The answer to this question is too complex to describe here. There are too many factors which are not specified in the question, such as load in pounds per linear foot, spacing of the 4X12 joists, as well as grade and species of lumber.
350x450mm with 12-16mm rebars on 5m span
cost of steel 12''x18' i-beam per linear foot?
For ceiling joists, the minimum dimension per the IBC is a 2 x 12 inch, with spacing dependent on the load. Ideally, these would be screwed to blocking between the joists.
Even using a 2x12 the spacing for 20 feet will be less than 12 inches on center. I would recommend splitting the distance with a double beam perpendicular to the joist run. This will allow you to go up to 24 inches on center. Your span will only be ten feet aproximately this way. I would double the beam. (2-2x12 joined together) Good luck. when building your beam make sure the laps on the beam are at least 6 foot apart and put a good wood glue on the 2x12s plus for added strength put 1/2 inch O.S.B. in between the 2x12 and I would also lag or bolt them together, at about 16 to 24 inches O.S.B. = Oscilating Strand Board.
Technically Yes, but you'll need to check with your building inspector because there are codes regarding structure that vary from place to place, and the inspector isn't going to pass something based on my say so.The old rule of thumb was 1 inch for 1 foot, so a 12 foot span would require a 2 x 12.A 4 x 8 isn't equal to a 2 X 16, or even 2 2 X 8's, but it should do if the load isn't too great.I'm guessing you want to go with 8" stock because you've got some headroom issues. You'd be better off structurally with an LVL (Laminated Veneer Lumber) or OSB (Oriented strand Beam) or a truss, but these are kind of pricey.If you get in trouble see if they'll let you go with them on 12" centers.
The recommended patio roof beam span according to the patio roof beam span table is typically around 10-12 feet.
The recommended pergola beam span according to the pergola beam span chart is typically around 12-16 feet, depending on the specific design and materials used.
Only if it is at least 12' long.
A double 2x10 beam can typically span up to 12 feet without additional support.
It depends on what the beam is made of.
Depends on the loads and the properties of the beam. Consult a structural engineer.
What size steel I beam do I need to span a 32 feet garage with a floored storage above and no posts
The recommended pergola beam span for optimal structural support and durability is typically between 12 to 16 feet, depending on the material and design of the pergola. It is important to consult with a structural engineer or contractor to determine the specific beam span needed for your project.
350x450mm with 12-16mm rebars on 5m span
The maximum allowable span for a double 2x10 beam in a structural application is typically around 12-15 feet, depending on the specific load and building codes.
The maximum allowable span for a double 2x8 beam in a structural application is typically around 12-15 feet, depending on the specific load and building codes. It is important to consult with a structural engineer to determine the exact span for your specific project.
That always depends on what the beam will be carrying. You will need to consult a building contractor to size any beam correctly. IT ALSO DEPEND ON ITS MATERIAL &ALSO HOW MANY STOREY CONSTRUCTION REQUIRED ON THIS