Rental Property Investor · Mercer Island, WA · Member since 2008 · 22k+ posts · 14k+ votes
18y
There are loans like this, but its unlikely it would be something you want. Its called a "blanket loan". In your case, you would also need it to allow partial releases so you could sell your old house and remove that part of the loan.
I'm guessing you're concerned about the down payment money. You have equity in your old house you want to use for a down payment on the new one. Something you might look into would be a bridge loan. It would get paid off when you sell the old one.
I would warn you to be careful in this situation. You don't say where you are, but in may places prices are down and sales are slow. It may take much longer than you expect to sell the old house, and it may sell for much less than you think. The single most important factor in selling quickly is price. Price your house correctly and it will sell quickly. Price it high, saying "I'm willing to wait longer to get what I want", and you'll end up getting less. It will set on the market a long time, you'll continue to pay the interest, and you'll end up discounting it to get it to move.
It may be better to make your offer on the new house contingent on selling the old one. That way you tie up the new house but aren't under the gun to sell before you close on the new one.