[Jacey]

Recently had the dreaded second opinion saying our 4 inch 3/8 lag screws should be 6 inch.

I looked at a six inch today..and it seems extreme to me.

The threads are 4 inches but there is about an inch of smooth shank under the bolt head, so really these look like they should be sufficient to me.

But what do I know. I didn't see a size recommendation on the Prescriptive Wood Deck Construction pdf..so wondered if anybody knew for a fact what is really necessary. We are going through a 2x10 ledger into 2x6 studs on 16 inch centers. Top and bottom. Thanks for any tie breakers.

 

[SeniorSitizen]

How about a dreaded third opinion.:biggrin2:

Three #14 flat head stainless screws 4" long per stud.

Screw Installation Instructions:
Bore a 5/32" hole 3-1/2" deep. In that same hole bore a 1/4" hole 1-1/2" deep followed by a counter sink.

The Mrs. can park her little suv on it if she likes. 3/8" lag bolts are nonsense.

Sometimes good things take just a little longer.

http://www.wlfuller.com/html/wood_screw_chart.html

 

[Msradell]

If you look at the prescriptive Residential Deck Building Guide issued by the IRC, a copy is available here: http://www.awc.org/codes-standards/publications/dca6, they require the use of 1/2" lag bolts! That guide is what most building code officials used for reference.

 

[de-nagorg]

Think of this , the first 1.5 inches of your lag is just biting on the ledger, not the actual rim and floor joist, so you are only getting 2.5 inches of holding with those 4 inch ones.

Use the 6 inch ones. Or whatever the inspector demands, because they have the POWER.


ED

 

[Mingledtrash]

Think of this , the first 1.5 inches of your lag is just biting on the ledger, not the actual rim and floor joist, so you are only getting 2.5 inches of holding with those 4 inch ones.

Use the 6 inch ones. Or whatever the inspector demands, because they have the POWER.


ED

Yep ask inspector on this one. In my area it is common to substitute 1/4 in. sds screws with a tighter pattern.

here is the engingeer letter but they are currently reevaluating as of 12/1/2015 this letter is no longer valid but i suspect it will be updated with a new one soon.http://www.strongtie.com/ftp/letters/generic/L-F-100DCKLIV14.pdf

Code-Compliant Spacing for a Sawn Lumber Deck Ledger to Band Joisthttp://www.strongtie.com/products/connectors/sds.asp#tables

 

[Jacey]

Ok..first off looks like you are coming from the inside out? So the ledger is just getting a nibble with the 4 inch. Ours are coming from the outside thru the ledger into the 1/2 inch OSB (another consideration) into the 2x6 stud top and bottom of the ledger every other stud..so 32" spacing. i agree they should be longer..they have 5 inch lags as well. I'm squinting to make out the chart, but maybe it's all there. Do you recommend I back out all the installed 4 inch lags..and redo it, or supplement what I have with longer beefier screws?

 

[de-nagorg]

I would replace all the 4 inch with at least 6 inch bolts.


ED

 

[Jacey]

Ok...can I get away with two bolts per stud on the 32" centers?

 

[de-nagorg]

Me personally I would use 2 bolts per joist on 16" centers,

but many will just put up the minimum required per the code for their particular community.

I do not agree with building to minimum code, because I like to build to exceed the average strength.

I have broken too many things that were made for the minimum required rules.

ED

 

[Jacey]

Me personally I would use 2 bolts per joist on 16" centers,

but many will just put up the minimum required per the code for their particular community.

I do not agree with building to minimum code, because I like to build to exceed the average strength.

I have broken too many things that were made for the minimum required rules.

ED

The pattern I've seen on the deck construction pdf has the pattern in a W shape, one per stud. I also read not to countersink as it would detract from the strength of the ledger..but many here say to countersink the bolts. Any comments on either of these points?

 

[ront02769]

See if your inspector will buy ledger locks. Perfectly acceptable around here. Six pinch, no worries, they go in like the proverbial hot knife through butter with an impact driver. Ron

 

[de-nagorg]

The pattern I've seen on the deck construction pdf has the pattern in a W shape, one per stud. I also read not to countersink as it would detract from the strength of the ledger..but many here say to countersink the bolts. Any comments on either of these points?

The W pattern is minimum acceptance.
I have already stated my opinion of minimum code compliance, do not do it.

As for countersinks , I wont do it for the reason stated, possible weakening of the ledger.



ED

 

[ron45]

Are we talking studs or joist.?
Big difference...

 

[de-nagorg]

Good point RON 45:

Trainee did state 2x6 studs in the original query.

Now I wonder if this is a second story deck.


ED

 

[Jacey]

Sorry, yes this is a second story deck. As i mentioned we are coming from the outside in thru 2x10 ledger, OSB sheathing into 2x6 wall studs. Still need input on staggered pattern of lagbolts vs what we have now as described in last post.

 

[Jacey]

Just caught your comment on the W pattern. We have 2 bolts one above the other on 32 inch studs. They are counter sunk. Can we go back and use the longer lags, and then do the alternating studs non counter sunk and with the recommended 6 inch lags to make it all good?

 

[de-nagorg]

Just caught your comment on the W pattern. We have 2 bolts one above the other on 32 inch studs. They are counter sunk. Can we go back and use the longer lags, and then do the alternating studs non counter sunk and with the recommended 6 inch lags to make it all good?

That is what I would do, with what is already done.

Replace the short bolts, install all longer in 16" OC, studs.

The only reason to countersink is to hide them from view, or to cover them with siding material.

So unless the owner has a preference, no countersink is necessary.



ED

 

[Jacey]

That is what I would do, with what is already done.

Replace the short bolts, install all longer in 16" OC, studs.

The only reason to countersink is to hide them from view, or to cover them with siding material.

So unless the owner has a preference, no countersink is necessary.



ED

The owner did have a preference, why we did that. Are you saying we can do them all countersunk if we replace the short lags and do the rest with 6 inch on 16" centers?

I am also concerned with extended bolt heads interfering with joist placement against ledger.

 

[de-nagorg]

Yes you could countersink all if desired. 16" OC.

It might take advanced math to figure out how to place the deck joists elsewhere if the bolt heads interfere, but it can be done .

It is easier to just countersink them. So do it to please the homeowner.

They are the one signing the check at the end, and them being satisfied is very important.

Just build is as safe as you can, that way you can be proud that you prevented a possible major injury to someone down the road a few years.

ED

 

[Mingledtrash]

I just wanted to add new info for sds screws and found just some general deck stuff from simpson.

http://www.strongtie.com/products/c...iantSpacingforSawnLumberDeckLedgertoBandJoist
The information in this letter is valid until12/31/2016
when it will be re-evaluated by Simpson Strong-Tie. Please visitwww.strongtie.com for additional pertinent information. If you have questions or need further assistance regarding this matter, please contact the Simpson Strong-Tie engineering department at 800.999.5099.

icc approval.
http://www.icc-es.org/reports/pdf_files//esr-2236.pdf

Flier with a lot of different pictures of deck hardware uses.
http://www.strongtie.com/ftp/fliers/F-DECKCODE13.pdf

tldr: sds screws are allowed and are much easier to use and actually stronger than 1/2 in lags when used at the spacing in the charts simpson provides.

also someone asked if you were going into studs or something code requires there to be a band joist behind your ledger. which also allows you to move you lags so your joists dont land on them.
bolt spacing is dependent on how long your deck is.
Always stagger your bolts in a w pattern.

bolt spacing R507.2
http://codes.iccsafe.org/app/book/content/2015-I-Codes/2015 IRC HTML/Chapter 5.html