Tilt up roof construction?

[Dberry]

Here's an idea for building simple gabled roofs faster and safer (especially steep pitched).  This just occurred to me so I haven't had a lot of time to poke holes in it, but here goes.

Assuming you have sheathed your attic area, you have a flat place to lay out your roof on the flat.  Precut bird's mouth and cut rafter heads & tails as you would normally, but instead of building it up in the air, build it flat on the deck, sheath it, put your roll roofing and shingles.  Then Tilt it up.   Standard gate hinges attached to the deck and pivoting at the tip of the bird's mouth will insure it doesn't slide off and place it in the correct position.  Brace it temporarily and then repeat for other half of roof.  Once both are done and braced a little higher than their final position, gable wall ends can be built and then the roof halves can be lowered on to it and cross ties installed.

I'm not seeing anything wrong with this idea right now, but there maybe something I've missed.  In any case it sure sounds easier than working on a steep pitched roof.

Let me know what you think!

Dan

[bartholomew]

I think it could work. Tilt-up roofs are commonly used with modular housing. With the first half up, I wonder if the braces would get in the way and make it more trouble than it's worth to do the other half as tilt-up. Also, I wouldn't be too comfortable working underneath it to build the other half. Maybe tilt up one half and build the other half conventionally?

[Amanda_931]

Bartholomew may have it right.  

A variation on that is how people sometimes do site-built trusses--Lay them out on the floor--with little blocks, then hang them upside down on the top plate (generally together), move them into place and turn them right side to.  Might be a trick to get the last one, if all the others are already fastened in place.  So I guess you do a temporary fasten on the last bunch.

[Dberry]

Good points.  I'm thinking the biggest worry might be wind and the panels acting like sails.  With some good rope and careful placement of safety stops, I think most of the danger can be mitigated.  Also I think you could build both roof panels on the flat, one on top of the other and then move them both into position on the same calm day.  I'm not adverse to working up in the air, or on staging, but it looks like the same thing can be built in half the time with tilt-up.

Thanks for the replies!  

[glenn kangiser]

Seems it could be done but unless broken into sections you will need equipment to handle it.  It will get heavy fast.

Ken Kern showed some designs in one of his books where the roof and support posts tilted up and connected in the center - these were utility buildings though if I recall correctly.  They were like two angled triangle braced tee's.

[Amanda_931]

I agree about the weight.

But if you want a really scary prospect, you could do something out of the Ianto Evans (et al) cob  book--put the roof up on temporary poles and then lower it onto your nice cob house.

At worst,  Dberry's idea obviously requires some planning.  Not sure but what the Evans scheme might not be started by people whose mantra is "but Ianto says..."

[PEG688]

[size=12]    Not worth the effort IMO. Like Glenn said it will get heavy fast , comp roofing starts out at 230LBS a sqr. so it would only work on a small building and you'd still need equipment or good rope and pulley techniques and a failure of any of those could result in bad things .

Good staging isn't that hard to build ,  

 Good luck, PEG  [/size]  

[Dberry]

I'm glad I asked.  

I did some quick calculations of my metal roof and it came to 2500 pounds for each half.  Even considering lifting only half of that on a pivot... 1200 pounds is much more than I was thinking when this idea popped into my pumpkin.  Guess I'll do it the old fashioned way.

Thanks all!