Expert: Bruce E. Johnson - 10/19/2009

Question
QUESTION: I am renovating 60 year old 15ft wide X 18ft garage with rotted out sill on 18ft side that appeared to rest on compacted clay. Excavation showed shallow rough poured concrete piers under each stud position about 1 foot deep under sill line.Concrete pour extends about feet deep, narrowing with depth. No studs are attached to piers or reach them. Only the sill touches ground.

The piers would be tough to pull out. I want to save time and effort. In this situation, could I pour tapered piers at 3 foot depth(NJ location) or would I have to pull out the old piers and put in a footing. If piers, how many to span the 18 feet.Can I put them between the old piers? Any construction points would be very appreciated.

ANSWER: Hi Mike, it would be best to install a new footing from the sound of things.  I hope this information helps please feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com

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QUESTION: Thanks Bruce. Because the existing cement pours are about 2 feet deep, they would interfere with the new footing work. I was hoping I could just sink new piers and avoid work of removing old cement pours. Then my plan was to build up the height needed with cemented block on the new piers and add a 4x6 sill tied into the block. Is this constructuion idea sound or do I have no choice but to remove the old footings and trench for a new footing?

Answer
Hi again Mike, if the old footings have been holding up the wall and your only problem is the bad mudsill then you can probably just cut the bottom of the studs up high enough to slip a 4x6 pressure treated mudsill in on top of the existing footing piers without having to add new piers.  It was hard to say from your previous letter how much support your previous foundation was giving.  I have done similar fixes  before and they worked fine.  I hope this information helps, please feel free to write again regarding this or other matters, sincerely, bruce e johnson..bejohnsonconsulting.com