Question about concrete footings

gwilks98 · 07-20-2009, 02:37 PM

I'm not sure if this is the correct forum but, if I were going to put a concrete footing down to help secure a deck, what size jbolt would I need to use?

The guy at Home Depot seemed to think 6" was fine, but I wasn't sure. If you look at any major deck resource, they don't seem to specify.

Daedalus · 07-20-2009, 09:05 PM

I don't know if it's defined by building code or not, but it ought to depend on what you're anchoring. If you're going through the broad face of a single 2x4 I would think 6" ought to be fine, as you could have over 3" of the J embedded. If you're going through 2 2x4s or a 4x4 then 6" might be a bit short. The anchor's good if it's not the first thing that fails.

Jeffbx · 07-21-2009, 05:55 AM

I didn't bolt mine. They're in 48" holes with a 12" concrete pad - the 4x4 sits on the pad & then it's filled in with pea gravel all around (12" diameter hole, I think?)

12 years later, they seem to be holding up pretty well.

Prngr44 · 07-21-2009, 09:05 AM

I also poured piers for the deck... no footings.

renovation · 07-21-2009, 11:15 AM

here i just put 4x4 or 6x6 42 inch deep with cement. then i lag bolt the beams using 2-3/8x3in in bolts though the beams to the 4x4 or 6x6 and i use lags with washers. check with your local building inspector as to what his requirement is. in other areas i know you dont have to be as deep as in michigan for your posts do to frost reqirements. also here i dry bag the cement and let the ground mosture set the cement. but not all the time do i dry bag. make sure you are below the frost line for your area when digging your post holes as i have seen and had to repair decks that were not deep enough and started to heave!
also if you ever think you may add a hot tub to your deck now is the time to add extra framing.i want to see pictures of your progress as you build your deck

gwilks98 · 07-21-2009, 04:49 PM

Bah...I didn't want to bury the post in the concrete because of how exact you better have it when the concrete sets. That's why I'm using footings: I get a bit of mercy room.
I took a longer look at the code and my county requires 8" min for Jbolts. (I'm using 6x6 posts for a 3 foot high deck.)

Thanks for the help. I'll post some pic's.

07-20-2009, 02:37 PM	#1
gwilks98 Vice Admiral Join Date: Aug 2000 Location: StL Posts: 4,300	Question about concrete footings I'm not sure if this is the correct forum but, if I were going to put a concrete footing down to help secure a deck, what size jbolt would I need to use? The guy at Home Depot seemed to think 6" was fine, but I wasn't sure. If you look at any major deck resource, they don't seem to specify. __________________ "I know the pieces fit, cause I watched them fall away." "Cold silence has A tendancy to Atrophy any Sense of compassion." MJK

07-21-2009, 09:05 AM	#4
Prngr44 Rear Admiral Lower Half Join Date: Feb 2003 Location: St. Louis Posts: 2,620	I also poured piers for the deck... no footings. __________________ http://otthouse.blogspot.com

07-21-2009, 11:15 AM	#5
renovation Admiral Join Date: Jan 2003 Location: You could pick up Lindsay Lohan for less than a intel 990x, and still have money left over to bail her outta jail Posts: 5,029	here i just put 4x4 or 6x6 42 inch deep with cement. then i lag bolt the beams using 2-3/8x3in in bolts though the beams to the 4x4 or 6x6 and i use lags with washers. check with your local building inspector as to what his requirement is. in other areas i know you dont have to be as deep as in michigan for your posts do to frost reqirements. also here i dry bag the cement and let the ground mosture set the cement. but not all the time do i dry bag. make sure you are below the frost line for your area when digging your post holes as i have seen and had to repair decks that were not deep enough and started to heave! also if you ever think you may add a hot tub to your deck now is the time to add extra framing.i want to see pictures of your progress as you build your deck __________________ You could pick up Lindsay Lohan for less than a intel 990x, and still have money left over to bail her outta jail Last edited by renovation : 07-21-2009 at 11:19 AM.

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07-20-2009, 09:05 PM	#2
Daedalus Lieutenant Commander Join Date: Dec 2002 Posts: 824	I don't know if it's defined by building code or not, but it ought to depend on what you're anchoring. If you're going through the broad face of a single 2x4 I would think 6" ought to be fine, as you could have over 3" of the J embedded. If you're going through 2 2x4s or a 4x4 then 6" might be a bit short. The anchor's good if it's not the first thing that fails.

07-21-2009, 05:55 AM	#3
Jeffbx Fleet Admiral Join Date: Mar 2000 Location: Michigan Posts: 9,390	I didn't bolt mine. They're in 48" holes with a 12" concrete pad - the 4x4 sits on the pad & then it's filled in with pea gravel all around (12" diameter hole, I think?) 12 years later, they seem to be holding up pretty well.

07-21-2009, 04:49 PM	#6
gwilks98 Vice Admiral Join Date: Aug 2000 Location: StL Posts: 4,300	Bah...I didn't want to bury the post in the concrete because of how exact you better have it when the concrete sets. That's why I'm using footings: I get a bit of mercy room. I took a longer look at the code and my county requires 8" min for Jbolts. (I'm using 6x6 posts for a 3 foot high deck.) Thanks for the help. I'll post some pic's.

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