I think it would be good stewardship to save about 10% for future needs such as building programs or emergencies which might arise above the ordinary...... and to teach the flock to do the same.... tithe 10 and save 10 and then live within your means. The community church might wish to cap the limits at some point .... for instance.... if the savings reaches a percentage or a multiple of the then existing annual budget.... or earmark an amount or percentage of excesss to go for a specific goal or ministry,..... sponsoring mission trips, church building, starting community outreach programs, adding needed full-time or part-time staff, etc.
I don't think Jesus was against building a barn to store against lean times: I do think that parable was about excessive hoarding of wealth during times when one has abundance beyond measure of needs or stewardship for the future and fails to use the excess to minister to needs apparent around him. The rich man had barns and sufficient to secure his present and foreseeable needs.... but wasn't satisfied with his abundance.... so much so.... that he was greedy for more and too selfish to acknowledge God's goodness and providence towards him and minister with the abundance God gave him to others in need.
To equate this to building a new church.... If one sees a ministry is growing and the church is too small to contain the people who attend... and there is abundance enough within the body, and other major ministry needs are being balanced and addressed, to build a new building which will acomodate more people.... then build.
But if the growth is stagnant..... and that because within the body and the community, the people have no vision.... or the community itself is stagnant or shrinking, it is foolish to build larger when potential for growth is lacking: In the latter case..... the church might expand its ministries to other areas such as sponsoring missionaries, offering a ministeral student a scholarship, or developing other forms of outreach to those in the community unable to benefit from church attendance and participation..... like nursing home visits, a soup kitchen and Bible study for the elderly the poor and the hungry.... a ministry to the disabled such as transportation, home visits, tape ministry ..... a family outreach providing a 'baby-sitting' nursery at an appointed time during the week or month where the church provides supervision of children under a certain age.... complete with entertainment and Bible stories.... so parents get a night off together.
I also think that such accounts are preferably kept within the control and the confidence of a select few and trusted members...... and available before the business meeting as a spoken report as opposed to a published report passed out to all the members or visitors which might attend.... IOW, the general budget and active accounts receipts and expenditures.... are published.... but the savings is secured requiring a minimum of several signatures and approval by 'the board' for withdrawals, and the accounting of balances given only a brief oral report in the business meeting. In this case.... once funds become active (i.e. a deposit or a withdrawal) that becomes part of the published report.... showing either the deposit to savings or the transferr from savings into the active accounts.... but the balance in the savings account is not published to keep it from those who might speculate... gossip.... or use avarice to extort the dedicated stewardship of the body.
Just thinking.