Removing purlins and ceiling joists

hey all! i have a workshop to which i have fitted a car lift...but i now need to remove the ceiling ties(to which there never was a ceiling fitted), and the purlins which are half way up the 45degree rafters, in order to be able to lift the car into the roof space suficently enough to allow standing room underneath. i know the only way is to suficently strengthen the rafters so that they dont sag and install collars higher up. but i want them as high as possible..not just the third of the way up that is recomended. so my thinking is to strenthen the rafters with u chanel 3 or 4 mm steel cupping and screwed or bolted to the raters. then using steel strips as the collars but higher up...say in the top third. has any one any experience of this method or any comments? all very welcome! (arcitect due to advise later next week..but would like some feedback on my ideas)
cheers!
steve
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Yea but think about what those horizontal supports hold together, THE WALLS from separating. Depending on type of construction you may be sorry if you do it wrong when it loads with snow. You should consult an architect, so if it falls its his buck - liability for steering you wrong.
I was hired to remove a wall, I told the customer to hire an architect to aprove it. He did, the ceiling and beams fell down, the architect payed .
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You are removing the bottom of the triangle. Rafters develop a great deal of lateral thrust, trying to push the top of the outside walls out. The ceiling joists prevent this. The collar ties help prevent it and help stiffen the rafters.
You will need to compensate for this structural removal. One method would be to create a structural ridge. This project will not be inexpensive.
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<< i have a workshop to which i have fitted a car lift...but i now need to remove the ceiling ties >>
Prediction: your architect will run the numbers and tell you to tear the structure down and rebuild with the right ceiling height. Your building inspection department won't issue a permit. You will wind up building an addition of the correct dimensions and moving the lift to that location with proper permits, etc. Automotive lifts require a 14' or better clearance. That should have been noted in the installation instructions. Let us know how it turns out and good luck.
Joe
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r.p.mcmurphy wrote:

<SNIP>
Just a wild guess, but if you are in UK, you may get additional answers by posting to: UK.D-I-Y
Jim
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As others have posted, you are unlikelty to get any permit approved. 45 degree is a steep roof and thus has considerable force trying to spread the walls. Your proposed steel reinforcement really wouldn't do the job IMO. One approach to consider if your architect says your proposal won't fly: Tear off the roof, add knee-walls to raise the walls high enough to put on a normal roof. Yeah, spendy but not as much as finding your roof sagging.
Harry K
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