Garage site work helpful thoughts needed......

[River19]

In the Spring we are thinking about building a garage/barn of about 24x26 off to the side of our long driveway. The challenge is we have a heavily sloped driveway that has some effective and very necessary drainage as the land slopes down from the road and we have a couple culverts diverting water from the high side to the lower side. Of course we would like to site the garage on the low side as it is the only real spot we have. In between 2 of the drainages......as you come down the driveway the entrance to the garage would be off to the right as the drive curves left.....

I was thinking we could build out a 3 sided retaining wall, load it with fill and then packed gravel for the base for the garage. (site marked with an X in the pics below in between the two trees (which may need to come down).

Clearly I would need to dig out the drainage runs (which are clear in the pics as we had a good opportunity to see with the snow melt and rain) and add some good rock to those to stabilize the runs. We would slope a small driveway to the garage off the main drive with the drainages both before and after the garage itself.

Am I crazy to try executing this plan? I know many people on this forum have years of experience so I was hoping for some guidance and "watch outs" so I can properly plan this out and avoid making costly mistakes.

Thoughts?

 

[EddieWalker]

From the pictures, it looks like you will have to build up the site considerably. For me, the term "retaining" wall is more for keeping land away from an area. When building up a pad for a building to sit on, you need to be thinking more about a raised foundation with poured walls if you want a solid floor, or building it on posts and leaving the drainage alone under the building.

For such a small building, I think that building it on piers would be the most cost effective.

 

[River19]

From the pictures, it looks like you will have to build up the site considerably. For me, the term "retaining" wall is more for keeping land away from an area. When building up a pad for a building to sit on, you need to be thinking more about a raised foundation with poured walls if you want a solid floor, or building it on posts and leaving the drainage alone under the building.

For such a small building, I think that building it on piers would be the most cost effective.

Thanks for the thoughts........I can check of local code will allow for piers. I am trying to stay away from a poured foundation of any type as it will literally double the cost of the project.

When I was thinking retaining wall I was thinking something like the attached picture from someone else's project.....

 

[chim]

Hard to get a feel for the grade. Could you do a bank barn and get an extra floor in the deal?

 

[oosik]

Exactly my thoughts. SONO tubes - heavy plank wood floor - built up ramp to access the garage. Then you could construct a very specific drainage pattern to avoid swampy areas. The elevated floor of the garage - just sufficient to allow air flow underneath.

This is how I constructed my cabin in AK. It was on sloped ground. Drainage was not an issue. Getting a level floor without massive excavation was. We constructed the cabin in 1976 and it's still a sound structure after 45 years.

 

[dodge man]

Two questions. Concrete floor or gravel? In your first pic it looks like there is a shallow ditch running right to left. Am I correct? If so you will either need to put the building behind that and install a culvert in the ditch or move the ditch. Looking at the pictures it looks like it would be easy to get the floor to low and have water run in it.

 

[River19]

Two questions. Concrete floor or gravel? In your first pic it looks like there is a shallow ditch running right to left. Am I correct? If so you will either need to put the building behind that and install a culvert in the ditch or move the ditch. Looking at the pictures it looks like it would be easy to get the floor to low and have water run in it.

Was planning on wood framed floor on a gravel base. The two current run off paths are on either side of the site really so I was going to dog those out and make them a more formal "creek bed" of stone to stabilize the ground from washing away more soil and make it a more defined path.

The piers might be a real option at least for the back half of the structure and maybe grade the front even with the hillside.

As Eddie Walker mentioned initially above, if I were to execute my original plan it would take a significant amount of fill with a ~4' retaining wall of block in the back with the side retaining walls starting at the height of the back wall and decreasing as they meet the grade.......

Options.......

Appreciate the thoughts.....

 

[JJT]

In the Spring we are thinking about building a garage/barn of about 24x26 off to the side of our long driveway. The challenge is we have a heavily sloped driveway that has some effective and very necessary drainage as the land slopes down from the road and we have a couple culverts diverting water from the high side to the lower side. Of course we would like to site the garage on the low side as it is the only real spot we have. In between 2 of the drainages......as you come down the driveway the entrance to the garage would be off to the right as the drive curves left.....

I was thinking we could build out a 3 sided retaining wall, load it with fill and then packed gravel for the base for the garage. (site marked with an X in the pics below in between the two trees (which may need to come down).

Clearly I would need to dig out the drainage runs (which are clear in the pics as we had a good opportunity to see with the snow melt and rain) and add some good rock to those to stabilize the runs. We would slope a small driveway to the garage off the main drive with the drainages both before and after the garage itself.

Am I crazy to try executing this plan? I know many people on this forum have years of experience so I was hoping for some guidance and "watch outs" so I can properly plan this out and avoid making costly mistakes.

Thoughts?



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I'm in a similar climate zone as you and went with footers and 8' concrete foundation under my attached garage. A few years later I built a 1200 sq ft detached shop/garage and put it on a slab, on top of several feet of compacted stone. Either will work in your climate, neither of my buildings have moved in 20 years. Both have french drains around the perimeter run to daylight.

 

[dodge man]

If it is just a wood frame with no concrete, I’d just put it on a gravel base and call it good.

 

[River19]

Did some site walking this morning and I think we can pull off the original plan with ~20yds of fill. The difference in slope between where the front of the structure would go and the back is only ~3 feet so doing some very rough math I think an area of 30x32 or so with a 3' retaining wall at the back and 0' at the front should be about 20yds of fill before crushed stone and yes French drains around the perimeter.

But the first order of business is to take out some trees that look sketchy for future storms, then get those existing drainage run-off areas deeper and more formalized then fill with rock. I think that will work fine.......plus it will give me some decent project work in the Spring/Summer...........