Well assuming the attic eats 6db that statement is wrong.
Attic beam measurement.
When cutting your beam pocket add 1 2 to the steel beam width measurement to allow for an easier installation.
On longer spans the beam may require much more bearing space as indicated by this table.
Covering the ceiling joists in the attic using plywood is a cheap way to make better use of the wasted space in your house.
Use of joists in attic flooring.
The formula for the section modulus is beam width times beam depth squared divided by 6.
A two 2 by 6 standard beam has actual dimensions of 1 5 by 5 5 inches which would give a section modulus of 1 5 x 5 5 x 5 5 6 7 6 which is not enough for this example.
The subfloor installation is easy.
Rafter is a sloping beam usually wood that supports a pitched roof.
There could be many rafters supporting a roof.
Step 3 screw an eye hook into the beam where you made the mark.
Back up to the pulley on the attic.
Attach a pulley to it by sliding the pulley s hook into the eye.
A pair of rafters is called a couple.
A 1 4 wave would be 0 dbd at best probably worse but a 6 element beam would be 8 dbd so it looks like the attic beam antenna would win by about 2db assuming same height above ground.
Fortunately this is a fairly easy fix.
Joists and rafters must be strong enough not to break when loaded.
You can sister the joists by cutting 2 x8 boards the same length as the joists applying construction adhesive and affixing each to a joist with nails.
Bedrooms and habitable attic floors l 360 30 psf.
Cut a length of rope equal to this final measurement.
You might open up your attic and find bare joists with fiberglass or cellulose insulation between the joists.
We used a bosch green line laser to connect both beam pocket locations and then used a speed square to mark cut lines directly on the joists.
Any lumberyard will be able to furnish the beam and other materials.
The beam system we show will work for nearly any opening up to 12 ft.
Attic floors with limited storage l 240 10 psf.
Unlike stiffness live loads and dead loads are added together to determine minimum design values for strength.
Tie a knot in one end to prevent it from accidentally slipping out of the pulley.
A 2 by 8 beam would be sufficient.
Strength of a material is obviously important.
We have learned from our experience to use at least a 3 1.
The 2012 irc code calls for a minimum of a 32 o c.
Staggered pattern with at least a 3 x 120 nail.
Beams of more than one ply must be fastened together with either nails or bolts.
Step 4 run the rope through the pulley.
To start each cut a circular saw was used and finished up with a reciprocating saw.
Our 12 ft long beam was made from doubled 11 7 8 in wide x 1 3 4 in thick lvls laminated veneer lumber a very common strong type of beam that looks exactly like thick plywood boards.
