JLC had an article on it a few years ago. Don't remember what they used, but the front piece had a miter cut for the side piece

 

Never found a good way. That inside plank is going to stretch in the sun and move the joint. Screws and plugs could be as good as it gets.

 

https://www.jlconline.com/deck-builder/deck-stair-upgrades_o

Or another idea

https://www.jlconline.com/tools/fastening-tools/power-tools/composite-deck-stair-detail_o

 

Dekmount 8' Stainless Steel Hidden Fastening System®

DEKMOUNT HIDDEN FASTENING SYSTEM® 8' Stainless Steel Hidden Fastener provides a clean, beautiful and finished deck free of visible nail or screw heads protruding from the deck surface. Dekmount hidden fasteners are recommended for a clean, professional look. Start from the wall or house and...

www.menards.com

 

• Pocket screw underneath.
• Trim screw from outside.
• Glue with biscuit, dowel or domino.

 

I would pocket screw it to the 2 tread boards, on the bottom side.

 

Galvanized tie plate on the bottom of the tread sticking out what ever distance you need. Install tread, install end cap with screws from the bottom.

HRS 16 in. 12-Gauge ZMAX Galvanized Heavy Strap Tie

Screw through the miter and back of the riser will prevent droop.

thinking about it you could install all of the tie plates on the stringers prior to installing the treads.

Tom

 

Painting the edges is a good option

 

Thanks for the replies. I’ll have to put some thought to how I’ll do it. Pocket screws would be great but I don’t know if they will work because the decking is scalloped on the bottom so I’ll have to see if I can pocket screw it.

 

This is the decking profile.

 

So 3 places to pocket screw.

 

Run the skirt board up 3/8 and notch off the nubs of the plank overhang. Paint ends

Ok I'll stop now

 

Do pocket screws in composite even hold like those in wood? I've never tested it. Anyway, pocket screws to the side, as Leo indicated. But you might be able to put screws through the scallop to the front with the right length and angle. I would also use whatever adhesive is compatible to help prevent the nosing on the front from breaking off from people stepping on it. You'd have to preassemble the treads with this method. You're not going to have enough overhang to the side over the stringer to pocket screw after installing the tread or to catch the corners on the front.

You could make your own plugs from edge grain scrap and face screw it. I'd use adhesive with that as well. This is what I would do.

 

Do pocket screws in composite even hold like those in wood? I've never tested it. Anyway, pocket screws to the side, as Leo indicated. But you might be able to put screws through the scallop to the front with the right length and angle. I would also use whatever adhesive is compatible to help prevent the nosing on the front from breaking off from people stepping on it. You'd have to preassemble the treads with this method. You're not going to have enough overhang to the side over the stringer to pocket screw after installing the tread or to catch the corners on the front.

You could make your own plugs from edge grain scrap and face screw it. I'd use adhesive with that as well. This is what I would do.

The lead tread would not have an applied bullnose. It's pretty notched.
Composite mushrooms terribly. Maybe pre drill a couple of sizes down so it just screw threads bitting. Shrug

 

So the front of the tread uses a jack miter to connect the side nosing? The front tread in the picture appeared longer in depth than the one against the riser, minus the nosing. It looks like an applied nosing all around. In any case. if the front nosing is part of the tread, then what's the issue? You could attach the sides however you want since they will never see any foot traffic.

 

No one would be stepping on the stair edge it’s only the side that would need finished. I’ll do some samples with pocket screws. Never thought about making my own plugs I have different size plug cutters but don’t use them that often. I think I even have a quarter inch plug cutters so maybe I’ll also sample some GRK trim heads with quarter inch plugs. I have painted the ends on some jobs in the past but it was full 5/4 decking not scalloped.
i also thought about putting a small bead of brown quad for an adhesive that stuff really bonds.

 

Pocket screws do not hold well in composite decking.

Tom

 

They strip out easily

 

Load it up with 2P10R and smoosh them together.

 

Is that for exterior use and uv resistant?

 

a spline from same material and clear quad max

 

I like the spline idea.

 

I like Tom’s idea of the tie plates. With incorporating adhesive I feel it would be the sure fire way things line up and stay lined up.
The right adhesive, tacked with a brad nailer, then set with trim screws or hand driven trim nails is like the lazy dowel system that I think would be easy enough to conceal and go unnoticed.

 

Would clear PVC primer and cement work?

 

Looks like a particle board mixture not PVC

 

It’s just a PVC cap now.

Tom

 

The amount of brain power being expended on this surpasses the cost of the extra lumber and fasteners to picture frame it.

 

Brain power, now that’s funny.

Tom

 

Was just going to say is it done yet?

 

No. That’s next weeks job. I just wanted to get some input.

 

I like to run that around as a small band. Like a 1x2 on edge.

Run treads flush to skirts and stringers. Then wrap with 1x2 on edge. Slightly different look but makes the stair treads look chunkier.

Use Camo fasteners with plugs. Or stainless 15- gauge finish nails. A little 2P- 10 or other CA glue on the miters.