20'x30' or 24'x25'?

[Pauljt]

Hi guys. I am in the planning stages of building a small shop in my back yard. Municipal restrictions here will limit me to about 600sq.ft. The shop will not be used for vehicles other than motorcycles and will be a detached structure. I also have a 1.5 car attached garage. I plan on putting down a concrete slab and building on it. Originally I was thinking 20x30 but I'm not certain. I would like to build it with overhead storage space so I guess I need to go with rafters....or attic trusses. Is there any advantage to building it 24x25 as far as overhead clearance in the attic is concerned? I am also restricted on the height of the building to 16'4". How much "headroom" can I achieve given these restrictions? Thanks for any input.
Btw...2nd post for me. I put one in the intro section. This forum is an awesome resource.

 

[ard]

Welcome!

Are you looking to match the shop to any features (ie roofline/pitch) on the home?

Just shooting from the hip, w a 3/12 pitch you can get 13ft of height, then 3ft for the peak of the roof. give or take. However, depending on the home, building a structure that looks like it 'goes' with the home is a way to maximize property value.

Id rough in stuff like plumbing for future use. If only a few pipes coming up into the slab, then capped- stubbed outside below frost. Who knows, sell it as a 'future inlaws quarters'.

 

[u2slow]

Originally I was thinking 20x30 but I'm not certain. I would like to build it with overhead storage space so I guess I need to go with rafters....or attic trusses. Is there any advantage to building it 24x25 as far as overhead clearance in the attic is concerned? I am also restricted on the height of the building to 16'4". How much "headroom" can I achieve given these restrictions?

Is this a peak roof height? Or a 'mean' roof height? With a pitched roof, the mean height is measured half-way up the slope.

Do you have any plans for lean-to's or carport on the side(s)? (often excluded from sq-ft restrictions). If you put them in now, and it brings your eaves closer to grade, it lowers your mean roof height, allowing you to build your enclosed space taller.

I went with 20x36' for my shop (753 sqft restriction) with a full 36' length carport on each side. If memory serves, my interior ceiling height is actually slightly taller that the maximum-allowed mean roof height.

 

[2level]

How big is the attached 1.5 car garage? How close to the house will your new detached garage be?

 

[Pauljt]

Stop asking hard questions lol. I think the 16'4" is peak height. I won't be going with carport(s). The 1.5 car garage is actually a single car garage. About 12 by 22 or so. The new garage will be eighteen feet back from the house. Basically what I'm wondering is how much storage space I can create up top if I use rafters. I'm thinking that if my walls are 8ft high then I could conceivably have 8ft up top (to the peak). But I don't know if that creates a sensible roof pitch. I'm not up on those calculations.

 

[2level]

Knowing whether the 16.4 height is peak vs. mean/average is key to that calculation. To answer your 20'x30' vs. 24'x25' question, I recommend the later. Even though you don't want to use it for 2 cars, a potential buyer may. And the close distance to your house ups the odds of that significantly.

 

[gtcs]

My previous shop was 24.5x24.5, this was a good size for just about everything, which is great if you want to sell the place later.

I built a car and 2 bikes in there , had a car an a bike going at the same time actually. It does allow some storage above, even though I was stuck with a low pitch here.



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[NUTTSGT]

You definitely need to know where and how they measure the max height.

You could incorporate a work bench into a section of pallet racking in one side. This will give you plenty of storage, a place to work and possibly taller ceilings rather than losi g it for attic storage space.

 

[Pauljt]

I checked the website. 16'4" refers to peak height.

 

[GTFiero]

Go 24x24 to keep in 8’ spacing for post or cost effectiveness. Go with 12’ wall and 5/12 roof trusses with a 3/12 cathedral ceiling. Roof will keep you under the 16’6” overall and cathedral will give you about 13’6” inside height. All measures here approx, you may be able to go to 6/12 outside and 4/12 inside. An energy heal on the trusses may ad 12” in height of trusses.

 

[Pauljt]

When you give two different pitches for the outside and inside that is what is known as a scissor truss? Or some variation?

 

[PhantomEB]

24x25 is what I would do. Calgary measures wall height from floor to where wall meets the ceiling. Scissor trusses definitely will make it feel a lot bigger than it really is but then all you doing is paying for heat. I would just go 10’ Ceiling unless you planning a hoist.

We need to know what your usage is gonna be as well. What type of vehicles?

 

[Pauljt]

The building usage will be mainly for motorcycle repair. I'm not concerned with getting a vehicle in there. I don't even have the clearance on the "driveway side" of my house to get into the back yard with a car. Motorcycle...no problem. I have quite a few bikes and although I will be down sizing I plan on keeping busy with projects and repairs.

 

[spudley]

When you give two different pitches for the outside and inside that is what is known as a scissor truss? Or some variation?

Yes, but you won't get any upper storage with scissor trusses.

 

[BillK]

Paul,
My detached is 24 x 24 and is fine even with a car in there. You could do a Gambrel type roof and get a lot more storage upstairs.

http://www.roofingcompare.com/styles/gambrel.html

 

[GTFiero]

When you give two different pitches for the outside and inside that is what is known as a scissor truss? Or some variation?

That's right. It also creates a cathedral ceiling which gives a little more headroom than a standard truss/flat ceiling.

 

[ludakris04]

24 x 25

 

[cadunkle]

For bikes, never a car or truck due to inaccessible, I would be inclined to go with 20x30. Longer dimension can be useful for continuous shelving. Bikes can be packed in pretty tight along the length when not in use and leave more open space toward one or either end.

 

[ddurrett896]

I'd just go 24x24. I'm a fan of building as big as possible, but you're going to waste a lot of material on that last foot.

 

[kasander]

24 x 25 will be slightly cheaper than 20 x 30 in terms up framing, sheathing, siding, and insulation materials.

24 x 25 x 8 = 784 sq ft
20 x 30 x 8 = 800 sq ft = an extra 2 studs (assuming 16" centers), partial piece of sheathing, 2 pieces of siding (assuming hardi plank siding), and an extra piece of insulation.

Now that I do the math, it's negligible unless you are trying to save every penny.

 

[Scott91370]

BIGGER. Once you put stuff in it the floor space will shrink fast.
I would do 20x30 so a truck will fit in it you will and be able to walk around it without issue. At 24 it gets tight fast.

 

[steel 35]

There should be no 20s in a garage.

 

[Road_runner]

Go bigger! I built a 24 by 24 two years ago. If I had had the room I would have gone 30 or 36 wide.

As an aside the 24 deep allows for a workbench and still enough space at the front of the vehicle, but I would really like the extra width to get more wall space for cabinet storage and racking.

Recognise you have size limitations, so it comes down to personal choice. With the 24x24 I can use the back wall for workbench and cabinets, which I couldn’t do at 20 deep. Space between vehicles is more compromised at 24 wide than 30 wide but I make it work with a bit of planning and moving over the vehicle I am not working on from the centre of its bay.

Good luck with the build no matter what size you go for....

 

[PhantomEB]

My 24 square, 10’ ceilings. Off-road truck is dedicated a spot. Quad goes in when it needs to for maintenance or to be ready for the ride that week.

It’s all about tool placement and using wall cabinets and tool boxes to your advantage.

I would never go less than 24 deep. My main goals are nothing on the floor next to the vehicles from the front doors up to past the front bumpers. That floor space is a premium to me.

 

[Pauljt]

I've decided to go with 20'x30'. Gonna be post frame construction. Started clearing the site yesterday. Had to remove a 24' above ground pool that was in the middle of a 30'x 36' deck. Should finish the deck removal tomorrow. I'll start putting up some pics as soon as I figure out how. Gonna have lots of questions for you guys. Thanks for the input so far.