Attaching brackets to old concrete

[Ray-CA]

I need to attach several large Simpson brackets to concrete that was poured in 1940. My questions are:

1) Should I use Tapcon's (or equivalent) with epoxy
2) Threaded rod epoxied into a hole then attach the bracket with washers/nuts

If I use the threaded rod/nut option, is there a Loctite type product that is rated for exterior application?

Thanks,

Ray

 

[rtz]

What about Lead Anchors?

 

[GMCGarage]

Can you give us dimensions, and loads? if you are close to an edge, i would go with epoxy. Tapcons should not need 'loctite' if properly installed.

 

[brownbagg]

i like red head drop in anchors but they also the drop in bolts anchors too. epoxy nice ut not cheap and holes need cleaning good.

 

[DieselNut88]

There are large Tapcons available up to 3/4" in diameter. They have very good holding power. Mcmaster carr carries them.

 

[maxpat82]

tapcon or expanding anchor.

 

[matt_i]

The tapcon + epoxy is interesting. But might be hard to inject into a hole that's only 1/4" dia (just guessing here at typical Simpson wood brackets with around #8 or #10-ish sized holes)

Make sure you procure a blow-gun with a pencil-tip that goes as deep as the hole is drilled. Blow out dust until there is no more dust to blow out, working around in a helical pattern. Then you are ready to apply the epoxy.

The metallurgy of the Tapcon seems very hard and somewhat brittle to me. I think that's a requirement of having to "tap the concrete". I've twisted several off that looked like a brittle fracture. I think with a B7 threaded rod (approximating Grade 5 material) you could get a more balanced ductile material. Might need stainless depending if treated wood, salt air or other exterior exposure is going to be in play....

 

[signcrafter]

Do not use tapcons with epoxy.

Lots of options depending on how things go. You can go with traditional tapcons or the larger 3/8" and 1/2" diameter ones that are 4" or so long. You could also go with a redhead wedge type fastener like mentioned.

 

[readhead]

Edge distance is pretty important. Concrete that old may have a pretty sketchy mix design. I would use B7 all thread or an equal galvanized product if required. Drill the hole 1/8" oversized to allow room for the epoxy. Clean the hole very carefully. Fill the hole half way and install the rod. Allow time to cure and your in business.

Wedge anchors in old concrete are a crapshoot. There can be large stones to get through and I have seen voids in the concrete. Wedge anchors and LDT's work great but epoxy solves most problems.

 

[Ray-CA]

Thanks for the information.

I'll attach some photos with measurements in about an hour or so. We'll be attaching 8-ft 4x4 pressure treated posts in order to finish our fencing.

If I do with Tapcons, I was going to use the large 1/2" or larger ones, providing that I can drill a sufficient enough (diameter and depth) hole to drive them into.

This is basically the bracket I'm using: https://www.strongtie.com/boltedcolumncaps_columncaps/cc-ecc-eccu_productgroup_wcc/p/cc.ecc.eccu and will be using it upside-down, attaching the saddle to the concrete and the "ears" to the 4x4 posts. Plan on attaching through the pre-drilled holes on the sides and drilling new holes on top to attach down into the curbing.

Ray

 

[readhead]

Why wouldn't you just drill through the wall and thru-bolt the bracket? I can't see a need to bolt down through the top. You can also order the CC's with the straps the other way which I think will be a better connection for the posts.

 

[wssix99]

Why wouldn't you just drill through the wall and thru-bolt the bracket? I can't see a need to bolt down through the top. You can also order the CC's with the straps the other way which I think will be a better connection for the posts.

This would be a lot easier and a lot less costly!

 

[Ray-CA]

Sorry, but I guess I should have explained further. I'm not attaching to a wall, but rather a curb. It was poured in 1939-40 and carbon steel pipe was used instead of re-bar. The curb varies from 5 5/8" to 6 1/4" wide and 14" to 18" deep. I don't have access behind the curb to through-bolt it (nasty neighbor and the existing fence is fully on her property.)

I'll be drilling 4-holes to attach through vertically and using at least 2-of the horizontal ones.

Here are some photos.....

Ray

 

[RocketScott]

Those are going to rust out in no time.

You can get them in galvanized but I'm not sure that's the best solution for your situation.

 

[readhead]

The plot thickens. Fence next to a fence. Nasty neighbor. Hummmm. That CC is non stock with the straps turned. I have built brackets for just that condition. We did a top and one side with the straps just like your picture. Obviously the CC's will work but do you have an option to build or have some built? How many do you need? Even if you pay someone it would probably be cheaper to have them built and you won't have to drill the Simpson hangers. I think epoxy is definitely the right choice for this condition.

 

[ard]

That curb looks pretty ...light. If there is no rebar in there, you are one crack away from failure. Correct me if wrong, but there is no footing, right? Just a curb on grade?

Id whack out the curb at each post- 12, 18 inches wide, dig a hole/footing down 30-36",- and drop in a heavy duty simpson PB anchor- same straps as you have, but now set in concrete. you could re-form the curb to align with the old curb.

Ive done a few wood fences like this, no wood in the ground; future repairs are bolt on; the simpson anchors have a standoff; you can use 8-12" of sonotube to get it a bit higher.

But if that curb has no rebar and no footing....I just dont see it lasting.

 

[readhead]

Ard is probably right. We were focused on attaching to the concrete and ignoring what is attaching to the concrete. A strong gust of wind could blow over the fence and the curb.

 

[Ray-CA]

Sorry, but I guess I should have explained further. I'm not attaching to a wall, but rather a curb. It was poured in 1939-40 and carbon steel pipe was used instead of re-bar. The curb varies from 5 5/8" to 6 1/4" wide and 14" to 18" deep. I don't have access behind the curb to through-bolt it (nasty neighbor and the existing fence is fully on her property.)

I'll be drilling 4-holes to attach through vertically and using at least 2-of the horizontal ones.

Here are some photos.....

Ray

The curb is 14 to 18 inches thick (top to bottom) and has two rows of carbon steel 3/4” pipe inside, in lieu of rebar. We’ve removed a small section of this elsewhere in the yard and it’s a chore I don’t wish to repeat. Additionally, the curb does a great job keeping water runoff from the neighbors flooding our yard.

This length of fence will only be 40-ft and there will be two 6-ft long 6-ft high side fences coming of at 90* to hide the spa and give some lateral support to the perimeter fence.

Thanks for all the input and advise.

Ray

 

[redmondjp]

Looking at the pictures of those brackets, I'd suggest drilling two holes on the top side of the bracket, one in the center on each side of the uprights, and installing two concrete anchors into the top of the curb as well.

 

[ard]

The curb is 14 to 18 inches thick (top to bottom) and has two rows of carbon steel 3/4” pipe inside, in lieu of rebar.

OK, I was looking at the pictures, and the red dirt stains on the concrete looks like just dirt!

I am thinking that I would not use expanding type fasteners- stuff that wedges to hold. It may seek to break that concrete. So my vote is threaded rod, epoxy in.

 

[wssix99]

Those are going to rust out in no time.

I agree; particularly with the flanges so close to the ground. Those things are really expensive. (I also had to have some of the 6X6 version custom galvanized for a special deck application - it cost me a small fortune.) I'm not sure why regular 4X4 base posts woudn't suffice here, attached into the top of the curb.

So my vote is threaded rod, epoxy in.

If sticking with these brackets, this is what I would do. Some of the holes are really close to the edges and there is minimal concrete cover over the pipe in the curb. That could make it prone to chip out if one were to use a compression anchor or a screw-type anchor.

 

[frankthezapper]

Looking at your photos I reckon you do have room to through bolt; you would need to make a back plate with tapped holes (fairly accurately), slide it down behind your kerb, there would be a bit of jiggling and cutting to get your bolts to the correct length; that would solve all your worry of splitting with wedge anchors.

 

[tapered-pin]

(scratch previous post)

why not just drill vertically into the curb and expoxying a threaded rod down into the curb, drill an accompanying hole into the post and use the threaded rod as a pin to support the fence.