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In my new flat I will build a huge platform into one of the rooms. It will be very much like a loft bed, but wider. I'm in a very early planning phase. The room is about 3m across (no plan or exact measurements available for now) and I want to span this width with beams. I'm seriously considering using steel t-beams instead of wooden beams. Products for fastening wooden beams are readily available. What would be the best way to secure steel beams to the wall?

While I'm open to other options, I'm mostly looking for a product or thing that I can bolt to the wall and that will allow me to fasten my beam.

Some facts:

  • The beams will be perpendicular to the wall plus minus a few degrees
  • The walls are thick 30-40cm, probably masonry
  • Any cuts in my beams will be off by a few mm, so I need some tolerance along the beam direction
  • The flat is rented, bolting stuff to the wall is ok but I won't chisel a hole in the wall or similar
  • I want to avoid columns, unless the best fastening option is not good enough
  • I have a master mason & carpenter whom I'll run my ideas by
  • The room has a ceiling height about 4m

Dimensioning Note
The beam will span around 3m. let's say I and some of my stuff stand right in the middle, for 150kg. This would mean roundabout 0,75kN linear force on the support and a torque of 1,125 kNm. Let's add a safety factor of 2 and ignore (for an unknown additional safety factor) that not all my weight will be supported by one beam. We are at 1,5kN linear force and 2,25 kNm torque if I cantilever the thing. This is what the wall and fastenting will have to bear. If there's no reliable way a structure bolted to a masonry wall can support this, so be it. But I'd ba amazed since I've seen builds pretty similiar that didn't collapse. I didn't pay close attention to the fasteners, though.

  • What is the purpose of these beams? Are they structural (meaning they should support something and if so what?) or are they decorative? – python starter Jul 16 '15 at 8:16
  • Is this a rented flat or an owner occupied flat? – Michael Karas Jul 16 '15 at 8:20
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    If you're moving about on it, then my advice is consult a structural engineer. Also, if you're planning on fixing something that substantial in a rented property, I would consult the lease very carefully beforehand! This sounds like significant structural work, rather than putting in a screw to hold up a picture (and in the UK even putting in a screw is normally prohibited by the lease). – AndyT Jul 16 '15 at 10:10
  • Neither a mason nor a carpenter is a structural engineer. They may be able to help you with the practical details of the connection, but they are unlikely to have the expertise to carry out structural calculations for the beam and its connections. – AndyT Jul 16 '15 at 12:08
  • I've seen platforms similiar to what I plan to build, with wooden beams (which makes proper fastening easier). I think steel was a trigger phrase. I think you overestimate the loads etc. But then, better safe than sorry. – mart Jul 16 '15 at 12:34
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T-beams can be connected to walls by welding a flat plate onto the end of the T-beam, drilling holes in this endplate, and then bolting through those holes onto the wall.

Alternatively, brackets can be bolted to both the wall and the beam. Example of a simple connection. Example of a full moment connection. (Both examples are for I-beams, but the principle is the same.)

In your situation, it appears you are talking about significant structural works (i.e. you are talking about walking on the platform). The idea of a DIYer attempting this worries me significantly. If you don't know methods for connecting a T-beam to a wall, I suggest you are unlikely to know how to correctly size the T-beam, or design a sufficiently strong connection. I advise you to consult a structural engineer.

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I would strongly discourage your idea of gaining storage space in the manner you are describing. Instead procure some free standing shelving units that you can place along all of the walls. There are a multitude of styles available from rivet lock types to near industrial wire shelving that have adjustable shelves to accommodate varying sized items.

Using shelves like this does not damage the rental property (as long as you protect the floor in some cases) and you can take them with you when you re-locate. There are some additional advantages as well:

  1. You get multiple levels of storage instead of just one.
  2. You can stand up on the normal floor in the middle of the room instead of crouching over on or under the platform that you envision.
  3. More items remain visible and accessible as opposed to shoving everything into the back corners of some deep platform.
  4. Normal centrally located ceiling lighting in the room still remains useful.
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There are some typical ways to support steel beam in a wall.

  1. Choose right section.
    I guess that I-beam would suit You better than T-beam, as I-beam has two flanges - both will work and make it durable, but apart of this upper one will help You to attach anything (platform), lower one will make it much more load-bearing than web of T-beam (if You intend to fit T-beam with flange on the top).
  2. Make proper supports.
    Three ways to do this:
    • Place the beam inside the wall. To attach steel beam to the wall You will need to make sockets (holes) with concrete under-beds. Without these there will be too large tension from end of the beam to the wall, so the wall may crumble. Concrete under-bed will help to redistribute this force to larger area. I guess You could make some google-search for details.
    • Another way is to make a connection via welded plates on both ends. This must be done with proper measurement and by welder (more people involved). These can be bolted to the wall, depending on loads, measures, etc.
    • You can make spatial structure. Wall connections would be (generally) for spatial stiffness purposes, loads could be delivered to the floor by some columns. More steel, more cash, but least intrusive to wall I guess.
  3. The platform.
    You could use it to make these beams stiff in horizontal plane. If You make rigid fittings to beam's flange, whole structure will work nicely. You may try to talk with some experienced peeps (some of them work in shops where You will buy Your steel) about that.
  4. Last but not least - wall strenght.
    There are walls and walls. Try to figure out what kind of wall is that (if masonry - what materials and dimensions it has), post it here or talk about it with some pro (civil engineer?).

Michael Karas pointed out another issue in comment - is it Yours - the flat? You will definately need an approval to make that change.

  • Hi Marek. The "shelf" is known as a flange. Using an I-beam will give increased bending stiffness and bending capacity but less shear capacity (compared to a T-beam of the same weight). If you place the ends of the beam inside the wall, as per one of your suggestions, then having the bottom flange (i.e. having an I-beam) would definitely make it more suitable than a T-beam; however, this doesn't match with what the OP wants. – AndyT Jul 16 '15 at 12:05
  • @AndyT Thank You. I just edited my answer with Your naming suggestion. As for shear forces resistance, I think that it will not decide here as bending forces will determine it's load-bearing potential (shearing forces doesn't really matter in most cases). Of course, everything depends on the case (here - the span and load distribution). – Marek Oleszczuk Jul 16 '15 at 12:28
  • Of course shear force matters. If a structural engineer designed a beam by only considering bending, and ignoring shear, they wouldn't last long before getting fired! – AndyT Jul 16 '15 at 12:35
  • @AndtT Well, yes, that is right. I'm not saying that it does not occur or one do not need to take it into consideration. I'm saying that bending force resistance will (most probably) be dominant. We could make calculations and display percentages of strain, it could show what I have on mind. – Marek Oleszczuk Jul 16 '15 at 12:50
  • Ok Marek, I think you mean that most steel sections on the market, if simply supported with a uniform load, would fail in bending before shear? It's outside my own experience to know that without checking, but I would be happy to believe that if you say so. – AndyT Jul 16 '15 at 13:04

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