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HELP Securing heavy PT wood topper on 5' cinder block wall.

ZooKeeperNikki's picture

The purpose of my current project is to coyote-proof the yard of our pet sanctuary so I can allow the small pets access to the yard. The yard is already cat-proof and dog-proof. Our feline and canine friends have enjoyed 24 hour access to the yard for 10 years. We recently heard reports of a coyote coming around the area and I need to keep him outside of our yard. The wall at the back of the yard is the least coyote-proof at this moment because on the back side it is only 4'tall. On my side, it is 5' tall. I had a carpenter construct some 3'Hx6'W louvered fence panels which we plan to attach to the top of the wall. I had to come up with something that didn't leave a legde on top of the block wall (or anywhere else) as a step for the coyotes (or for our resident creatures).  I chose vertical louvers that span the depth of the wall (or nearly so). They are 2x8 spaced about 3" apart at 45 degree angle. I asked my carpenter to copy a wall topper made with 1x boards but he insisted we use 2x. I had no idea how heavy PT 2xs would be in comparison to what I originally had thought to build. I have links to photos of the wood topper and the block wall (with current "cat-proofing" installed) here:

The fence panels are constructed of PT 2x8 and they are heavy. I am in southern california on the coast, we don't get much wind, rain, or snow (think it's happened once in 30 years). I am not really worried about weather affecting this fence but there is a concern of hardware rusting out from the ocean air. I am careful to use only screw approved for PT lumber but not sure how the heads will fair with ocean nearby. We do also get quakes so I want to be smart about how I mount these heavy toppers. I want them to stay up forever- or at least 10 years.

My thought was to use 4x4 from the foot of the wall all the way to the top of the topper every 6' (where two toppers will come together). I would screw the toppers directly into the cap of the block wall and also into the 4x4 post. However, if I can get away with it, I'd rather use 2x4s instead of 4x4 because I think it will make the job easier. I'm only 110lbs and can't easily work with a PT 4x4x8. What I would love to do is use the 3" Tapcons I already have to attach a 2x4 to the wall (at the grout lines?) and then attach another 2x4 flush to that with Deckmate screws. Would that give me the strength of a 4x4?  Maybe I can add another 2x 2 2xs on the other side of the wall? Would you screw into mortar joints (I think this is the "web"?) only?

I would appreciate some sensible advice.... not too sensible, as we are on a budget.

Many Thanks,

Nikki and the menagerie

Nicki (post #206939, reply #1 of 12)

What is the make up of that wall?  Looks like long brick or are those thin full depth block?  Wall thickness?  

What did the carpenter that built these and saw the wall recommend?

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


To Calvin (post #206939, reply #3 of 12)

Thanks for helping Calvin. I don't know much about masonry so please bear with me. The wall is 7 3/4 thick, the blocks are 15 1/2"W x 3 1/2"H. The wall is in great shape with only sime tiny cracks along some seams.

My carpenter doesn't know much about masonry walls. I am here because his plan was to simply secure it to the block cap with tapcons and make a fascia to secure the bottom of the fence topper to the top block. I know that is not the best bad idea so I started asking others for their opinion and hope that in this online community of experts I will find the support I need.

I had my friend who is a masonry contractor come by and look at my wall and the toppers. He said to mount 4x4 from the top of the footing to the very top of the topper, but he didn't tell me what to use or how. I didn't think to ask him about using two 2x4s instead. That occured to me last night after reading a post on this forum. It would be a more affordable option in the long run, I think. 

I do feel 4x4s on just the one side of the wall would do the trick of keeping that topper up forever. I also think 4x4 would look nicer, I just can't carry them very well since I injured my shoulder I'm not sure I'd be up for more complex work like using large anchors, having to drill larger holes, and getting the epoxy inside the blocks. Also, I'm pretty sure the heavy duty bolts that would anchor in a block wall and go through a 4x4 are  $5-6 a piece. This would be out of my budget.

I have a hammer drill and can see myself handling 2x4's and installing them with tapcons with no problem. Tapcon are supposed to have a 400lb+ weight rating so I'm not concerned that they would pull out. I'm only concerned the 2x4 could snap in a quake. I want something more substantial and don't know enough about wood to know if adding another 2x4 would give it almost as much strength as having a 4x4 to begin with.

Maybe there is a metal post that could do the trick?

Thanks in advance for your help!

Nikki (post #206939, reply #4 of 12)

Sorry, just got home and am now engrossed in getting dinner, trying to watch baseball and hopefully readying mysefl for tomorrow.


I am not familiar with those block-but...........

Tapcons are great in concrete-not so in mortar and expecially not so in soft mortar.

You'd be better off with a drop in anchor (Red Head makes them, along with Hilti) for mortar applications I believe.............or, a plastic anchor (Expandet if they're still in biz).  These use your mounting bolt to expand, trapping the anchor and resisting pullout.

Tapcons thread into concrete, which in mortar isn't always so foolproof.

Through bolting would be great-you'd sandwich the block with a large washer on the other side.


If you have found tapcons to be good in that wall, then have at it.


The two 2x4's would be ok, a 4x4 perhaps better looking-but you'd be countersinking the fastener to get the proper depth. 

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


Great Idea (post #206939, reply #6 of 12)

I like the through bolting idea. Just have to find 12" bolt that will holdup to the ocean air. Thanks for that suggestion.

If anyone else has other suggestions, I won't be tackling this until next week so please share.


Thanks a bunch!



I hate to say this after all (post #206939, reply #2 of 12)

I hate to say this after all you've done so far, but it appears to me that your toppers will provide an easy toe-hold for a cat or coyote to make a 2-stage jump that will carry them over the wall.

Have neighbors used a similar setup successfully?

I don't have any brilliant (post #206939, reply #5 of 12)

I don't have any brilliant ideas, but I would at least think about putting a 2x4 on each side and through-bolting once or twice.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Fasteners (post #206939, reply #7 of 12)


Those wall panels do look.....very heavy.  The 2x4 ea. side and screwing the panels together @ the 6' intervals seems like a good plan.  The fasteners should all be stainless if you are within 2 miles of the ocean or their lifespan will be very short. 

Gary- Research and Development


Thanks Gary and Dan.  I feel (post #206939, reply #8 of 12)

Thanks Gary and Dan.  I feel best about through bolting so I like that you also support that plan. Now, I think I'll use 4x4 on one side, since it looks like I'm going to have to hire someone big and strong to do the work for me.

As for the person who goes by the handle "rdesigns", though I believe a coyote could get his paws to the top of this fence, this style of fence would slow one down enough to alert my dogs to it's presence. Also, the jump to the top of the fence from the neighbor's property is only 7' but the minimum height from the ground in our yard to the top of any fence or patio cover/roof will be 8'4" with no furniture, trash cans, or other objects at the wall to facilitate escape. A coyote should be smart enough to know not to jump into something it can't get out of with it's prey in it's mouth. If one did manage to get into the yard and made any noise (claws scratching on the fence), the big dogs would hear it and attack. I am not concerned about who would win that fight as our pack consists of at least 3 large dogs. With some of these being sheperding breeds, they are keen to the smell of coyote. These shepherds would wake from a dead sleep at the whiff of a nearby coyote. If only I could convince these dogs to sleep outside ;)


Thanks for all your helps. Keep any helpful tips coming.


Nikki & the zoo

I would consider adding an (post #206939, reply #9 of 12)

I would consider adding an electric fence to the top of your wall

While your pack may be big, (post #206939, reply #10 of 12)

While your pack may be big, coyotes can be pretty smart, and have been known to lure dogs out to a better ambush point.  And they can kill bigger dogs.

I had a smaller English setter that would jump our redwood fence, and I think those are around 5' - 6' tall. 

YAY!  I love WYSISYG editing!  And Spellcheck!


How much money are you into (post #206939, reply #11 of 12)

How much money are you into this project?  How much more are you going to put into this?  Regrets aside, I would tie plastic mesh (heavy kind used around construction site) around 10 foot wire fence poles and lean it against the wall and weigh it down with rocks or something.  Try discouraging first before a bunker. 

If continuing with what you have is cheaper, then by all means.  Nail down 2x4s to both sides of the wood fence long enough to span the wood fence, block fence and into the ground about a foot, raise and lean against the block fence?

That wood fence is too heavy to be sitting above people without its own footing.

I forgot to mention that (post #206939, reply #12 of 12)

I forgot to mention that there will be spikes on top of the fence. I have been in contact with a "coyote trapper" in our area. He used to work with the Dept of Fish and Game as a contractor to locate and trap coyotes for relocation or euthanasia. He has coyote-proofed many properties. His advice was simply to use carpet tacking on top of the existing block wall. I couldn't do that because it would put neighbors and neighborhood cats at risk of getting their hands/paws cut. I live in California where it's easy to be sued, so I have to reduce our liability where I can. I figure the taller fence with small/tasteful warning signs"Warning Fence Spikes, Keep Off" ought to do the trick.

As for the flexible construction fencing, that is a great idea. Unfortunately, that is not an option. The neighborhood I am in is a very nice one and I cannot build anything that doesn't look nice. I'm surprised I got away with the white marine board I've been using. I am still waiting to hear from the city as to whether or not carpet tack strip is legal. If it isn't, I can use less dangerous spikes such as these:

I do like the idea of an electric fence that I could put on thop of the block wall (and leave my curren't cat-proofing in place). I had researched these for several days when we had a cat that was getting to the top of the fence. Aan electric fence requires the animal be "grounded" to deliver a shock. If an animal jumped to the top of a wood fence where there was one "hot" wire it wouldn't work, but it might work on brick? If it's a two wire system that has a ground wire and "hot" wire, you have to ensure the intruder/escapee touches both wires. I just don't see how that would work right on a block wall that is 8" thick as you woudn't know where the animal would be placing it's paws. Maybe using a few rows of each would do the trick but I wouldn't know how to design that (loop them back and forth?). I am open to trying the electric wire as an alternative. It would be a better option because we could span the full 100' of wall and the fences on the side of the property. I don't think the neighbors could sue me if their kids got shocked. Anyone have experience with hot wire fencing on block walls?