Many of these US builders rely on these regional banks for financing on their construction projects. There are an estimated $650b in unrealized losses in the US when you mark to market these bonds. To put things into perspective, Silicon Valley had about $16b in unrealized losses. The potential for this to be a country wide contagion event is very high. I suspect, some of these banks are not going to have the liquidity to provide financing for these developers. The Bank Term Funding Program will provide liquidity so that depositors have access to their money and not necessarily to provide more loans.
Without the financing, the housing market will freeze. We are already in a housing recession and this financial crisis is only going to compound the problem for developers/builders.
Btw, when the debt ceiling gets raised, expect the situation to get worse. Mortgages are going to go higher and the economy is going to break. Historically speaking, the Fed pivots about 3 months after peak terminal rates but this is just confirmation that the recession has arrived.