DIY Home Improvement Forum banner
1 - 20 of 25 Posts

·
Registered
Joined
·
25 Posts
Discussion Starter · #1 ·
I am building a 10x10’ addition on the rear of my house for a laundry room. I have already contacted the city and am in the process of obtaining the permits. They had checked my preliminary drawings and everything looks good. I head down tomorrow to show them my finished plans. Here in Norfolk, VA the footers need to go to a minimum depth of 12”. My plan is to have 16” wide footers with 12” of depth. Then I will lay one layer 8”x8”x16” cinderblocks. I will also have 18” long threaded rod in the concrete. I will then attach a 2x8” sill on top of the blocks using the threaded rod. Couple of questions:
1) How far apart do I need to place each rod? 16”?
2) Where do I buy threaded rod? Checked Home Depot and they only had rebar and had no clue when I asked them about threaded rod for foundations.

Thanks
 

·
Registered
Joined
·
25 Posts
Discussion Starter · #2 · (Edited)
Did some searching and I think I found what I need regarding spacing.

1/2" diameter 18" J bolts spaced 12" from each corner and each end. Then 4' O.C. after that.

So for a 10x10 addition (3, 10' walls) I will use a total of 9 J bolts. One placed 12" from each end and corner and one halfway down each 10' wall. Does this sound correct?

Still not sure where to buy these.
 

·
Civil Engineer
Joined
·
5,832 Posts
I bought 12 inch J-bolts at a big box store not long ago. I don't recall seeing 18 inch bolts there, you may have to go to a real lumber supply house. I would suggest grouting the voids in the block, this will strengthen the J-bolts as well. Use hot dipped galvanized bolts, cost more than ordinary steel, but will last much longer. By the way, if you grout the holes in the block, you may be able to use 8 or 12 inch J bolts, check with your building inspector.
 

·
Registered
Joined
·
25 Posts
Discussion Starter · #4 ·
Thanks. I will do that tomorrow. The 18" size was based on a diagram the inspector gave me to show how he wanted the plans drawn up. The example was for a larger addition so I may be able to drop it to 12". I had planned on grouting the voids in the block.
 

·
Registered
Joined
·
1,943 Posts
Don't forget to use Drylock (or similar) between the concrete and any PRESSURE TREATED wood. Always use PT against concrete, which means galvanized bolts.
 

·
Registered
Joined
·
3,466 Posts
"Always use PT against concrete, which means galvanized bolts."

A question: I thought the new chemical(s) being used for PT wood eat up galvanized metal and stainless or coated fasteners are needed?
 

·
Civil Engineer
Joined
·
5,832 Posts
Bob22 is correct, the majority of PT sold today is ACQ, which contains a high percentage of copper. The copper is capable of interacting with ordinary galvanized bolts and causing damage. However, there seems to be considerable debate as to whether hot dipped galvanized bolts (rather than other types of galvanized bolts) can resist attack from ACQ lumber. I put my entire deck together using hot dipped galvanized bolts, and of course PT lumber, and after almost a year there seems to be no reaction. The vast majority of decks I have seen are built using galvanized bolts, many of which are not hot dipped. Of course, many older decks do not use ACQ lumber.

There is the option of using stainless bolts, but they are expensive, and not so easy to find. Also, there are over 100 varieties of stainless steel, and most varieties of stainless steel are not specifically rated for contact with ACQ lumber. Chances are even if you find stainless bolts, you are not necessarily going to know if that specific bolt is rated for contact with ACQ lumber. This is a difficult problem which I have not seen a definitive answer to.
 

·
Registered
Joined
·
1,943 Posts
Yes, I've always been told hot dipped galv or SS, but after reading those links a little bit I am beginning to wonder WTH to use. This is nutso. Why the H have PT wood if you "can't" (maybe) hold it in place? I wish I had a 55 gal drum of creosote....
 

·
Registered
Joined
·
3,466 Posts
Jklingel: I didn't read all the links but the Simpson one seems most detailed with supporting data. I'm guessing that galvanized (hot dipped not electroplated) would work. Have you asked the local authority what they want to see? Eventually it will come down to that.
 

·
Concrete & Masonry
Joined
·
3,890 Posts
I've always been under the impression that hot-dipped works with the modern ACQ.

As for finding the 18" anchor/J-bolts, if you have a Fastenal, they'll certainly be able to get them within a day or two. I would also try to order them from a local hardware store. That's actually where i order most of mine from.
 

·
Registered
Joined
·
1,943 Posts
Jklingel: I'm guessing that galvanized (hot dipped not electroplated) would work.
I am hoping that by next year, people KNOW, but I suspect the jury will still be out somewhat. I want fasteners that will last the life of the building, like everyone else wants. This stinks. I think I will start looking for SS j-bolts. I wonder if a roofing tar smeared on the bolts and under the washers would help. Further research is in order here. Thanks again to the two engineers who supplied the critical info. j
 

·
Registered
Joined
·
25 Posts
Discussion Starter · #15 ·
Got my permits today. Turns out I only need to use 7" minium J bolts for the size addition I am doing. These should be easier to find. I think I was confusing the guy at HD when I was calling it threaded rod. Thanks for the tips about the bolts.

Another question: Our plan calls for 12" deep footers by 16" width. Do I need to use rebar in the footing to reinforce or can I just pour the concrete into the mold and level? My father, who is assisting on this project seems to think for this size footing we do not need rebar to reinforce. I want to make sure it is set up correctly before we have the inspector come visit. We plan to start digging out the footers next week.

Thanks again.
 

·
Registered
Joined
·
4,113 Posts
Check on whether you locality requires rebar in strip footing like you explained. There is not a structural requirement usually, but for only one course of block it may be necessary or is a prescriptive requirement.

You will need anchor bolts longer than 7" if they are embedded in the footing, have to go through the 8" high block, the 2" sill and still have enough projection for a good washer and nut(s). I would imagine 12" as a minimum, but longer lengths should be available at any good contractor/masonry supply. - The spacing on the bolts will be determined by the local codes to develop enough uplift resistance.
 

·
Registered
Joined
·
25 Posts
Discussion Starter · #17 ·
Thanks for the reply. Actually the bolts do not need to go into the footer and instead only need to be cemented in the block so 7" would work. I also found out the spacing only needs to be 6' O.C. for the bolts. Our plans call for 3 bolts on each wall. I will check into the rebar. On my drawings I do not indicate any rebar in the footings and the inspector who went over my plans did not mention them however when researching the project, most of the footing form images that I have found show suspended rebar.
 

·
Civil Engineer
Joined
·
5,832 Posts
Although your local code does not appear to require that the j bolts be any closer than 6 feet, I recommend that you place them 4 feet oc. I also suggest spending a few extra dollars and getting longer bolts that make it into the slab, although again this does not appear to be a local code requirement. The reasoning is that the only thing holding your structure down is going to be the j bolts plus gravity. Norfolk can get hurricanes, and it would be unfortunate if you lost an entire building because you saved a few dollars on some j bolts.

I am attaching a photo of a house that was destroyed by a hurricane, you can see some of the j bolts are still sticking up where the bottom plate used to be. Not enough j bolts in this case.
 

Attachments

·
Registered
Joined
·
25 Posts
Discussion Starter · #19 ·
Good points. My plan is to place the J bolts 4' O.C. and I'll look into the longer bolts. Thanks for the reply.
 

·
Registered
Joined
·
4,113 Posts
I lived in the Tidewater area for 4 years and knew the codes were pretty sloppy, but not requiring anchor bolts to really be attached to the foundation is totally inept.

A single course of block is not enough to hold a house in place, left alone for uplift. - If you are in Strawbridge, south of VB, every home eventually will be oceanfront, so the water may get you defore the wind.

Dick
 
1 - 20 of 25 Posts
Top