Garage Ceiling Span
I need storage space, bad. No basement under the house.
I have a 20′ deep by 30′ wide garage that was put up by a local garage specialty builder. It currently has a 4 pitch hip roof. I have had thoughts of taking the roof off and rebuilding it with an attic above and gable ends.
I have a height restriction, and the maximum elevation is defined as 11 feet to the center of the gable end, so that puts me at ~14 feet to the top. The current stud walls are 8′.
I checked the local big box, and the “room in attic” trusses will exceed the height restriction. I priced them out anyways, and they are not inexpensive. I have not checked with a different vendor. These trusses would give me a roughly 8′ wide x 6′ tall x 30′ of clear space. Plenty of room for things like ladders and light but bulky items. A side door is planned in the gable end to get long stuff up there.
Placing a steel beam at 10′ is not an option, as I do not have proper footings for that load. Busting up what I have and starting over isn’t an option, either.
I also need a ceiling so I can insulate heat the space. The current 4′ on center and 20′ long 2 x 6 rafter ties are not up to the job.
Are there any reasonable options to clear span 20′ while providing useable storage space?
Where's the door, and how wide?
(And how do you feel about posts?)
There is a 16' overhead door and a double 36" (72") man door on the 30' side.
Left to right: 12" wall, 16' door, 18" wall, 6' door, 5'-6" wall.
It may not add up, going from memory , but that is the general idea.
South wall has (2) 36" w x 24" h awning windows. No other windows in the walls.
Posts? Don't want them, and no existing proper footings for them.
Existing slab is a monolithic thickened edge. There is a bit of slope to the lot where the garage is located, so there is quite a bit of concrete in the back.
I have a 32'span
and I-joists make for the storage attic floor. Not stout enough for a living space, the china would rattle in the cabinet.
Downside might be size and cost of these joists-but you are running them the 20' span I would guess. I have a knee wall that raises the rafters up a couple feet so the storage can go all the way to the perimeter. Some engineering necessary (or not) on those so they don't spread.
Yes, joists would be parallel to the 20' wall.
You'd likely need a bigger header over the 16-foot door.
Yeah, I was just thinking about that.
Probably 2 14" LVL.
What kinda sucks is I am in the process of redoing all of the siding. There was an 8' x 20' patio that was under the garage roof, so it was relatively easy to wall it in... then the siding needs to be redone- no way to match or patch in vinyl without having it look like crap.
Worst case scenario, I would have to redo the few pieces at the door. Then, the rest of the walls would have to be built up to match the 14" header (12" header in there now).
I couldn't swing doing it all at once $$$
Do it hybrid with Light Gauge Steel and wood
10" Steel floor joists will span 20' for light storage and use wood or steel rafters coming down on the floor joists above walls or headers. Make sure that at the eaves there is proper structural connection between the rafters and floor joists ends with 8 or 10 fasteners at each location. This is the key that holds everything toghether by this framing method. To have sufficient clearance roof pitch may need to be 12 in12.
For the 600 sf attic, floor joists only out of steel should cost about $1000 at a wholesaler like the one we use locally. Adding steel rafters is another $1000 to $1200. It includes all connectors, tracks, straps, fasteners and tools required for the job.
In our area labor to install steel should cost about the same as materials.
If you need framing details how to correctly connect steel to steel or steel to wood, the steel material supplier can provide them at a cost of around $500.
At the 16' door you may be able to stay with the 12" header by reinforcing it with 2-12" light gauge steel members.
You've been asked to lose that big banner ad you carry on your posts. The adivice you give is tarnished by the fact you seem to think that huge advertising is kosher here. It's not.
You gonna do the honorable thing or just keep ignoring people that ask you direct questions?
Last I checked it's impossible to change you sig.
Can't change it?
Is the edit button gone in the profile? I know there's no other info there but the sig line. Is that gone too?
I changed mine by adding a line.
And now tried deleting that line. Seems to have worked both times. Give it a try.
Every time I try to change my sig it tells me "That email address is already registered". Tried both Firefox and IE. Tried several different variations. Tried it many times over the past months, including once this morning.
my usual response.
I've come to learn that on this site, what one can do or see is not necessarily able to be done by another. Now, that's progress.
I have seen steel truss assemblies on commercial buildings in my area. Many of the parts are preassmbled on the ground for smaller pieces and hoisted with a crane. I worked on one job where the whole roof truss structure was built in place.
Probably a decent weight savings over wood.
Might be one option to consider.
A 12/12 roof pitch is not an option. That will blow the height restriction, and I do not like mansard style roofs.
Maybe you just need to add a basement to the garage.
Man, I wish that was a realistic possibility.
Raising the roof
In this case what you need to do is build a flat roof (maybe with a slight monoslope down toward the back for drainage) 6 feet above floor level. This will also give you a much larger usable storage area.
Depending on your snow conditions you may be able to use 8" light-gauge steel rafters spanning 20' and spaced 24" on center. You don't need trusses with steel framing on this size structure.
The total cost will be higher since you will have more wall area to build, which can be made out of wood or steel studs spaced 24" on center.
Again, the devil is in the details, you or your framer needs to know how to connect wood to steel and steel to steel and other issues such as stiffeners, bridging, bracing, strapping, hangers, clips and so on.
I have considered this.
Aesthetically, in my opinion, it sucks. I know someone that has a garage built like this, and it does not sit well with me visually. At least in his area, it is acceptable. There are other buildings that look similar. He has a 2 story house.
Where I am, there are not too many people with detached garages, mainly because the side lots don't work out so well for access. My subdivision is almost all ranch type homes. A huge flat top garage would not fit in well.
Functionally, it would work and fit my needs.
I think a commercial style flat roof would kill resale value, unless someone with interests or needs like mine wanted to buy it. I do not see moving anytime soon, but I need to balance things a little.
Just walling off the 8 foot patio has made a big visual difference. It is only 8 feet, but it looks much bigger.
I was hoping to move a while ago, but the escalating prices put nearby areas out of reach. Now, well we all know what is going on out there.
Personally, I'd also check the aesthetics of your proposal which will add much mass and maybe a different roof angle. Maybe you don't care about that stuff. But even people who don't care about aesthetics seem to oo and aa at things like a nice Lambourgini.
Also, I'd suggest thinking out of the box on the roof height restriction. Maybe there are options that you haven't thought of even w/ the dislike for mansard style (which I respect). Maybe you could hip the last 2-3 ft above the new storage doorway and get away w/ it. If it is storage, seems like 7 ft should be more than adequate, maybe even 6 ft (I'm 6'6" so I may not like 6 ft ceiling in storage, depending on what is stored and frequency of access).
Maybe you should consider some type of open storage to below? I'm trying to encourage a rethink since you seem to be placing road blocks up for all kinds of options. Times like these may warrant exhausting virtually all options methodically.
Maybe a nice shed out back ...
That is on the list.