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-   -   deck - beam to post connection (??) (http://www.diychatroom.com/f14/deck-beam-post-connection-9414/)

brocasArea001 06-25-2007 09:45 AM

deck - beam to post connection (??)
 
Hi All,

I might have a bit of a problem....

I did fair bit of planning on the structure of my free standing deck (spans, beam size etc) and decided to settle on a deck plan in the back of a deck book. (at least I though I did enough dd)

It's a low lying deck (deck surface 10" above grade at the lowest point) ...so I am using 2x6 for most of the framing. The deck-book plan recommended attaching the (4x6) build up beam to the side of the post (which will be very short) attached with 1/2" x 7" carriage bolts for 2 reasons:

a. There is not enough space for the beam to sit on top of the post.
b. You can avoid the troubles of ensuring the footing + piers are at the exact height (which you would have to do it the beams sat directly on the footing).


so... I followed this advise and now have piers of approximate height and precast 4x4 metal brackets installed into the concrete.

As I am about the begin construction of the frame I have read (aka googled) that installing the beam this way is not recommended and that notching a 6x6 is preferred. Unfortunately I didn't go the j-bolt route and already set my 4x4 anchors into the wet conrete (which isn't wet anymore). :wallbash:

Is attachnig the 4xbeam to the side of the post with a couple of carriage bolts okay ? Notching the 4x4 say 1.5 inches will not be possible because part of the beam would have to be inside the 4x4 anchor (because the deck is so low).

Use a stubby little 4x4 "shim" to get the correct height and sit the post on top of that?

This could be a big negative for a combination of first time deck building AND not requiring an inspection of the plan/construction.

Any suggestion would be welcome.

cibula11 06-25-2007 11:15 AM

Some prefer that the beam sits on top of the posts so that the load of the deck is resting on the post, not the carriage bolts.

However, attaching the beam to either side of the post is an extremely common practice by professionals.

Is your beam already put together? I've not seen a beam attached to only one side of the post and not sandwiched between the beam.

It sounds like that could be a problem, but maybe it has been done that way.

brocasArea001 06-25-2007 11:24 AM

Thanks for the reply...

No the beam is not put together, nor the post set. (my wife just called and said the lumber has just been delivered)

All that's assembled are 12 4 foot footings with a 4x4 post anchor set in concrete in each.

Because of the height problem the joists will be hung from the beams rather that sit on top. Is sandwiching the post between 2 2x's still applicable in this scenario because they would only be hung from the inside 2x? (would I need to install a 4x4 every couple of feet down the run of the beam between the posts?)

WNYcarpenter 06-25-2007 11:34 AM

I'm not 100% certain I understand, it sounds like your piers are too high to more than a miniature post under the beam, but not quite high enough to set the beam directly on the pier. Close???

Can you be a little more specific...what's the actual measurement between the bottom of the beam and the top of the pier where the grade is closest to the deck....a picture would be even better!

One way would be to use a wider rim joist that sits diectly on the pier nailed to the end of the beam and shim under the beam with a chunk of 4x4. I would recommend that before bolting to the side of an extremely short post.

WNYcarpenter 06-25-2007 11:48 AM

cibula11's suggestion should work for you (sandwiching the post and through bolting. Hanging joists off a beam is common practice. It's a little more time consuming, but in your case you don't have much choice. Make sure you use joist hangers and the appropriate fasteners.

atlanticwbconst, if he picks up on this thread, will have good advice as always and often times posts links to manufacturers and their suggested installation procedures.

brocasArea001 06-25-2007 12:44 PM

2 Attachment(s)
You are correct. The height of the pier was intentional too low and impresise. If I was precise in pouring my piers then I have poured them at the exact height so I could sit the beam directly on the pier and forget the post.

However the plan I followed indicated that getting the exact pier heights accross the entire deck to be at the perfect height is very difficult so it suggested using a short post and attaching the beam to the side of the post at the appropriate height to ensure everything is level, and then trimming the tops of the posts to be level with the beam.


The height of the pier is about 2" off the grade. The max height beam + pier + decking is 10" (lowest point). The joist would hang from the beam.

Sitting the beam directly on the pier would be okay if all my piers were at the correct height, but I'm willing to be they are +/- inch or two.

Perhaps using a shim is the best option is using a 4x4 shim and sitting the beam on the shims, as you suggest. This shim sizes would like likely vary between 2-4" accross the entire deck (because of a slight grade).

Here are a couple of crude pictures I drew up .... they are brutally out of scale, but hopefully you get the idea.

The first photo is what is suggested by the book. The green in the anchor. The brown in the post. The grey/green in the built up beam. The blue is the carriage bolts. The entire beam is on the outside of the anchor/post.

The second photo is what I think you suggested. With the brown being part being a shim (or a really really short post), and the beam sitting inside the anchor with carriage bolts.

brocasArea001 06-25-2007 01:05 PM

Quote:

Originally Posted by WNYcarpenter (Post 50407)
cibula11's suggestion should work for you (sandwiching the post and through bolting. Hanging joists off a beam is common practice. It's a little more time consuming, but in your case you don't have much choice. Make sure you use joist hangers and the appropriate fasteners.

atlanticwbconst, if he picks up on this thread, will have good advice as always and often times posts links to manufacturers and their suggested installation procedures.



Thanks WNY.... not being even close to a structural engineer or carpenter the sandwhich post makes me wonder....

Will not the inner 2-by of the beam will be the only part of the beam supporting the joist? What does the outer 2-by (the outer slice of bread of my post sandwhich) do for the structure. I can see this working if the joist sit atop of the sandwhich but attached the the inner?

Thanks.

WNYcarpenter 06-25-2007 01:23 PM

Pic #2 is the way to go. It's actually a pretty darn solid attatchment. You should be fine!

KUIPORNG 06-25-2007 01:32 PM

Option 2 seems to feel better in terms of safety and easier to install... provided the shim being minimium at certain height... as if it is too short... I think the shim may hot be strong enough... I would do option 2 if it can be done... before trying option 1...

brocasArea001 06-25-2007 01:33 PM

thanks ....

off to HDep to exchange 22 7" carriage bolts for 6" ones....that should save me about 15 bucks.... also I should probably get some spacers for the built up beam so the width will be equal to the anchor width (nominal 4-by lumber).

Again...thanks for the suggestions.

Jeekinz 06-25-2007 03:31 PM

Brocas, can you post the title of the book so I don't buy that one?

brocasArea001 06-25-2007 03:59 PM

actually this book wasn't the only to suggest this method....but most sources of info have the beam either notched in a 6x6, sitting on top, or have the post sandwiched between 2-bys.

Here is a link that describes bolting the beam to the side of the post...

http://www.cedaroutdoors.co.uk/deck_building/

so...I'm still a bit confused.

What if one of my shims is only 1 inch thick? Will it crack, compress over time, rot?

What if I want a post to extend above the deck? and cannot place the joists on the beam due to height restrictions, and am using 4x4 posts?


I'm really beginning to wish I planned for 6x6 posts.

The book was: Decks - Plan, Design, Build by Steve Cory
another book: "Decks" by Creative Home Owner Press also shows this a choice.

WNYcarpenter 06-25-2007 04:00 PM

Quote:

Originally Posted by brocasArea001 (Post 50419)
Thanks WNY.... not being even close to a structural engineer or carpenter the sandwhich post makes me wonder....

Will not the inner 2-by of the beam will be the only part of the beam supporting the joist? What does the outer 2-by (the outer slice of bread of my post sandwhich) do for the structure. I can see this working if the joist sit atop of the sandwhich but attached the the inner?

Thanks.

By sandwhiching you are eliminating the interior 2x from the beam...the end result in actuality is that you don't even have a beam at all, just a left side and right side bolted together at the beam....This practice is done when the joists ride atop the faux beam. In your situation, you'd have to increase the dimension of your 2x up to code allowing one single member to carry the weight of hanging joists. I really wish I had a cad program to ease the translation!

KUIPORNG 06-25-2007 04:35 PM

With WNYCarpenter explanation, now looks like you should go with option 3 which is sandwiched beam/post... with empty inner beam... then you can solve your extended posts issue, footing being too high...etc. issue... it make sense to me... may be you need to go back to HD to get those long bolts again...

Jeekinz 06-25-2007 05:01 PM

Check this out http://www.cornerhardware.com/home_i...ing_details/49

I don't have any good pics of my deck. It was built by an iron worker that worked on NJ/NY bridges and tunnels. I added a sunroom on it and the sunroom company couldn't believe how well built it is. They just threw the sunroom right on top without and structural modifications.


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