Anyone any good at steel beam calcs

Need to rebuild double garage flat roof.

Currently held up by 2 x pretty scary "home laminated" plywood nonsenses that I have propped.

Beams need to be C 6.5m depth, supporting 7ft timber cross members, supporting ply deck then butyl membrane.

What size/spec steels do I need?

If I wanted to lift out car engines with winches attached to one or other beam, would that need a different spec?

TIA

Jim K

Reply to
JimK
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Reply to
newshound

I used to work in the steel fabrication and erecting game for many years, and for what you want I would say something like a 6x3 RSJ would be fine just to hold up the roof. You would have to find the spec of 6x3 RSJ and then work out how many you would need from the area of the roof.

For lifting a car engine out with a chain lift you would need something a 10x5 RSJ, but the sizes are all metric now, so you would just pick the equivalent.

All the above is mostly guestimations as I don't haveenough info about your garage roof.

Reply to
Bob H

Er... so ask away?.....

Jim K

Reply to
JimK

Well for a start, how big is the garage. What sort of engines: Fiesta or Jaguar / Range Rover.

Reply to
newshound

Er well it's a double garage, the depth is 6.5m as per the OP....

Engines - assume medium average weights

Jim K

Reply to
JimK

When you are talking about beams, depth is usually the vertical direction. OK, so your garage is 6.5 metres from front to back. What is the dimension from side to side. Which way do you want the steel beams to run. What sort of walls have you got to support them at each end. How many do you expect to have. You mention 7 foot timbers in the OP. What are their dimensions and which way do these run?

Reply to
newshound

Oh yes, and does it have one door or two (with a brick pier in between).

Reply to
newshound

Usual trick to avoid uprating a beam for the odd engine out point load is to have a couple of acrow props to fit either side of the vehicle when applying such loads.

Reply to
Bob Minchin

Even just one side, especially if the car isn't positioned right in the middle.

Reply to
newshound

/ When you are talking about beams, depth is usually the vertical direction.

You were asking about the garage. I am asking about beams...

/OK, so your garage is 6.5 metres from front to back.

Correct.

/What is the dimension from side to side.

Double garage? 2 x 7ft doors etc So say 6m external side to side.

/Which way do you want the steel beams to run.

Does it matter? Front to back say

/What sort of walls have you got to support them at each end.

Brick/block

/How many do you expect to have.

As few as necessary. 2 say.

/You mention 7 foot timbers in the OP. What are their dimensions ?why?

/and which way do these run?/q

Er from the beams to the walls? a bit longer than 7ft....

Surely its the total load of the deck + snow weight that defines all this? Spread over 4 walls & 2 beams? Add snow factor on top plus allowance?

Jim K

Reply to
JimK

Usual trick to avoid uprating a beam for the odd engine out point load is to have a couple of acrow props to fit either side of the vehicle when applying such loads. /q

Good idea thanks.

Jim K

Reply to
JimK

Er, no. You are talking about lifting out car engines using the beam. This will drastically change the loading. However, my garage uses an 8 x 5.5 inch beam for your span and the ceiling joists are 5 x 2. The beam provides a king post support for the concrete tiled roof and the deflection is less than 5mm ( probably about

2). Note that beams are specified by weight per foot/metre for a given external size and this decides their performance. The easy way to answer your question is to ask your local structural steel stockist, who will know off the top of his head what you need. A car engine is unlikely to exceed 500Kg and if this is specified as the mid point loading then you should be OK. The distributed roof loading will not exceed 30lb per square foot for snow conditions IMO. If you want to do it the hard way, go to the local library and find the standard text books, which will have worked examples to show you how to do it. Bear in mind that you need pad stones(concrete) under the beam ends and will need at least 6 inches of support for a 5.5inch beam.
Reply to
Capitol

/> Surely its the total load of the deck + snow weight that defines all this? Spread over 4 walls& 2 beams? Add snow factor on top plus allowance?

Er, no. You are talking about lifting out car engines using the beam. This will drastically change the loading. However, my garage uses an 8 x 5.5 inch beam for your span and the ceiling joists are 5 x 2. The beam provides a king post support for the concrete tiled roof and the deflection is less than 5mm ( probably about

2). Note that beams are specified by weight per foot/metre for a giv

Snip

thanks for the info on you roof. How big is your garage?

NB you appear to have taken my perhaps simplistic summary of the overall roof loading puzzle to somehow be a justification for extra loads when lifting engines out of cars :-)

I can work around that with Bob's suggestion to acrow the beam if I ever do use it as an engine hoist.

Jim K

Reply to
JimK

About 19' x19' internally.

Reply to
Capitol

importantly what will support beam ends ... plain wall, double thickness piers ? How much bearing will beam have on this support (needs 150mm at least)

Reply to
Rick Hughes

6"x3" with a 6.5m span ... and could have a central point load of ~750Kg for an engine ... seems a small beam for that. Wouldn't a 7"x4" (178 x 102) be a better fit ......... but I don't have calcs to do this.

You can also find 2nd hand RSJ's in scrap yard .. just pay scrap weight.

I used 8"x4" when I needed them for a garage, to allow for lifting an engine.

Reply to
Rick Hughes

/ -show quotedtext -importantly what will support beam ends ... plain wall, double thickness piers ? How much bearing will beam have on this support (needs 150mm at least)/q

Indeed - they will have proper pads to bear on to proper appropriate sizes.

Jim K

Reply to
JimK

/newshound

Not enough information./q

Do you have enough information now?

It seems to have gone a bit quiet since I replied to your last notable post...

Jim K

Reply to
JimK

to get to low deflection over a flat 6 meter span you need serious wood. I've got 12x12 oak here for that span..

Id say 7-8" deep RSJ is what you want and a crane to install it.

Reply to
The Natural Philosopher

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