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-   -   Switch to Trex Elevations (http://www.diychatroom.com/f19/switch-trex-elevations-149123/)

jensor 07-04-2012 07:43 AM

Switch to Trex Elevations
 
I have a 20x14 PT deck. I'm switching to Trex. I decided after buying the decking, I should also do the Trex Elevations so the decking doesn't get wavey due to the imperfect wooden joists. I have 4 posts since my current 2x10's span the 14 ft. The deck is only 6" off the ground if that so a drop beam is not possible. The header beam is currently two 2x10's that the joists run into (no cantilever). On to my questions.

If I go to Elevations and start over...they are 8" joists. So I need an 8" ledger. Should I put the new elevations ledger ON the existing ledger or replace it all together. Also, since the existing ledger is 10", the new ledger is 2" shorter so my existing holes won't line up right. Drill new holes?

Back to the header beam, same thing. I assume I should replace it with the Elevations beam? Should I replace it with 2 beams or would one suffice? If two beams, should I bolt them together like I did the wood? Since these won't warp maybe I don't need to do that or just bolt it in a few places so it doesn't slip?

I'm also picture framing the deck with surface mount posts as railing (I think). Surface mount posts need support underneath so I figured I'd add a steel block (horizontally though) flush with the joists for the post to grab onto. Anything wrong with that logic?

I've seen lots of great answers on this site, great site. Appreciate any advice on the above. Thanks.

joecaption 07-04-2012 08:19 AM

Quote:

Originally Posted by jensor (Post 957557)
I have a 20x14 PT deck. I'm switching to Trex. I decided after buying the decking, I should also do the Trex Elevations so the decking doesn't get wavey due to the imperfect wooden joists. I have 4 posts since my current 2x10's span the 14 ft. The deck is only 6" off the ground if that so a drop beam is not possible. The header beam is currently two 2x10's that the joists run into (no cantilever). On to my questions.

If I go to Elevations and start over...they are 8" joists. So I need an 8" ledger. Should I put the new elevations ledger ON the existing ledger or replace it all together. Also, since the existing ledger is 10", the new ledger is 2" shorter so my existing holes won't line up right. Drill new holes?

Back to the header beam, same thing. I assume I should replace it with the Elevations beam? Should I replace it with 2 beams or would one suffice? If two beams, should I bolt them together like I did the wood? Since these won't warp maybe I don't need to do that or just bolt it in a few places so it doesn't slip?
http://www.nadra.org/consumers/decks_glossary.html

I'm also picture framing the deck with surface mount posts as railing (I think). Surface mount posts need support underneath so I figured I'd add a steel block (horizontally though) flush with the joists for the post to grab onto. Anything wrong with that logic?

I've seen lots of great answers on this site, great site. Appreciate any advice on the above. Thanks.



I find your post a little confusing, may be just some of the terms used.
There are no "headers" in deck constrution. Not sure how a "steel block" comes into play when adding the railings. A simple drawing or picture may clear things up.
Just how far off are the floor joist that you think you need to go to all that extra work?
Any composite decking I've worked with states in the install directions to not install any closer then 12" from the ground. Reason being is for air flow to keep the decking from molding up.
Most also say to have the joist no further apart then 16", 12" of your installing on an angle, how far apart are your joist?

jensor 07-04-2012 09:39 AM

Switch to Trex
 
1 Attachment(s)
Sorry about that. The header - I mean the beam that is opposite the ledger that the other end of the joists hang on to. The ledger and "the beam" are level, but over time the wood joists bow. So now they are off 2 inches from the highest board to the lowest. I'm afraid even if I replace the wood joists, they will do that again over time creating waves in the trex decking. Attached is a pic of half my deck. Totally open to suggestions.

framer52 07-04-2012 09:57 AM

So your joists have a 2" dip in them?

Exactly how far do they span?

What is there size?

jensor 07-04-2012 10:02 AM

The joists are 2x10's spanning 13 feet (unlucky I know) - this I thought met the requirements. Yes, some have bowed 1.5 to 2 inches. So if I flip them, then there is a hump. And by what I can tell on other threads, it looks like 1/2 inch here and there will make the trex decking look wavey....that's why I was thinking about steal - which is 8" so I'd have 2 more inches under the deck for venting.

framer52 07-04-2012 10:38 AM

steel would be fine.

I don't care for man made decking material.

mae-ling 07-04-2012 10:42 AM

1.5 to 2" is a lot, I have not seen that before.
Unless they are cracked.

jensor 07-04-2012 10:45 AM

Not to be a pain, I had a few question in the original thread. If I go to Elevations and start over...they are 8" joists. So I need an 8" ledger. Should I put the new elevations ledger ON the existing ledger or replace it all together.

I also asssume I should replace the beam with the Elevations beam? Should I replace it with 2 beams or would one suffice? If two beams, should I bolt them together like I did the wood? Since these won't warp maybe I don't need to do that or just bolt it in a few places so it doesn't slip?

framer52 07-04-2012 10:49 AM

If it were mine, I would rip it out and redo the whole thing.

mae-ling 07-04-2012 11:48 AM

If you are going that far I agree go all the way and use the whole system.

robertcdf 07-04-2012 05:50 PM

Wow... a lot of people don't know what the elevations line is, for those that don't know what elevations is, it is a Cold rolled galvanized steel system with a powdercoat finish, it's identical to the system I use except I don't powdercoat it (they actually use 1 5/8" width joists, I like 2" better). As someone who has been building steel frame decks for 3 years I can tell you that as long as your loading is typical (15# SF DL, 40# SF LL) then the 8" joist will span your 13' without problem, you can use the "Single" beam that they have and put your support posts 8' apart and you'll be golden. I would remove the existing ledger and install the steel ledger, seal up the old holes and install new bolts and holes (try to avoid laying out bolts where they are close to an old one)

I would opt for posts that come through the framing instead of top mounting, if you do continue to top mount then use a block of lumber (maybe a redwood 4x8) that is attached to the framing.

One thing to keep in mind is steel deflection is different than wood deflection, you'll "feel more bounce" in your deck with steel joists but it's perfectly normal.

Your local building department is likely going to require and engineers stamp for you to go forward with this project since steel as deck framing is considered "non conventional"

kwikfishron 07-04-2012 06:22 PM

Quote:

Originally Posted by robertcdf (Post 957992)
One thing to keep in mind is steel deflection is different than wood deflection, you'll "feel more bounce" in your deck with steel joists but it's perfectly normal.

There shouldn't be any "bounce" in a deck or any floor for that matter, regardless of material used.

robertcdf 07-04-2012 06:57 PM

Quote:

Originally Posted by kwikfishron (Post 958014)
There shouldn't be any "bounce" in a deck or any floor for that matter, regardless of material used.

Clearly you don't have a clue what you're talking about. Look up deflection. There are allowable loads and if you know how to make a floor deflect you can make ANY floor deflect.

I've seen a commercial floor at a concert move 2" - 2.5" because of the jumping fans, it was in a commercial building with a steel floor system and concrete floor. At no time was I worried about safety because I understood deflection.

robertcdf 07-04-2012 07:05 PM

Quote:

Originally Posted by kwikfishron (Post 958014)
There shouldn't be any "bounce" in a deck or any floor for that matter, regardless of material used.

Here is a good little course so you can begin to understand deflection. http://www.ronblank.com/courses/ufp06a/ufp06a.pdf

If you don't like the minimum code for deflection (maximum movement) then specify something more to your liking, however that raises the costs and material usage to compensate.

kwikfishron 07-04-2012 07:22 PM

Quote:

Originally Posted by robertcdf (Post 958038)
Clearly you don't have a clue what you're talking about. Look up deflection. There are allowable loads and if you know how to make a floor deflect you can make ANY floor deflect.

I know about and understand deflection robbie, just because it may always exist doesn’t mean you can or should be able to feel it.

If you want to include “ a bouncy deck is perfectly normal” in your pitch that’s up to you, it won’t happen in my world though because there will be no bounce to explain away. :laughing:


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