Raising Shed Roof

A

aidank

Well-Known Member
In the process of reroofing a lean to shed 22 feet wide at the minute and I want to raise the roof at one side.

Sheets are coming off and timbers will be coming off as a few are rotten, existing rafters will get new bolts as they are 50 years old, all in all essentially starting from scratch, recycling timbers where they are in good condition.

The line of pillars I want to extend are railway lines. I want to extend by ~75cm, go from 2m to 2.75m

The man I am getting sheeting etc from proposed the following,
  • A 7" RSJ directly on top of the railway line.
  • Attach to RSJ using 12mm flat strip 50mm wide bolted to the web of the railway and the web of the RSJ.
  • The web of a railway is 16mm thick, I need to measure again to be sure, he proposes to use more flat strip as appropriate at either side of the RSJ web to fill the gap.

I see a problem, the web is the weakest part of the RSJ, and only approx 3.5mm thick, would a 5" or 6" channel be a better choice rather than RSJ, much more meat in the channel iron ?

Anyone ever lifted a shed roof via extending Railway line pillars ? how did you do it

Things I cant do due to space limitations
  • Bolt a piece of RSJ to the widest part of the railway, eve chute of another building is in the way
  • Cut the Railway off at the bottom and put in a new RS
 
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Have lifted many sheds using rsj plated both sides and slid down existing upright and bolted through. That's the way the suppliers of the sheds wanted it done and they are the people signing off on it. As an extra though we always would run a bit of weld round the joint too, its more for the look of things for the customers though than added strength.

Never done it with railway line though but the principal is the same.

I wouldn't worry about the web thickness of the rsj.
 
paddy1001 said:
Have lifted many sheds using rsj plated both sides and slid down existing upright and bolted through. That's the way the suppliers of the sheds wanted it done and they are the people signing off on it. As an extra though we always would run a bit of weld round the joint too, its more for the look of things for the customers though than added strength.

Never done it with railway line though but the principal is the same.

I wouldn't worry about the web thickness of the rsj.
Click to expand...

Thanks for input.

One other Question @paddy1001, what is the recommend fall for a gutter. Im going to guess at least 1" per bay ?

Doing some googling throws up "Slope each gutter run down toward the downspout about 1/4 in. for every 10 ft. of gutter", but that is in American where it is dryer.
 
aidank said:
In the process of reroofing a lean to shed 22 feet wide at the minute and I want to raise the roof at one side.

Sheets are coming off and timbers will be coming off as a few are rotten, existing rafters will get new bolts as they are 50 years old, all in all essentially starting from scratch, recycling timbers where they are in good condition.

The line of pillars I want to extend are railway lines. I want to extend by ~75cm, go from 2m to 2.75m

The man I am getting sheeting etc from proposed the following,
  • A 7" RSJ directly on top of the railway line.
  • Attach to RSJ using 12mm flat strip 50mm wide bolted to the web of the railway and the web of the RSJ.
  • The web of a railway is 16mm thick, I need to measure again to be sure, he proposes to use more flat strip as appropriate at either side of the RSJ web to fill the gap.

I see a problem, the web is the weakest part of the RSJ, and only approx 3.5mm thick, would a 5" or 6" channel be a better choice rather than RSJ, much more meat in the channel iron ?

Anyone ever lifted a shed roof via extending Railway line pillars ? how did you do it

Things I cant do due to space limitations
  • Bolt a piece of RSJ to the widest part of the railway, eve chute of another building is in the way
  • Cut the Railway off at the bottom and put in a new RS
Click to expand...

Railway girders are joined with plates called fish plates. They are a heavy plate with bolts each side. If they can carry the 300 ton iron lady, I'd have no worry about them in my shed. If you know a lad working on the railway there should be no problem getting them because they were just dumped when the railway lines were relaid with continuous track back in 2000. Otherwise, anywhere selling sleepers and girders should have some of them.

railway-fish-plate-250x250.jpg
 
had an old round roof + leanto type shed reroofed this summer, its now an A roof, what the contractor did was very simple but seemed to work well, he fitted H irons onto the tops of the railway pillars, basically the H iron had a flat plated ends so they sat onto the tops of railway pillars and had 2 legs that slipped down either side of the mid part of the railway pillar and was bolt thru, the railway pillalrs were already holed
 
aidank said:
Thanks for input.

One other Question @paddy1001, what is the recommend fall for a gutter. Im going to guess at least 1" per bay ?

Doing some googling throws up "Slope each gutter run down toward the downspout about 1/4 in. for every 10 ft. of gutter", but that is in American where it is dryer.
Click to expand...

There is no hard and fast rule for the fall in guttering, the size of the outlet will determine how quick the water drains from it, not how fast the water gets to it, the American one may not be far away as they get a lot of rain at times too.
We tend to put the guttering on just a fraction off level and it works well, too steep and the water reaches the outlet quicker than it can drain down it so builds up and flows over the side.
Obviously the number and size of outlets will vary depending on the length of the shed and how big the roof is.
 
aidank said:
In the process of reroofing a lean to shed 22 feet wide at the minute and I want to raise the roof at one side.

Sheets are coming off and timbers will be coming off as a few are rotten, existing rafters will get new bolts as they are 50 years old, all in all essentially starting from scratch, recycling timbers where they are in good condition.

The line of pillars I want to extend are railway lines. I want to extend by ~75cm, go from 2m to 2.75m

The man I am getting sheeting etc from proposed the following,
  • A 7" RSJ directly on top of the railway line.
  • Attach to RSJ using 12mm flat strip 50mm wide bolted to the web of the railway and the web of the RSJ.
  • The web of a railway is 16mm thick, I need to measure again to be sure, he proposes to use more flat strip as appropriate at either side of the RSJ web to fill the gap.

I see a problem, the web is the weakest part of the RSJ, and only approx 3.5mm thick, would a 5" or 6" channel be a better choice rather than RSJ, much more meat in the channel iron ?

Anyone ever lifted a shed roof via extending Railway line pillars ? how did you do it

Things I cant do due to space limitations
  • Bolt a piece of RSJ to the widest part of the railway, eve chute of another building is in the way
  • Cut the Railway off at the bottom and put in a new RS
Click to expand...
I know you said you can't cut off the pillars at the bottom, I'm guessing they may be in a wall? But is there one pillar that could be cut off easily enough? We took down a lean too a good few years ago locally and put it back up here, only the low side pillars were useable but they were too short, and were a different size to anything modern, we ended up chopping up one pillar to lengthen 3 others and then bought one new pillar the right length, it was the simplest way and guaranteed they were a perfect match for welding up.
 
kverneland es 80 said:
A lot of sheds extended with rail track here.we just use some rail track and modern fish plates
Click to expand...

where did you get the fishplates ?

one thing I have never seen for sale is a fishplate

Derived from wikipedia
In rail terminology, a fishplate, splice bar or joint bar is a metal bar that is bolted to the ends of two rails to join them together in a track. The name is derived from fish, a wooden bar with a curved profile used to strengthen a ship's mast.[1] The top and bottom edges are tapered inwards so the device wedges itself between the top and bottom of the rail when it is bolted into place.[2] In rail transport modelling, a fishplate is often a small copper or nickel silver plate that slips onto both rails to provide the functions of maintaining alignment and electrical continuity.
 
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railway-fish-plate-250x250.jpg


The type of joint used in the picture is designed for a specific application, the type of joint that the op needs would have to be specifically designed to take into account wind loading, snow loading, dead load, live load, size of existing steel, size of proposed steel and to do it properly would need to be designed by a structural engineer.
 
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