Garage mezzanine

[stuartris]

Hi hoping for some advice on a project, I’ve been a fabricator welder in structural steel for 30years but I am not astructural engineer so any input/feedback is welcomed. I recently started to build a garage mezzanine for storage the garage is 2.5M to the eaves and 4m to the ridge with the span between the walls 4.1M apart from the bottom course of blocks which are wider than the rest. I have bolted 75x75x8 angle to the 2 sidewalls of the garage 2440 long to give me a mezzanine full width of the garage x 2440 depth. I have then used 100x50x3 as joists spanning the 4.1 metres between the side walls seated on and bolted to the angle at 400mm centres I have used 100x50x3 for 2 rows of cross bracing and to catch the end of 2440 18mm plywood boards I have also put in 10 posts,legs out of 50x50x5 all bolted connections with welded brackets. Will this be adequate to support a reasonable load, I won’t be putting any anvils or such like up there. Like I said previously any

and all feedback is welcome positive or otherwise.
Thanks

 

[gaz1]

your post is wrong you want to move it under the center beams to support them

as thats the better place for them the rest is fine

 

[brightspark]

well it looks well substantial i wouldnt be worrying about anvilles on it or anything else , even the ones in warehouses are only half of that and pressed light gauge steel

 

[tom2207]

unless your a sub contractor for the Abrahams battle tank armour , I dont think you will have many issues .

 

[addjunkie]

The two verticals spoil garage access…a heavier joist, across, and then others to the back wall woukd have been suffice for storage.
An 8” I girder would have been suffice, block pillars to support the ends.

 

[stuartris]

The two verticals spoil garage access…a heavier joist, across, and then others to the back wall woukd have been suffice for storage.
An 8” I girder would have been suffice, block pillars to support the ends.

I know what you mean about access but it’s at the back of the garage where I intend to put my bench under it the mezzanine only projects 2.4 metres from the back wall and the garage is 10 metres long so not too much of an issue. Thanks for the comments and advice

 

[minimutly]

Only thing I did differently on mine was use a lot less steel, but used planking (7 by 1and 3/4) or similar between the steel.
Two ways of skinning a cat.

 

[stuartris]

your post is wrong you want to move it under the center beams to support them

as thats the better place for them the rest is fine

View attachment 498232

yeah i agree that would be the strongest place to put them, the short cross members were put where they are to catch the ends of 8ft boards. I compromised on putting the uprights where i did as i am going to wall in that area and have my bench and tools etc in there (and a kettle obviously} and i did not want too narrow a doorway. planning on a weld cutain door.

 

[stuartris]

Another question i would like to ask members is this, i would like to fit an electric hoist to lift stuff on to the mezzanine, i have a piece of 203 x 102 x 23kg beam 9.6mm flange thickness 4m long but i have limited height and every few millimeters i can save matters, if i cut the beam in half lengthways down the web giving me 2 100x100 T sections which would save me 100mm of possible lift height and give me enough to cover almost the full length of the garage. would an inverted T section be strong enough for the beam trolley hoist and load it will be bolted every 1600mm to the roof trusses.

 

[gaz1]

im sorry but its never about compromise if you have to compromise then you change your structure

those strength up rights are there for a reason under the cross members if you wanted a compromise then you would have changed your cross members in the middle to match your strength points

ive also just noticed your rear cross members that are supported with the angle iron also poorly done id advise changing them so the post is under the beams and not offside never mind the loading of just one bolt an a piece of angle iron as support for the whole floor

Another question i would like to ask members is this, i would like to fit an electric hoist to lift stuff on to the mezzanine, i have a piece of 203 x 102 x 23kg beam 9.6mm flange thickness 4m long but i have limited height and every few millimeters i can save matters, if i cut the beam in half lengthways down the web giving me 2 100x100 T sections which would save me 100mm of possible lift height and give me enough to cover almost the full length of the garage. would an inverted T section be strong enough for the beam trolley hoist and load it will be bolted every 1600mm to the roof trusses.

not a chance with a poor structure like that

 

[MattF]

your post is wrong you want to move it under the center beams to support them

They're not centre beams though, are they. They're noggins, (or whatever the term for metal structures is).

 

[addjunkie]

Another question i would like to ask members is this, i would like to fit an electric hoist to lift stuff on to the mezzanine, i have a piece of 203 x 102 x 23kg beam 9.6mm flange thickness 4m long but i have limited height and every few millimeters i can save matters, if i cut the beam in half lengthways down the web giving me 2 100x100 T sections which would save me 100mm of possible lift height and give me enough to cover almost the full length of the garage. would an inverted T section be strong enough for the beam trolley hoist and load it will be bolted every 1600mm to the roof trusses.

Do the roof trusses have a cross beam, stopping both sides sliding out over if over loaded? If they dont Id not be hanging extra weight from them.

 

[Agrismith]

The two posts at the front are doing very little. The front beam is clear span the same as all the others. Except being at the front is only capable of receiving a theoretical load 1/2 that of the centre beams. As you can only load one side of it. Either every beam needs those two columns or or none of them do. I'm sure someone on here can do the maths for you to work out your exact loading but I would reckon you have about 5x as much steel in that as the cheap mezzanine kits come from.
Any weak point would be in the connection to the walls. I would be very easy to add to this by mirroring your angle iron on the top side should the need arise.
I would be tempted if I where you to draw a line with a sharpie along the bottom of the angle allowing you to monitor it. And add to if necessary. If you see any drop.

 

[knighty]

The two posts at the front are doing very little. The front beam is clear span the same as all the others. Except being at the front is only capable of receiving a theoretical load 1/2 that of the centre beams. As you can only load one side of it. Either every beam needs those two columns or or none of them do. I'm sure someone on here can do the maths for you to work out your exact loading but I would reckon you have about 5x as much steel in that as the cheap mezzanine kits come from.
Any weak point would be in the connection to the walls. I would be very easy to add to this by mirroring your angle iron on the top side should the need arise.
I would be tempted if I where you to draw a line with a sharpie along the bottom of the angle allowing you to monitor it. And add to if necessary. If you see any drop.

the front beam is the only one spanning the full length, the rest are made of 3 joined together across the beams at 90' running front/back

the front beam is holing up those front/back beams

 

[Agrismith]

the front beam is the only one spanning the full length, the rest are made of 3 joined together across the beams at 90' running front/back

the front beam is holing up those front/back beams

Double check photos. The beams are clear span wall to wall and front to back beams are 6 little short lengths. Pic no. 4 shows the clear span beams prior to the short lengths being inserted.

 

[stuartris]

The two posts at the front are doing very little. The front beam is clear span the same as all the others. Except being at the front is only capable of receiving a theoretical load 1/2 that of the centre beams. As you can only load one side of it. Either every beam needs those two columns or or none of them do. I'm sure someone on here can do the maths for you to work out your exact loading but I would reckon you have about 5x as much steel in that as the cheap mezzanine kits come from.
Any weak point would be in the connection to the walls. I would be very easy to add to this by mirroring your angle iron on the top side should the need arise.
I would be tempted if I where you to draw a line with a sharpie along the bottom of the angle allowing you to monitor it. And add to if necessary. If you see any drop.

Thank you valuable observations exactly what I was looking for, thanks

 

[stuartris]

im sorry but its never about compromise if you have to compromise then you change your structure

those strength up rights are there for a reason under the cross members if you wanted a compromise then you would have changed your cross members in the middle to match your strength points

ive also just noticed your rear cross members that are supported with the angle iron also poorly done id advise changing them so the post is under the beams and not offside never mind the loading of just one bolt an a piece of angle iron as support for the whole floor

The design of anything is a series of compromises, I want it to be strong and light or I want it to be good quality but low budget etc. I don’t understand why you think the cross pieces which would be noggins in a timber floor (as someone else pointed out) would be where all the load is concentrated? They help distribute the load between more than one beam I could have gotten away with not using them at all they were mainly to screw the ends of the boards too. I also don’t understand where you think one bolt is loaded with the force of the whole floor? They help distribute bolts between the upright and the angle are just to stop the upright from moving, the load will be on the upright. If you could please clarify your points for me I would give them more consideration.

Thanks

 

[Bobupndown]

Looks pretty robust to me. You're not needing a structural engineer to establish if it will take the weight of 100 people. For storage of garage  junk important stuff id be perfectly happy to work under that construction.

 

[Dilkris]

Personally - I would put a car up there, (if you could), and not worry about it.
Well done !!
I shudder to think what it cost.

 

[Morris]

Personally - I would put a car up there, (if you could), and not worry about it.
Well done !!
I shudder to think what it cost.

This.
As long as the wall fixings are good then I would happily store a car up there.
I very much doubt that those posts add much tbh.