Is it common for deck to warp?

Reply

  #1  
Old 03-20-20, 01:40 PM
M
Member
Thread Starter
Join Date: Apr 2019
Location: United States
Posts: 67
Received 0 Votes on 0 Posts
Is it common for deck to warp?

Hello,
I built a small deck last October and the other day I noticed that it looked like it was warped. When the deck was completed it was level all the way across but now when I use a level it looks like the front left corner (closest one in the picture) is sloping down? You can see form the pic it looks like it has warped. The deck is level starting on the far side near the door but at about the half way point it begins to pitch away from the house and gets worse as I get closed to the left front corner. Is this common or has something shifted? The only thing I can think is maybe the concrete footing moved or dropped so the deck followed?

I was thinking of just jacking it up and putting a shim where the footing is to see if it straightens it out. Or should I not worry about it just yet. It's not drastically un-level.

Thanks


 
Attached Images  
Sponsored Links
  #2  
Old 03-20-20, 02:14 PM
M
Forum Topic Moderator
Join Date: Mar 2005
Location: USA - N.E.Tn
Posts: 46,649
Received 178 Votes on 158 Posts
I couldn't tell from the pic - what does the deck have support wise on the front side? How many 4x4s and where are they placed?
 
  #3  
Old 03-20-20, 02:43 PM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Location: USA
Posts: 24,175
Received 338 Votes on 310 Posts
Yes, your footing undoubtedly sank. It's a strange place for a post in the first place, not being at the corner of the deck. Scratching my head at that one.

Current deck codes say that deck posts must be 6x6... foundations must be below frost, and post foundations closer than 5 ft from the house must be at the same depth as the house fittings, since that zone is always disturbed soil. (I.e. soft and prone to settling).

So it looks like your deck is probably sinking for multiple reasons. Yes, shimming it is probably your best bet. It will probably change from year to year if it's not on a solid footing.
 
  #4  
Old 03-20-20, 03:15 PM
M
Member
Thread Starter
Join Date: Apr 2019
Location: United States
Posts: 67
Received 0 Votes on 0 Posts
I attached some picks from underneath, The post are only about 3 ft away from the house but the footings are below the frost line, I went over 3 feet for each footing. I thought it was all good because my neighbor used to do construction and said it all looked good as I was telling him my plan?

Name:  under deck1.jpg
Views: 45
Size:  14.8 KBName:  under deck2.jpg
Views: 44
Size:  20.3 KB
 
  #5  
Old 03-20-20, 04:34 PM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Location: USA
Posts: 24,175
Received 338 Votes on 310 Posts
Only if the house foundation is only 3ft deep and that soil has never been disturbed. If there is a basement, all that soil has definitely been disturbed. That's why that code exists.

Wow. Looking at the pic... that is not a good design. How far does that beam cantilever anyway? That is likely a big part of the problem. Check the bottom of the beam for level between your two footings. Then check the bottom of the cantilevered part of the beam to see if its level. It could be sagging because its cantilevered so far. Beam cantilever can't be more than the beam span (distance between your two posts that are on footings) divided by 4. So if its 8 feet between your posts, your beam cantilever should only be 2 ft. Beam gussets like you have aren't found anywhere in codes, either... so technically they aren't helping... they aren't really structural.
 
  #6  
Old 03-20-20, 05:07 PM
M
Member
Thread Starter
Join Date: Apr 2019
Location: United States
Posts: 67
Received 0 Votes on 0 Posts
Thanks for the info. I'll check for level tomorrow, it's late here now and the sun is down. If the gusset is what I think it is, it wasn't added for support, I had an extra piece of wood so I just added it for no particular reason. The beam is just under 14 ft long, the span of the deck but I have 3 footings, not 2. Here's how the beam was built and is what I wanted to be the main support. The cantilever is probably only about 2 ft, if that. Other things under the deck I just added to try to make it sturdier but I don't think I needed to add any of it. Again, at about the 9 foot mark is where it starts to get unlevel a little at a time. Up until the 9 foot mark it's still perfectly level. It seems I may have misunderstood the code. I basically used the measurements on my back deck for this cantilever because my back deck is also 14ft, and was built when the home was built. They're 8 inch joists.
 
Attached Images  
  #7  
Old 03-20-20, 05:18 PM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Location: USA
Posts: 24,175
Received 338 Votes on 310 Posts
Must be the perspective of the camera then. Your photos in post #4 make it look like the cantilever is even longer than the span between posts.

your cantilever is not 14 ft long. Cantilever is the portion of your beam that is unsupported. 32" according to your drawing.

49" is your beam span for the purpose of calculating beam cantilever. (Beam cantilever has nothing to do with the total length of the beam or size of deck.) So 49 4 is 12.25"... which is the maximum the beam should cantilever. See DCA6 table 3 and figure 5. (The DCA6 is a code compliant guide based on the 2015 IRC.)

But if it starts leaning at 9ft, then 1 of your 3 posts must be sinking... doubt the cantilever is sagging but it could be.
 
  #8  
Old 03-21-20, 02:12 PM
M
Member
Thread Starter
Join Date: Apr 2019
Location: United States
Posts: 67
Received 0 Votes on 0 Posts
So I can't explain it but the beam is pretty level when placing the level underneath but it does look like the joists have moved a little bit away from the header board. So it probably is a matter of the footing settling and taking the deck with it. I'll try some shims and see if it moves anymore?

Thanks for the help.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: