Attached Garage Door relocate and wall rebuild

[yukonsc]

I need a little help on this -

This is an attached garage the walls were built directly on the slab with kiln dried wood, this combined with some poor drainage issues (solved now) caused a significant amount of rot to the wood. 2 of the 4 walls - back (Currently has garage doors) and side (new door location)

In its current configuration the doors are on the load bearing side of the roof (Truss Roof). I want to relocate the doors to the side of garage and put an 18' x 8' door in. (24' Wall 10' Ceiling).

I know I am going to need to build a temp wall on the bearing side and level the roof before demoing and construction. In addition there is a little roof sagging and the door headers also have sag in them (Measured and Visual). As I mentioned there is a significant amount of rot - resulting in supports no longer existing etc. This is a late summer/fall project before the snow comes.

Questions:

The slab is now dry and stays dry with the draining issues resolved this is my dilemma should I just build the wall with a PT sill plate and a moisture barrier under it? Or should I put a CMU (1 or 2 courses of concrete block and build on that) The issue with the CMU is I have never worked with it or laid a course. This would be built directly on the slab either way. I figure the kiln dried support the roof for 40 years...

For the Garage door side - Should the LVL header span the entire wall ex: 24' header or use a 20' header? I have seen both methods used but I can't figure out the benefits.

I have looked through the IRC and couldn't pick it out - if you guys have a reference I would appreciate it.

All that said I am open to input and suggestions

In addition any construction details would help too for any of the methods you guess suggest.

 

[8man]

Location might help. Here we don't use CMU. Moisture barrier and then PT wood on the concrete. The Header need only span the 18' opening with enough overhang on each end to allow the correct support, like your example, the 20' should be adequate with Jacks under each end. Sounds like you are on tract.

 

[T_R]

I think if your drainage issue is solved and the slab is dry you would be fine replacing the sills with PT. Tons of garages are built like that with no issues.

 

[dfiler2]

The advantage in using a 24' header is there are no weak points. I realize a 20' header with a top plate does strengthen it quite a bit but a full length header in this case will be much stronger as far as flex in that wall is concerned and with it now being on the gable end I personally would use a full length header.

 

[yukonsc]

I am in Northern VA. (Outside Washington DC).

Thanks for your input. I'm glad no one said "you're crazy". Going with a PT sill plate will make my life a lot easier. I should have mentioned the eave overhangs are ~24" .

Do you know where I could find the construction details for the header wall? I am wondering about the bracing and mounting details for the LVL. (I understand the jack and king studs) The straps and #and size of nails or screws etc.

 

[CWBullock]

Hi there, before building any thing, I would suggest to have a pest inspection over there as you said there is a moisture problem. When we recreated our garage then we had done demolition baiting New York City and also other pest inspection.