Attaching ledger board to brick and block wall?

Question

I'm building an enclosed 1 floor addition on the side of our house which will extend our side entry to become a mudroom and provide for a pantry off our kitchen.

We need the space under the addition to be open for various reasons, so are using a post foundation and ideally a ledger board against the existing house. i.e., the framing will be constructed similar to an attached deck.

Our house was built in the 40s and is 2 wythe brick and block solid masonry top to bottom. So its brick on the outside, CMU on the inside, tied together with header blocks every 7th row. This is NOT brick veneer on wood construction.

I'm getting this permitted. I can't seem to find guidance on how to attach the ledger board in a way that complies with 2018 Virginia Residential Code, which is based on the 2018 International Residential Code. I do see how to attach the board to CMU. Can the same apply to brick and block? If not, does anyone know a code compliant way to do this using a ledger board?

Answer 1

The International Residential Code (IRC) provides common system designs that you can invoke to construct a home with very little input from an engineer. I suspect that soil classification could be sufficient input so that you could build an entire home with no other engineer inputs. Any time you want to do something out of the ordinary (like attaching a new structure to an old structure or putting a deck on your roof), however, you'll frequently need input from an engineer.

The IRC's R301.1.3 provides the code compliant method for detailing your ledger:

Where a building of otherwise conventional construction contains structural elements exceeding the limits of Section R301 or otherwise not conforming to this code, these elements shall be designed in accordance with accepted engineering practice. The extent of such design need only demonstrate compliance of nonconventional elements with other applicable provisions and shall be compatible with the performance of the conventional framed system. Engineered design in accordance with the International Building Code is permitted for buildings and structures, and parts thereof, included in the scope of this code.

If you understandably don't want to pay for a full set of drawings, there still exists lots of room for DIY. Running your joists parallel to that ledger board could substantially reduce the engineering cost, but you're still going to need an engineer.

Answer 2

MULTI-WYTHE MASONRY WALL : ADHESIVE OR SLEEVE TYPE MASONRY ANCHOR. MINIMUM 6" EMBEDMENT. STAGGER BOLTS. SIZE AND SPACING SUFFICIENT TO TRANSFER LOAD. SEE MANUFACTURER'S LITERATURE FOR BOLT CAPACITY.

Page 33 (actual p. 37) Drawing E3, which isn't particularly helpful because it's a side view.

https://www.chicago.gov/dam/city/depts/bldgs/general/EZPERMIT/PorchGuidelinesMay2011.pdf

I do two per cavity, staggered, half of which always feel like they didn't grab so well. Can't remember if I used 3/8" or 1/2" sleeve type. Whatever they are, they're 8" long.

1/2" x 8" Tapcons are $90 a box but that's what I'd probably use now. I'd rather fail to meet code then it fail. And if your code supersedes my code, then I want to 'meet' your code. People died and then the city of Chicago put this out for free.

Pocketing the edge beams is another way but that's no fun at all, and there's no drawing. Edge beams can also be hung on overly elaborate brackets {drawing 3B, page 29 (33)}. Either of those ways the, now needing to be sistered ledger, hangs off the edge beams with joist hangers, slightly away from the building, which does facilitate tuck pointing.

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Plot your joists first, including space for the hangers, so they don't end up being in the way.

Answer 3

The "question" did not identify how high this connection is above grade or if there is a continuous footer (strip footing) below the existing wall that extends outward from the wall but an alternative could be to place treated wood posts, each end, against the wall surface. These could extend down to and bear onto the strip footing, this would remove all of the gravity load from the wall and carry it to the existing foundation. Fasteners between the new structure and the existing masonry would still be necessary to provide for lateral loads but could be greatly reduced in size and/or spacing from what is needed to transfer combined lateral and gravity loads. Fastener size/spacing selection should only need to be based on pull out capacity; which should be readily available, from the fastener manufacturer, for the substrate material. I guess you are talking Virginia, so probably no frost walls with continuous footings on which to rest new posts. Could still use posts at existing wall to carry gravity load, if soil bearing can accommodate the load.