How to best fix a ledger board for a lean-to onto existing corrugated shed

[matzpersson]

Hi,

I am a new member to this forum and I have a project that I am working on which i hoping to get some advise on.

I had to take down previous lean-to as it was falling apart and getting dangerous. I am planning to replace it with a timber structure essentially made up of 190x45mm MGP 10, H3 rafters and beams with corrugated sheets on top.

I am trying to decide how to best fix the ledger board to the existing shed (190x45mm board). The existing shed have a corrugated sheeted high wall with hardwood timber trusses behind. I have attached a couple of picture outside and inside for reference.

As the replacement lean-to is 4x6m (actually smaller than the old one), I don't think putting timber connectors through the ledger board and into the trusses will be enough. One alternative solution I was considering, additional to timber connectors into truss, was to put a "double ledger board" meaning one ledger board on the outside for the rafters to hang on and one board on the inside of the shed with galvanised bolts through both boards clamping them over the trusses and creating enough structural strength. 

Appreciate any suggestions with this. Pictures show existing shed with slab for lean-to as well inside pic of the trusses behind the front wall.

Thanx,
Matz

[EricL]

Hello @matzpersson 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about fixing a ledger to your shed.

Before you make any attachments, I suggest having the shed's structure evaluated to confirm its ability to withstand the extra weight of the ledger and the new building you're installing. Seeking advice from a structural engineer or a builder will assist in assessing your sheds load-bearing capacity and guarantee that installing the new building won't jeopardize the stability of the current shed.

Attaching the ledger to the roof trusses is one method of anchoring your new building to the shed. But there is also the option of having it freestanding and anchoring posts to the concrete base and just sealing the gaps between the shed and the new building with flashing. In this manner your shed won't have to take on any new structural weight. 

Let me call on our experienced members @Dave-1 and @Nailbag for their recommendations.

If you have any other questions we can help with, please let us know.

Eric

[Dave-1]

Morning @matzpersson 

Welcome to the community Its a good place to wander through and see what can be done. Only down side is it can chew up a lot of time as there are so many options! 

I like the idea of a frestanding option, connected with flashing that @EricL has mentioned. Mainly because whenever I have built something it shouldnt need another building/wall to support itself in any way. It may take extra resources/time to configure right but would rather not have the wobble stopped by an existing structure as then both structures are weaker.

If you do go down the track of a ledger board id suggest to remove the strip of corrogated tin so the surfaces are flush with each other. I would also suggest to have the board attached to either top or bottom of the trusses but not middle. Purley as I think they would be stronger points to attach to.

Dave

[Nailbag]

Hi @matzpersson before even reading both @EricL and @Dave-1 replies, the first thing to mind is why the need to even connect to the exiting shed? It wont provide any additional support other than the continuity of the final design finish. I would plan to build the new shed which will require a building permit to be freestanding to the existing shed then incorporate flashing to provide a weatherproof shield between the two structures.

Regards, Nailbag

[matzpersson]

Thanx @Nailbag @Dave-1 @EricL for all the advice. All makes sense. Will keep you posted with how I go