Trump: They're trying to open up the basement, when you open up the basement, it's the most expensive space to build, they're going down into the water, so they have to build a reverse bathtub, it's very expensive construction.

The claim breaks down into several components: 1) There is an effort to open up or renovate the basement space; 2) Basement construction is among the most expensive types of building work; 3) The renovation involves going below the water table, requiring special waterproofing measures described as a 'reverse bathtub'; and 4) This results in very expensive construction costs. Evidence from multiple credible news sources confirms that the Federal Reserve's $2.

5 billion renovation project includes extensive work below ground level, which has significantly increased costs.cnbc.comcnbc.comFederal Reserve quietly responds to Trump administration attacks over renovationpbs.orgpbs.orgHow Trump could use an expensive Fed building renovation to oust Powell Construction below the water table typically requires complex waterproofing and structural measures to prevent flooding, often referred to colloquially as a 'bathtub' or 'reverse bathtub' design in engineering contexts. This aligns with Trump's description of the technical challenges and high expenses involved.

While Trump's framing may be simplified and used rhetorically in political attacks against Federal Reserve Chair Jerome Powell, the core factual elements about the basement renovation and its cost drivers are supported by authoritative reporting. There is no evidence that Trump’s technical description is fabricated or grossly inaccurate, though it omits broader context about the project's scope and purpose.

Alternative explanations for cost overruns include general inflation, supply chain issues, and project management factors beyond just basement waterproofing. However, Trump's focus on basement construction costs as a key factor is consistent with expert understanding of such projects. The verdict is Mostly True because while the statement captures essential facts accurately, it lacks nuance about other contributing factors to overall expenses and may be politically motivated.