Span between deck posts?

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Old 06-14-07, 02:52 PM
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Angry Span between deck posts?

Planning to build a 16' x 19' deck. The max. height might be 4'.

Ledger is 19'. It measures 16 (out from the house) x 19 (along the house).

I intended to put 2 rows of posts (piers) with 3 on each. What is the maximum span between 2 posts on a row? If i leave 7 feet apart, there will be 2.5 feet hanging on both sides.

In my situation, will 4"x4" enough for the posts?

Thank you.
 
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Old 06-15-07, 04:40 AM
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What you propose will give adequate vertical support, but you didn't mention the size of your rim joisting and whether or not you will be doubling them. On the left coast, post and beam construction is prevalent, meaning you will get constant support on the inside row throughout the span, by installing a 4x6 beam on top of the supporting posts. 4x4's are ok, but you will get alot more support from 6x6, and carrying the exterior posts through the rim joists to form your handrails makes a very firm support
 
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Old 06-15-07, 10:35 AM
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Thank you. my deck frame will be more or less like this. Double click the image itself to see more clearly.

http://s186.photobucket.com/albums/x133/lightening2/?action=view&current=Deckframe.jpg

Can I use 4x6 treated woods as posts, not beams? I hesitate to use 6 x 6, because it might be a bit difficult to cut.
 
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Old 06-15-07, 04:48 PM
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I like the use of the 2x10 beams, which is better than what I suggested. I really wouldn't use the 4x6's as posts, as their symmetry will throw you off when you turn a corner (one 4 and one 6, if you know what I mean). The 6x6's aren't difficult to cut. Mark you length, use a swanson square and score a line around the post. Cut with a circular saw along the line on all 4 sides. This will leave you with a small square center cut to make with a reciprocating saw. Just watch your foot when you make this cut as 6x6's are heavy.
My suggestion on the 6x6's was mainly for you to carry them through the decking and use them as newel posts, but I see you plan on post and beam, so none of your posts will exit at the corners. I still find using 6x6's as newel posts for the handrails cutting a notch and allowing them to hang down and bolt them to the rim joist a firm way of attaching them.
 
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Old 06-16-07, 08:01 AM
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I personally quite using 4x4's a long time ago for anything other than railings. 90% of our decks are built with bases like the pic you posted where the beams are sat ontop of the post supports, and I like to use 4x6 exclusively for this. I can notch it out to set twin 2x8/2x10/2x12 depending on span we're after and still have a leg up so we can run our SS cariage bolts through to attache the beams to the post.

http://img.villagephotos.com/p/2004-9/824085/stabenowdeckintpic.jpg

If your using 4x4's with the beam sitting on top you can buy the brackets that sit on top of the 4x4 posts and then the beam sits in the brackets so it's all shear weight like these

http://img.villagephotos.com/p/2004-9/824085/Wilsondeck002internetpic.jpg

But I have'nt done this in years, 4x6's make life alot easier IMO

It's not until we get into some weird situations that I ever step upto 6x6. For the normal run of the mill deck that is just above grade, it makes no sense to me for the added labor/time wasted cutting these things, the added weight of toting them around, additonal bracket costs/etc...waaay overkill for no apparent reason. Now if the deck is 8'-10' in the air, supporting a roof that covers the deck, supporting a hot tub, etc....then I will use them (6x6's) but not for a run of the mill deck like your describing.
 
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Old 06-16-07, 09:06 AM
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Thank you Chandler for your reply. I will use 6x6 as posts. Just feel I have to cut to their exact height before installing, while the books said we cut after erecting the posts with a jig saw.
 
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Old 06-16-07, 12:57 PM
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Just saw IHI's replay thank you for your reply and images. My origianl question relates to the span between posts. Now I got more answer for the posts.
I notice, IHI, your 1st image has a wide span. Is it using 4x4 posts?

your 2nd image has smaller spans.
Still not so sure if my span is 7 feet, will 4x4 posts be strong enough.
Will it be OK to double the 2 x 10 as beams on top of 4x4 posts with 7 feet span?
 
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Old 06-16-07, 11:30 PM
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[quote]Just saw IHI's replay thank you for your reply and images. My origianl question relates to the span between posts. Now I got more answer for the posts.
I notice, IHI, your 1st image has a wide span. Is it using 4x4 posts?

your 2nd image has smaller spans.
Still not so sure if my span is 7 feet, will 4x4 posts be strong enough.
Will it be OK to double the 2 x 10 as beams on top of 4x4 posts with 7 feet span?[quote/]

Span between post corrolated directly to beam lumber being used, 2x8's can span upto 9' so if your using 2x10's and wanting to go 7' oc, you'll be overkill, you could actually step down to 2x8's @ 7'oc. All depends on live load, but for a no frills, standardized deck you'll be fine using 2x8/2x10 7' oc with 4x4 posts....just DO NOT make the mistake of cariage bolting the beams to the side of the posts-set the beams directly ON TOP of the posts. The new ACQ2 lumber EATS all metal except stainless, so all the galvanized stuff that's sold in stores will eventually deteriorate and fail. They sell stainless steel joist hangers, but they are spendy at around $9-10/ea, but if you use standard galvanized joist hangers they do sell a plastic stickey wrap you cover the boards with prio to setting them into the joist hangers to make a barrier so the hanger does not fail....we lost a bunch of money when the stores switched over to the ACQ2/arsenic free lumber since nobody told us it ate metal...we had quite a few jobs we had to go back and redo.
 
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Old 06-17-07, 04:34 PM
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Thank you IHI for your additional information about the hangers. two followup questions.

First, when I double the 2 x 8 as beams, how do I bolt them together?
If they are not longer enough, (as my deck is 18.5' long) do I make one shorter, the other longer and overlap these 4 pieces? Or if i cut them exactly the same length? How to connect the two sections then?

Second, as for the hangers, maybe, i can paint those hangers with some anti-rust paint. What do you think?

Thank you again.
 
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Old 06-17-07, 05:37 PM
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You will have some waste on the beams, but make sure ANY joint falls directly on a post, you DO NOT want a joint hanging mid span, that is dangerious and serves no purpose for structure integrity at all. Your posts will be close enough together that you can get 10' beams, and then for the end posts, I try not to let the beam overhang the post by more than 12". 24" is max allowed here for cantilever situations, but I still prefer to keep it 12" or less. But design the post layout, even if it calls for an extra post so the beam sections wwill fall directly on top of the post...do not try to have a joint mid span.

Do use the paint, initally it seems like a viable, cheap solution, but it is a cheap, short term solution since paint and exposure means the paint will eventually wash away. There are plenty of homeowners and even contractors that are still building with standard practices of the old treated lumber and no barrier, but after all of the things we had to go back and replace after the inital material swap over...it's just a mater of when and how quickly the metal deteriorates. High moisture area really accelerate how fast the metal rots.
 
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Old 06-17-07, 08:46 PM
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Thank you again , IHI,

I know what you mean. The only problem I see now is that my beam will overhang by the rim for about 24". I have to add a post to reduce it.

For the hangers issue, I might use screws to fasten them, so that in case they got rotten, it will be easier to replace them.
 
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Old 06-17-07, 09:50 PM
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They do make structural screws, but do not think you can just use any old SS screw....there is no sheer strength to them and that is why screws have always been forbidden in structural issues...screws bbreak/snap off, whereas nails will just bend.

Do some research, they do make screws rated for these applications, but they are not cheap, the ones we've tried in the past for ledgers run about $30/box, and keep in mind the hangers use 10 screws per hanger depending on joist size.

Just a big double edge sword all the way around...must be a conspiracey with all the manufacturers since you have to use this and you have to use that in order to get anything done and none of it's cheap.
 
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Old 06-18-07, 07:36 AM
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Good. another follow up question.

Do you people attach the ledger board directly to the vinyle siding or cut the siding off and attach the board to the plywood wall? then caulk the top seal?

I saw both ways in different books and videos. Maybe, another double edge sword issue.
 
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Old 06-18-07, 04:17 PM
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Sont even think about attached it through vinly siding, or siding of any kind...that ledger board is the only thing preventing collapse on the house side, so it is VERY important that thing is secure as it can be. Remove all the siding down to original exterior sheeting, then where your putting your ledger, cut out that section of sheeting so it's ledger board connected directly to homes wood frame....if the exterior sheeting is old 3/4" lumber you can leave that in place and just be sure to fasten the lag bolts/ledger screws into the studs...if it's horse hair board/asphalt board you can remove that down to studs, and put OSB/plywood of the same thinkness in it's place then attach the ledger.

After the ledger is in place/attached, they make plastic flashing that will sit on top of ledger board and fasten to house to make the seal/flashing joint, then your decking will sit on top of the ledger flashing. I like to run a bead of silicone to the back of the flashing before attaching it to the home as an extra precaution.

Use the
DIY books for reference, but pleae, please do not use them as a mean to build a project, I have a neighbor that called me up a few weeks back and asked if I could stop by and give him some pointers....he was trying to build a deck with no real world experience and the book had him all screwed up, using methods that are now dangerious in light of the new metal eating chemicals in the wood (he built the deck 5' off the ground and did the old sandwich the post between the beam and carriage bolt them together trick...not good since the entire sheer weight of the deck is dependant on the cariage bolts sheer strength...which is not going to be much after a few years and these new chemicals....also if your using treated lumber, but your decking boards as tight as you can, DO NOT use the old method of a nail to space boards...give it a few months in the sun and you'll have plenty of gap from shrinkage...you give it an 1/8" now your going to end up with 3/8-1/2" gaps between each board....not good.
 
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Old 06-18-07, 09:08 PM
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Thank you IHI, I am going to use composite board as floor material, not to use Trex brand as mentioned in another thread.
 
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Old 06-18-07, 09:20 PM
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If your going to use composite, take a serious look at Correct Deck CX. It has the hidden fastner system and looks fantastic when it's finished, very easy to work with, just kinda spendy is all...but it should be the lst deck you ever do, and no maintenance at that

Hers'a a few pics of one we did with the Correct Deck CX:

http://img.villagephotos.com/p/2004-9/824085/RunchyDeck003intpic.jpg

http://img.villagephotos.com/p/2004-9/824085/RunchyDeck002intpic.jpg

http://img.villagephotos.com/p/2004-9/824085/RunchyDeck001intpic.jpg

I goto a professional decking forum, and the deck only guys were all talking this product up as the best composite on the market, so when I bid this job the customer wanted a composite material, so the Correct Deck was my first choice. After working with it, I can say it will be my first choice again...good stuff.
 
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Old 06-20-07, 10:15 AM
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Thanks, IHI, your reply can very well answer the question of another thread for the "Composite Decking Brand Options".
 
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