Garage renovation/vaulted ceiling & removing "ceiling joists"

brandonlaundry

So in order to gain some precious, usable hang out space to our tiny house I've decided to build out the 18x18 stucco garage. Previously the garage had giant, sliding barn doors that didn't work anymore. First step, I built up the floor off the concrete slab, removed the doors, framed in the extra on the sides and installed 150" patio sliding doors all the way across the front. I wanted to maintain a little bit of a tool/shop area in the back, So I framed a wall about a third of the way into the space and have plans to drywall it. This wall is floor to roof. Up until this point, there were 3 true 2x4 "ceiling joists" running across the garage from left to right. These sparse "Ceiling joists" as I'm calling them, were sitting on top of and nailed to the top plate of the left and right walls . There were also 2 2x4's running from front to back that were nailed into the left to right 2x4s. This all created a very flimsy grid of support. When I framed the wall 5' from the back, I tied the front to back 2x4s into the newly framed wall and cut off the remaining 2x4 that was running into the space I wanted to renovate into hang out space. This still left 2 of the three 18' 2x4s that run from left to right across the space. My question is this: now that I've built a wall that supports and is tied into the roof and walls across the back third of the garage, do I need these 2 saggy (previous to my work saggy) 2x4s that run from left to right? I understand that they are there to keep the walls from pulling away from each other, but with the addition of the framed wall, the closure and framing of the previous wide open front and drywall on the lower walls, am I providing enough structural support and can I remove the 2x4s running left to right to create a vaulted ceiling? What are my options?

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nap

No, you cannot remove those. Your one wall is not adequate to restrain the spread along the entire length of the walls. In fact, from your picture, it doesn't appear as your cross tied wall provides a continuous connection from outside wall to outside wall. It appears there are two boards butted to each other over the stud second from the right. Only if there is a solid foundation under that wall would it be adequate to perform as a load bearing wall so unless you have done that, you need an adequate tie between the two outside walls.

So, without a proper foundation under the wall, you will still have spread as the support compacts.

You can leave those cross ties in place and finish the ceiling as you wish. It just means you will have exposed cross ties in the space. It is often included intentionally like that as an architectural detail. You can box them to make them larger so they appear to be "beams" rather that boards or simply finish them out with some finish of your choice.

brandonlaundry

Thanks Nap. That newly framed wall actually sits on and is bolted to the original concrete slab. I've noticed that the two crossing 2x4s are attached to the top plate of the wall, but not the roof rafter. Are these cross ties being used for wall support or as collar ties? What you're suggesting is a decorative truss, correct? Like a scissor tie (i grabbed an image and attached it)? Would that provide the support needed to avoid any wall deflection?

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mrgins

The image you posted would not give you the support you need, especially if you get any significant snow fall. All you need to do is incorporate a tie from plate to plate above the new wall and then an exposed one at the other 1/3 place in the addition. This month's edition of Fine Homebuilding or Journal of Light Construction shows how cables were used to pull in an exterior wall. The cables were left exposed and done in a way that made them part of the exposed structural elements and obviously less visible than a 2x tie.

nap

a collar tie, from my understanding, is a cross tie near the peak of the roof. It is to keep the rafters together at the peak during periods of uplift. They would not provide adequate restraint to tie the walls together to prevent spread as the leverage applied would easily overpower their ability to restrain the rafters.


the boards you are dealing with would simply be joists as far as I understand.

They are intended to prevent the spread of the rafters which are attached to the walls so both would end up spreading. I cannot tell you which is the most proper method of attaching but since the rafters are attached to the top plate of the wall, to me, it becomes a moot point.

to the ties on the trusses; not what you are looking for.

no. just suggesting you can dress up the joists that are present.

Gary in WA

As said earlier, the rafter ties need to stay in place; http://myconco.com/ComEngProb.html

The 2009 IRC makes a distinction of rafter ties/collar ties; http://publicecodes.citation.com/ico...002_par018.htm

If you change the rafter ties to larger size, follow the nailing of the rafter/tie connection, scroll down to the last Table 802.5.1(9) here; http://publicecodes.citation.com/ico...002_par023.htm

Gary

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brandonlaundry

Thanks guys. I really appreciate the info and especially the link to the free code guidelines. Very helpful.

Gary in WA

Glad we could help! Come back again soon....

Gary

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