House Foundation Formwork 3

[rory704]

Looking at putting in my own foundation for a new house. The basement I'm planning is to have 10' high walls. Any suggestions for the best/easiest way at forming this? I'm currently considering using 10' lengths of plywood with 2x lumber for bracing with tie-backs.

 

[DTGT2002]

With regard to the stick built formwork, the design and construction is not overwhelmingly difficult. That said, it does require sufficient engineering ability to ensure that you have adequate capacity to support the expected loading. Much of the pour rates listed in typical form tie manufacturers info presented on snap tie packaging is outdated and does not represent the nature of modern concretes with admixtures. That said, a reduction factor of 1.4 can bring the given rates inline with what is todays safe principles.

With a jig or mass production approach, you could make your panels en mass one day set them the next and work to prepare them thereafter. However, by yourself this will be nearly impossible. Most stick built systems can be panleized around 4x8 sheets of Plyform - plyform is not simply plywood. It has subtle differences in production not limited to preapplication of form release agent that make it different that what you will find at your home improvement center.

For the heights you are taking about with that square footage, stick built walls would likely be the approach we would use. That said, we would have some means of hoisting you wont like have and our crews are led by foremen with years of experience. We can beat the linear footages listed above but I don't think you can.

If you had one run of wall to complete, without corners and other details that really benefit from experience, I would be more encouraging.

At the height you are working with, prescriptive tie layouts would be adequate and industry norms would not likely require an engineered drawing for such situations.

I design and oversee formwork and shoring operations for a living. If I were in a similar situation, I would round up a favorable supervisor and crew and pay them for a weekend of work. I would work happily amoung them, but I would not expect myself to handle it.

If you are having trouble finding contractors in your area, try contacting your local commercial construction supply or contacting form tie manufacturers and see who sell their products and who uses their products in the area. Several manufacturers are Dayton Superior, Meadow Burke and Gates amoung many others.

Formwork is far from an exact science, but requires a skill to do it well and not waste money. With your scope of work, the blowout you were warned earlier of could very well cost you as much as the form rental when you account for cleanup, lost materials and time to reset and prepare to pour again.

Best of luck,

Daniel Toon

 

[trs48]

I was a contractor prior to becoming a Civil Engineer. This may be some of the best advice you will ever receive...
DO NOT try to form and place your own concrete foundation. I will almost gaurantee it will end in failure and cost you a lot more then hiring a knowledgable contractor to do it in the first place. There are so many things that can go wrong and result in failure I hesitate to even start. Watching someone perform there job is not real world training. The reason it may look easy is because they have had their share of catastrophies and learned from them. Stay at work, do what you know, and let the contractor do their job.