I want to raise the height of the ceiling in my 21’x23′ garage. It was built in such a way that it is about 11.5 inches below the ceiling height of the main house, which puts it at about 7′ above the foundation wall. Working with standard 4’x8′ stock can be a real pain!
I have the opportunity to correct this with my reroofing project. Here is what I’d like to do:
On top of the stud walls, place two 2×12 boards with a 1/2″ plywood spacer between to make a beam with a 3.5″ width. A 1/2 threaded rod with large square washerand nut every 5′ would help secure it to the existing wall, suplemented by StrongTie LTP4 shear connectors every 4 feet. Beam would be screwed together every 6″, top and bottom with #9 3.5″ coated deck screws. Corners would be reinforced with A88 corner brackets (two per corner) secured by six 3/8″ 3.5″ lag bolts. The interiot wall would then be faced with 3/4 ply sheathing, further joining the new header beam to the existing walls.
First of all, is this just a stupid setup? I chose this meathod as the 2×12 boards spanned the distance perfectly, and I can handle them where a full size LVL would be too heavy for me to lift. Between the sheer wall, the bolts, the shear ties, I think I’ve got the shear aspects covered. This is going to be topped by a ashphalt shingle roof.
Second of all, do I need an engineers report and an architects plan to get a permit for this, or would the fact that this is just a basic header beam mean the inspector would be happy just eyeballing this?
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I have'nt a clue about shear walls in CA., I'm on east coast.So you taking down rafters and the ceiling joists?
Why not take off top-plates too and 'sister' your longer studs next to original ones.Granted, there are probably elec.wires . Just an idea.
it would probably work - for that one wall out of four that connects to the house. Now how'bout the rest? Since you are tatolly changing the configuration of the walls, I'm fairly sure they would want you to upgrade to wahtever the newest version of shearwall they are now enforcing - not that I know anything about Calif.
Since you are going this far, I would be trying to get ten feet of cieling height. An eight foot cieling is a PITA too, but 10' gets pretty handy.
A simpoler idea since you are replacing rafters et all would be to use a structural ridge beam and loft the cileing - no cieling joists. Still low cileing at walls but gain at lest three feet in center of room, I suppose.
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There already is a structural ridge beam, so no joists to worry about :)! Good idea though - that beam was one of the reasons I liked this house. I might even do something stupid later like sanding and staining it.
I guess I'm unclear about what actually makes a shear wall, and where its members are located. Adding 3/4" plywood sheathing to the interior seems better than just a 1/2" plywood sheet on the exterior. Does a shear wall need that on both sides?
Though 10' might be interesting, I'm just looking for a simple solution - hence a single site made 4x12 beam around the rim. It also matches the house better. I don't want to build a barn among the low and long ranch styles!
No electrics to worry about, BTW - except for what I decide to put in.
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A shear wall ius built to resist shifting and wracking in seismic movement or other extreme live load conditions like high winds. The design and detals are spelled out by engineeres and codes beyiond what I can offer.But if you are staying with the walls you have now, and if your ridge beam is truly a structural beam capable of handling things wiothout the cilieng acting as rafter ties, then you are not doing any structrual work and should be grandfathered. Describe your beam and how it is supported and the rrafters tied to it. Or shoot up a photo or two.
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In my area (FL) that would be considered a structural modification and require an engineering signoff.
Headers are normally strapped off to the studs on either side. It looks like Paul's continuous header could be strapped to each stud or at whatever interval the engineer decides. If it's strapped both sides that should be more than enough to keep it from rolling off the top plates.
As for the threaded rod? On an original building I would have spec'd all thread, epoxied into the footing or coupled to embedded bolts, continuous through the top plates and a 3" square washer and nut to top it off. Spacing of the all thread is usually all corners, each side of any penetration and at least 4' o.c.
If Paul already has the required seismic hold downs for the original structure it seems to me that strapping the header, both sides, would be sufficient. Include also a continuation of the external sheathing to the top of the header. The joint of the continued sheathing may not be allowed at the same point as the top plate/header junction, with the reason being an unbroken expanse of sheathing over a break in the framing is stronger. The engineer would also spec the nailing pattern for any shear wall application.
If I wanted to use all thread through the center of my new continuous header, I would cut off the existing all thread somewhere below the top plate in the wall cavity, add a coupler and an additional length of all thread to get it above the header. Then replace the washer and nut and crank it down. If Paul, or the engineer is concerned that the structure is not properly tied to the foundation, then a retrofit with spaced all thread would be the ticket.
Don't forget to strap down the rafters to the header, the new top plate.
There's an article in last months JLC about raising a ceiling, and the second floor along with it...up, up, and away Don't worry, we can fix that later!
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You can buy the article online for $3.50 (I think).http://www.jlconline.comThen research and you can select by the issue and then article.Very instesting article. They raised both the 2nd story ceiling and the first floor ceiling.So it had a lot about jacking up the structure (and keeping it in one piece while they did).And with the location there was not the concern about earthquake resistance.So not a lot of direct carry over, but I think it would still be worth it for you to read.
Thanks for the tip on the article, I got a couple of them saved now.
raiseroof.jpg is how they did it, and raiseroof2.jpg is how I propose doing it. I think I have at least the strength they have, if not more. They use T straps on the inside wall, I will use 3/4" plywood from the floor to the top of the beam, continuosly across the walls.
Seeing this, is there anything obvious that should also be done?Rebuilding my home in Cypress, CA
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Rats, I subscribed a month too late!
Bet you got the special price offer in the mail and couldn't resist. :o)
The existing walls are stuccoed on the outside (3/4 to 1" thick). The walls have a 1x6 cut into them at a diagonal - no external shear support besides that. Now I can add an external shear walll to the outside, but I'd only be able to go down to the top of the existing 2x4 (the top one of the two that currently ring the top). Any deeper would entail major exterior rework that I'd rather do later. Do you think this would be enough to attach to on the exterior - since the internal shear wall is 3/4" plus shear plates under that?
Those rafters have strongtie H1's on every one, BTW. Thanks for your info!Rebuilding my home in Cypress, CA
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Here, I figured out how to do the pics side by side now:
How they did it:
View Image
How I propose:
View Image
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Paul, I am in Ca. and recently did a major remodel on my old victorian.
I would advise you to have someone familiar with your city's building department draw you a set of plans w/ engineering stamp.
What you are proposing will require engineering, and while most towns are okay with owner/build, they frown at self design proposals.
Look in ads/ local papers to find someone you can work with, it is not that expensive.
As an example of possible problems- I have never seen a shearwall designed with screws. While it may seem like a good idea, it is probably not part of a tested system, which is what the city wants to see.
Good luck with your project.
How bout that! I been thinking that you weree using wall bolts to tie into the adjacent wall of the house with a hung beam. Amazing how bright it is in here when the lights come on!
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Paul,
Since you are touching the space you are fair game for a full earthquake retrofit. Plan on Strongwalls on either side of the garage door, foundation tie downs, etc. etc. I'm in the middle of my garage upgrade right now and it's amazing how many #'s of Simpson products are going into it.
All I did was push the back wall out 4 feet (to the end of the cantelevered overhang) and change the flat roof to pitched. Massive bolts everywhere, 3 Strongwalls, on and on...
Now, I suspect that my (or should I say my Architect's) engineer went overboard, but each city can be very different on their expectations. I'd suggest taking in a sketch of your project in to the city and chatting them up about their expectations and ask for their recommendations for engineers who do your size jobs. That's worked for me before.
By the way, 3/4" is overkill - even my over-the-top engineer spec'd 1/2".
There could be a whole separate thread about lawers and what they've done to the cost of building - I've been told by my GC that engineers are personally liable for their designs as long as they are alive.
Wayne
Thank you for suggesting I go to the Building department!
First, I was trying to find a Residential Building Engineer to run this by and get stamped. HA! Everyone in the phone book was Commercial ONLY. The City would not give out names of places they knew of - though I was able to squeeze one name out. I called him up and he was CRYING he was so busy.
So, I took my drawing above, and a new front one I did quickly, and took them down to the office. After about a half our of going through the details, specs, etc. APPROVED! Couldn't believe it could be that easy.
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Glad to hear you got approval, but I'm unclear how this is a solution.
Correct me if I'm wrong and I'm sure that is possible, but a doubled top plate on a wall is strong since it's width is greater than it's heigth. 3.5" to 3" high. You are bolting your extension to the old top plate. Extending this top plate to 14.5" high only weakens the top plate against horizontal failure. Without continuous studs extending to the top of the wall, I can't see how sandwiching plywood over the seam gives it enough strength.
Well, here's what I see comparing it to a regular 8' wall:
12" down on an 8' wall are 2x4 studs providing a total of 3.94 square inches of wood per foot. A 3/4 plywood sheet gives 9 square inches of wood per foot. In one of the two horizontal force directions (Inside to outside), it's at a mechanical advantage to a reguar stud in that it is both in shear and it is farther away from the axis of motion (the opposit sid eof the seam). Obviously the inverse is true when the force runs the other way (outside to inside) but in that case the 1/2" rods hold the axis of motion to the center of the beam/header, making the seam at the plywood a compresion force.
I grant that in one direction it's not great, but I do not think that it is bad. This is also ignoring the support given on the corners by the other walls. This is also ignoring the backing the the rafters give the top of the wall - these rafters are backed by both a ridge beam and the identical wall on the opposite end. That compensates for forces againt the outside to the top (tipping it over) - like a tree branch or crane bumping into it for example.
Another realistic failure scenario could be driving the car through the wall from outside to in - tipping it over from the bottom up. In this case, it realy shines. A car penetration along a wall bearing the rafters would create an opening of shatered studs... with a nice 4x12 header over top. I could put a door in that hole! :)Rebuilding my home in Cypress, CA
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"Another realistic failure scenario could be driving the car through the wall from outside to in - tipping it over from the bottom up. In this case, it realy shines. A car penetration along a wall bearing the rafters would create an opening of shatered studs... with a nice 4x12 header over top. I could put a door in that hole! :)"
My 15 year old daghter ( on her drivers permit) put that to test last summer. Unfortanately she hit the corner of the garge knocking it off the foundation and dropping the door header.... She now doesn't confuse the gas with the brake.
Thanks for the explaination. In retrospect it isn't much different that running a 17' Lam for a garage door. I am curious why you are choosing this approach with the stucco repair and all when the new roof could be constructed with the cross bracing (ceiling) placed at 10 or 11' feet? Was suggested earlier.
First of all, I'm glad that header didn't make here a former daughter!
As for the height question - 2 reasons:
Simplicity - While I wanted a higher roof edge and ceiling, I wasn't sure how to do it. Then one day while working I came to the realization that the nominal width of a 2x12 was exactly the difference I needed to make the wall an exact 8' height (8' + a few more inches with the foundation wall). Laying down a beam is ALOT simple than creating a new short stud wall, or removing the existing head rail and sistering new studs up then refastening... you get the idea.
Look and feel - All of the houses in my neighborhood are low slung ranches built in 1960. Actually mine is the only one with a 2nd story - it was built over the patio instead of the house. Raising the garage to heights of 10-11 feet would give me problems with the look from the street. At 12 inches I can extend my eaves out and my board and batten style up - basicly it stays in proportion. Add 2 or 3 feet more vertically... much harder to integrate into the existing style of the house, without having to add dramatic new elements like windows or architectual details. These would also add to cost and complexity. Also, I'm not fixing the stucco. I hate the stucco pattern the last owner left me - Fan shaped crecents... everywhere... like the scales of a belly up fish. One visitor sumed it up nicely "Oh. It's like that everywhere." Gag. Some time in the future it will go. For now, I can just extend the board and batten motif around the garage in this new section, which brings the design element arount the house instead of just in front.
Besides those high minded reasons, there is a 3rd practiacal reason. A bedroom window facing over the garage limits my upward progression. Adding that foot means there is 4" gap between the flashing and the corner of the window.Rebuilding my home in Cypress, CA
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