building a deck need advice/help

[ffjosh]

Planning my deck project. Need some advice/help and don't see any good deck forums.

Size 20x12 feet. Biggest I can go.

Deck will be free standing.

Im going with a beams to hold my deck.

The beams will be made out of 2 2x10s on 6x6 posts that are notched.

The joists will also be 2x10s. Could be over kill?

Anyways from info I gathered I'm trying to figure out what is good and bad info.

Beams will be 20 foot long.
I read I could put the first and last post 2 ft in from the ends. Then I only need one more 6x6 post in the middle. That's a post at 2 ft, 10 ft and 18 ft. Does that seem like enough posts? I was thinking at least 4.

Now how many beams total? I also read (calculator) I only need 2. One at each end. 12 foot seems like a big span not to have center support. I'm thinking 3.

Any input welcome.

 

[skippy24]

I would check with your local codes first. Here is the standard document for deck construction: http://www.awc.org/publications/dca/dca6/dca6-12.pdf. There are some variables like wood type and such.

 

[ffjosh]

Thank you. I will be reading this for sure.

 

[rlitman]

I'm missing something.

Are you planning to run the decking the long way or the short way? Sounds like you're planning on getting 20' long deck boards, then have the joists run the short way, and the beams run the long way.

12' is a doable span for a 2x10. Especially since the actual span from beam to beam will be closer to 11' when you figure in all four 2x10's in the beams.

 

[ffjosh]

I'm missing something.

Are you planning to run the decking the long way or the short way? Sounds like you're planning on getting 20' long deck boards, then have the joists run the short way, and the beams run the long way.

12' is a doable span for a 2x10. Especially since the actual span from beam to beam will be closer to 11' when you figure in all four 2x10's in the beams.

Sorry decking will run the long way. Yes 20 foot boards as I have found them pretty reasonable price.

So yes your right. Part of me figured it would be as my house has 2x10s (could be 12s but don't think so) and there spanned 12 foot in spots with a lot more weight.

And I might put a overhang. That has yet to be decided

 

[thewatusi]

It might be cheaper to do 8' / 12' decking with staggered joints. Visually it would break up the lines and be better looking IMO

 

[theoldwizard1]

The beams will be made out of 2 2x10s on 6x6 posts that are notched.

You made my day !

Too many DIYer through bolt or lag the beams to the face of the post. Guaranteed to fail, CATASTROPHICALLY !

You could probably use "built up" posts; 3 - 2x6 nailed together. Check local codes.

 

[ffjosh]

It might be cheaper to do 8' / 12' decking with staggered joints. Visually it would break up the lines and be better looking IMO

I like your idea.

Be easy to stagger the ends too.

 

[Terra Nova]

Any lumber yard worth it's salt will have an engineer or someone on staff who will do the beam span calculations for you. They will also know any local code requirements (for instance my county requires beams to be bolted to posts, no notching posts ) Just tell them exactly what you told us. 12 x 20 free standing deck, direction of the decking and what materials you want.

2 ft overhands with 2x10 joists is not overkill but you'll be just fine. I have 2 ft overhangs and it's not bouncy at all. You'll want to go with 2x12 beams, at at least that's what I ended up with, with 6' spans between posts.




Edit: This is the one I built 4 yrs go, before it was stained using a Sikkens transparent mahogany.

View media item 47958

 

[ffjosh]

You made my day !

Too many DIYer through bolt or lag the beams to the face of the post. Guaranteed to fail, CATASTROPHICALLY !

You could probably use "built up" posts; 3 - 2x6 nailed together. Check local codes.

Honestly I almost did it this way and had other bad ideas lol

Been doing lots of research is why I changed my mind.

 

[Glacial_Speed]

Maybe I'm reading this wrong, but are you trying to make the beams by putting two 20 foot long 2"x10" pieces together? If I read that correctly, you might consider making the beam by using a few shorter pieces (2 twelve footers and two eights )sistered together.

__________________________ ___________________
! 12' ! 8' !
-----------------------------------------------------------------
8' ! 12' !
-----------------------------------------------------------------

I just think the odds of finding two 20 foot long pieces that are straight enough to create one beam might be difficult. And working with 20' pieces is a pain in the backside.

It would be better to have the beams move in from the edge about a foot, so the span becomes 10' with a one foot overhang on each side. The span is not a problem for my deck and I used 2x8s for joists.

What are you using for footers? Are you in a frost zone? The reason I ask is that the footers on mine had to go down about 30 inches so it was easier to have a trench dug with a backhoe rather than do several individual holes. But then again I used 5 4x4 posts instead of three 6x6 posts. Oh I also used the simpson strong tie beam holder things for the top of the post, (and different ones for the bottom that went into the concrete).

EDIT: Damn I type too slow and think too much.

 

[ffjosh]

Any lumber yard worth it's salt will have an engineer or someone on staff who will do the beam span calculations for you. They will also know any local code requirements (for instance my county requires beams to be bolted to posts, no notching posts ) Just tell them exactly what you told us. 12 x 20 free standing deck, direction of the decking and what materials you want.

2 ft overhands with 2x10 is not overkill but you'll be just fine. I have 2 ft overhangs and it's not bouncy at all.

Good idea. Forgot I have a buddy that works at a local lumber yard.

 

[ffjosh]

Maybe I'm reading this wrong, but are you trying to make the beams by putting two 20 foot long 2"x10" pieces together? If I read that correctly, you might consider making the beam by using a few shorter pieces (2 twelve footers and two eights )sistered together.

__________________________ ___________________
! 12' ! 8' !
-----------------------------------------------------------------
8' ! 12' !
-----------------------------------------------------------------

I just think the odds of finding two 20 foot long pieces that are straight enough to create one beam might be difficult. And working with 20' pieces is a pain in the backside.

It would be better to have the beams move in from the edge about a foot, so the span becomes 10' with a one foot overhang on each side. The span is not a problem for my deck and I used 2x8s for joists.

What are you using for footers? Are you in a frost zone? The reason I ask is that the footers on mine had to go down about 30 inches so it was easier to have a trench dug with a backhoe rather than do several individual holes. But then again I used 5 4x4 posts instead of three 6x6 posts. Oh I also used the simpson strong tie beam holder things for the top of the post, (and different ones for the bottom that went into the concrete).

EDIT: Damn I type too slow and think too much.

My original idea was 2 20 footers but like you said that's a pain. So I'm thinking 2 10 footers that bolt to the post in the middle. At least that's what I have read is the best way to do it.

 

[starquestMM]

Sounds like a good plan! Very close to how I built mine. Biggest difference was I used 2x12s for the beam, mostly to minimize waste from the stair stringers.

As for 3vs4 posts.... are there any house windows or doors to plan around that could dictate your post layout? What about angle bracing? Pick something you like to look of. Some details will look better with a post at the end and some wont.

 

[ffjosh]

Sounds like a good plan! Very close to how I built mine. Biggest difference was I used 2x12s for the beam, mostly to minimize waste from the stair stringers.

As for 3vs4 posts.... are there any house windows or doors to plan around that could dictate your post layout? What about angle bracing? Pick something you like to look of. Some details will look better with a post at the end and some wont.

There is a basement window but it shouldn't be in play. The deck should be to the side of it.

Not sure if ill have room for bracing. But do plan on adding some if possible.

Btw whoever asked about frost line. Yes I have to set my posts at least 30 inches

 

[SlappyWhite]

As an alternative to cement footings-posts check out screwpyles. Cheaper and IMO better.

 

[CTyankee]

Whatever size 2X material you double up to create your beams, space them apart with shims run vertically ( 1 1/2" X 1/4" is good) and place them at the points of your fastener layout.

Never make your plans based on the same length as the material size you are buying. Figure on trimming the ends of ALL the material you are going to buy.

 

[Pluribus]

Just finished my second deck last year, and I encourage you to go with the full-length boards for the surface, whether you're going to use composite or wood. I'm a big fan of the look of no **** joints on the surface. To me, it looks really clean doing it that way.

All the boards run a little long on composite, so I trim the ends, then router the cut edges.

Note that the siding will be replaced this year, and I'll be taking care of proper flashing at that time. The existing deck was in much worse shape than the siding, so that was a priority!

 

[rlitman]

Make sure you use floating connectors like eb-ty and do not screw down 20' long deck boards or expansion/contraction will warp it like heck soon.

I'd stick to 20' length pieces on everything you can. The delivery truck is bringing you long deck boards anyway. Less joints is better.

 

[Tim The Tool Man]

Bolting the beam to the side of the post is a very bad idea! Notching the post (for single 2x's) or resting the beam on top of the post (for built up beams such as 3 2x's) is a far safer way to go. Use metal brackets in either case to further strengthen the post to beam joint.

 

[CoconutPete]

Overkill? Hell no!

I used 2 2x12's for posts on notched 6x6's on 6 concrete piers for my 14'x16' freestanding deck with 2' overhang on either side. The inspector told me I could probably park my 330CI on it without issue.

 

[rlitman]

Bolting the beam to the side of the post is a very bad idea!

Well, I didn't know this when I built my last deck in 1984. The planking has been replaced several times since then. The beams and joists are all just fine.

What I did was to use a pair of 2x12's. One on each side of a 4x4 post so there's around 3 1/2" between the two 2x12s (the 4x4 posts were just fine because they're under 2' tall). Drilled two 1/2" holes through, and put in 1/2" carriage bolts with washers to hold it all together at each post. There is no way this is going to fail.

The maximum span on that deck is around 6', and if you jump up and down on it, it's moves about as much as a patio.

Now if you're talking about using just lag screws to hold the beams, or bolting the beam to only one side of the upright without incising it, yeah that's not going to cut it.

 

[MoonRise]

Check local Code requirements first, and then check the local Code requirements.

The Code-required construction details have changed a bit over the years.

For instance, 4x4 posts used to be allowed, but 6x6 or 8x8 posts have been the requirement (for a while now). Lag-bolting the beams to the posts used to be allowed, now the requirement is to 'notch' the posts or use post-cap metal attachment brackets. etc, etc, etc.

Check your local Code requirements for deck construction.

 

[ffjosh]

Just finished my second deck last year, and I encourage you to go with the full-length boards for the surface, whether you're going to use composite or wood. I'm a big fan of the look of no **** joints on the surface. To me, it looks really clean doing it that way.

All the boards run a little long on composite, so I trim the ends, then router the cut edges.

Note that the siding will be replaced this year, and I'll be taking care of proper flashing at that time. The existing deck was in much worse shape than the siding, so that was a priority!

I do like that and it would help against seams looking funny when it gets older

 

[ffjosh]

Bolting the beam to the side of the post is a very bad idea! Notching the post (for single 2x's) or resting the beam on top of the post (for built up beams such as 3 2x's) is a far safer way to go. Use metal brackets in either case to further strengthen the post to beam joint.

I am notching it

 

[ffjosh]

Thanks to you guys and your ideas I got approved. I never even looked at the code book just emailed him and he said I am for sure within code.....made me laugh.

Only difference is I'm going with 2x12s for my beam and my deck boards will be 12 and 8s instead of 20s. Just because that's all they had.

I'm thinking it might look funny. Ill have to lay it down and see but I might have to cut them down more

Edit: and I will have 4 post per beam.
1 ft 7 ft 13ft 19ft

 

[Dave88LX]

Overkill? Hell no!

I used 2 2x12's for posts on notched 6x6's on 6 concrete piers for my 14'x16' freestanding deck with 2' overhang on either side. The inspector told me I could probably park my 330CI on it without issue.

I'm actually planning a 14'x16' free-standing right now, pretty much have my ideas down, just calculating beam/span etc. Would love to see your plans/pics if you have them!

 

[Burgerkong]

I'm actually planning a 14'x16' free-standing right now, pretty much have my ideas down, just calculating beam/span etc. Would love to see your plans/pics if you have them!

Here's mine (I have a thread in Free Parking, but the order is whacked, so this is just the pics):

https://www.flickr.com/photos/51597184@N03/albums/72157654024693434

 

[Jeff95TA]

I didn't see this mentioned, but regarding notching the posts, you're only supposed to notch one side so the two boards are sandwiched next to each other into one built-up beam.

Looking forward to pics!

 

[jd_1138]

Check local Code requirements first, and then check the local Code requirements.

The Code-required construction details have changed a bit over the years.

For instance, 4x4 posts used to be allowed, but 6x6 or 8x8 posts have been the requirement (for a while now). Lag-bolting the beams to the posts used to be allowed, now the requirement is to 'notch' the posts or use post-cap metal attachment brackets. etc, etc, etc.

Check your local Code requirements for deck construction.

Yeah wouldn't these Simpson strong ties be stronger than notching? Because then you'd have the load of the beams directly on top of the 6x6 posts, and with the metal connectors and carriage bolts/washers the connection should be stronger.

But notching should definitely be strong enough.

 

[csp]

It might be cheaper to do 8' / 12' decking with staggered joints. Visually it would break up the lines and be better looking IMO

Break up what lines? The OP stated he is using 20' decking boards. There won't be any joints or lines to break up.

 

[B964]

I built a deck for a friend in other county couple years ago. I had the pleasure of a building inspector that was a real professional. This guy not only recommended some approaches I had not thought of but also gave input on some non code related aesthetics. He also let me slide on a technicality after the fact. Said he thought it was BS anyhow.
Maybe yours is like that also. Since he/she is going to be final say anyhow go talk to him/her about your plans.

 

[CoconutPete]

I'm actually planning a 14'x16' free-standing right now, pretty much have my ideas down, just calculating beam/span etc. Would love to see your plans/pics if you have them!

This is the rough sketchup of what I built. I can't believe i found the file this fast.

Contrary to what the drawing leads you to believe, I did put a sliding door in that wall. Lotta fun with both electrical and an asbestos wrapped duct

 

[Dave88LX]

Here's mine (I have a thread in Free Parking, but the order is whacked, so this is just the pics):

https://www.flickr.com/photos/51597184@N03/albums/72157654024693434

Nice work! Love the layout with the framing and diagonals.

I've been looking at some different load span calcs etc. It appears you just went balls-out with the build so that you could drop a bowling ball on there and not have it shake? Triple 2x12s beams, three of them. Was the middle beam necessary or just wanted to? I can't tell what the dimensions are.

What about the blocking in the middle there?

Did you originally have a different beam design? I saw some pics with through-bolts.

Thanks!

 

[Burgerkong]

Nice work! Love the layout with the framing and diagonals.

I've been looking at some different load span calcs etc. It appears you just went balls-out with the build so that you could drop a bowling ball on there and not have it shake? Triple 2x12s beams, three of them. Was the middle beam necessary or just wanted to? I can't tell what the dimensions are.

What about the blocking in the middle there?

Did you originally have a different beam design? I saw some pics with through-bolts.

Thanks!

They're actually 2x8's if I remember correctly, will have to go out and double check. Originally we wanted to bolt the boards through the post but leveling them was a PITA since the guys that dug and poured (and inserted the post brackets) did them crooked. After heeding the advice from members here and others, I ripped down the boards and bolted them together to make beams then sat them on top.

It was super overkill because why not lol, but definitely that middle row/beam was not necessary. And if you haven't noticed already, it's a freestanding deck. I installed bracing since those 4x4's were originally for the railing posts (was going to sheath them in PVC or something) and cut them to length already so they couldn't go back, might as well use them up.

The blocking was installed since it was a pretty long span and I didn't want to rely on the hurricane ties alone. Plus since I was laying out the decking on a bias, the blocking gave me an additional spot to fasten down the middle of the deck boards.

The way I look at it is this: there's a minimum code, but if you want peace of mind instead of fretting over how to achieve the minimums exactly, overbuild a little. Just a little.

 

[MushCreek]

If it's more than 30" off of the ground, wait until you read the railing requirements in the 2012 Deck Building guidelines!