4x4 PT deck post: crack?

taurusaurus · 10-08-2007, 03:11 PM

Hi, all. I'm rebuilding our side deck (12' x 5', 40" floor height), and am well along in the process -- just starting on the stairs -- but I've noticed something disconcerting: two of the three (brand new) 4x4 PT posts have developed vertical cracks almost along their whole length. The support structure I've chosen is a 'sandwich' of two 2x10 beams on either side of the 4x4 posts, bolted in place.

I'm pretty new at this stuff, but have done a lot of research. I just don't know whether I should be especially concerned about this or just chalk it up to shifting and/or the wood drying out naturally. If the worst-case scenario arises and I have to replace them, I believe I can do so with some appropriate jacks.. but as you can imagine I would rather not.

Thanks in advance for any feedback or suggestions!

N.B. I turned this photo on its side to get the largest image.

scorrpio · 10-08-2007, 03:48 PM

Looks like checking due to drying out. It is surface only, not structural. If posts were indeed splitting, they'd 'buckle out'

robertcdf · 10-08-2007, 06:42 PM

Did you get a permit for your project? I ask because as far as I know the sandwich design is not allowed by most codes. It puts too much weight on just the bolts and the holes in the lumber.

Reason bolts are not the best idea... On my last project I had a pier and post that needed to support over 8,000 LBS of downward loading. Not many bolts would handle that kind of loading.

taurusaurus · 10-08-2007, 07:06 PM

scorrpio: Thank you for your reply. I of course wanted to seek advice about this right away in case it would be of concern later on. If the only indication I would get that the splitting has become more dire, is when the post buckles, that would be a sad day... I don't suppose there are any measures I should take, splitting or no?

robertcdf: Good question. I'm actually rebuilding to spec what was there before, but with a proper foundation. The old deck was truly a disaster waiting to happen... which is why I was quite worried by the cracks I mentioned. The small size of the deck, along with it's longest edge being a house-mounted ledger, enabled us to use our beam design.

Darylh · 10-08-2007, 11:16 PM

If I were you I would place some 2x4 blocks 16 - 24 inches long under each 2x10 for extra support. 45 the bottom for a more pleasing look. I assume there are at least 2 bolts in each post on each side right??

taurusaurus · 10-09-2007, 08:35 AM

Darylh: Thanks for the suggestion. I have been pondering how best to get this back to where I feel it is solidly built, and that might be a good approach. Yes, I used two 1/2" x 7" bolts for each union of post to beams.