Low-Cost Method for Forming Concrete Footers
chuck77
| Posted in General Questions on
I am using ICFs to form a foundation stemwall and am pondering different ways to form a 16″ x 8″ footer that doesn’t require a ship load of 2 x 8 or 2 x 10. I can’t form it using the trench walls because county code requires 38″ w x 12″ deep compacted structural fill below the footer for my soil type. My thought is to use ripped plywood with some kind of wire or snap tie and 2×4 strongback with some fill holding the bottom in. If using plywood, what is a good sealer to use for saving and further ripping the plywood to use as furring strips for siding? Any cool cheap ways to form footers?
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Replies
Not particularly inexpensive, but definitely effective (and I'm using to form a footer on a garage project) is the foot hold system, http://www.thefootholdicf.com/
Use the 2x4's that you are going to frame your interior walls with! Problem solved!
Matlock, I like those, the lightness of them, that's a great idea. They ought to make 8" too. I'll check it out further.
Scott, would you put a sealer on the 2x4's to keep them cleaner since i'd also use them for support on the ICF stack?
What about FastFoot?
http://www.fab-form.com/fastfoot/fastfootOverview.php
Chuck,
Q. "If using plywood, what is a good sealer to use for saving and further ripping the plywood to use as furring strips for siding?"
A. The product you are looking for is a "form release agent." Lots of manufacturers sell form release agents; here are a few links to give you an idea of what's available:
http://www.wrmeadows.com/duogard-voc-compliant-form-release-agent/
http://www.lmcc.com/products/debond_form_coating.asp
http://www.noxcrete.com/form_release_agents.shtml
Chuck, We reuse the 2"x8" footing forms as headers, blocking and sometimes for floor joists. If you decide to re-use the plywood for furring, strip the forms quickly and clean them well. Concrete is murder on saw blades and hardened concrete on the furring will make your siding wavy.
Thanks everyone. Since I'm a one man crew on most of this project I look for methods that are light, strong, and modular. It would be cool to see a plastic spacer similar to the foot hold icf system but made for 8" strips (or other widths) of plywood so it could be assembled at the prescribed width, carried, and set as a rigid assembly where they are joined with a stake or block and the rebar tied to the spacer. You could also assemble these with pieces of fabic or poly that could wrap over the top and keep the plywood clean similar to the Fastfoot system. Since 2x4's will be the most used dimensional lumber for the interior walls, exterior siding support (like the Larsen truss), roof truss bracing, and other jobsite duties, I'll probably go with Scott's suggestion to use 2x4 and backfill the bottom to hold in the concrete.
Been asking myself the same question for some time ..
I've used Fastfoot and it is very efficient,
the only problem is that the resulting shape of the footing does not allow for easy insulation
to be installed on the footing afterward, so it is only ok to use if you do not wish to insulate the footing itself. But, if you manage the installation wisely, you can save ~ 20% of concrete while working torward a trapezoidal optimal shape using Fastfoot ,
( which resulted in nearly 7cubic meters of concrete saved on 1 of my projects )
Fabform also have a nice "adjustable" stand for use with ICF and their footing bags
which allows you to single pour ( pump cost savings ) while correctly leveling the ICF forms .
I thank Matlock Jeffries for pointing out "thefootholdicf" .
It is new to me and looks like a nice product, altough a bit expensive and lack of adjustment ?
We really need a product that would "envelope" the footing in an insulation barrier while allowing for ICF leveling and low use of disposable materials.
Some ICF manufacturer offer different thickness of concrete spacing such as Quad-Lock,
and the thicker ones can also be used directly as footings if the size meets code .
( example using a double tie block of ~ 16" concrete as footing under a 8"icf wall setup )
Would still be interesting to see a product that would optimize concrete shape while providing
a substantial insulation quality and material/labor savings.
Chuck, Drive by a build site where the footers are going in. In my area we have subcontractors that just do footers with their forms at a price you would love to pay.
But if you just want to buy wood and reuse it do so, the concrete is tough on blades after but that's about it and many contractors who are not specialized concrete sloppers do so.
I prefer to sub it... but am actually using some left over forming to do a small footer soon. 2x12, 1x12 rough sawn, 3/4" plywood... all good... Get err done... my man. Spring is here.
i like to use 1/2inch osb ripped down to width. 8 inch in your case on the table saw. you want the top of the footing as perfectly level as possible for your icfs. thats the cheapest way ive found
Have you looked at Form A Drain? I'm considering it for my home build.
https://buildblock.com/products/accessories/form-a-drain/
When 16" x 8" is spec'd, that means 8" nominal, so you can get away with two 2x4's at 7" or 2x8's at 7.5". Using ICF's you need a rigid base to mount the bottoms. If you used ripped OSB you would need to back it with 2x4's anyway, so you might as well go with 2x dimensional lumber to start with.
Form release comes in 5 gallon buckets for about $35 to $80 depending on type/brand. You put it on with a garden pump sprayer. After tearing down the forms clean the wood with a pressure washer.
I'm using 2x8's for my footings because the house is designed with 8" walls. Also using metal stakes with nail holes to hold the footings in position. No cross ties on the footings, just the stemwall, which in turn supports the footing. If you do a monolithic pour the first pass is only the footings and the concrete is a stiff mix so not as much outward pressure.
If all you are looking for is to keep the concrete off of the plywood forms, just put a strip of 6mil poly on the concrete side of the form, stapled to the top edge. Inexpensive and makes taking the form off much easier.
I know this is old but thinking about a footer and stem wall for an unheated utility building. around 30 x 40. Plan on cmu stem wall - 7 courses - on a 8 x 20 footer (6 x 16 min). I will dry lay, surface bond, and grout block. In thinking about forming footers, I was taken by the fastfooter. Thought about a 3' wide trench, level with gravel, and lay out blocks for forms, then line with plastic. Seemed simple - maybe a little dirt outside of blocks. Quick, blocks in a good place for laying wall, virtually no extra cost and very little extra labor.
If I had a boat load of the nail stakes, I'd use the 2 x 6 rough sawn that will be studs and line with plastic ala fastfooter, but those are over $3 each and little future use. I don't find rental options near me.
Thanks!
I have seen footings formed with poly or house wrap. Use a 2x4 to set your top elevation and suspend a "bag" inside of this form. Most of the production builders in my area are doing this now.
IRC 403.1 says "All exterior walls shall be supported on continuous solid or fully grouted masonry or concrete footings, crushed stone footings, wood foundations, or other approved structural systems.." What is a "fully grouted masonry footing" look like? Would not 12" blocks grouted meet this for a 8"block stem wall? If you need reinforcing, 12" bond beam blocks. Seems so simple - dry lay blocks, surface bond, and bring in the grout. I'd put down 4 or so inches of gravel, pea gravel if not too much more, dry lay the entire wall, surface bocn, and grout. Not much from google. This: https://countryplans.com/smf/index.php?topic=13132.0
PS - plumb bob - what is suggest is my alternate - just would be a lot simpler if I had or could rent a pile of steel stakes with nail holes to make leveling easy and sure.