DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (http://www.diychatroom.com/)
-   Building & Construction (http://www.diychatroom.com/f19/)
-   -   Lifting garage roof a foot. (http://www.diychatroom.com/f19/lifting-garage-roof-foot-156933/)

Squeakyhinge 09-15-2012 10:28 PM

Lifting garage roof a foot.
 
My 2 car garage has a very low ceiling. It was built in the 30's. I want to insulate and drywall the ceiling and walls. The ceiling has no real trusses, just rafters and joists(I think that's what they're called).
I think a support in the center would be required if loading the joists with drywall; however, there's no room for a support post because the tracks for the garage doors are there. If the sill plate up, including roof system, were raised and a course of concrete block added(btw its all block under the roof), there would be room for a "support beam" above the tracks.

Please forgive if this sounds extremely unprofessional, but i just thought i would throw this idea out there to see if im barking up the right tree; To raise the roof from the sill plate up, I would use four bottle jacks, one for each corner. I would insert 4x6's through the top course of block(spanning how long?) under each corner. It seems the real question is how long should the 4x6's be? And would these be strong enough. It's about the lowest pitch roof there is (for referral).

Another option comes to mind; I suppose I could insert a "hidden" support beam instead of lifting the roof and adding a course of block. This way I wouldn't have to get posts or rent bottle jacks. I see how this could be accomplished with a steel ibeam but would prefer something more diy 'ish. Thanks for taking the time to read this. I look forward to hearing from you.

GBrackins 09-15-2012 10:53 PM

could you just raise the ceiling joists up a foot? just a thought ....

if they are continuous joists (from top of wall to top of wall) just remove one and raise it up a foot and nail it to the sides of the rafter. then the next one, and so on ....

Squeakyhinge 09-16-2012 11:23 AM

Quote:

Originally Posted by GBrackins (Post 1010700)
could you just raise the ceiling joists up a foot? just a thought ....

if they are continuous joists (from top of wall to top of wall) just remove one and raise it up a foot and nail it to the sides of the rafter. then the next one, and so on ....

That sounds good; what should I use for beam and post(s)? I'm randomly guessing a couple 2x6's for the beam and a couple pressure treated 2x4's sandwiched for one or two posts, to support drywall. It's a two car garage with extra six feet of length.

Thank you.

Squeakyhinge 09-16-2012 11:27 AM

Also, now I'm wandering if I should go even higher to allow for an extra panel to the garage door, but I will need about 2 feet for the panel and support beam.

GBrackins 09-16-2012 12:53 PM

a couple of photos would help out .... I'm not understanding what your beam is?

Squeakyhinge 09-16-2012 01:02 PM

Quote:

Originally Posted by GBrackins (Post 1010963)
a couple of photos would help out .... I'm not understanding what your beam is?

The joists span the whole garage. If I drywall the ceiling, it seems the joists should have some extra support.

GBrackins 09-16-2012 01:03 PM

what size are your joists? will you have storage above the ceiling?

Joe Carola 09-16-2012 01:04 PM

Quote:

Originally Posted by Squeakyhinge
Also, now I'm wandering if I should go even higher to allow for an extra panel to the garage door, but I will need about 2 feet for the panel and support beam.

You don't need a beam for this. You nail the new rafter ties in first one foot up on every rafter, then you remove the existing ceiling joists. We call these clipped ceilings.

Some cases you might have to put a beam underneath the existing ridge, collar ties or vertical supports. This all depends on spans, size of rafters, pitch of roof and snow loads.
What you want to do is done all the time. It has to be designed by an architect or engineer. No one here can tell you what you really need but can help you with suggestions.

GBrackins 09-16-2012 01:07 PM

if you measure the distance from the top of wall to the ridge your rafter ties typically are installed in the lower third of that measurement

http://publicecodes.cyberregs.com/ic...9_8_sec002.htm this is the section of the 2009 International Residential Code, the basis for most local and state building codes. this link will give you the span tables for ceiling joists based upon live and dead loads and deflection limits.

tony.g 09-16-2012 06:05 PM

1 Attachment(s)
Can you fix a timber runner centrally along the tops of the ceiling joists, and suspend this from the ridge with timber hangers, as per sketch. This would halve the span and strengthen the joists considerably for supporting lining.

allthumbsdiy 09-16-2012 11:56 PM

Quote:

Originally Posted by tony.g (Post 1011120)
Can you fix a timber runner centrally along the tops of the ceiling joists, and suspend this from the ridge with timber hangers, as per sketch. This would halve the span and strengthen the joists considerably for supporting lining.

My garage has a floating ceiling (no beam support where ceiling joists are lapped) and it has the exact same setup as your drawing, except:

1. mine has 1x3, holding 2x6 ceiling joists

2. vertical strip attached to every other rafters.

I may be way off base but I think attaching to rafters make more sense as that would exert horizontal forces on the ridge board as well as to the opposing rafter whereas attaching to the ridge board would only exert vertical force on that structure.

tony.g 09-17-2012 08:56 AM

4 Attachment(s)
Hi AllThumbs; attached are some pics showing a loft ceiling being boarded and supported as on that sketch.

Span is 12ft, ceiling joists 2x3 and rafters 3x3. To beef up the ceiling I screwed a 2x4 runner along the tops of the joists at mid-span, and supported this with 2x2 hangers bolted to the runner and screwed to cross pieces just below the ridge.

There's nothing wrong in principle with supporting some load off the ridge board, because the board is rigidly propped by the rafters.= (assuming the rafters are nailed to the sides of the ridge).

allthumbsdiy 09-17-2012 11:26 AM

I wish I had your roof pitch.

Based on your pictures, you attached the vertical piece to your collar ties, which in turn are attached to your rafters :)

BTW, I just realize we are kinda hijacking OP's thread so I will mute myself.

Squeakyhinge 09-17-2012 12:57 PM

Quote:

Originally Posted by tony.g (Post 1011120)
Can you fix a timber runner centrally along the tops of the ceiling joists, and suspend this from the ridge with timber hangers, as per sketch. This would halve the span and strengthen the joists considerably for supporting lining.

Thank you. This is exactly my garage with a little less steep roof pitch.
My next question is about ventilation after sheeting the ceiling. The only facia is a 1x3 trim board covered mostly by the gutter. I'm guessing "gable" vents?

mae-ling 09-17-2012 11:22 PM

Air should come in the bottom and go out the top. Use insulation baffles in every rafter bay, to give air flow above the insulation.
May need to 'fur down' the rafters where they slope and meet the wall, or use Styrofoam, or blow on insulation (ugh brain is dead as to the right name)


All times are GMT -5. The time now is 07:57 AM.