Building a crawlspace foundation, how to know where put piers?

Question

Hey,

I am in a middle of a flip right now and one piece of the project is to do a crawlspace because of an extension.

I have hired a concrete company to do it. They have already poured the concrete "borders" of the extension to get ready for the bricks around. But when I asked him how much and where he is going to put the piers, he said that he needs a foundation plan.

But the problem is that I have already pulled a building permit for the extension and they have requested only a site plan.

What would you suggest me on doing? Should I go and try to pay for the foundation plan or there are really simple rules for that which I can learn really quick to tell him where to put the piers?

Thank you

Dustin Allen · Answer

@Lior Golan

This is something for an engineer/architect to determine. An architectural designer can also draw the plan for you and have the engineering signed off. Either way, this is a complex math problem that depends greatly on the loads to be carried and so many other factors.

Ed O. · Answer

Foundation plans are pretty simple. Unless you're building something exotic or massive, your foundation provider should be very comfortable laying out piers. Unless mandated locally or as described in the first sentence, hiring an architect for something simple would be a poor use of funds in my opinion. Whoever designed the house should also be able to generate a foundation plan in minutes.

Lior Golan · Answer

Got you, so it seems like I do need foundation plan.

Bill B. · Answer

Is this a tiny one room extension? Seems weird the city would approve any plan that didn’t meet their requirements without piers if they were required.

Jared W Smith · Answer

This is not the recommendation the OP should be going off. Based on the original post he has hired a concrete company. There is no mention of a designer. It appears the OP is fairly clueless on this scope of work sheerly by the post title in itself. Why wouldn't you hire a professional to walk you through an area you lack clarity and is as important as THE FOUNDATION of the house?? Amazes me how "hiring an architect... would be a poor use of funds.." is thrown out there in such a critical part of a home. Build it correctly the first time and avoid future problems.

To generally answer the OP and for those reading this in the future, foundation piers are located below what ever framing the home has. It supports beams and load bearing walls allowing the loads (dead, live, snow, etc.) to be transferred into the ground. Typically the local Building Codes has minimum loads for each use (broken down to per SF) occurring in a house/building. Following the calculation of the total loads present, you must utilize tributary area to pin point which loads are direct to what load bearing walls or posts will carry it. Piers are then sized accordingly for the loads and the capacity of the soil present. Soo in other words, get an architect or engineer to do the plan and then have the concrete company follow it.

Jared W. Smith, RA (NY) - Principal Architect @ Architect Owl PLLC

Building a crawlspace foundation, how to know where put piers?

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