Detached Garage - 30 x 24

[johnharris]

Hi All. Just joined the forum as I will be building a detached garage. I recently moved from MA to TN. I miss the attached 2 car garage in the MA house daily.

It will be a stick garage with vinyl siding.

Here is the plan so far:

>30' wide x 24' deep
>4" deep slab
>two 10' garage doors
>two walk in doors (front and back)
>six windows
>2 post hydraulic lift

Living in the county area no permit is needed to build non living units. Another great county rule is no limit to building space nor bordering neighbors property.

The slab was planned to be poured this week but rain delayed it to next week. Chert will be packed first, rock leveled, plastic to keep moisture free, then pour the nylon fiber concrete. The borders will get 3 feet deep turndowns with rebar.

To start the framing I'll put pressurized 2x6s sill plates on the borders using 1/2" wedge anchors. One contractor also suggested putting sealant under the sill plates to keep moisture out.

I'll wire from the house with 8-3 wire and install breaker box for garage.

I haven't determined the height yet. With the 2 post lift the walls will be at least 10 feet high or maybe even higher.

Instead of pay to get trusses built then installed I'm panning on making my own rafters. It will leave more ceiling space for lift and should cost less.

If it remains dry I'll post pictures of the slab next week.

More hints on building it or even corrections are greatly appreciated.

 

[Mr onetwo]

You will be sorry at the present size if you do any serious automotive work.In my opinion it should be a minimum of 28' wide by 36' deep but 40' is better.Plan on a lift location and pour the slab 8" or thicker there.Also run some conduits from side to side for power and internet. A center trench drain is also very nice to have.Good luck. 2 post lift requires 12' ceilings.

 

[Mr onetwo]

You need sill seal under the plates and perhaps termite protection also.

 

[twistedstang]

I just started a shop then same size. I would have preferred a little bigger but was limited due to being in town.

 

[jetnow1]

Consider putting block courses to lift the walls from the slab, helps with the height and gets the walls away from the splash zone near the ground, makes termite tunnels visible, and you can get 12 foot height with 10 foot studs. Depending on local building practice and desired insulation levels this could be the difference between 2 by 4 studs and 2 by 6 studs. Grout the cells in the block and set j bolts to hold the plate.

 

[johnharris]

You need sill seal under the plates and perhaps termite protection also.

Thanks for the tip Onetwo. I'll throw Sil Seal under the plates and some termite protection.

I gave thoughts of making it deeper. It will give more room between neighbor's property. Will also save me some chert, rock and topsoil filling. The far end of my driveway has a deeper sloping hill. The middle and front end of driveway has much less slope.

Due to recent rain slab is delayed to next week.

 

[johnharris]

Consider putting block courses to lift the walls from the slab, helps with the height and gets the walls away from the splash zone near the ground, makes termite tunnels visible, and you can get 12 foot height with 10 foot studs. Depending on local building practice and desired insulation levels this could be the difference between 2 by 4 studs and 2 by 6 studs. Grout the cells in the block and set j bolts to hold the plate.

Hi Jet. Are you referring to putting concrete blocks on the outer edge of the slab then put sill plates on top of them?

 

[johnharris]

Finally got the slab poured last Saturday. I changed the dimensions to 28' x 28' due to my neighbor's property line and the big slope in the backside of the garage. I needed to fill the slope with 2 triaxle loads of chert. I tampered down the chert with a skid steer for hours then let it settle for 2 weeks before adding on the 3/4" rock. The slab is 4" thick with 2 spots that are 8" deep for the 2 post car lift. The footings are 10" deep and 12" wide with 2 pieces of 3/4" rebar. As you can see in the pic I added in the L anchor bolts and piping into the slab.

 

[johnharris]

I already made 43 pieces of 10' long 2x4 studs at my friends sawmill. These are real 2" x 4" studs made of poplar wood. Need to make at least 60 more studs. I'll let them dry out for awhile waiting for lumber prices to drop. Down here they want $28 for 4x8 OSBs.

 

[johnharris]

I'm still scratching my head on how to make the roof.

I need clearance for the car lift so one plan is to put rafters into a ridge beam. The rafters will be 1.5" x 6" and ridge beam 3" x 8". Need to make the rafters only 1.5" thick so they'll fit into hangers. To eliminate the ceiling joists on the top boards I'll need to support the 30' beam with 2 outer posts and 1 post in the middle of garage.

The other plan is to wait for lumber prices to drop and have scissor trusses made. Even thought the scissor trusses will give more clearance do I need to make the walls 11' high for the 2 post car lift?

 

[Mick56]

With all the fire damage on the West Coast, I wouldn't expect prices to be coming down anytime soon.

 

[johnharris]

I spoke with a local building inspector last week and a state building inspector today. To build with rafters the 30' beam would just needs to be a spliced 2 x 10. Where the beam is spliced in the middle one post will be needed using two sandwiched 2 x 6s. This is calculated with using Southern Yellow pine that has a hardness of 870 lb/ft.