Deck project: Impact driver vs hammer drill for framing?

Hey all, I'm building a 12x16 deck this spring. Got the plans and materials sorted, but I'm stuck on which tool to buy for driving lag screws into the ledger board and decking. I have a cordless drill but it struggles. Should I get a dedicated impact driver or a hammer drill? Budget is around $150. Need something that'll last. Thanks!

Dave, for deck framing you want an impact driver all the way. Hammer drills are for masonry. An impact driver will drive those lags without stripping or snapping bits. I use a DeWalt 20V Max and it's a beast. Milwaukee Fuel is also good. Grab a set of impact-rated hex bits too. You won't regret it.

I second Pete. Impact driver is the right choice. I built a shed last year with a cheap Ryobi impact driver and it handled everything. But if you got the cash, go brushless. Also, make sure you predrill for the ledger board - it minimizes splitting. What size deck? Got any pics of the plans?