# Attaching retainer wall forms to foundation



## TRUEPRO (Apr 10, 2012)

You retainer wall will fail like this. You need a base footer for the wall to sit on preferably 8" wide. Not sure why you need to secure the forms to the original foundation? If you must, pre drill and use tapcons.


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## dbeamer (Jul 22, 2012)

I did not mention it will be on a 12" wide base & rebar for a single pour. How do I get the end of the retainer wall close to the foundation and provide a support for the poured concrete?


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## TRUEPRO (Apr 10, 2012)

Obviously your not having a professional build these forms? Not the hardest task but kinda hard to explain to a novice (no offense). 

Ummm....where to start... Ask mort or joecaption or canarywood they could prob explain a little better lol sorry


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## concretemasonry (Oct 10, 2006)

Where are you located?

In many areas it is recommended to NOT directly tie a exposed retaining wall to a house foundation, because they see different temperatures and moisture, so they move differently.

I have seen retaining walls heaved by frost enough to cause costly repairs to a home, including some underpinning.

Dick


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## TRUEPRO (Apr 10, 2012)

Ya and concretemasonry too their the ones to ask**


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## dbeamer (Jul 22, 2012)

I do not want to attach the finished wall to the foundation. I was asking about attaching the forms to the foundation with a 1/2" expansion joint between foundation and the retaining wall. An easier way while keeping the space between the wall and foundation small is the goal.


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## dbeamer (Jul 22, 2012)

I'm located in Santa Cruz, CA and I'm sure that don't allow connecting to the foundation.


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## pls8xx (May 2, 2009)

Your proposed wall footer is not wide enough, suggest 24". And the footer should be separated from the house footer as well as the wall separated from the foundation. Will the new wall footer be above the elevation of the house footer? Use several vertical rebar ties from the new footer into the wall.

I assume since there is so little concrete in this project that you will be mixing on site. Do the footer and wall in two separate pours. 

Do not attempt to hold the forms together by attaching to the house foundation. This is not a good way to counter the force the wet concrete will have against the forms. Butt the forms against the house foundation with the expansion material between the forms stuck to the house foundation. The wet concrete will push the expansion material hard against the foundation wall for a tight fit.

Do you need help in making the forms?


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## dbeamer (Jul 22, 2012)

Thanks for the great info. The wall footer will be above the house footer. I planned on using vertical rebar from the footer to the wall. I will be mixing on the site. I wanted to do a mono pour to avoid putting in a water stop. Since I plan to use drain pipe, rock and cloth behind the wall it is not a big issue. 
Is the main reason for doing the footer separate is to provide stability to hold the forms butt up against the house foundation, assuming all forms and bracing are adequate? I've seen the force of cement bulge, twist and break forms to often, so I wanted to avoid any weak spots with this project. I envision the cement pushing the forms away from the house foundation. Will a few 2 x 4's at a 45 degree angle, along with a separate footer, bracing the 4' long wall end toward the house foundation be enough to hold it against the house? 

Dick


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## pls8xx (May 2, 2009)

Try to hang the forms in the air to do it in one pour and it will come out a mess. A flat footer gives you something to hold the forms in place and adjust for a perfectly vertical wall face.

External bracing can be used to hold the forms against shifting away from the foundation. If it were me, I would probably extend the footer a bit beyond where the wall will end and put in a J bolt. Do a light broom finish to the footer around the J bolt to give the added wood a good "bite". After the forms are in place a doubled piece of 2x8 can be drilled for the J bolt as a bottom cleat for the forms. An additional brace would be needed at the top of the forms. 


Build the wall a few inches back from the front edge of the footer so that if you later want to add a brick or stone veneer you have a base to start from.

Do not use external bracing for the face panels! The front and back form panels need through-the-wall ties; snap ties or 3/8 allthread with bolts.

Holding the wall forms vertical can be easily done by running chain from near the form top to a secure ground connection a few feet away. Do a chain both from front and back panels at both ends of the wall. Leave slack in the chains when installed, then gather up the slack with a turnbuckle. The chains will force the form down tight against the footer and by loosening one turnbuckle and tightening the other you can adjust the form position to a perfect level.

If you are confused on anything I can maybe do a graphic or photo.

The pros may not do it this way but it works for this homeowner.


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## dbeamer (Jul 22, 2012)

Thanks for the very good recommendations. I never would of got the idea of using chain and turnbuckles to hold the form down and vertical. It sounds perfect and I have plenty of chain and turnbuckles. The j bolt idea with details was also needed. 

I was planning on use x type flat snap-ties but can't find anyone local that stocks them. The simpson tie's I believe only work with 2x's. They have the heavy duty round ones but I didn't want to deal with the extra lumber and snap-tie wedges for such a small job. I could always order the x type on line, but not sure what size plywood they use. You mentioned 3/8 allthread with bolts. Is that a brand name or just threaded rod with a bolt on one end. Could you tell me how to use the allthread so I could remove them for a finished look. I know the round type of snap-ties have coils imbedded so the rods can be turned out, but this would still require all the extra wood and special clamps. All of your advice has helped a lot. Thanks again.


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## pls8xx (May 2, 2009)

To pour a lot of low garden walls I made my forms 48" wide by 32" high. They are re-useable bolt together forms from things you can get at the hardware store. The graphic below will give you a general idea. If you decide to go this way I'll give some more detail.


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## pls8xx (May 2, 2009)

Some wall. The plastic spacers were later tapped out for re-use.


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## Mort (Nov 26, 2008)

Pouring it monolithically would save some time, but building the forms for that is kinda complicated. You'd probably be okay with something as short as you're thinking (taller walls and it'd blow out, and your kids will learn a bunch of exciting new words), but don't make it harder than it has to be. 

I don't remember seeing it, but make sure you don't just stab some vertical rebar in the footing for the wall and call it good. It has to be bent and tied in to the rebar in the footing, or it won't stay in there.


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## jomama45 (Nov 13, 2008)

To stop water migration through the foundation wall/retaining wall joint, you need something like this:

http://usa.sika.com/en/solutions_products/02/waterproofing/02a015sa99.html


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## dbeamer (Jul 22, 2012)

Mort, Thanks for the tip on using rebar. I plan to use plenty of rebar from the footing to wall and horizontal rebar also.

pls8xx, The pictures explain a lot. I might try your method if I can't find the x-flat ties. Your method seems easy & practical since you can use them over again. One reason for building my wall was to keep rain water away from the foundation. Using your method I would have to deal with sealing the holes with grout. 
What size & schedule PVC worked best? I am surprised you could push the PVC out easy. How long did you have to wait to do it?

jomama45, Have you used this sikaswell s-2 product? I haven't had much luck before with similar products on driveway and foundation cracks. Do you recommend it mainly for sealing concrete joints. Does it expand a lot? The total average rainfall at my house during the winter is 50 inches, so I have a lot of water issues.


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## jomama45 (Nov 13, 2008)

dbeamer said:


> jomama45, Have you used this sikaswell s-2 product? I haven't had much luck before with similar products on driveway and foundation cracks. Do you recommend it mainly for sealing concrete joints. Does it expand a lot? The total average rainfall at my house during the winter is 50 inches, so I have a lot of water issues.


Absolutely, and it works as it should. This isn't some cheap product you'll find at a big box store, it's a professional product that you may find hard to source. There are other products that will do the same thing, and come in a simple roll, that may be easier to find locally............


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## pls8xx (May 2, 2009)

dbeamer,

Before form assembly, I coat the plastic spacers with full strength mop&glow and let it dry. After the pour, the spacers are not hard to remove. I have a tool made from a long bolt with two washers between two nuts at the bolt end. I grind the washers to a tiny bit less than the outside diameter of the spacers. The end nut centers the tool in the spacers and a sharp tap with a hammer drives them out.

I leave the bottom row of holes open to serve as weep holes. Since they are a few inches above the wall footer, if I have installed behind-the-wall drainage, no water comes through them as long as the drainage is working. If the drainage should ever fail, it's better the water be released through the weep holes than risk damage to the wall from hydrostatic pressure.

The holes also serve other useful purposes. After the spacers are removed, a longer piece of pvc (water or electric conduit) can be driven back into the wall and then extended with additional pipe. Thus water hydrants, lights, power outlets, switches, and phone connections can be wall mounted.

The holes also are a big help in forming steps. After building step side walls, I have a reusable plywood panel with cleats for step riser boards that is positioned on the side wall and bolted in place using the wall holes.


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## dbeamer (Jul 22, 2012)

pls8xx, 

A lot of good details. I am getting curious. Do you spend a lot of time thinking of better ways to do things or have you done so many cement projects that you learned these neat tricks along the way? I would assume that you were in the cement business or still are. 

I haven't found a supplier of the x-flat snap ties yet, so I might use your method. Leaving any of the tie rod holes open as weep holes won't work in my situation. I've started working on the footing. 

What diameter pvc spacer did you use? From the picture it looks like a schedule 40 type. Did you choice a 3/8 allthread size because it would fit the pvc diameter best or it provides ideal strength? 

Thanks again for helping me with the project.

Dick


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## pls8xx (May 2, 2009)

I like to have a clean font edge on my footers and a means to screed the concrete pour. Refer to the graphic below.

I start by digging a part of the footer 3.5 inches deep. A 2x4 is drilled edgewise with 7/16 inch holes about 2 to 3 feet apart. The board is put in place and a 12 to 18 inch piece of # 3 rebar is driven through the holes. I vary the length based on soil hardness. The board fits tight on the rebar and can be adjusted up or down to grade. Dirt or sand is used to fill any gap between soil and board on the side away from the footer. The excavation for the footer is then completed using the board as a guide. When the footer is poured, it's only important to get a good level from the board to where the back of the wall will be.


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## dbeamer (Jul 22, 2012)

pls8xx, 

Good idea on using the rebar. I used a 2x6, since I have plenty available. Your method is faster for sure. 

Dick


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## dbeamer (Jul 22, 2012)

pls8xx,

You said to coat the plastic spacers with full strength mop&glow. If that works for the spacers will the mop&glow or similar wax work on the wall plywood forms or do you recommend something else as a form release agent? I heard diesel works! 

Dick


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## pls8xx (May 2, 2009)

Dick,

I've been tempted to use mop&glow for form release but haven't. My forms are painted with polyurethane and I like to clean and repaint them about every 4 or 5 uses. I'm afraid the mop&glow might be hard to remove for repainting. Almost any oil or wax product will work on a slick painted surface. I tend to use a sheen of motor oil put on with a sponge and all excess wiped off. 

My forms have now seen around 15 uses over 8 years, which has reduced the forming cost for any wall section to a very low amount. Once you have done a successful concrete project, you start seeing all kinds of things to be done. And your friends start showing up wanting to do a wall at their house too.

Contractors would not want to use my bolt system. It doesn't adapt to the tall walls that contractors need to pour. And the setup time is a bit more, increasing the labor cost. Homeowners should probably stick to walls less than three feet high. The bolt system adapts well to a project divided in to small phases that a homeowner can handle and reduces material costs (no one use snap tie expense). And all the forming materials are available at the local big box store.


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## Mort (Nov 26, 2008)

I've heard about Mop n Glo recently, oddly enough. A guy at work heard that you can put that on your mixer drum and concrete splatter won't stick to it. No matter how hard you try to clean those stupid things, you always seem to miss something. 

I imagine it also would be a good substitute for form oil.


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## pls8xx (May 2, 2009)

The type of PVC used for the spacers in my system is not important. Any half inch PVC will work. Below are two spacers.










If the thicker walled pipe is used, then you will need to grind a bit off the corners of the end nut on the knock-out tool so it will fit inside the pipe.


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## dbeamer (Jul 22, 2012)

pls8xx,

Thanks for all the good detail. I am getting a clearer picture how the project should go but I still have more questions. I don't want to "assume"! I will be using your method, as I haven't found a supplier of the x-flat ties unless I want a box of 100. It's not so much the cost as I never get rid of surplus supplies meaning I will have them for ever and your method is more practical. 

Was your graphic of the forms an end or top view? Assuming it is an end view, did you run the 2x4's horizontal the length of the form with spacer bolts going through 2x4's? It seems like it may give the form more support. Having the allthread go thru the 2x4 edge vs the surface would also give more support as recommended when using round snap-ties or do you think it would be overkill? 

The graphic did not show any other 2x4's as framing on the plywood. Were 2x4's used horizontal at the footing edge and top edge to frame the plywood?

When you extended the wall pouring another section, did you overlap the forms holding them tight against on the already poured wall with pvc spacers & allthread? 

And the last question for now. Since I don't want water leaking thru the wall, especially on the lowest spacer holes, I was thinking of modifying the pvc spacer. I am thinking of breaking up the pvc pipe into two pieces with a coupling extender in the middle with female thread on each end, solid in the middle, and a washers at each end of the extender to hold the pvc in place. I haven't looked for the extender at the hardware store yet, but I think someone should make it. What do you think? Looks are not a problem on the bottom row of spacers as they get covered with dirt. The top rows I'll try an pull/twist the pvc out.


Dick


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## pls8xx (May 2, 2009)

_"Was your graphic of the forms an end or top view?"_

End view. Here is a photo of partially assembled forms ...










_" Assuming it is an end view, did you run the 2x4's horizontal the length of the form with spacer bolts going through 2x4's? It seems like it may give the form more support. Having the allthread go thru the 2x4 edge vs the surface would also give more support as recommended when using round snap-ties or do you think it would be overkill? "_

The horizontal boards serve several functions. Yes the bolts go through the 2x4s that lay flat against the form panels. This spreads the force and prevents the bolts being pulled through the plywood. The board itself adds support from the panels bending. These boards also lock adjoining panels together and keep them in align with each other.

Since you will be mixing by hand and filling the forms slowly, the bottom will get a set before you reach the top. The boards shown will be all that's needed, but you might want to add a third row of bolts to go 48' high (my forms are 32")

Where you fill all at once from a truck, another board is added to the forms at the top of the bolt boards and placed edgewise to the panels.

In the graphic below I show 4 panels and the boards that connect them. Note that some boards are 4 ft and some 8 ft. The holes in both are offset 1.5 inches from the holes in the panels making the boards overlap to the next panel assuring panel alignment. The 8 ft boards lock panel to panel. The additional boards nailed to the bolt boards, and edgewise to the panels, span the joints in the bolt boards and give additional strength against bowing during the pour.


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## pls8xx (May 2, 2009)

_"When you extended the wall pouring another section, did you overlap the forms holding them tight against on the already poured wall with pvc spacers & allthread? "_

Yes, the forms are lapped back onto the existing wall 3 to 4 inches.

The forms always need a cap board to close off the forms where the wall will end. For this reason I make my wall thickness to match the standard width of lumber so I don't have to rip a board for the cap. Most of my walls match a 6" wide 2x6. The spacers are cut 1/16 inch longer than the board width because the spacers dimple into to the plywood panels a bit.

In the graphic below I show details for a first pour and then an extension to the wall length. Note that rebar extends beyond the first pour into where the second pour will be.


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