Garage Attic Question

[wonderfred]

I have viewed the beautiful "1000 footer" that msgross has posted on this site.
I am close to finalizing my plans for a similar garage with the following specs:

28 wide (gable end) x 35.5 deep 20 ft. to peak
8-12 pitch roof
two garage doors - 10 wide x 9 high
main level ceiling 10.5 high
engineered floating cement pad

I want to have an attic upstairs for storage, etc. with steps at the rear of the garage. Is it worth my while to have walk thru attic trusses with the 8-12 pitch roof? I know it will be about 9 feet walking down the middle, but will the pitch of the roof rapidly kill my floor to ceiling room as you walk away from the centre which would not make it worthwhile?

Any suggestions and opinions are welcome. Thanks

 

[Stuart in MN]

Not exactly the same, but here's a construction photo of my garage. It's 24 x 40, and the attic trusses have a 10/12 pitch. This is before I put down a floor, but you can see there's quite a bit of room up there. The pitch of your roof is shallower but the overall width is greater, so I think you'll have a similar amount of space.

 

[jkwilson]

It really depends on what you plan to use it for. You'll be down to 6ft on 4ft either side of the center, so it won't be a really practical living area. You can store a bunch of stuff in that size space. You'll need to talk to a truss builder to know exactly how much space you'll have available.

 

[dfiler2]

I built a 24x24 a couple of years ago with an 8/12 pitch to match the house. I have about 4' at the shortest point. Works great for storage, I put in an aluminum pull down attic ladder and also put in a loft door on one end. The loft door has worked out really well, I can stand in the bed of my pickup and hand up bicycles and other larger items.

 

[astroracer]

My 26' x 28' was built with loft trusses.

I have a 14' x 28' office area up there. I am sitting in it right now typing this. It is very comfortable and there is plenty of room.
I also built storage cabinets into all of the kneewalls with bookcases and drawers.
With a 28' gable you should have 15' or 16' of width up there. The room would be HUGE!
There is a TON of storage in those kneewalls also. Don't sheetrock over them...
Mark

 

[finn]

if you are adding permanent stairs, I would think attic trusses are a must, as the stairs imply frequent use and potential living space.. Attic trusses would have the highest dead load capacity.

An alternative is storage trusses. Mine had half (from memory) the load capacity of attic trusses on a 32 foot span, but with pull down stairs are adequate for my use. I selected them because, at the time, they were a significant cost savings over the attic truss design.

I doubt that the inspector would approve of them (storage truss) if I had incorporated permanent stairs.

Regular garden variety trusses are unsuitable for any real storage.

An 8/12 pitch on a 28' wide building should provide a nice, usable ares.

 

[Jlbc212]

My garage is 28ft deep and framed with attic trusses and a 10/12 roof pitch. I specified trusses 16" o.c. The floor span in the attic is 14ft. wide. The ceiling is approximately 8ft high and approximately 6ft 6inches across. The floor is rated for a 40 pound/square foot live load. I access it from a door on the outside gable. With a 12ft high ceiling in the garage, interior stairs would have taken up too much garage floor space.

 

[WECSOG]

Pic's of my 26'x 40" garage shop built with attic trusses...1040 ft down stairs and 640 up... The ceiling in the up stairs is 8' with knee walls. the up stairs is 12' wide, with 12' dormers on the front and rear.

It was well worth the cost to put in the upstairs!!!

front


Back

Side


Upstairs.




During construction.

 

[Jlbc212]

Pic's of my 26'x 40" garage shop built with attic trusses...1040 ft down stairs and 640 up... The ceiling in the up stairs is 8' with knee walls. the up stairs is 12' wide, with 12' dormers on the front and rear.

It was well worth the cost to put in the upstairs!!!

front


Back

Side


Upstairs.




During construction.

How did you span the floor/ceiling in the center section?

 

[jnkpile]

The last truss looks to be three or four thick to carry the load.....

....on closer inspection it looks like maybe 6 or so
No no, there's 5, final answer.

 

[wonderfred]

Thanks to everyone for your excellent responses. Looks like I will go with the attic trusses. After seeing some of the dormers...that means I have another decision...dormer or no dormer !!

 

[earthworks]

Mine (still in construction) is 32' wide attic truss. 8/12 pitch yielded a 12' wide by 7.5 'high room (angles down to 5'). The trusses design depends on local codes and snow loads. My bottom cord is 12" thick making my peak height 21'8". I'm envious of these guys telling you they get a14' room in a 28' truss. Especially when I paid seven grand for my trusses.

 

[Gerald O]

If you want a big attic that maximizes attic volume then just build it as a true 1.5 story building with a real floor and rafter roof. Attic trusses are just a way to get a small usable storage space relative to the attic volume.

 

[Gerald O]

Mine (still in construction) is 32' wide attic truss. 8/12 pitch yielded a 12' wide by 7.5 'high room (angles down to 5'). The trusses design depends on local codes and snow loads. My bottom cord is 12" thick making my peak height 21'8". I'm envious of these guys telling you they get a14' room in a 28' truss. Especially when I paid seven grand for my trusses.

Part of your problem is the 8/12 pitch. Steeper roof pitches yield wider usable attic areas. I've got a 14' wide attic room over my garage under a roof that is only 24' wide. But it has a 10/12 pitch and the knee walls are at 4'.

 

[earthworks]

Part of your problem is the 8/12 pitch. Steeper roof pitches yield wider usable attic areas. I've got a 14' wide attic room over my garage under a roof that is only 24' wide. But it has a 10/12 pitch and the knee walls are at 4'.

I actually wanted 12/12 to match my house, but that put me at 28ft high and 20 is the max without a bylaw amendment.

 

[WECSOG]

The last truss looks to be three or four thick to carry the load.....

....on closer inspection it looks like maybe 6 or so
No no, there's 5, final answer.

Yup.. Five thick. They carry the load of the dormer section which was conventionally framed.

"Flying" the bundled trusses into position..

 

[WECSOG]

How did you span the floor/ceiling in the center section?

2X10's were used to span the center floor / ceiling area. They were hung off the 5 "bundled" trusses on each side. I used 1 1/8 T&G for the floor/ ceiling.

 

[RonB001]

A few housed ago, I built a 24 x 28 garage, with the trusses spanning 28'. I used attic trusses, and raised the heel just a bit. I ended up with a nice, usable 12 x 24 room upstairs.

Regards,
RonB

 

[sd171]

Here is a resource I used to estimate attic truss room sizes:

View media item 72238
I have attic trusses with a 24' span, a 9/12 pitch and an additional 1' added to the standard truss design to move the bottom chord down. The ground floor has a 9' ceiling and the attic has an 8' ceiling.

View media item 72070
View media item 72110
View media item 72109
View media item 72123

 

[theoldwizard1]

Okay, any of you guys building with attic trusses, what is your motivation over a "common rafter" design ?

I am guessing that it is a big labor cost savings. It is probably easier to have them engineer in a higher static floor load.

 

[BMW Rider]

I built my original 24' x 32' garage using attic trusses. the span is across the 24 dimension and the roof pitch is 5.5/12. It's an unusual roof pitch, but it was done to maximize the height in the attic space and come in just at the height restrictions for the local codes. It gives me just under five feet in height in the attic space which is eight feet wide down the length of the garage. Although I have to stoop to get around up there, the space is so great to have available for extra storage - and it is quite full. I have a fold up attic ladder for access.

 

[russellmn]

Don't rule out a Gambrel roof (barn roof) Mine is 28x44 and I have no knee walls... ridge beam and rafters...




upstairs is my 2 bedroom house.

 

[Apex Structures]

The best value in price should be seen if you keep the room width equal to 1/2 the span distance. Make sure the top chord size is adequate for your insulation needs.