Composite deck

I'm replacing PT deck boards with composite in a few weeks. Temps will probably be in the 50s when I install them. How much do composite deck boards expand/contract with temp and do I need to gap the board more than what the fastening clips provide?

 

I have never done anything differently due to temperature.

 

Composite is not effected by temps or weather. If using invisible clips everything is snugged up!

Great decision, you will never regret having made that decision. my 14 year old deck still looks as good as the day it was installed.

 

Only drawback is it's expensive. But will pay for itself over the long haul.
I would not use vinyl or composite on fencing, however.

 

The deck boards are expensive but I expected that. It's the cost of the other stuff that surprised me. Fascia boards at $125 for a 12' board, $300 plus for hidden fasteners plus posts, caps, rails and spindles. Originally my intention was to use Trex Transcend composite rail sections w/new PT posts. But at nearly $300 per rail section I am rethinking that. I may reuse the turned PT spindles that I now have with new PT rails and posts. Or I may look for a different brand of rail sections. I'm 77 so I'm not especially concerned with longevity.

Any preference for deck board fasteners? I prefer hidden and I am looking at either the Trex style or the Camo edge clip.

 

Fasteners are largely personal preference unless the manufacturer requires a certain practice.

Some depends on the decking you choose, (if using grooved planks they need to fit the profile) but generally if using Trex, the Trex Hideaway fastener is fine for the field, Trex or Camo edge clips for the edges, Cortex screws and plugs for places you can't use blind fasteners... sometimes Deckmaster Grabber kits are useful instead of face drilling.

 

This is my first time using composite so I'll probably have even more questions. I have built a couple of decks in the past but have always used PT wood. My existing deck that I'm renovating is 20'X16 and just under 5' off the ground. I'm rebuilding because I'm tired of staining and painting and this summer I found half of the PT bottom rails were rotting.
I am using composite boards for steps. I have 5 stringers 16" OC with two 2X8 for 15" treads. If I switch to composite boards for the treads I haven't figured out how to make up the difference in tread thickness. I don't want to cut new stringers. Are spacers on the stringer acceptable or is there another way to make up 1/2"?
My plan is to rip the groove off the outer composite board and ease the cut edge with a router. That way I can install the riser under the tread nose to avoid that exposed seam. If the deck board treads are spongy is blocking (2X4 on edge) acceptable for stiffening a tread.
My last head scratcher is covering the exposed ends of the deck boards so I don't have to see the ugly grooves on the underside. My plan is to allow the boards to overhang the rim joist a couple of inches and then install fascia butted under the overhang. That doesn't cover the underside.
Last question - I'm submitting the permit application next week. I built this deck almost 40 years ago and I know code has changed. At the time I installed 4X4 PT posts through bolted to outside of the rim joist cutting the 4X4 post to overlap the joist. My understanding is that the code has changed and that joint is not acceptable. Is that correct

 

Cut them flush and use fascia boards to cover the rim and the deck!

 

May be a fine line, but your not building the structure your replacing the deck, IMO a permit is not needed!

 

Things got a bit more involved when I started demo of the existing 5/4 PT deck boards. I ended up scrapping several PT posts and I had to replace several 2X8 PT joists that were showing signs of rot at the ends. After replacing the joists I checked the deck for flatness. Measuring from rim joist to rim joist there is some variation, as much as 1/8" between adjacent joists and in one spot just a bit more. That was not noticeable with the wood decking.

Now I'm concerned that the deck will be wavy because the composite boards are so flexible. Is there a rule of thumb for variation in joist height for composite?

 

I would be shocked to not find any height variation in PT joists. I dont recall seeing any specifications for the composite material but if your only seeing 1/8" your not going to have any issues.

 

Marq - Thanks for the response. I'm a bit relieved because I do not want the deck to look like crap when I'm done.

 

This is my standard, "use composite material" deck picture. This is a couple years old but at 14 years and still the same.

Tell me the cost difference is not worth 14 years of no sanding, no staining, no board replacement, a wise investment!

 

Mark - What fasteners did you use. I bought the Trex hidden fasteners that are supposed to provide 3/16" spacing between boards but because of the way the board edges are routed the gap ends up looking like3/8" instead. And the "hidden fasteners ain't hidden. I am not happy with them and will probably try another brand.

Not especially happy with the Trex boards either. I had to use spreader clamps to get the boards to line up.
. .

 

Last 3 decks were Timbertech with their concealoc hidden fastener. never an issue!