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need to jack up second floor roof

keystonemw's picture

need to raise existing roof in order to increase head room in room above garage, any one with ideas how to do this safely. the room is 14 feet x 20 feet with a gable roof. I can not find any resources on this.

(post #97441, reply #1 of 20)

you're kidding, right.......

(post #97441, reply #2 of 20)

I did the same thing...mine was smaller. 12 x 18 or so. It wasn't easy. I've heard of roofs larger than that size being reinforced, sawn, then lifted with a crane.


Jake Gulick

CarriageHouse Design

Black Rock, CT

Edited 2/15/2005 2:40 am ET by LATEAPEX911

Jake Gulick   CarriageHouse Design Black Rock, CT

(post #97441, reply #3 of 20)

Tear it down and reframe it. It might be possible to jack it, but it would be done by house movers who know how to jack things safely... not by you.

(post #97441, reply #4 of 20)

I don't know where you are, there is a company in the Boston area that does that.  I think they use a system that resembles the pump jack staging setup (much stronger though).  I thought it would be easier and cheaper to demo and build new but they said that was cheaper and quicker.  This house was going from a 1.5 floor cape to a 2.5 colonial.

(post #97441, reply #5 of 20)

Since nobody else said so, welcome to BT.

BY putting "jack up" in the title, most of "us" are inclined to think you mean that literally.  Which is possible, the TOH crowd used jacks to raise a ceiling a few episodes ago.

So the answers to your question are both defined and limited by the terminology used.  If you want to know how to get more head room creatively, you kind of have to say so.  My first mental image was of a bunch of bottle jacks straining agaist a roof structure bowing the second floor down in a sort of "don't do this" video kind of thing.

I'm going to guess that you mean "jack up" as in "raise the structure."  One of the posts--sort of--explained exactly what that takes.  First, remove the existing structure, then raise new structure at the desired height.  (Please be advised your AHJ--Authority Having Jurisdiction, the Building Department or Inspector--may require plans and permits for such an activity; getting a "stop work" with half the second floor roof off would sore tempt weather Fate.)

In other words (IOW), tell us more.  (Click on the blue "marty" and fill in some of the profile info, too, while you're at it, please--location can be important).

Occupational hazard of my occupation not being around (sorry Bubba)
I may not be able to help you Occupational hazard of my occupation not being around (sorry Bubba)

(post #97441, reply #6 of 20)

Strip all the DW out of the room.

Remove the windows for reuse and cover the holes.

Table frame (52733.1 ) four new walls, finish the exterior on the table.

Prep the roof for craning.

Hire a crane.

Set the roof on the ground.

Set the old walls on the ground.

Set the new walls in place.

Set the roof back on.

You'll need the crane for 1 day.

Trim the outside corners. Finish the inside.


A Pragmatic Classical Liberal, aka Libertarian.

I'm always right!
Except when I'm not.

(post #97441, reply #7 of 20)

While some people here think its nuts, I have actually seen it done on a whole house here in Charlotte, NC. What was more impressive was the fact that the roof had 3 different ridge line all at different heights. Imagine a 20's bungalow. After bracing the roof by building beams to run along all the different eave lines, a crane lifted it up and clearly the preassembled walls were put in place. What was nice was that all the gable and eave detail was kept and didn't have to be recreated. Really slick stuff.

Be sure to have an engineer look it your plans before you go off and start this.

(post #97441, reply #8 of 20)

Actually, I'd seriously consider jacking from the floor, vs taking the roof off. Would raise the windows, of course, but probably that's goodness.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #97441, reply #9 of 20)

Marty, how high up are you wanting to take the roof?

"Live Free,
      not Die"


(post #97441, reply #10 of 20)

Consider lifting the whole structure instead.

Make the existing garage area the 2nd floor.  This may actually be easier than removing the roof.  This was done a lot in 19th century New England.  It was the cheapest way to build an addition.

The conventional way to get more headroom is by building dormers.

(post #97441, reply #11 of 20)

Maybe the process of raising the roof should be abandoned. Consider removing the second floor joists and lowering them. This will only work though if there is sufficient head room in the existing garage. The problem I would have with raising the roof is how would you maintain water tight integrity during the move? You are not going to see if any cracks or splits show up in the decking, or if the whole roof structure twists upon liftoff. Then there is the process of resquareing the roof  once it is being set in place, quite a difficult task when you a talking about a structure that large. 

On the other hand, the process of demolishing some sheetrock. sawzalling the nails in the joists and then lowering them is a lot less intimidating. plus the material cost is less. If I were given the responsibility of rasing the roof, the amount of bracing material required too keep the roof from shifting would be almost as much as the roof itself.

If, in the end, raising the roof is the only way to complete the project make sure to tie the structure together in every direction possible. especially across the bottom. I would tie braces from one rafter across the ridge to the other rafter every 2 feet from the plate to the ridge and then tie all of that together in the opposite direction. Again maybe this sounds excessive but all that roof will have to do is camber out a few degrees and you will struggle to no end to get that roof to fit again and if it doesn't fit right it will leak period.

One more thing, if you do lift the roof, try to have all the walls and the new plate ready to install immeadiatly. This way, if you can afford the crane time, you can lift the roof strait up and quickly install the higher walls. I would resist greatly setting the roof on the ground. The more often you transfer the stress from crane to solid surface the more it will flex and flexing would have to beconsidered the enemy in this project.


(post #97441, reply #12 of 20)

OK, well, you all will laugh at this, but, resisting good judgement, here's what I did.

My situatiion was that the 3rd floor  attic on my Victorian wasn't high enough for real use. 18" made a big difference. So....

My ballon framing top plate stopped about 18"above the floor. I tied the roof across the gable  with many 2 x 10 collar ties. Then I added diagonals from the corners on the collar ties. I placed the collar ties about 10" up the rafters, and then added a full length 2 x10 nailed flat to the rafters at the base on each side. Roof pitch is 12/12 or so.

Once I had the roof dimensionally stable, I cut it free at the top plate, but I sawed under the plate leaving the studs dead headed, so to speak.

I devised a jacking cradle, and proceeded to jack each side, using the 2 x10 nailed to the rafters as the jack receiver,  by 3/4"  at a time, trying to maintain levelness all the way up to my 18" height. (3/4" was so I could use 1x stock for spacers.)

The secret was making the cradles that held the roof in position while I jacked the other side. They need to be stable, obviously. I race cars, so I had a few jacks on hand. The roof size was about 13 ft wide and 18 feet long, was originally cedar but had 3 layers of ashphalt.

Once up to the desired height, I infilled my studs, (I made some changes to the studs, etc,  that aren't applicable here, so I'll leave that out.)

My main reason for deciding to use this technique was that I had to do it alone, (it's my own house) and I know I could never get it done any other way in the weather window, and sure enough, it rained as I finished the job...but problem..I had a roof over my head!  Also, keeping all the trim intact was a nice bonus.

Admittedly, it's not for everybody, but it can work.

Jake Gulick

CarriageHouse Design

Black Rock, CT

Jake Gulick   CarriageHouse Design Black Rock, CT

(post #97441, reply #13 of 20)

So, working alone, you went up the whole 18inches by 3/4 increments all in one day and had an 18inch high open space to the outdoors around the 13x18ft roof

that you then infilled with your miniature stud wall and dropped the roof back down upon it?

How many jacks did you use and were you concerned over the possibility of an all-falling sideways effect on the jacks?

Successful ingenuity. Milkbones and a hat tip to ya.

be brave and bold 

"Live Free,
      not Die"


(post #97441, reply #14 of 20)

Well, that's pretty much it...but I spent the first day of the weekend creating the "stuff" birdsmouth jack to roof adapters, and my other paraphenalia, as well as shoring the roof up with the bracing.

The second day of jacking was long, too much ducking and crawling and such! LOL.  I used 4 jacks at a time, and got into a rythm. One side, then the other. Was i concerned about the whole thing falling off?? YOU BETCHA! Man that thing weighed a lot more than a ton, and if it started moving, it would be very tough to stop the moment. I cross strapped it to the existing structure thinking that in the event of a total catastrophy, it would at least land on in a good spot, instead of leaning against the neighbors house! THAT would be UGLY!...

As it was, I went slowly, tried to ensure that at any point the maximum failure would be a 3/4" drop...and going in I was of the mindset that if, at any point I was concerned with the procedure, I could just stop, and reassess my options.

Jake Gulick

CarriageHouse Design

Black Rock, CT

Jake Gulick   CarriageHouse Design Black Rock, CT

(post #97441, reply #15 of 20)

Oh ok So you kept the continually heightening gap filled with your 3/4" boards stacked so in the event of a failure it might fall a quarter or half inch onto those boards?

Then removed them to put in the mini-riser wall.

Did you secure the 3/4" boards down in any way or just stack them?

*shhh*Did you get a building permit? heh heh

be inquisitive

"Live Free,
      not Die"

Edited 2/20/2005 5:36 pm ET by razz


(post #97441, reply #16 of 20)

Late, at first I was thinking that your very small roof wouldn't be that heavy. I went back and read that it had three layers of ashphalt. That made it kinda heavy!

All in all, I'd probably take about the same tact, but I'm not sure what you were trying to accoplish with the diagonal bracing. Also, I would have been very concerned about the bearing of the jacks.

I've raised stuff like that with nothing more than spring braces.


Just because you can, doesn't mean you should!

Warning! Be cautious when taking any framing advice from me. There are some in here who think I'm a hackmeister...they might be right! Of course, they might be wrong too!


keep looking for customers who want to hire  YOU.. all the rest are looking for commodities.. are you  a commodity ?... if you get sucked into "free estimates" and  "soliciting bids"... then you are a commodity... if your operation is set up to compete as a commodity, then have at it..... but be prepared to keep your margins low and your overhead  high...."

From the best of TauntonU.

(post #97441, reply #19 of 20)

You are correct. I was very concerned with the bearing of the jacks, and had a fixture that went under the jacks to spread the load over the floor joists. I tried to lift evenly to keep the point loads under control.

I added the diagonal bracing to try to help maintain the squareness of  the overall structure, and it seemed to me that is I did that, the loads would be better distributed.

One one hand, I know that i am no engineer, but on the other hand, many engineers have told me I have good instinct and am a "good seat of the pants engineer", which is, of course, a backhanded compliment as well as a jab...LOL...but i thought if I could manage the risk, it would be a worthy project. Seemed crazy, but sometimes I have to let my previous biases go, and think freely.

Jake Gulick

CarriageHouse Design

Black Rock, CT

Edited 2/20/2005 8:33 pm ET by LATEAPEX911

Jake Gulick   CarriageHouse Design Black Rock, CT

(post #97441, reply #17 of 20)

I'd sure love to see some photos of that, if you got any. Hard to imagine you were in the frame of mind to snap pics, tho...

(post #97441, reply #18 of 20)

Too much reflecting glare from the bulging eyeballs.

be nerves of steel

"Live Free,
      not Die"


(post #97441, reply #20 of 20)

Razz...yes, i did periodically screw things down, and the 3/4" "pads" or spacers were not small.

Funny comment about the glare off my eyeballs! I did snap some pics....I will try to find and scan them.

At one point, the roof was up a good 12 or more inches, and the thought occurred to me: "There are deciding moments in life that can make you a hero...or a complete ####....this is one of thos moments" And I ran to the Depot to buy a few more back up straps!

Jake Gulick

CarriageHouse Design

Black Rock, CT

Jake Gulick   CarriageHouse Design Black Rock, CT