I think the best thing for both of you top do is to seek the advice of a Real Estate Attorney. This may cost you $250-$400/hr, but it will be money well spent. I would also advise you to keep this on a cordial, "neighborly" interaction. Keep both sides informed, and try to collaborate on the solution. At all costs, do not make this an adversarial relationship.
This can be worked out with sound legal advice, and cooporation.
If you need an attorny to contact, let me know.
The first is the fact that in order to perform work on the side of your house, the scaffolding will encroach upon your neighbor's property by a foot. Unless there is a specific ordinance in Oakland that requires the adjoining neighbor to consent (I'm unaware of any), you will be trespassing or encroaching upon his property if the work is performed without his consent or license.
The second problem you described has to do with your neighbor having "a lot of drainage and water lines on our side of the property line." Arguably, if this has been going on for more than five years, your neighbors may have created a prescriptive easement over your property to maintain the drainage and water lines you describe. That is something you'd have to disclose if you were to ever sell your property.
I suggest that you seek a resolution to both these issues by trading him a limited license for your limited use or encroachment in exchange for his acknowledgment that the drainage and water lines are allowed on your property as an "at will" license.
It is something that you will want to discuss with an attorney.
Jeffery P. Woo, Esq.
Sedgwick, Detert, Moran & Arnold LLP
Complex Rental Property Group
Based on the information you provided, I would suggest you speak with a Real Estate Lawyer. It sounds like what your neighbor is asking for are easement rights to your property. You are also asking for temporary access to his property to provide access to your property.
This may not be a quick process, but I would recommend speaking with a lawyer first to help you determine the best solution. You may also want to try to find out if your neighbor has a family member that might be able to help facilitate so you will be able to get your rennovation project up and going in a more timely manner.
Hope this helps,
Alain Pinel Realtors