# lagbolts to support a deck



## angusmdmclean (Jun 28, 2010)

Monday August 6, 2010:


Deck Repair.
In order to best support and secure wooden railings to a deck I have to use lagbolts screwed through 2 pieces of pressure-treated lumber (1 1/2"thick) and screwed into another piece of pressure-treated lumber (1 1/2" thick) attached to the joists. [Now 3/8" lagbolts have been recommended to me; presumably 6" lagbolts are available.]

The question arises as how best to do this. I am thinking I need to drill a pilot hole through 2 pieces and into the third piece of lumber. Now what length and size drill bit would I need to accomodate the depth of the 3 pieces. Please can I be advised as to how to implemen this plan;

Angus


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## Gene Howe (Feb 28, 2009)

angusmdmclean said:


> Monday August 6, 2010:
> 
> 
> Deck Repair.
> ...


Bell hanger bits are available. Some of mine are 3/8" X 12" long. I think that you can find them even longer. Electricians use them a lot. I bought mine at an electrical supply house.
You might also look into a screw with the name "Timber Lock". Log framers and landscapers use them. No pilot needed and far less work and expense. Below is a link.
http://www.mcfeelys.com/category.aspx?cat=hex-timber-screws&s_kwcid=TC-2539-3326591749-e-417285477


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## firehawkmph (Apr 26, 2008)

Angus,
Do you have access to the underside? I like to use 1/2" carriage bolts to secure the railing posts to the deck. In conjunction with the carriage bolts, Simpson sells reinforcement brackets that go underneath and tie the skirt to the joists. They really stiffen things up. Just another way to do it.
Mike Hawkins


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## angusmdmclean (Jun 28, 2010)

*lagbolts to support deck*

Tuesday August 10, 2010:

Gene: Thanks I will look at your suggestion. Right now I do not know what a "bell hanger" looks like, but I will look it up tThe other option, which circumvents having to drill a pilot is interesting.

Mike: Yes, I do have good access to underneath the deck. I know what a carriage bolt is, since I have one here. I think it is a 6" carriage bolt", but in fact is less than 6" and it is 1/2" thick. So my question for this option is how to best drill a 1/2" hole through the 3 pieces of 1 1/2" lumber?. I have an excelletn Bosch drill but what would be a suitable bit to go through the 4 1/2" of pressure treated lumber. { ir would have to go through the 3 pieces}. Please can you comment

Angus


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## angusmdmclean (Jun 28, 2010)

*lagbolts to support deck*

Tuesday August 10, 2010:

Furthermore to give a better description of my plan I enclose a drawing of the wood below the deck. {On the left hand side the wooden railing needs to be supported.} I am thinking to add a piece below as shown and the lagbolts or equivalent would be secured from LHS vertical wood in teh horizonatl plane through and into the new piece of wood. Furtehr comments suggetions are welcome.

Thank you,

Angus


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## firehawkmph (Apr 26, 2008)

Angus,
The added piece in your drawing won't add much holding power to your rail. You would be going right into the endgrain. Drilling through treated lumber is relatively easy. Use any decent quality spade bit. Try this link for Simpson Strong tie. It is a pdf file specifically for deck construction. It shows there different fasteners and how they are used.
http://www.strongtie.com/ftp/fliers/F-DECKCODE09.pdf

Mike Hawkins:smile:


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## angusmdmclean (Jun 28, 2010)

Wednesday August 11, 2010:

To Mike: Thanks for outlining the flaw in my plan and for providing the link to the Simpson products. Clearly your recommendation, as I understand it, is as follows.

(A) not to insert the new piece of wood, since it does not add much additional support.

(B) Use 1/2" carriage bolts plus Simpson ties (as per your original post).

(C) Drill the 1/2" holes for the bolts through the 2 vertical pieces of pressure -treated lumber using good quality spade bit

I do not have experience in this field so please excuse my prevarication.

Amy further comments are welcome. Compass coordinates are first hand experience, which I lack.

Angus


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## Gene Howe (Feb 28, 2009)

angusmdmclean said:


> Tuesday August 10, 2010:
> 
> Furthermore to give a better description of my plan I enclose a drawing of the wood below the deck. {On the left hand side the wooden railing needs to be supported.} I am thinking to add a piece below as shown and the lagbolts or equivalent would be secured from LHS vertical wood in teh horizonatl plane through and into the new piece of wood. Furtehr comments suggetions are welcome.
> 
> ...


Aha! The Timber lock/timber tite screws are the ticket for your deck as per your drawing. One suggestion. Turn that "added" board so the edge grain is presented to the screw. Screwing into end grain is not a good idea. 
A bell hanger bit is just a long twist bit. Electricians use them when wiring through floor joists or other thick wood structural members.
You might, if you still need to bore holes, look into bit extensions. IIRC, they will take a 3/8 shank bit and require at least a 9/16 hole. I use them to drill for 1/2" carriage bolts through 4X4s with 2X8s on either side,


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## angusmdmclean (Jun 28, 2010)

*lagbolts to secure deck*

Wednesay August 11, 2010:

Here is picture of the LHS of deck from the outside: the tall vertical piece of wood is what I am working on. I have been successful with the 1/2" spade bit and had no difficulty drilling the holes. I plan to add one support piece of pressure- treated lumber (18") on the outside over this piece of wood. I will also drill 1/2" holes through this piece and I will use a carriage bolt ( 6" x 1/2") through the 3 pieces of wood. I will use a wrench to tighten the bolts underneath the deck.

I have not decided as yet on what Simpson ties to use 


Comments are most welcome and appreciated,


Angus


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## angusmdmclean (Jun 28, 2010)

To Gene from Arizona: I think your approach is to rotate the added board as per drawing through 90 degrees so that it is parallel to the floor of the deck? I am not used to the terms "edge grain" and "end grain." Please confirm. I have bought some Timberlake bolt screws 6" long by 3/8".


Angus


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## angusmdmclean (Jun 28, 2010)

*Lagbolts to suport deck*

Saturday August 15, 2010:

To Gene: here is the drawing as a picture. Let me correct above message. As I understand it you are suggesting rotating the "added piece of wood" through 90 degrees so that the end grain is presented to the screws. As such the end grain would be parallel to the joists. Now I do not see a way I can do this and have it best support the Timberlake supported bolted structure.

Please can you comment

Angus


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## angusmdmclean (Jun 28, 2010)

*Lagbolts to secure deck*

August 18, 2010:

Here is an update. I have added a new vertical piece of wood to secure the existing structure on outside (LHS) of raiing. I used the 6" bolts also I used 4 4" Timberlok fasteners. I had difficulty screwing the Timberlok hexagonal screw fastners into place with my 9.6 volt drill driver. I found my Bosch cord electric drill had the power needed to go through the 4 1/2" of wood. In future I will probably drill a guide hole first at least to get a start and then use the Bosch drill.

Here is the structure I now have. I am looking to get advice on installing a post on the deck floor next to this railing (inside the railing) with a view to continuing to add stability to this structure.

I will create a new post and seek advice.

Thanks,

Angus


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## firehawkmph (Apr 26, 2008)

Angus,
If you are going to add 4 x 4 posts to the inside of the deck, I would carefully locate them, cut out the flooring so the post will just fit through. You want the post to extend to the bottom of the floor joists. You need to have the post up against the joist and bolt it through with the carriage bolts like you did. I use 1/2" carriage bolts. You also have to make sure the joist is secure, especially if it is the end joist forming the skirt around the deck. That's where some solid bridging and the simpson tiedown brackets come into play. You don't want the joist to wiggle once the post is bolted to it. 
Mike Hawkins


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## angusmdmclean (Jun 28, 2010)

*Lagbolts to secure deck*

Thursday August 19, 2010;

To Mike: Thank you for reviewing my material. My immediate plan is to continue with the same approach on the outside of the deck above. 
Also I need to add some Simpson ties as you suggest. At that point I will see what I have achieved regarding stiffening the structure. When I am standing on the deck I will asses the wobble associated with the railings at this left hand side. Then, if the wobble is too much, I will think about a post on the inside.

Simpson Ties

At the perimeter end joist (LHS) there is the junction with the deck (that you stand on). The deck sits on top of the joist at right angles and is in horizontal plane. Above the deck wood another long piece of side wood in the same vertical plane as the end joist is affixed on the inside of the deck (see photo). Thus the horizontal deck wood is sandwiched between this vertical long piece of inside left hand side wood (above) and the end joist (below). One source of the wobble is between this long piece of vertical side wood above the horizontal deck and the horizontal deck itself.
I am thinking to try a Simpson ties on the _outside_ that are straight (180 degrees) and can be screwed into the vertical piece of side wood over the deck and into the end-joist. It would be a bridge of metal covering the 3 pieces of wood.

Other possibility come to mind is right angle ties on the* inside *of the vertical side wood and attached to the surface of the deck. But this may spoil the appearance of the deck.

Comments appreciated,

Angus

ps if you look at the photo carefully you can see the piece of wood I added outside of the deck.


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