No, foundation in this sense means established believers, not established doctrine.
Nope...
Acts 16:6 Now when they had gone throughout Phrygia and the region of Galatia, and were forbidden of the Holy Ghost to preach the word in Asia, 16:7 After they were come to Mysia, they assayed to go into Bithynia: but the Spirit suffered them not. 16:8 And they passing by Mysia came down to Troas.
Why had the Spirit forbid them to build or establish assemblies in parts of those areas there?
1 Peter 1:1 Peter, an apostle of Jesus Christ, to the strangers scattered throughout Pontus, Galatia, Cappadocia, Asia, and Bithynia,
Those parts in those areas, were not his responsibility to gospelize.
Thus, the following from Paul to the Romans - in light of the above...
Romans 15:14 And I myself also am persuaded of you, my brethren, that ye also are full of goodness, filled with all knowledge, able also to admonish one another. 15:15 Nevertheless, brethren, I have written the more boldly unto you in some sort, as putting you in mind, because of the grace that is given to me of God, 15:16 That I should be the minister of Jesus Christ to the Gentiles, ministering the gospel of God, that the offering up of the Gentiles might be acceptable, being sanctified by the Holy Ghost. 15:17 I have therefore whereof I may glory through Jesus Christ in those things which pertain to God. 15:18 For I will not dare to speak of any of those things which Christ hath not wrought by me, to make the Gentiles obedient, by word and deed, 15:19 Through mighty signs and wonders, by the power of the Spirit of God; so that from Jerusalem, and round about unto Illyricum, I have fully preached the gospel of Christ. 15:20 Yea, so have I strived to preach the gospel, not where Christ was named, lest I should build upon another man's foundation: 15:21 But as it is written, To whom he was not spoken of, they shall see: and they that have not heard shall understand. 15:22 For which cause also I have been much hindered from coming to you. 15:23 But now having no more place in these parts, and having a great desire these many years to come unto you; 15:24 Whensoever I take my journey into Spain, I will come to you: for I trust to see you in my journey, and to be brought on my way thitherward by you, if first I be somewhat filled with your company.