Lean-To Storage Addition Advice

[Mr. Roboto]

This is pretty much a copy/paste from the post I made in my ongoing garage build thread, but I think I'll get some more visibility if I start its own thread in this section, since im looking for advice. And obviously not everyone follows along my build thread!

I'm in the very early planning stages of my next big project. I'm considering building a lean-to off the back of my garage for additional storage space. I am thinking approximately 10x20. I already have a shed, but it's pretty full with all your typical lawn and garden stuff. The main purpose of the lean-to will be to house all of our outdoors stuff. Camping gear, snowboards, skis, bikes, kayaks, fishing equipment and the largest thing to plan around, an ATV (which I don't own yet, but someday). Figure the ATV should weigh about 600lbs. Here is the back of my garage as it currently sits:

Picture something like this, on a larger scale, for what I have in mind:

I'm looking for advice on how to go about building it. One of my biggest concerns is building it as tight as possible to keep rodents from getting in. In my head I have 2 options. 1 would be to build the whole thing up on piers, much like how I built my deck. Attach a ledger to the side of the garage, frame a floor up with 2x10s, supported by a 2x12 beam. lay a 3/4" T&G plywood floor and build everything up from there. The pros to this would be not having to grade the land, and I could do it all myself. Kind of like this below, but much more beefed up. The cons are that I did have a hell of a time digging the footings for my deck which is 30' away due to all the rocks in my yard, so that won't be so fun going through that all over again.

The other option would be to have a slab poured off the back, and build up from there. I really like this idea, as I think it would be the strongest solution, but would also probably be significantly more expensive, as I'd have to hire it out. But, I really have no idea how much it would cost for the grading and a 10x20 slab, so maybe it's not as bad as I think. If I did, what would I need, standard 4" slab?


Hopefully this makes sense. Like I said, still in the very early stages, but that's what I am thinking so far. I tried searching around for any threads, either on GJ or elsewhere, where someone has gone through this, but I didn't have any luck locating any. If anyone can point me to something, it would be great - I love learning from others who have already gone through it.

Thanks in advance!

 

[DJL1967]

Any thoughts on opening the back of your garage so you can access the building from the garage? I am currently looking at doing the same thing just slightly smaller scale at 6x20. I am considering a 2x6 treated floor 12" OC with 3/4" treated plywood and another layer of 3/4" T&G plywood floor. I will insulate the floor with spray foam as my plan is to have this as my workshop (workbench, cabinets, tools etc). I've been back and forth on concrete vs wood framing and will most likely go with wood D/T cost and simplicity.

 

[Mr. Roboto]

I did consider blowing a large portion of the rear wall out, but decided against it for a few reasons. 1, id like to maximize storage space in the garage and lean-to, and having that wall adds a lot more area for hanging things. And 2, I want to hide the mess in there. Out of sight, out of mind. There will be a man door connecting the 2 though

 

[earlthegoat2]

When I built my garage, I built a ledger board for hanging rafters into it for a future lean to addition. I also installed flashing above this ledger. I did this while installing the siding. Since, Matthew, I was able to cut and dry a respectable amount of construction grade lumber. A month ago I determined it was suitably dry. I poured concrete cylinders for posts and ran a header board for the rafters sit on. I put rafters 2 ft on center and ran 2x4 purlins to accept the metal roofing (which I just ordered today) Here is a brief photo progress.







This is 22 x 14 ft dimensions. This is planned to have a concrete floor sometime in the future as well and it is planned to only ever be open. However, I have planned on the possibility of walling it in and could do so in the standard pole barn type of way.

I think in your situation, you need to determine if you want a concrete floor or not and then go from there. If it were me, I would pour the concrete. After reviewing how you plan to build the floor if you were to build it the way you built your deck then that would actually cost quite a bit too and maybe only marginally less than concrete and concrete would be much more satisfactory I would think. Check out the costs of every component of that floor build before you rule out a 10x20 concrete slab. I estimate the cost of your floor as well as the piers and footing prep work to be near $1000 dollars. My garage slab of 24x40 cost 3900 for 6" thick w/ vapor barrer, termite treatment, and wire mesh. A quarter that size should be right around less than or equal to 1000 I would think if you like me, did all the form work yourself.

 

[captain14]

There have been 2 build threads here in the past 4-5 months about lean to construction.

1. Built to the rear of his garage with a side load and a roll up door.

2. Built to the left of his garage. He got a deal on the trusses so he built it with 3-4 posts and installed the trusses. Later on he enclosed it for his wood shop I think.

3. He built it on the rear of his garage for his lawn equipment and tools. Drive through for his tractor. That wasn't a very big build though.

I'm On my phone and don't have much luck with cut and paste. I'll look tomorrow on a desktop and see if I can find both and post links here. I did post comments to all three so I will check my history to see if I can find them.

Did you try lean to build and garage journal in a google search?

 

[Stuart in MN]

One thing to remember is that it needs to have a similar foundation as the garage - in other words, if the garage is built on a slab, put the lean-to on a slab; if the garage is on a frost footing, the poles or footings for the lean-to need to be down below the frost line as well.

The reason is that otherwise, the garage structure and the lean-to structure may move up and down independently from each other as the ground freezes and thaws.

 

[ZacSpade]

Definitely pour a slab in your situation IMO

you want to drive an ATV on there as well as your connected to something that has a concrete slab

 

[bczygan]

Slab!

 

[captain14]

http://www.garagejournal.com/forum/showthread.php?t=45328&highlight=Lean+garage

http://www.garagejournal.com/forum/showthread.php?p=6139425#post6139425

Here's two I found

 

[matt_i]

One thing to remember is that it needs to have a similar foundation as the garage - in other words, if the garage is built on a slab, put the lean-to on a slab; if the garage is on a frost footing, the poles or footings for the lean-to need to be down below the frost line as well.

The reason is that otherwise, the garage structure and the lean-to structure may move up and down independently from each other as the ground freezes and thaws.

This would be my advice as well. Don't allow a lean-to, to compromise your main structure. I think you could do a quick and easy trench-foundation + slab in a monolithic pour. Any driveway or basement guy could finish the floor if you had the forms all ready. My belief is that concrete gives you the greatest protection against rodents....as well as a few spring traps left here and there for backup

That and paying attention to flashing the transition from siding to roof. I would buy a piece of grace Ice+water shield peel & stick and apply it to the bare wood deck, half on the wall and half on the new roof, as a good start.

It looks like you have vinyl, so I would also plan on bending some flashings from trim coil for the sides of the new build, direct any leakage back to the "hook" of the next piece of siding which has holes punched in it for drainage.

 

[Mr. Roboto]

When I built my garage, I built a ledger board for hanging rafters into it for a future lean to addition. I also installed flashing above this ledger. I did this while installing the siding. Since, Matthew, I was able to cut and dry a respectable amount of construction grade lumber. A month ago I determined it was suitably dry. I poured concrete cylinders for posts and ran a header board for the rafters sit on. I put rafters 2 ft on center and ran 2x4 purlins to accept the metal roofing (which I just ordered today) Here is a brief photo progress.





This is 22 x 14 ft dimensions. This is planned to have a concrete floor sometime in the future as well and it is planned to only ever be open. However, I have planned on the possibility of walling it in and could do so in the standard pole barn type of way.

I think in your situation, you need to determine if you want a concrete floor or not and then go from there. If it were me, I would pour the concrete. After reviewing how you plan to build the floor if you were to build it the way you built your deck then that would actually cost quite a bit too and maybe only marginally less than concrete and concrete would be much more satisfactory I would think. Check out the costs of every component of that floor build before you rule out a 10x20 concrete slab. I estimate the cost of your floor as well as the piers and footing prep work to be near $1000 dollars. My garage slab of 24x40 cost 3900 for 6" thick w/ vapor barrer, termite treatment, and wire mesh. A quarter that size should be right around less than or equal to 1000 I would think if you like me, did all the form work yourself.

Thanks for the pics, that came out great. So did you just do the site work and forms yourself, and had someone else do the pour?

There have been 2 build threads here in the past 4-5 months about lean to construction.

1. Built to the rear of his garage with a side load and a roll up door.

2. Built to the left of his garage. He got a deal on the trusses so he built it with 3-4 posts and installed the trusses. Later on he enclosed it for his wood shop I think.

3. He built it on the rear of his garage for his lawn equipment and tools. Drive through for his tractor. That wasn't a very big build though.

I'm On my phone and don't have much luck with cut and paste. I'll look tomorrow on a desktop and see if I can find both and post links here. I did post comments to all three so I will check my history to see if I can find them.

Did you try lean to build and garage journal in a google search?

I did try a google search, but most of what I found was for an exposed parking lean-to

One thing to remember is that it needs to have a similar foundation as the garage - in other words, if the garage is built on a slab, put the lean-to on a slab; if the garage is on a frost footing, the poles or footings for the lean-to need to be down below the frost line as well.

The reason is that otherwise, the garage structure and the lean-to structure may move up and down independently from each other as the ground freezes and thaws.

Gotcha, this was my thought as well. I question, though, since my garage has a foundation that extends down below the frost line, and I simply pour a slab above the frost line adjacent to it for the lean-to, will they now rise/fall at a different rate?

http://www.garagejournal.com/forum/showthread.php?t=45328&highlight=Lean+garage

http://www.garagejournal.com/forum/showthread.php?p=6139425#post6139425

Here's two I found

Awesome, thanks, I will ready through those.

This would be my advice as well. Don't allow a lean-to, to compromise your main structure. I think you could do a quick and easy trench-foundation + slab in a monolithic pour. Any driveway or basement guy could finish the floor if you had the forms all ready. My belief is that concrete gives you the greatest protection against rodents....as well as a few spring traps left here and there for backup

That and paying attention to flashing the transition from siding to roof. I would buy a piece of grace Ice+water shield peel & stick and apply it to the bare wood deck, half on the wall and half on the new roof, as a good start.

It looks like you have vinyl, so I would also plan on bending some flashings from trim coil for the sides of the new build, direct any leakage back to the "hook" of the next piece of siding which has holes punched in it for drainage.

Sounds like the slab route is the preferred method from most of the replies. I really should just get a few quotes for it to see what it costs. I can very accurately estimate the cost for a pier style base, and it will be easy to compare the 2. Do you really think I'd need to trench a foundation as well, or could I get by with just a slab?

 

[Orionrising]

Your garage appears to be on a stem wall. Unless you build a frost protected slab you need posts to frost depth.

Sent from my Moto G (4) using Tapatalk

 

[finn]

My shed has a wood floor.

It provides a very nice home for various rodents and critters, including mice, chipmunks, squirrels, a visiting skunk, and the current inhabitants, a couple of rabbits.

I strongly recommends a slab.

 

[earlthegoat2]

I have a little concrete experience so yes, I did all the form up and site prep myself and then hired a crew and watched them like a hawk. They were not perfect but they were cheap and did not jeopardize the strength of my slab in any way.

 

[Stuart in MN]

Gotcha, this was my thought as well. I question, though, since my garage has a foundation that extends down below the frost line, and I simply pour a slab above the frost line adjacent to it for the lean-to, will they now rise/fall at a different rate?

Probably yes. The garage foundation won't move any appreciable amount but the lean-to slab will go up and down. You probably need to plan on frost footings of some kind for the lean-to.