double mud sill & steel beam questions
Hi
I am in the early stages of planning a new home and have two questions:
1) In many of the FHB articles I see double mud sills with shims in between to level the joists. Looking around at several (18) different houses under construction I have never seen this done – its always a single mud sill. Has the accuracy of formwork and screeding improved that much since these articles were written? Is anyone still doing this?
2) Assuming I go with a steel beam for the main floor support (roughly 26’x40′, 1.5 story) what are the best options for connecting 2×10 joists? I am not totally againsts simply lapping them over top, with a 2×4 bolted to the top flange. Alternatively, to preserve basement headroom, if I were to go with joist hangers on the side what are some key points? For example it would seem to me nailing top mount hangers to a 2×4 on the top flange would not be that durable in an earthquake. That is to say I would like more redundancy than relying on a series of inline top nails not to split the entire face off the 2×4. (Are there any common details for having the joists bear on the bottom flange or extension of, or ledger…)
Thanks
John
Edited 6/16/2009 11:44 pm by JohnWalker
Edited 6/16/2009 11:44 pm by JohnWalker
Edited 6/16/2009 11:45 pm by JohnWalker
Replies
I would use a single mud sill and level it with mortar if the foundation isn't level enough. It is possible to get very, very close to perfect with a laser level when setting forms, but you may still want to either use grout under the sill, or grind off the high spots while the concrete is still green.
Have the steel supplier punch holes thru the web so you can bolt 2x to the beam, and then use typical side-mount hangers. No need to get into any of the top-flange stuff.
Ideally your beam will be shorter than your joists, so the subfloor floats a bit above the steel and the sheetrock rides a bit below it. With 2x10 joists a W8 beam is ideal.
running the joists into the side of the beam doesn't work, then all your HVAC and plumbing can't pass over the beam ...
running the joists into the side of the beam doesn't work, then all your HVAC and plumbing can't pass over the beam ...
Flush beams whether they are steel or wood are done every day. You have to find another route to run the duct work, or go underneath.Joe Carola
Is anyone still doing this>>>>>>>>>>>>.
Not here!
Assuming I go with a steel beam for the main floor support >>>>>>>>>>>>>>.
I prefer a wood beam, using LVL etc. if you need more strenght. We are wood butchers not steel workers!>G<
You can use a much smaller beam in steel than in wood. It can be a huge advantage and it's extremely easy for the average carp to prep a steel beam for hangers, especially if the supplier punched bolt holes in it.
I know Dave, it is just me spouting off on steel beams. I really don't like using them, even though we have to in some situations.
Out here in earthquake country, at least one inspector occasionally gets cranky about too many/too large of shims in a mudsill (double or single) and requires extensions on the foundation strapping. Extensions on the strapping mean overlapping a second 24" long 1/8" thick steel strap over the first (I think it's 8" - 12" minimum overlap for the joint?) which creates a big PITA for the siding crew.
-t