The definition is not limited to first lien transactions

The creditor makes a construction loan to finance the initial construction of the consumer’s principal dwelling, and the loan will be disbursed in five advances

3. Exclusions. Add-on and discount finance charges are not prepaid finance charges for purposes of this part. Finance charges are not prepaid merely because they are precomputed, whether or not a portion of the charge will be rebated to the consumer upon prepayment. (See the commentary to § (b).)

4. Allocation of lump-sum payments. In a credit sale transaction involving a lump-sum payment by the consumer and a discount or other item that is a finance charge under § 1026.4, the discount or other item is a prepaid finance charge to the extent the lump-sum payment is not applied to the cash price. For example, a seller sells property to a consumer for $10,000, requires the consumer to pay $3,000 at the time of the purchase, and finances the remainder as a closed-end credit transaction. The cash price of the property is $9,000. The seller is the creditor in the transaction and therefore the $1,000 difference between the credit and cash prices (the discount) is a finance charge. (See the commentary to § 1026.4(b)(9) and (c)(5).) If the creditor applies the entire $3,000 to the cash price and adds the $1,000 finance charge to the interest on the $6,000 to arrive at the total finance charge, all of the $3,000 lump-sum payment is a downpayment and the discount is not a prepaid finance charge. However, if the creditor only applies $2,000 of the lump-sum payment to the cash price, then $2,000 of the $3,000 is a downpayment and the $1,000 discount is a prepaid finance charge.

(24) Residential mortgage transaction means a transaction in which a mortgage, deed of trust, purchase money security interest arising under an installment sales contract, or equivalent consensual security interest is created or retained in the consumer’s principal dwelling to finance the acquisition or initial construction of that dwelling.

One creditor finances the initial construction of the consumer’s principal dwelling and another creditor makes a loan to satisfy the construction loan and provide permanent financing

2. Lien status. For example, a consumer might assume a paid-down first mortgage (or borrow part of the purchase price) and borrow the balance of the purchase price from a creditor who takes a second mortgage. The second mortgage transaction is a residential mortgage transaction if the dwelling purchased is the consumer’s principal residence.

3. Principal dwelling. A consumer can have only one principal dwelling at a time. Thus, a vacation or other second home would not be a principal dwelling. However, if a consumer buys or builds a new dwelling that will become the consumer’s principal dwelling within a year or upon the completion of construction, the new dwelling is considered the principal dwelling for purposes of applying this definition to a particular transaction. (See the commentary to §§ (a) and (a).)

4. Construction financing. If a transaction meets the definition of a residential mortgage transaction and the creditor chooses to disclose it as several transactions under § (c)(6), each one is considered to be a residential mortgage transaction, even if different creditors are involved. For example:

i. The creditor gives six sets of disclosures (five for the construction phase and one for the permanent phase). Each one is a residential mortgage transaction.

i. A residential mortgage transaction finances the acquisition of a consumer’s principal dwelling. The term does not include a transaction involving a consumer’s principal dwelling if the consumer had previously purchased and acquired some interest to the dwelling, even though the consumer had not acquired full legal title.