Di it yourself foundation question

[Davegmc]

I'm looking at building a 20 x 30 cabin. Most likely will have a footing and then a 2 ft concrete foundation. I'm trying to do this myself (amateur) on a shoestring budget. My question is, is it practical for a do it yourselfer to make his own 2 ft forms? Or would it be prohibitively expensive? How would they be constructed and how could you ensure you wouldn't have a form failure? I've also thought about laying blocks but then I'd have to have grout pumped in. Not sure about the availability of grout or its cost? Would I be better off having a pro do this (5K)?

Thanks!
Dave

[Squirl]

It depends.  If you are adventurous and confident, you may be able to do it yourself.  It also depends on what codes may apply.  I have to comply with the 2010 ICC for NY.  So my research usually can comply with that. It also always helps to have an extra hand when working concrete.
I started a few topics on it here:
http://countryplans.com/smf/index.php?topic=10917.msg139179#msg139179
http://countryplans.com/smf/index.php?topic=10916.msg139408#msg139408
I am currently doing it here:
http://countryplans.com/smf/index.php?topic=10998.msg140867#msg140867


With a two foot wall, you are very lucky. I would go a straight pour for everything in one shot.  In the ICC you are not required vertical rebar for a 6" concrete wall that short.  One piece of rebar should take care of the  horizontal rebar requirement for the ICC too for a 2ft wall. There are usually some exceptions if you are in a seismic category zone D or greater.  You would have to double check with your local building department.
http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_4_sec004_par003.htm

The reason you are lucky is concrete is heavy and the taller the pour the more pressure at the bottom of the form, possibly causing a blow out.  You can find all the hardware and guides for building the forms in the links at the bottom of the thread I started on poured concrete foundations.  They have a system now for a wall and footing in one pour.  The connectors are pretty cheap too.   They are designed for 2 ft tall walls.  I am building a 20x30 also.  I think all the connectors  would be around $100-$150 for a wall that size.  I will use some local material pricing.  So with a 20x30 you have around 100 linear feet of walls.  A 4x8 sheet of plywood cut in half would be exactly the two sides of the two foot wall.  So 100 ft/8ft of plywood is around 13 sheets of ¾ in ply for $20 a sheet or $260.  Also you would need around 2 rows of 100 feet of 2x8s for the footing or 200 ft of 2x8s.  With a 2x8x10 around $9 here, I would estimate $180 for the footing forms.  A 100 ft wall 6 inches thick  and 2 feet tall would be a rough 100 cu ft of concrete. A 100 ft footing 12"s wide and 7.5" deep would be around 62 cu ft.  So about 162 cu ft of concrete, or around 6 yards.  With a little extra and concrete costing around $100 a yard here, I would estimate $650 in concrete.  Also you would need 100 linear ft of rebar.  They sell the 20 ft pieces here for $7 and you would need 5 for $35.  So a very general materials estimate of $1300-$1500 to DIY.  It would help to have someone with experience double check your work or help out at the pour.  Maybe you can pay for just that.

[Davegmc]

Hello: I need to build my own foundation wall forms. I haven't been able to find 3/4 MDO plywood at the big box stores.  They do have melamine faced 3/4 particle board. Would that work okay for 2 foot foundation wall forms. Or would you recommend a ACX? plywood that I could spray with some kind of parting agent (Diesel?)

Thanks
Dave

[Squirl]

I would use regular 3/4 inch plywood. 

I believe Alan and a few others have poured their footings against wood without any release agent. The forms popped off after a few days and they were able to reuse the wood.  I believe Flyingvan used fabric to protect his forms.  From what I read the pros use releasing agents, usually used motor oil, because they don't have the time to sit and let the concrete naturally cure and shrink.  They need to take their forms and move on to the next job the next day.

Hopefully with that method, you could reuse most of the forms for subflooring, you would just need a bunch of 2x4's to use as blocking where there is not tongue and groove for the subfloor, but it should still save you a bunch of money.

Since the thread I had started on pouring forms is in the great vast sea of other posts:

If you are building your own forms you can find all those fast forming clips the contractors use here:
http://www.awardmetals.com/product_rapiform.htm
http://www.dhcsupplies.com/concrete/conmiscellaneous.htm

I like the first link because it shows all the specifications of how to use their products to build a concrete form, such as spacing and load calculations.

[boltpost]

Excellent links, the Award Metals have great products and download instructions, thank you !

[UK4X4]

excellent links- that award metal system looks to be so easy to do-

[davidj]

I think timing is a big deal with how easy forms release.  It seems pretty easy after a few days but forms left for a few weeks can get really tough.

Particle board doesn't survive well at all when when - it could get very interesting if you have a big rain storm a few days before the pour.

[Davegmc]

This must sound like a dumb question. On the website Squirl references they show attaching bottom form brackets to the top of the footing. The brackets are permanent and become part of the pour. What is the best way to attach these brackets to the concrete footing? Assume the concrete will be cured for about 2 weeks. Thanks! Also the pins don't show in the right location on the member map.