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frank090870 04-17-2009 07:09 PM

help - pressure treated 4x4 deck posts splitting
Hi all,
I build a 13x13 free standing deck last fall using the new pressure treated lumber. I used (6) 4x4 supports with knee braces bolted at 45's using 1/2 bolts resting on concrete piers. We did not seal it before winter and now this year I've noticed that all of my 4x4 deck support posts and railing posts are splitting length wise, some pretty significant. Is this normal for the new p.t. lumber and more important should I replace the support post for strength. I realize it is wood and *&^# happens to wood exposed to the elements but I do not see it to this extent with the old p.t. lumber? I'm concerned with the strength of the supports and my deck collapsing and hurting someone. any suggestions?

Just Bill 04-18-2009 06:15 AM

Not unusual with PT wood. It is called 'checking'. It usually is not a structural issue, but you should seal them as best as you can to keep out water. Freezing water is the worst, since once ice gets it it can continue to force the split open further. Sealing PT wood early is the best way to reduce the problem, but it is almost impossible to prevent it. Can you post a pic, so that we can see how bad they are.

CrossWorks 04-18-2009 09:16 AM

Welcome to world of Pressure Treated lumber and young growth lumber at that. Now days, they grow trees so fast to chop them down that the grain lines are so much farther apart then in the old days.

It is what is; but like Bill said, send along some pictures if you can so we can determine whether your lookng at a structural issue or not.

jaros bros. 04-18-2009 09:42 AM

I never use 4x4 pt posts for this reason. Any support posts should be 4x6 or 6x6. 4x4 tend to split and twist a lot. Plus, notching them to accept different framing member is out of the question. They also don't look aesthetically appealing.

CrossWorks 04-18-2009 09:55 AM


Originally Posted by jaros bros. (Post 261819)
I never use 4x4 pt posts for this reason. Any support posts should be 4x6 or 6x6. 4x4 tend to split and twist a lot. Plus, notching them to accept different framing member is out of the question. They also don't look aesthetically appealing.

Hear Hear! Amen to that! So many times I see these 3rd story fire escapes built with 4x4 posts and cringe!:eek:

frank090870 04-18-2009 01:29 PM

thanks for replying
3 Attachment(s)
thanks for the replying. Here are a couple of pics. I went through all the building inspections etc. for the construction of it. It passed all code requirments. It stands 3ft off the ground on the low side and 6' at the high.

frank090870 04-18-2009 01:34 PM

does anyone know of an epoxy type putty that I could use to fill them in to keep the water out or should I just use a regular wood putty before sealing. If not anything else just for appearance.

frank090870 04-18-2009 01:56 PM

here are some more pics
6 Attachment(s)
here are some more pics

CrossWorks 04-19-2009 08:01 AM

Well a few things to point out:

What I see there, I see all the time. The 2x4 support that has the lag bolt going through it, (Just screw in a 3" deck screw from the edge, one on each side staggered about 6" apart)

As for the rest of it, it all looks to common and is not severe in my opinion. However, putting an oil base stain will seal it up pretty good for the next couple years. But I don't see it getting much worse because it will not have 100% direct sunlight during the day being that it is under cover of the deck.

And finally, my complements to your contractor who built the deck. It doesn't take but a second to know when someone know's what there doing and how good their doing it. You choose well to hire him!

Gary in WA 04-19-2009 01:04 PM

Nice looking deck. I would put some waterproof caulking in V - joint of the braces to direct the water running down them in a rain, outward. Instead of inward, where the brace end grain would suck it up by following the through- bolt.

I can't tell but you may not have the minimum code required handrail, 2-7/8" maximum width.

Notice the pictured rectangular ones: Be safe, GBAR

frank090870 04-19-2009 02:32 PM

thanks for the complement
Thanks for the complement :thumbsup:. I built this deck my self. The heavy lifting I called on some buddies and theres the result. After sealing I'm going to run a bead of silicon at the 45's to divert water. Now that I've built this I find my self looking at every deck I pass and see waht I could of done better or kick my self for not doing what I see. As far as the rail I have an aux. rail attached to the side of the 2x4 that holds the ballisters.
Yeh I tried just using a 2x4 cap as a railing and the code guy had me put an aux. rail on. Thanks for all the input. I'll seal the deck and just keep an eye on it.

CrossWorks 04-19-2009 04:05 PM

1 Attachment(s)
Your welcome.:wink:

What struck me was that I normally build my beams in this fashion:
Attachment 9728

But in your case by going on top of a 4x4 creates a "tippy" beam unless you use metal brackets....and you did. The thing is, this also is a solid way of putting it together, but I have seen many deck beams like yours without the braces and that my friend is scary!

Good work

frank090870 04-20-2009 06:55 PM

crossworks nice clean looking deck!
I know what you mean about the tippy deck feel, thats why I added the bracing. My deck is also a free standing deck, so I added bracing in both directions. I like the way you braced yours. It looks a lot easier to construct. It was a pain boring those c'bores for the bolts. I had to make up a jig to use on my drill press.

CrossWorks 04-20-2009 08:11 PM


Originally Posted by frank090870 (Post 263141)
It was a pain boring those c'bores for the bolts. I had to make up a jig to use on my drill press.

I wasn't gonna say :whistling2:

If you ever end up doing another deck, I highly recommend using Lag Screws from GRK. (Check it out) And if your hardware store doesn't have them, or local construction hardware store, they should!! They are rated for load baring purposes and are very quick to install with a drill when using the correct star bit. No need to pre-drill either These in my opinion have made the common galvanized lag bolt obsolete for ever!! No more socket wrench aaaand sore wrists!!

I know...I know...NOOOW I tell you! Live and kids know it to well.
Take care

KOHNSTRUCTION 04-22-2009 11:28 PM

hey you can try to use some of that plastic wood, (no really that's the name of the stuff) to fill in, you can use it on those cracks too, the stuff turns to concrete when it dries, you need a belt sander to get it off, but it can be drilled planed shaped what ever , i think its stainable as well.
hey nice deck

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