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mhcptg 01-24-2014 11:15 PM

Restructuring Unsafe Deck Railing
3 Attachment(s)

I've done a lot of DIY projects over the years, but normally things that are a bit closer to my day job. Now I have a deck safety challenge that's a bit outside of my own ability. I bought my first house this year, and I had to find one that had a few things wrong with it, or other buyers with tons of cash would have come in and outbid me.

The deck seems fairly well built as far as the framing and the guts, I did some calculations on the total weight of the deck and the people on it, versus the expected support ability from the footings and the soil and everything looked OK there. The deck boards are some kind of off-brand or on-brand Trex or other composite, and seem more or less new, minus a bit of sun discoloration. It doesn't rattle, shake, or otherwise appear unstable. The stair treads were a bit loose, but I realigned them and reassembled them with some 3" exterior grade screws and now there's not even a squeak there.

The only real problem left is that the railings weren't built right, and I am pretty sure if I leaned on or fell into the longest one I could rip it right off the deck or crack it in half and take a nasty fall.

They tied them in with lag bolts to a PT 2x6" going across the back of the deck. But the 2x6" isn't connected to the deck joists, it sits out past them, and they didn't bring the rail down the inside in a hole through the deck boards either, so I can't see how to get in behind with a second sistered 2x6" to reinforce it either.

I explored the Simpson Strong Tie website looking to see if they had anything good for reinforcing this and getting it back up to code but I didn't see anything jump out at me there either. So now I wanted to seek some second opinions from others before I figure out my next move. I attached a few pictures, an overview of the long unstable rail, and a pic of how it's attached on the outside, and how the inside doesn't tie into enough of a support rail, but just one single wobbly 2x6".


joecaption 01-24-2014 11:36 PM

#1 A deck that sized never should have been built with 2 X 6's, two narrow.
4 X 4 beams under the deck are going to sag , twist and curl.
Post should have been mounted like this.

mhcptg 01-25-2014 12:26 AM

I agree it should have been structured with more lumber. Fortunately they didn't use any 4x4"s in the underframe.

I get what you're saying about mounting the posts, I wanted to do the same thing, but I'm trying to ask how to restructure it now, without having to destroy it and toss out materials that are still good, when it's not the material's fault it wasn't done quite right.

Are there ways to salvage it, by sistering up the beams and making it more sturdy?

kwikfishron 01-25-2014 05:41 AM

199 Attachment(s)

Originally Posted by mhcptg (Post 1296351)
Are there ways to salvage it, by sistering up the beams and making it more sturdy?

Blocking between the rim and the first joist at each post would stiffen things up considerably. Replace the lags with through bolts while you're at it.

Olcrazy1 01-25-2014 09:22 PM

Without doing anything major to stiffen the structure and also notching the post if you just want to work with what you got I would remove the lags and get long bolts. Big washers in the outside and inside or maybe even a metal plate on the inside and lock washers and nuts to tighten the whole thing up. One or two bolts on each post 1 if u keep the lags, 2 if u pull them out.

Davejss 01-25-2014 09:48 PM

Hard to say from the pic but that deck may be close enough to the ground to not require a rail. Check your local codes.

mhcptg 01-25-2014 11:06 PM

You guys are giving me some good ideas.

They did attach the posts to the 2x6" with through bolts, but the 2x6" rim itself isn't well enough attached to the underframe.

I am going to take a close look in light of the advice and see if I can get the 2x6" more securely attached to the underframe so it can't shift around anymore.
So far I am thinking I'll sister it up to a second 2x6" to stiffen up the rim, then attach to the joists and bring them up to the rim and attach with hangers to get it anchored better.

Then, get some longer better bolts and some big plate washers to anchor the posts to the double 2x6". It won't be perfect but I think it'll be a big improvement over what I've got now. I don't have to boil the ocean, but I just don't want anybody getting dropped on their head if they lean the wrong way... me included... I am a pretty big heavy guy!

mhcptg 01-31-2014 02:28 AM

Thanks for helping me figure it out guys... I started on this guy after work a few nights this week. I finally found this awesome article from a mechanical engineering journal, where they illustrated why virtually all deck rail posts tend to be unstable and unsafe, and how to do a better job and pass the code for real, using SST or USP type connectors to reinforce the joints:

Their procedure wouldn't work on my deck because they required the joists perpendicular to how they ran in my deck. But I thought about their advice a while and came up with something similar that's not quite as good but close enough to be a hell of a lot better than what I had before.

I detached some of the deck boards around the post to gain access, then installed blocking from the rim joist to the second joist, 3.5" apart to tightly fit the post. I reinforced the hell out of the blocking with Galvanized 90 deg. USPs with the HDG nails on every corner, and bolted the post onto to the blocking with Qty 2, 1/2" x 8 galvanized through bolts, with proper washers, torqued on nice and tight.

Before replacing the deck boards I notched them with a jigsaw to make room for the post to come through from below. Everything seems to be pretty rock solid with this setup. Now I am cranking through one-by-one correcting each unstable post.

When it's done I'll make some more photos for the next person who gets stuck in this bind, so they'll have a good point to start from...

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