what we are looking for when we need the existing basement foundation wall to be certified for addition
do you have an examples of certification letter
You need to know if it has the capacity to support the new loading all the way down to the soil.
Generally speaking you'd want to know thickness, height, concrete strength, reinforcing size and locations, footing size and depth. etc. If you don't have some of those values then you need to make the appropriate assumptions and have a game plan in place for when the assumptions are incorrect.
REgarding a template letter, it's not something that is so cut and dry it's just changing the address, just write a letter indicating what you did to analyze, what you assumed and need confirmed. And indicate what, if any, remedial work is required to get the existing structure up to snuff to support the addition.
If you determine that it isn't feasible economically to do it (the foundations don't work and would be cost-prohibitive to upgrade for example) then tell them so.
