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-   -   patio cover/roof footing question (http://www.diychatroom.com/f19/patio-cover-roof-footing-question-20618/)

toolbeltmamma 05-04-2008 05:10 PM

patio cover/roof footing question
 
I will be setting my CBSQ (Simpson column base) in a freshly poured 18X18X12 concrete footing for my patio cover.

Any suggestions on how I would keep it square and level while the concrete sets?

A little background. I poured my patio 14 years ago and have had to cut my concrete for 3 footings, 18X18X12D. I am in Calif. and I have pulled a permit to do this.

Deck 05-06-2008 12:26 AM

3 Attachment(s)
Do permits in CA require post bases to be set in concrete?

I am not a contractor but I did something similar just recently. I'd guess you'd use a plumb bob for the exact position and then a rafter square and a level to make sure you are plumb and level.

I recently poured a post footing because I'm repairing my deck. I don't know if any of the following can help you, but here's some more information on what I did.


Instead of setting the base in the concrete, I set a j-bolt. I can secure an adjustable post base to the j-bolt. Some people call j-bolts "anchor bolts." Other people here will have to weigh in on whether or not this type of base is proper for your application.

You can find hot-dipped galvanized (HDG) j-bolts at Home Depot in the building materials aisle. They are like $1 each, and come in different sizes, like 1/2"x6" and 1/2"x8". You'll also need the same diameter HDG washer and nut. Which is in some aisle near hardware.


When pouring a footing, it's very important that you secure the concrete tube so it is level and does not move. Also FYI you might need an inspection before you pour.

Once I leveled the cardboard sonotube form, I secured it to wood blocks for support. After I poured, I took a 1x1 (or something long and slender) and poked down inside the form. This allows the concrete to settle apparently, and then you can add more concrete if necessary. I then screeded.

Next I used a plumb bob that I lowered from the center of where the rotted post was previously attached to. This gave me the position of the bolt. Here's a picture:

http://img210.imageshack.us/img210/1639/footing1ie4.jpg



I took a j-bolt and wrapped the first 1" of thread in painters tape. Then I inserted the bolt in the concrete so that slightly less than 1" would stick out. It's important that you have about 1", but less is better than more. Because if you have more than 1" you'll have all sorts of other problems. I'd try for 3/4" or 7/8" or something. Don't push down too hard or else the bolt can sink farther than you intended. Also, you have to work fast when you do all this because you don't want the concrete to set before you can insert the bolt.

Here's a picture after I inserted the j-bolt, and the concrete had dried some:

http://img169.imageshack.us/img169/724/footing2co0.jpg


If you go this route, you'll also need to buy a post base, and it has to be hot dipped galvanized if you are using pressure treated wood for the post.

For a patio cover, if you are using a 4x4, check the Simpson section for ABA44. You'd need 6 10d nails, hot dipped galvanized. Note that ABA44 requires a 1/2" bolt but if you were using a 6x6 (ABA66 post base) you'd have to anchor a 5/8" j-bolt and secure the post to the post base using 16d nails. Also, note that the AB series (no additional A appended) apparently allows for more wiggle room (they don't sell them here in NY).

Here's what ABA44 looks like:
http://img253.imageshack.us/img253/9659/postbasepu9.jpg


Note that I'm using a special spark-plug attachment to my socket wrench. This attachment isn't 1/2" but it can turn 1/2" nuts (3/4") and I needed something that would be able to take in about 1" in height.



Also, if you are nailing anything I would predrill with a 3/32 bit. The reason being pressure treated wood at Home Depot is really FAT and will shrink. I'm sure there's a better way to put that but I don't know the right word. And make sure the post is plumb/level in the base before you predrill each hole. The way I'm doing it is predrill a hole, drive in a nail, recheck plumb, predrill another hole, recheck plumb, etc. etc.

Also, note before that when you secure the post base to the footing, you're supposed to put a washer on, then turn the nut until it's "finger tight." Then you use a socket wrench to turn 1/3-1/2 of a circle. This was recommended by Simpson when I called their hotline. They directed me to their catalog:

Quote:

2008 Catalog, GENERAL INSTRUCTIONS FOR THE INSTALLER (Page 14), Section P
For holdowns, anchor bolt nuts should be finger-tight plus ⁄₃ to ⁄₂ turn with a hand wrench, with consideration given to possible future wood shrinkage. Care should be taken to not over-torque the nut. Impact wrenches should not be used as they may preload the holdown.
It seems like that's not enough torque to keep the base from moving when I hammer in the nails. I guess I'll find out soon enough.

Deck 05-06-2008 09:20 PM

Quote:

Originally Posted by Deck (Post 121246)
It seems like that's not enough torque to keep the base from moving when I hammer in the nails. I guess I'll find out soon enough.

It's not enough, I knocked the base loose. I'd recommend that if you are using one of these adjustable bases, after you have the position you want, trace around the outside with marker or something. That way if you knock it loose you know where to move it back to.

Now I have to find a way to re-tighten the nut. I'm going to take a dremel cutting wheel to the "O" part of my 3/4" combination wrench so that I can turn it into a "U", and then it should be slender enough to fit in so that I can turn the nut. In case anyone is wondering, the other part of the combination wrench that is already a "U" is too thick to slide in.

Deck 05-07-2008 11:45 PM

After all the trouble I had setting up the adjustable post base, maybe you'd be better off using a base set in concrete as you plan to. Please let us know what happens regardless.

BuiltByMAC 05-08-2008 01:55 AM

Quote:

Originally Posted by toolbeltmamma (Post 120942)
Any suggestions on how I would keep it square and level while the concrete sets?

A 2x4 on each side of the post base that spans the sonotube (or whatever footing form you're using)
use screws to secure the post base to the 2x4s

Mac

Deck 05-18-2008 03:04 PM

1 Attachment(s)
Hi toolbeltmamma, I'm wondering what type of connector you ended up using and how your footing came out.

For anyone who is interested, here is the tool I "adjusted" by cutting a section out of a 3/4" wrench using a dremel with a cutting wheel:

http://img167.imageshack.us/img167/1526/wrenchfx7.jpg


It allows me to snake in to the post base after the post has already been secured. This way if a post base is knocked loose I can tighten it (albeit slowly). Once again it's important not to overtighten. You can make a mark on the nut or something and then check it every so often as you tighten.

buletbob 05-18-2008 03:50 PM

What I have done in the past is put two TAPCON'S in the pre punched holes in the base cups. never had a problem with them shifting

Deck 05-21-2008 08:20 PM

Thank you bob, I will look into that!

SteveinMD 02-02-2012 10:14 AM

I decided to revive this old thread because I have the same predicament as the original poster. I will be embedding CBSQ post-bases for 4x4s for the four 8 foot legs of pergola. So having the post-bases plumb is important. If I understand Toolbeltmac correctly he suggested temporarily attaching two 2x4s to the post-bases so that they run horizontally. They would then rest on the edges of the sonotube which itself would ideally need to be level. It would seem this would require the concrete to NOT be poured all the way to the top which might make it difficult to screed for a smooth surface. If anyone can expand on this idea or provide a new one I would really appreciate it! I called Simpson and they didn't have any useful advice for this. Many thanks in advance.

Deck 02-03-2012 01:53 AM

Quote:

Originally Posted by SteveinMD (Post 842084)
If I understand Toolbeltmac correctly he suggested temporarily attaching two 2x4s to the post-bases so that they run horizontally. They would then rest on the edges of the sonotube which itself would ideally need to be level. It would seem this would require the concrete to NOT be poured all the way to the top which might make it difficult to screed for a smooth surface.

You are in Maryland? You need to check what your code requires, let us know what you find out. The original poster is in CA so he has it easy with his shallow footings. We are in a colder climate so we must go deeper usually. With pergolas I'm not sure, because if the entire thing is floating you may not need footings (but still a concrete pad). In New York for my deck footing I needed to go deep ( I think 3.5 - 4ft) and then wait for an inspection. AND once you put the tube in and pour you need to be a certain amount above ground too. I couldn't go flat with the ground with what I was doing. I think I was 6" above ground and that was code compliance. How deep you dig and how deep you have your sonotube and how much it is peeking out above ground matters.

With my concrete it wasn't like a soupy liquid where the fixtures would just sink into the concrete. I suppose you could set up some batter boards then run some wood on that then use a bunch of vice grips to hold the fixture straight once you put it into the concrete. It was never necessary for me to do that. I've done a bunch but of a different type of fixture. I'd guess just looking at your fixture it won't sink as long as your concrete isn't soupy. Here's a post I made a few years ago showing some concrete that I mixed. The guys say I could have used more water.

SteveinMD 02-03-2012 08:24 AM

Deck, yes I'm in Maryland and I already checked in with city over the phone regarding local building codes. It seems hard to believe, especially for this area, but the guy said a permit was not needed since it will be a free-standing structure not attached to the house but nowhere near the property line. He did say that building codes would require the concrete piers to be below the frost line which for this area is 24 inches. Simpson recommends 3 inches on either side of the CBSQ so I was planning on using 10 inch in diameter sonotubes. I wonder if I should dig a bit deeper into the code just to make sure this is correct before I start given that the depth in NY is nearly twice what I was told.

Upon further reflection I think I will take a ~ 2 foot piece of 4x4, attach two 2x4 sections that are 2 foot long to one end to make a "T" shaped structure, then temporarily mount this into a CBSQ. This would then be supported from below (via the 2x4s resting on concrete blocks etc) in the correct position over/in the sonotube. Before the concrete hardens I would verify that it is plumb. At least that is the plan. Because of the large amount of concrete needed and the need to haul quite a bit of equipment/supplies for this (I don't have a truck!) I am thinking of hiring a mason to do the footings.

abracaboom 02-03-2012 01:34 PM

The trick is not mixing your concrete too wet. If it is properly mixed, the base will stay put where you want it when you set it plumb using a small magnetic level.

SteveinMD 02-03-2012 01:57 PM

Yes, I suspect using a small level would get it as close to plumb/level as it needs to be. Having never used these post-bases before I wasn't sure how close to level they needed to be but your approach makes sense.

Deck 02-04-2012 03:43 PM

2 Attachment(s)
Quote:

Originally Posted by SteveinMD (Post 842991)
Upon further reflection I think I will take a ~ 2 foot piece of 4x4, attach two 2x4 sections that are 2 foot long to one end to make a "T" shaped structure, then temporarily mount this into a CBSQ. This would then be supported from below (via the 2x4s resting on concrete blocks etc) in the correct position over/in the sonotube. Before the concrete hardens I would verify that it is plumb. At least that is the plan. Because of the large amount of concrete needed and the need to haul quite a bit of equipment/supplies for this (I don't have a truck!) I am thinking of hiring a mason to do the footings.

I did my own footings. They really do take a while if you are mixing your own concrete. I used Sakrete and mixed one bag at a time. I did mine differently because I lined the inside of the sonotube with parchment paper so that I could easily remove the paper form and show off the concrete. Some of those tubes have a wax lining or people spray them with vegetable oil (I wasn't sure about that and I thought it would attract bugs) to remove them. If you look in one of the pictures I posted earlier in this thread you can see the parchment paper. Here is a picture of what it looked like when I removed the outer shell:

http://img684.imageshack.us/img684/9...removal015.jpg

If you read that other thread I linked to you'll see what it looks like if you don't remove the air pockets from your concrete. What I did after I poured my form is I went around the edge of the concrete being careful not to disturb the paper and just went up and down with a rod to remove the air bubbles.

No form I think will be 100.00% plumb. You could backfill some before pouring so that the form won't move in the hole. It involves shoveling in some dirt around the outside while you make sure the tube stays plumb.

As far as your code concerns I'd guess Maryland would have some depth. Personally I'd want something in writing. I don't know that this is your building department's responsibility as much as it is yours since you don't need a permit. Like I said in NY they have requirements where I am for both below AND above. Even if you don't have an above requirement it may still pay to go above. The reason my previous post had rotted is probably because it was at ground level. When you go above ground it prevents the water from splashing up and rotting the post I guess.

Also the girth of the tube! So for a 4x4 I needed 12". In fact I was set to use a 4x4 which is why I poured 12" wide tube but they made me use 6x6 post to support the girder on the 12" because code no longer allows 4x4 (what I had there previously). Technically I needed like 18"? wide or something for supporting 6x6 but they let me go.

Another problem you may have is rock sledge. They may or may not let you anchor into the sledge. If they do you'll have to drill into it with a masonry bit and then clean out the hole (scrub it with a dry toothbrush and then hit it with oil-free compressed air) and then put epoxy in and have rebar sticking out of it. You can't do that for just any old rock though it has to be equal to the depth or something. I had a lot of rocks. Just regular rocks and they were a pain in the aaaaaaaaaaaaaaaaasssssssssssssssssssssssssss.

More things to worry about. Underground utility lines. If you are in the back of your house in the middle of nothing that may not be a problem though. Septic tanks. I wouldn't dig at or around your septic tank or drywell. I don't know that to be the law it just seems obvious. I have a drywell that's pretty big in the backyard. If I were to get a backhoe and try to dig over it I'd punch right through its ceiling probably. Also bomb shelters. Don't ruin a good bomb shelter armageddon may be coming you never know.

Tube placement is difficult I think to square everything up. The CBSQ thingies you have have to be oriented properly so that the posts when installed will both be facing in the same general direction. Look at the pic below, bottom right looks fine and then bottom left the form is fine but the post base is kind of at an angle. Top right form is too far inset should be out a little more. etc etc

abracaboom 02-05-2012 03:06 AM

To set the bases square, use string lines. Set each base with the string almost touching the inside face of one of the flanges, parallel to it.


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