Critique of initial idea for a garage apartment

JackReese · Jun 8, 2016

I would like to build a small garage and have a modest living space above it. My idea is for a 24x16 garage, and has 16 foot walls, and an open ceiling, maybe with a dormer window or two.

My idea would be to do a pole barn type foundation using 20 foot posts 4 feet deep in cement. In checking prices on 6x6 pressure treated wood, I had the idea of maybe using 4x4 (true 4 inch) steel square tubing, and found that the steel is about the same price as the PT. The steel would be straighter for such a long post and at 1/8 inch thickness it would be stronger than the wood.

Are there pitfalls to this idea? Aside from the question of whether to use steel or wood is this design reasonably doable?

pmiranda · Jun 9, 2016

I've heard steel in the ground can have corrosion issues, but I have seen galvanized anchors in concrete footings used to bolt down steel structures. Dunno what has to be done to prevent corrosion where the two metals come in contact.

aptdweller · Jun 9, 2016

A steel building is likely going to have to be engineered, so you should factor in that cost as well. If you add you location to your profile, you might get more help specific to your area.

sands35 · Jun 9, 2016

ducksface said:
Your idea needs to start with building code in your area.
Many here say code doesn't affect them. Many are wrong.
The most rural of counties? Some have adopted International code.

Think of NOTHING concerning this project until you know, in writing, that it is viable.

Yes, know the local codes.

(IIRC) Pole buildings are not, typically, rated as dwellings. Fine for garages where people aren't in them ~10 hours day, but you may not get an occupancy permit.

Even if you aren't under a code jurisdiction, building to code at least IBC removes some liability down the road.

For a building that is finished out, I would be surprised if pole saved much money relative to stick. They can also move around a bit. OK without a drywall finish on the inside, but it may cause problems with an interior finish. A foundation for that size will be around ~$2-4k or so. Really not that much in the grand scheme of things.

You also need to think about re-sale value. Don't do something that isn't typical for the area. Not that it is "wrong", but different makes a hard sell when that time comes.

Cyberbear · Jun 9, 2016

From my observations here in the GJ, pole buildings often present problems not usual with stick built structures. The small size of your intended structure should work well when built properly on a slab and footers using all of the standard building methods. Living quarters above is a very good usage of available sq. footage, and if you need the comfort of building codes, then do what you must. Not mentioning where you plan to build, outside entry stairs is another question, pro/con., and the list goes on.

pmiranda · Jun 9, 2016

IMO pole building only makes sense for larger buildings, up until a steel building makes more sense when the truss length gets over ~30 feet. That's just a number I pulled out of the air. You won't really know the tradeoff until you price out the whole thing.
I think for a small building like yours, if you want a slab anyway you might as well stick-build. Since you're planning a second floor, I don't see any advantage to really high poles to support the roof, since you won't be taking advantage of the clear span, and I bet they cost plenty.

kbs2244 · Jun 9, 2016

If you are going to live in it, it becomes a "dwelling" not a "garage."
That means all residential codes apply.

pmiranda · Jun 9, 2016

In my city it's pretty much impossible to get permits to build a garage apartment without some variances which your neighborhors will shoot down.
Is this the N. Cali pole barn project?

JackReese · Jun 9, 2016

I live in a very Rural area of northern Cali, so before you jam code regulation down my throat, where I live most things are possible including a garage apartment. Having said that everything you build, these days, (according to a very experienced builder friend) requires an engineer to stamp off on it, even a traditional slab and stick built.

The garage floor won't have a concrete slab, I'll be using some form of gravel, so I figured a concrete footer foundation without a floor to tie it in would be pretty weak for a building that tall, no?

Spdstr280Z · Jun 9, 2016

Argh, I just typed a lengthy reply only to lose it...

Anyway, the gist of it was, the original version of my garage was 16X24 and I am trying to imagine it as two stories. As much as I like the idea of tiny houses and always thought I could live in a storage building, you are going to end up with a tall structure and not a lot of room. If you have anyone to worry about, like neighbors, it will look odd I am afraid. 16X24 is a pretty small space really, despite what I thought when I built mine. I ended up opening the ceiling and adding a 14X16. Which reminds me, if you have an upstairs on 16' walls, you are going to probably have an 8' ceiling down. That was the first thing I hated about the first version of my garage. Since I am imagining mine 2 story, maybe if you added the 14X16 I did to the front as a single story, then the 16X24 two story behind it, it might look a little more traditional (if you care) and give you quite a bit more room.

If you do move forward, have you seen the small space house stuff at Ikea ? They have some pretty cool layouts, I guess targeted at college students, apartments and areas of the world where a McMansion isn't a must have.

Edit - Found a not so great video of one of the Ikea set ups...

Good luck either way, and keep us in the loop !

Jason

pmiranda · Jun 9, 2016

OK, I couldn't remember if you were doing a slab or not. Pole construction is probably the cheaper way to go then.

John in OH · Jun 9, 2016

This topic has come up here on GJ numerous times before. Both my summer and winter homes are in very rural areas .... one in Ohio and one in Virginia. But, in either location, a building used as a dwelling is subject to specific building codes particularly those related to safety.

kbs2244 said:
If you are going to live in it, it becomes a "dwelling" not a "garage."
That means all residential codes apply.

Basically, you are not building a garage.... you are building a house with a underneath garage. Lots of issues with fire protection come into play. For instance, the garage ceiling will have to be fire rated. All penetrations between garage and apartment will have to have proper fire stops. And in VA, my rural county requires that a route of egress be provided that does NOT pass through the garage space. This basically means you need to have your stairway to the above apartment OUTSIDE of the structure, or fully separated from the garage space with a solid fire resistant wall and a separate door to the outside.

Regardless of how rural you think your county is, I sure doubt the local jurisdiction would sign off an occupancy permit for a dwelling that doesn't meet strict fire safety standards. Way too much liability for the county.

And, IMHO and as already mentioned, the dimensions you are using would appear to create a wierd looking structure.

JackReese · Jun 10, 2016

Yes there will be codes!!! The point about living in this rural area is that it can be done legally, with permits. Will I have to comply with codes for a dwelling, yes! So what. I was asking a structural questions, not a legal one.

This is an example of something dimensionally similar to what I want to do. What looks weird about it?

A_Pmech · Jun 10, 2016

Your idea, in and of itself, has merit. Building houses on stilts is often done in flood-prone areas. However, I don't think it's the least expensive construction method, as the structures required to distribute the load from the posts to the framing and the appropriate foundations exceed the cost of more traditional methods.

My place is a 24x40 shop below with a 24x40 house above. So, is some ways, similar to what you're proposing. At the size involved, traditional stick-built construction will likely result in a less expensive structure.

ddawg16 · Jun 10, 2016

JackReese said:
I live in a very Rural area of northern Cali, so before you jam code regulation down my throat, where I live most things are possible including a garage apartment. Having said that everything you build, these days, (according to a very experienced builder friend) requires an engineer to stamp off on it, even a traditional slab and stick built.

The garage floor won't have a concrete slab, I'll be using some form of gravel, so I figured a concrete footer foundation without a floor to tie it in would be pretty weak for a building that tall, no?

May I suggest you back off aggressive statements as above?

Gravel floor? Really? Guess you haven't spent too much time on a gravel floor.

My personal opinion.....you depend too much on your medical pot card to make it through the day.

maxpower_hd · Jun 10, 2016

JackReese said:
Yes there will be codes!!! The point about living in this rural area is that it can be done legally, with permits. Will I have to comply with codes for a dwelling, yes! So what. I was asking a structural questions, not a legal one.

This is an example of something dimensionally similar to what I want to do. What looks weird about it?

I know someone who did this same thing in NH. He is a single guy so he built a garage with an apartment over the top. The garage houses his tools and toys, snowmobiles, boat, ATV, etc. He had to get permits and build it as described basically but it is doable. It depends on your jurisdiction though. Some areas, like mine, will not let you have an apartment over a garage unless it is also attached to a house. Then you can call it an in-law.

APEowner · Jun 10, 2016

The floor in a properly designed foundation adds little or nothing to the stability of the walls and structure of the rest of the building. Depending on the soil and climate pole buildings can move around a lot with seasonal changes. In some cases so much that conventional drywall interior walls are impractical. A steel building may very well be a good option but I don't know that a steel pole construction would have any advantage over conventional steel or even stick built.

Spdstr280Z · Jun 10, 2016

JackReese said:
Yes there will be codes!!! The point about living in this rural area is that it can be done legally, with permits. Will I have to comply with codes for a dwelling, yes! So what. I was asking a structural questions, not a legal one.

This is an example of something dimensionally similar to what I want to do. What looks weird about it?

Nothing looks weird about that, but I understood you to say you were doing 16 fit walls, as opposed to that barn / hip style roof. If you imagine that building going two stories up, then a traditional roof on top of that, that was what i was seeing. Just afraid of it looking tall and skinny. Might not.

Jason

Sent from my Nexus 6 using Tapatalk

John in OH · Jun 10, 2016

JackReese said:
Yes there will be codes!!! The point about living in this rural area is that it can be done legally, with permits. Will I have to comply with codes for a dwelling, yes! So what. I was asking a structural questions, not a legal one.

This is an example of something dimensionally similar to what I want to do. What looks weird about it?

Geezzz, dude. Relax!! From the title of this posting I inferred that you wanted a critique of the "initial idea" for a garage apartment including all potential aspects, not just the wood vs. steel post issue. Sorry for my misinterpretation.

JackReese said:
I would like to build a small garage and have a modest living space above it. My idea is for a 24x16 garage, and has 16 foot walls, and an open ceiling, maybe with a dormer window or two.

My idea would be to do a pole barn type foundation using 20 foot posts 4 feet deep in cement. In checking prices on 6x6 pressure treated wood, I had the idea of maybe using 4x4 (true 4 inch) steel square tubing, and found that the steel is about the same price as the PT. The steel would be straighter for such a long post and at 1/8 inch thickness it would be stronger than the wood.

Are there pitfalls to this idea? Aside from the question of whether to use steel or wood is this design reasonably doable?

Specifically to your question, it's unclear to me if the steel posts you priced are simply straight steel tubes or are engineered steel tubes with all pre-engineered attachments for the girts, trusses, etc. Any advantage of steel may be lost in the increased complexity and time required to make attachments. I "assume" it would be necessary to have pre-drilled attachment clips welded to the steel posts either before or after erection.

As aptdweller has already mentioned above, steel construction usually requires some degree of professional pre-engineering and the fabrication of attachments and associated labor may offset any cost advantage of steel vs. wood. Don't know, just guessing.

The pic you posted of the garage style you have in mind looks quite nice and is a big help in my understanding of what you want to do. The roof line definitely mitigates my concern over height vs. width proportions (I've seen some really architecturally ugly garage buildings here on GJ). But I'm still not clear where the 16' walls come in. I also see they went with an external stair as I expected might be necessary.

I guess IMHO, I'd go with the opinion of several others here and lean toward traditional stick construction with a poured footer as being the best approach for what you want to build.

Spdstr280Z · Jun 10, 2016

Spdstr280Z said:
Nothing looks weird about that, but I understood you to say you were doing 16 fit walls, as opposed to that barn / hip style roof. If you imagine that building going two stories up, then a traditional roof on top of that, that was what i was seeing. Just afraid of it looking tall and skinny. Might not.

Jason

Sent from my Nexus 6 using Tapatalk

Here you go, not as bad as I expected...

Sent from my Nexus 6 using Tapatalk

sands35 · Jun 10, 2016

JackReese said:
Yes there will be codes!!! The point about living in this rural area is that it can be done legally, with permits. Will I have to comply with codes for a dwelling, yes! So what. I was asking a structural questions, not a legal one.

This is an example of something dimensionally similar to what I want to do. What looks weird about it?

Chill.

There are plenty of stock plans available for what you want to do. Dig around on the internet, find one you like, then price it out at the local lumber supply company / big box store.

Then contact the zoning / AHJ to see what you need there.

Then decide if you want to be the GC or hire that out.

(though it doesn't have to be in that order)

And pole construction for a dwelling may not be allowed, not to mention re-sale issues. Someplace I read you want a gravel garage floor? This will allow for moisture intrusion and you will track rock dust up to the living quarters. Not a great idea. Concrete isn't that expensive for what it does.

pmiranda · Jun 10, 2016

I was thinking that a porch, especially wrap-around, would break up the tall, skinny box look.

NUTTSGT · Jun 10, 2016

sands35 said:
And pole construction for a dwelling may not be allowed, not to mention re-sale issues. Someplace I read you want a gravel garage floor? This will allow for moisture intrusion and you will track rock dust up to the living quarters. Not a great idea. Concrete isn't that expensive for what it does.

Does NorCal have the same earthquake required building issues as other parts of the state ? :dunno:

A 16x24 pad four inches thick only requires 4 3/4 yards. I'm not sure what Cali concrete costs /yd but at about $100/yd, that's money well spent if the OP plans on doing anything in his garage other than parking. Not even mentioning the possibility of resale.

Critique of initial idea for a garage apartment

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