Clear span ceiling using smaller lumber

[Falcon67]

Offered for discussion and reference:

I found these pics I took in a house being built near us, this was a few years back. I took them because the build used some made up beams and supports allowing 2x6 lumber to span across a wide living room, about 24~26' wide x about 20~22' deep. Nobody left a ladder around so I got what I could with the phone. It appears they used 2x12s to sandwich a fabricated "truss" faced with OSB to span the depth. Then the 2x6s were just hung off that across the width. Pictures for your own interpretation.

 

[GMCGarage]

More than likely a engineered design. Bigger structural members supporting smaller structural members. No different than having a steel beam down the middle of a basement and it supporting 2x floor joists.

 

[6768rogues]

I like the attachment detail which does not include toe nailing.

 

[yeldogt]

So -- that's living space above? I would never do it without a cleat or hangers -- and they are not my first choice due to cost.

.. sometimes no choice. that looks to be using a nail or screw to keep in place

 

[Radix2]

It's interesting, I see a huge enclosed volume that could have been used for something if framed differently though. Not sure what was being optimized by doing it this way.

Did the wall height change after the walls were built? What's up with the ladder on top of the top plate?

 

[theoldwizard1]

If I was going to do something like that I would use a steel/iron beam as the load carrying element.

 

[yeldogt]

If I was going to do something like that I would use a steel/iron beam as the load carrying element.

It ends up being more expensive and requires another trade -- more blocking. Steel is great when you have no space or you want a huge open space under a foundation. I was going to use one in my new build -- but, I was able to get two equal spaced laminated beams and drop down the floor joist sizes.

There are some amazing wood beams available today

 

[Falcon67]

So -- that's living space above? I would never do it without a cleat or hangers -- and they are not my first choice due to cost.

.. sometimes no choice. that looks to be using a nail or screw to keep in place

No, this house has a really, really tall roof peak. Like 30 something feet. The guy framing the ridge almost needed an oxygen tank.

 

[GMCGarage]

If I was going to do something like that I would use a steel/iron beam as the load carrying element.

Whats the thoughts on that?

 

[Duck tape Bill]

How are the 2x6's attached to the beam? It looks like they are just nailed to the side of the blocking between them... I can't imagine this meets code.

 

[GMCGarage]

How are the 2x6's attached to the beam? It looks like they are just nailed to the side of the blocking between them... I can't imagine this meets code.

depending what state, they might not have a fastening requirement for ceiling joists.

 

[firebirdparts]

The structure is interesting; The 2x6's are not. In traditional not-trussed-structure, a 2x6 clear span would be perfectly normal (and in fact pretty much universal) for supporting a ceiling. Spans were traditionally limited to 24 feet because that was the longest lumber you could easily get. Normally, of course, they run the other way, parallel to the rafters. On a building 24 feet wide or less, they could (and would) go all the way.

 

[The Tool Tyrant]

The carrying beam is actually killing 2 birds with one stone. It is also being used to bear the load from the purlin (used to help support the roof rafters) struts.

Attachment of the C/J to beam is very common when not carrying a live load. 'Freeze blocking' aka, 'Pressure blocking' is used between the C/J, should be both end nailed and toe-nailed.

There is also a 'Strongback' (the 2x10? w/ the 2x4 nailed into it and the C/J) splitting the C/J span.

 

[ard]

I like the attachment detail which does not include toe nailing.

Caught that... Importantly avoids joist hangers that would then create irregularities that would telegraph through the Sheetrock and create a 'ridge' along the beam.....


If the beam and the ceiling joist are on the same plane, that metal joist hanger 'under' the joist will be 1/16-1/8 BELOW that plane.....

 

[lakeroadster]

So -- that's living space above? I would never do it without a cleat or hangers -- and they are not my first choice due to cost.

.. sometimes no choice. that looks to be using a nail or screw to keep in place

No, this house has a really, really tall roof peak. Like 30 something feet. The guy framing the ridge almost needed an oxygen tank.

Why use a free span truss design... and then not use the open space between the trusses?

If they had used regular trusses then no purlins and no 2 x 6 ceiling joists.

I don't see how that can be cost effective.

 

[The Tool Tyrant]

Why use a free span truss design... and then not use the open space between the trusses?

If they had used regular trusses then no purlins and no 2 x 6 ceiling joists.

I don't see how that can be cost effective.

Not all roof designs are conducive to using trusses. Due to size or complexity, many times it's easier and more cost effective to use conventional roof stacking.

 

[yeldogt]

OK -- not living space. Understand -- just to hold ceiling.

Looks to be wasted space? When I first looked at it --- thought it was a timber frame situation ...... I guess it's just a steep roof.

 

[n20junkie]

I like the attachment detail which does not include toe nailing.

I caught that as well. My father who taught me how to frame despises toe nailing.

 

[wssix99]

It's a creative way to minimize the material needed to make that dunce cap style roof. With the minimal material in that roof, I would hang out with other neighbors if there are tornados in the area...

 

[NUTTSGT]

I'll say this, it's interesting.

 

[Falcon67]

OK -- not living space. Understand -- just to hold ceiling.

Looks to be wasted space? When I first looked at it --- thought it was a timber frame situation ...... I guess it's just a steep roof.

Yes, lots of air up there. All hand framed, no "trusses" involved. Hod more pics of this house build, I might still find some. Were on a previous phone so may be lost.