Deck Ledgers and Exterior Insulation – GreenBuildingAdvisor

By Mike Guertin | October 16, 2024

Deck ledgers are usually the last of the challenges builders think of when tackling their first exterior insulation project. After all, ledger attachment is so easy—just drive a pouch full of screws, flash the top, and move along. That is unless there’s 2 in. of exterior insulation covering the walls. Then what? How do you fasten a deck ledger to a house with continuous exterior insulation? That’s what I will address here.

Just don’t do it

I have a few solutions to share, the simplest of which is: don’t do it. I don’t mean don’t install the insulation; I mean don’t install a deck. Instead, build a nice stone patio or better yet suggest to your clients they’ll be happy with a backyard meadow. This is the easiest way to avoid additional complexities in a build.

Unfortunately, it’s hard to dissuade clients from their dream deck. So, in keeping with the “don’t” idea—don’t attach the deck to the house. Build a free-standing deck. I’ll come back to the basics of building a free-standing deck, the advantages/disadvantages, and some building code information but first, let’s look at some fastening options.

Off the wall with specialized brackets

If I have to attach a deck to a house with exterior insulation, my preferred method is to stand the ledger off the face of the wall far enough so the exterior insulation—and in many cases the cladding too—can be installed continuously between the back of the ledger and the wall sheathing. There are four proprietary ledger-mounting brackets that will do the job. And there’s a site-made ledger standoff designed specifically for ultra-thick exterior insulation.

The Maine Deck Bracket (MDB) is well known in pockets of the…