I have to re-plank a deck on two sides of a summer cabin at Lake Tahoe. Existing 2x6x8′ planks will be replaced with 5/4×6 Trex. New joists between the existing ones will get me the required 16″ on center. The question I have has to do with spacing of railing posts.
Trex literature says to mount their railing posts maximum 6 feet apart. What would happen if the span were as much as 7’4″? Trex customer service folks are no help – just reading from a script.
I want to use the existing 6×6 doug fir posts because they also support the rim joists of the deck structure about 3’above grade as well as a skirt of dolly vardon siding. I could cut off the middle posts and mount Trex 4x4s to the rim joist at less than 6 foot intervals, but there would be no easy way to mount Trex posts at the outer corners without replacing the 6×6 posts that hold up the whole structure.
The deck extends 8 feet out from a ledger on the house. Total length of the outer edge of the deck is 44 feet, wrapping around one corner of the cabin.
There are four 6×6 posts about 7 feet apart across one wall of the cabin, then a span of about 8 feet to the outer corner of the deck and 8 feet again along the other side from the outer corner to a point opposite the house corner, then a shorter span to the stairs.
Has anyone violated the 6-foot span rule for Trex deck railings? Does another 18″ of span make the railings flex too much or is it something about the strength of Trex 4x4s bolted to the rim joist that makes them specify a 6-foot span?
Also, what sort of deck screws do you favor? I don’t mind visible screw heads on a gray deck planks as long as the stuff doesn’t pull screws loose like wood planks do when they swell up as the snow melts off in spring.
Thanks in advance for your help.
BruceT
Replies
Wra your posts with Trex rim stock, it's 3/4"x 71/4" I would'nt want to lose the strength advantage of using existing posts.If I do exceed the 6
ft. spread, I extend a ballister in the middle of the run clear down to the decking surface to eliminate railing sag. As far as strenght my top rail always consists of a trex 2x4 vertical with a 5/4 (decking) top cap. For screws I like the Trap-ease 3", the 2 1/2" don't always completely set flush with the decking surface if the joist wood is abit soft.
Edited 5/7/2006 12:04 am ET by GML
I didn't understand your reference to rim stock.I had intended to mount 2x4 Trex flat against the 6x6 existing posts and mount 2x4 top and bottom rails vertically to those with 5/4 cap screwed to the top 2x4 rail.Have you gone more than 6 feet apart with 2x4 rail and 5/4 cap?BruceT
Rim stock is simply a cosmetic piece of trex that faces the rim of the deck.Truthfully I usually only go about 5 ft. max between posts. I usually overbuild because in truth trex gets way limp when it's hot outside.
Thanks, that's not what I wanted to hear, but good info that I needed.BruceT
The problem with the trex railing, at least the last time I tried it was the amount of flex in it. If you look at the spec sheet even at 6 feet you have to run one to two spindles down to the decking. Also there is a lot of side to side flex in the hand rail. And if it behaves like the deck boards and gets softer if its hot I would not go more than the recomended spacing.
You could also use trex`s preformed handrail, they have the upper and lower sections and as far as the length you want to go with your hand rail, you can add support blocks every 16`` oc or even a little closer if need be and your rail should hold up fine.Why not just run your hand rail right into the 6x6 and use the trex fastener system .
You will want to lessen the span below 16" OC if possible. I've seen numerous decks with trex and weatherbest spaced at 16" OC and after a few years your flat deck may look like an ocean wave
Even in country where the weather doesn't get particularly warm in the summer.
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