I need to lift my garage to replace the old rotten out footing. The roof is sagging and it's the result of two things: the beam/footing rotting and providing no support and there is only one rafter joist holding the walls together. The roof is sagging considerably. What should I do first pull the walls together and put new rafter joists in and then jack it all?

Are u saying that the bottom plate and studs on one wall are rotten?

The rafters should have collar ties 1/3 way down from ridge board. There should be a tie every 4 feet. This will give u an "A" appearance.

The ceiling ties( which seat on the top plate) should be the same. The lumber size a minimum 2x6.

Build temporary wall about 2 feet from wall that is rotting. Use temp wall to raise to right height. Remove rotten plate and replace with pressure treated lumber. Remove rotten part of studs and install new stud along side existing stud and nail together. Remove temp wall.

Finish siding on outside.

Good luck

Chuck

I am one to start at the top(as it seems this one is near collapse) and secure it, rafter tie? do you mean a cross tie at the top of the walls,connecting one side to the other?

You lift the building a section at a time,this isn't easy or safe,I don't suggest you do this by yourself.

I have lifted barns by using jacks and plates of 1/4 in steel with right angle shoulders,the flat plate is bolted to the studs,lift,remove the sill plate,extend the studs to fit the new sill,lowered and moved to the next section.

You have to listen to the building when lifting, loud cracks can be a tell tale sign of collapse,if the building is leaning, it'll want to continue to lean that way, even more so when you lift.. this is not for the inexperienced.