What is this????

[Buck Hartley, CMI]

I have problems with these things I found in a attic today. What do you think of this type of construction?


Thanks! in advance for your input.

[dbelmont]

Pitiful framing to start with.

Looks like undersized rafters could have been bowing. So attempt made to decrease the span. Effectiveness depends in part on what those hacked 2x4's are resting on. Generally better to build such intermediate structures vertically so you don't introduce sideways pressure to the structure unless it is designed to handle that.

If I saw this my comment would definitely be calling for a qualified structural engineer to decide if this setup is adequate to the purpose regardless of how sloppy it looks.

[Jeffrey R. Pope]

It's a standard rafter system (as opposed to a truss system) which would not necessarily warrant a recommendation for a structural engineer.

The framing methods may be sloppy (better referred to as "non-standard"), but they can be addressed by a qualified framing contractor.

What type of roofing material does the residence have? This looks like an attempt to strengthen the framing to support a heavier-than-original roofing material like concrete tile, or perhaps slate. . .

[Buck Hartley, CMI]

Comp shingles are installed. House is four years old.

[Paul Pendley]

House is 4 years old???? Wow do you have licensing requirements for contractors in your area? That work is horrible and probably not sound.

[Jeffery L. Haynes]

Rafter are not necessarily undersized...... I have used 2x6's and spanned over 30 feet.....the trick is knowing where to break your loads down (spans) using purlinswhich is what these "hatchet framers" were trying to do. That is not the way to build purlins though.

If there are a set of stamped plans, a GC could review same to see that framing was done in accordance with the plans as well as correcting some of the shoddy work.

And by the way, you really don't want to brace those rafters vertically.......as long as your within 45 degrees your fine.....in many cases its better. You just have to account for where you are distributing the load from the roof all the way down to the foundation. If its a slab then you should have interior (concrete) girders to catch that load. Sadly, this is indicative that there are other framing issue that may not be seen.


regards

Jeff

[dbelmont]

Unless you know who built the home I stand by my belief that an engineer is the better recommendation in these circumstances. Not that a competent carpenter couldn't fix it. But if they are buying a home they may very well hire the same carpenter with his hatchet. Or hire someone who was trained by that hack.

The rafters can be braced at some angle other then vertical as long as allowance is made for spreading forces. But the goal is to distribute the loads downward. A vertical brace will do this without sideways forces. Of course as long as there is something other then ceiling joists to bear on. Either appropriately sized beams or interior bearing walls that go to ground.

If the current bracing is incorrect or inadequate then the rafter spans are excessive for the size of lumber used. When the bracing is correct and adequate then the span will likely be fine. At least in Kansas. So a real determination as to whether the rafters are adequate for the span is determined by the intended load. I have to remind myself that most areas of the the country don't design for a 70 or 80 pound live load.

Roof purlins (at least in my vocabulary) do not break the span of a rafter. A purlin is typically but not always used with a timber frame roof to create more bearing for sheathing. As such they are applied to the upper side of the rafters not the underside.

[Jeffery L. Haynes]

Purlin do break the span of a rafter otherwise it wouldn't be permitted in the code; they are also utilized for that purpose in many home plans.

"IRC-R802.5.1 Purlins: Installation of purlins to reduce the span of rafters is permitted as shown in Figure R802.5.1. Purlins shall be sized no less than the required size of the rafters that they support. Purlins shall be continuous and shall be supported by 2-inch by 4-inch braces installed to bearing walls at a slope not less than 45degrees from the horizontal. The braces shall be spaced not more than 4feet on center and the unbraced length of braces shall not exceed 8 feet."

More often than not vertical bracing is not possible because the purpose of the bracing is to transfer the load directly to a load point or bearing wall which inturns transfers the load to a load point in the foundation or slab. I have seen framers to vertical bracing over the middle of ceiling joists which is not permitted.

I have had to install microlams over a ceiling to carry the load of a roof but even in those cases the resting point of the microlams were on load bearing walls.
A good framer knows how to account for the loads.

Many modern roof designs are such that it is not feasible or cost effective to have 2x10 common rafters or use I-joist to achieve such spans although I have had to use I-joist for rafters on large cathedral ceilings and such.

Eitherway, I would call the hatchet job out.

[Jeffrey R. Pope]

Originally Posted by dbelmont

Unless you know who built the home I stand by my belief that an engineer is the better recommendation in these circumstances.

That would be like hiring an electrician to change a light bulb. A structural engineer is certainly qualified, but not necessary for this particular task.