of the top step as seen in the second pic. On closer examination, you are right, it is simple picture frame with crosscut mitres... Somehow I was seeing it as a right angle, not flat. MY BAD !! Jul 25, 2016 at 16:07
  • What type of glue is it required to use with fascia boards? Where do I glue? I am planning to screw each 16" into the trim joists anyways. Do I need glue too? The reason I am referring second solution is because I didn't order enough non-groove boards and now I have tons of extra grooved boards so I must put them in-use somehow :P ... So you said it's difficult because the hight of the stair is not even (which I imagine) and could be like 1/4" off?
    – HP.
    Jul 25, 2016 at 22:42
  • Each mitred joint should be glued with a urethane based waterproof glue. Liquid nails, and other brands are good. Every cut end that meets another cut end......Glue and screw it ! Use very small gauge stainless steel finish screws that have very small heads. Predrill and give a shallow countersink for a nice finish. Excess glue can be cleaned off after it dries with a utility knife. Jul 25, 2016 at 22:49

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