Okay, this is just for my general knowledge.
I’m planning on having my 1 car garage expanded to a 2-car garage and then have a 12×24 addition put on behind that. All the builders I’ve talked to suggested “keeping” the roofline the same (it’s a 2-story cape cod) for the garage/addition (well, it’ll be a few inches below actually) and have a bonus room above the garage/addition.
My question (again, I’m sure I’ll get this answered when the architect draws up the plans and all that):
The CURRENT ceiling rafters in the garage run the 20′ length and are 2×6. Obviously they’re going to tear off the roof and those rafters, but I’d like to know how they’re going to put something new in that can support weight for a “bonus” room?
Meaning, a 20′ span would have to have like 2×14 or something (even LVL, yes?)
Or do they “separate” the two car garage and use the shared wall as a bearing wall and then they only have to span 12′
Basically if they’re going to put a bonus room there, in order to keep the floor height the same in THAT room as it is on the 2nd floor, they’d have to use 2×8 (Or is there some odd way to “notch” the joists so that you can put a 2×14 or whatever in and have it hang “lower” in the garage). Or do they “raise” the floor in THAT room?
Again, just curious. This is most definitely something I’m not doing myself (plumbing/electrical yes, but not that heavy construction stuff)
Replies
the garages i have built have beam running in the center with a post or posts. the cjs sit on that. one garage has 8' walls the other 9'. cars fit in just fine.
tyke
Just another day in paradise
When I frame bonus rooms, we frame the walls, use I joists, which can definately span at least 20'(engineered properly of course) plywood the floor, put down 2 2x plates stacked, then stick frame the roof on that. In a development now where this is how all the houses are being done. No need to waste money on LVL. The one we are currently doing is a 24' span using 16" I joists. On a 20' span you might be able to use 14". Don't recall what size I used in the past though. Or you could even look into bonus room trusses. Just a regular truss with the middle left open. Specifically designed of course.
Just read your post again.... About the heigt issue lining the floors up. You could do 2 things (off the top of my head) Use LVL as a rim board all the way around the garage, keeping it flush with the inside of the walls, and to the height you need, and hang all the joists, or lower the existing walls.
Edited 4/3/2005 7:21 pm ET by podge58977
Forgot about I-joists. The one builder (I'm getting quotes/proposals from 3 diff contractors) mentioned that his architect would probably have to design trusses, so maybe that's what he was referring to.I don't necessarily mind posts in the garage, just didn't want to have the whole length "segregate" the two units.Thanks!
I had a similar issue, and I went with trusses. A truss will span 20' no problem and they can be engineered to whatever load you want for the bonus room as well. Chances are you'll get a bigger bonus room with trusses, but that all depends on the specifics of your project.
Hope that helps.
couple of points, don't get all hinky about using 8 foot ceilings in the garage and then have too stoop and duck upstairs in the bonus room..
7 foot celings are fine in garages if all you intend to do is get out of your car and go in the house.. I've evan seen 6'6" ceilings and they are fine too (unless you are over 6'6")
Don't spend money to save a wall. Tear the whole thing down and start from scratch. Your greatest expense isn't the 2x4's and some siding, rather it's the labor involved in patching around trying to use the existing stuff. I know that seems like hearsay but you'll quickly find out it's trueth..
Insulation is my pet interest. If you are starting from scratch seriously consider using SIP's instead of traditional stick building. The wallsbecome 200% stronger than stick built. The insulation is like a thermus bottle in that it's continuace and far more effective than fiberglas or celluliose.
Your archithect might not have a lot of experiance with SIP's and may try to steer you away from them, ( they's been in use for over 50 years) but most of the myths about them aren't true. the reason they aren't more common has to do with tradition rather than any problem..
Cost should be the same or cheaper than traditional methods of construction and the finish product will look and feel the same except they will be much cheaper to heat and cool plus they will be dramatically quieter..
Frenchy,Thanks for the info. I thought about SIPS but I'm not sure if the builder has ever worked with them before. It would certainly make the addition "install" faster.I think they're going to tear the garage walls down anyway. Currently, the garage is "lower" than the 1st floor of the house, so the current ceilings are like 10' so I have no problem lowering the ceiling to 8' or whatever.
We used attic trusses for the house we are building now instead of stick built. We only increased the size of the bonus room by about 6" in width and 6" in height over stick framed but the real 'bonus' was eliminating the two 18" LVLs that were needed to support the bonus room floor joists across the 24' span. This let us lower the garage ceiling about a foot for extra headroom in the bonus room. but still allow 8' garage doors. Our bonus room is about 14'x40'.
Regards,
Dennis
Hurnik
Like DJJ said, trusses are the way to go. My garage with a loft (bonus room) only needed 9 1/4" deep (2x10) attic trusses to open span 26'.
I believe they are rated for 30 lbs/sq/ft. If The Boss ever chimes in, He'd know.
WSJ
My garage is 22 feet wide with a den above. The floor is 14 inch wood i joists on 16 inch centres. Works pretty well, we don't notice any deflection.
Have a good day
Cliffy