> ## Documentation Index
> Fetch the complete documentation index at: https://docs.arc.io/llms.txt
> Use this file to discover all available pages before exploring further.

# How-to: Add collateral or borrow more against a loan

> Post more cirBTC to strengthen an open loan, or borrow more USDC against the same loan

Once a loan is open, post more cirBTC to strengthen its
[health factor](/app-kit/concepts/borrow-loan-health#health-factor), or borrow
more USDC for additional liquidity. Adding collateral lowers LTV while borrowing
more raises it.

## Prerequisites

Before you begin, ensure that you've:

* [Installed the App Kit SDK](/app-kit/tutorials/installation) and an adapter
* [Originated a loan](/app-kit/quickstarts/originate-a-loan) with the connected
  wallet

## Add collateral

Call `addCollateral` with the loan's `loanId` and the cirBTC amount to add.
Adding collateral improves the loan's health factor but does not change its
debt.

```typescript TypeScript theme={null}
const result = await kit.borrow.addCollateral({
  from: { adapter, chain: "Arc_Testnet" },
  loanId: "11111111-1111-4111-8111-111111111111",
  collateralAmount: "0.05",
});

if (result.status === "confirmed") {
  console.log("Collateral added:", result.collateralAdded.amount);
}
```

To see the resulting health factor before signing, see
[Preview Borrow operations](/app-kit/howtos/borrow/preview-a-loan-operation).

## Borrow more

Call `borrow` with the loan's `loanId` (not a `marketId`) and the additional
USDC amount. The SDK sizes any additional collateral needed to keep the loan
healthy after the borrow and pulls it from the wallet's cirBTC balance in the
same batch.

```typescript TypeScript theme={null}
const result = await kit.borrow.borrow({
  from: { adapter, chain: "Arc_Testnet" },
  loanId: "11111111-1111-4111-8111-111111111111",
  borrowAmount: "500.0",
});
```

To preview the borrow before signing, see
[Preview a borrow](/app-kit/howtos/borrow/preview-a-loan-operation#preview-a-borrow).