How to attach porch ledger when there is no band joist
I am adding a porch addition to the front of a century-old house which has no band joist to attach the ledger board to. The house sits on a poured basement foundation with about 14″ of the concrete above grade. The top of the finished porch floor will be about 9″ above the top of the concrete foundation. I am wondering if there is an acceptable way to anchor the ledger board from the concrete foundation below, rather than going to a freestanding porch (complicated by the fact that there are multiple buried lines in the area the footings would go, not to mention the added work/cost)
I should also add that we plan to install 4″ of rigid insulation to the house exterior, plus furring strips for the siding…further complicating a solid ledger attachment.
Any thoughts appreciated,
shawn
Replies
Of course, that, by itself doesn't provide much shear strength, for vertical loading. (Though I suppose you could run the things at an angle.)
I'd add blocking between the existing floor joists to allow use of something like ledgerlocks, timberlocks or one of the other load rated screws to attach your ledger. Many wouldn't double up the blocking, but it gives a much more substantial mounting point. It's quick, easy and if done right very solid.
It's also possible to bolt a leger to the foundation and rest the new floor joists on top of it along with enough wood to make up the elevation required, but it's more work and doesn't provide the pull out resistance at the floor level unless something like a few seismic anchors are used. Along the same lines if you are in a highly seismic area or tile will span between the old and new areas those anchors are probably a good idea even with the blocking for the most ridgid connection possible.
Free standing decks are great, but for the finished surface of a porch it's better served with a solid connection to the house.
Good luck!
Bolt beam brackets to foundation.
Some years back I had a similar problem, in that the siding was vinyl and I didn't want anything to do with trying to bolt on a ledger and having to get the flashing right to keep water out for all time. I had a welding shop make up a number of beam pocket brackets from 1/4" steel. I drilled into the concrete foundation, bolted the brackets on, and dropped the beams into those. The joists rested on those beams. Rock solid attachment, with no penetration of siding and no flashing issues.
Porch
Shawn,
What is the perimeter of the porch sitting on? What type of flooring are you using on the porch? Are the porch joists going to be at the same grade/elevation as the existing? The 4" insulation shouldn't be an issue, if it is applied above the porch grade.
The porch will be 8' deep and 35' long (running the entire length of the house). I plan to pour concrete footings using Sonotubes to support the outside edge of the porch, as well as the vertical posts extending up to the new roof extension. Flooring will most likely be cedar decking, although composite decking is still a possibility. The porch joist should be at the same level as the house floor joist, give or take an inch or so. The porch will be open with railings for starters, although future plans involve screening the entire thing in.
Thanks for the suggestions so far. I am leaning towards the 'bracket method' to support the house side of the porch floor. I'm thinking of anchoring vertical pieces of 4x6 PT to the existing exposed concrete foundation wall, and resting the joist framing on top of these vertical members. Tying it all together with metal plates. This should give me the finished floor height I need, as well as the allowance for the 4" of rigid foam board, and I won't have to penetrate the house wall to do it.
Any further suggestions appreciated!
Porch
A perimeter foundaton would help with the floor shear, bracing may be needed with the pier/post method. Sounds like you are on the right track by bolting to the foundation, view this pdf from our website for some examples of attaching to the existing structure-http://www.screwsolutions.com/assets/images/decklok-diag-baune.pdf. Also, estensive line of fasteners for projects like yours.
The railings could also help with some shear factors, will the roof be sheated with plywood??