Roof tiles on truss structure

[lfoster]

The weight of these roof tiles brings up another question.

This is the first time I have seen the tiles installed on a 2x4 truss roof system, 24" oc with OSB decking. In the past it has been stick construction, 2x8's, 2x10's or 2x12's.

This is an upscale builder, $300k+ range. The houses under construction in the area looked the same (same builder). Not in city limits, no city inspectors.

Is it standard to use the 2x4 truss method?

Thanks for the help,
Linda

[Bruce Thompson]

I'm not going to be much help to you, but I wouldn't say it's standard. In my area, tile roofs are just now becoming common place on the higher-end homes and I've only done one. I posted here several months back b/c of the tile roof/weight question (I had a wall bowing too). Didn't get much response though.

I figure the guys in California, Florida and Arizona have more experience in this than do I.

Where is Utopia?

Bruce

[gbeaumont]

Hi Linda,

The acceptability or not of 2 x 4 trusses to support the weight of a tile roof is an engineering call, as this is new construction I would check the original architects plans to ensure that the roof was designed for those loads, it is not beyond reason that the roof design was for shingles and that tiles were installed as an upgrade.

BTW, down here in FL we commonly see tiled roofs employing 2x4 trusses, the real issue is the truss engineered loads.

Regards

Gerry

[Jeffrey R. Pope]

Truss spacing is determined by the engineer. It would be uncommon to see 24" spacing under a concrete roof in CA because of our seismic zone, but it may be sufficient in other parts of the country.

edit - I see Gerry beat me to the punch. . .

[lfoster]

All feedback is welcome.

The whole neighborhood is roof tiles, not just an upgrade from shingles.

I'm sure it has been engineered from the beginning, just doesn't look strong enough to me. Of course, I tend to overbuild if it's at my house. Make it look really 'butch' (to quote a friend).

BTW, Utopia is about 80 miles west of San Antonio, in the Hill Country. Bandera, Garner State Park, etc.

Thanks fellas.
Linda

[Christopher Currins]

Linda this is a quote from a site I found a few weeks ago. Like Gerry said it should be described in the plans.

Colorado Roofing Association

"Most building departments require a stamped letter from a structural engineer
that confirms that the roof framing will support the additional weight, with or without reinforcement. Typically any new roofing material with an installed weight over 7 pounds per square foot (psf) will require this certification. Since light weight (7 psf) products are not prevalent in Colorado, a maximum installed weight of 11 psf is typically used."

http://www.crownjade.com/id9.html

[Brian E. Kelly]

This mornings tile roof truss pics.

[lfoster]

Got another question, then. Do you ask to look at the engineering papers, or include it in the report for the client to follow up?

[Larry D. Kage]

Originally Posted by lfoster

Got another question, then. Do you ask to look at the engineering papers, or include it in the report for the client to follow up?

It would be in my report for the client to verify.

[Brian E. Kelly]

Originally Posted by lfoster

Got another question, then. Do you ask to look at the engineering papers, or include it in the report for the client to follow up?

If the whole neighborhood is like this then it looks ok to me.

[Richard A. Hetzel]

The fact that trusses are made of 2x4's has nothing to do with their load-carrying ability. It's all about first, the span of the trusses, and their spacing, and then the design of the trusses themselves. If it's like most projects, the architect will have required engineering calculations by the truss manufacturer, and they may or may not be filed with the building department. Good departments will require them, so they may be public records.

Although I'm not an inspector myself, I don't believe that actual verification of the truss adequacy is the responsiblity of the inspector. I agree with others, that the inspector should raise the question, and suggest that the owner or prospective buyer verify that the trusses were in fact designed for the actual dead load of the tiles.

[Brian E. Kelly]

Should the buyer also verify the foundation design????????????

[Richard A. Hetzel]

As an architect, one only does that foundation calculation once. Normal foundations are so overdesigned that a few pounds of roof tile will not be noticed. Most typical house foundations could easily take another floor or two. That's why we can add whole stories to a house without modifying the foundation.

[Barry Adair]

Unless the builder/owner is willing to furnish the documents/information on-site during the inspection I just quote TREC.

This report is intended to provide you with information concerning the condition of the property at the time of inspection. Please read the report carefully. If any item is unclear, you should request the inspector to provide clarification. It is recommended that you obtain as much history as is available concerning this property. This historical information may include copies of any seller’s disclosures previous inspections or engineering reports, reports performed for or by relocation companies, municipal inspection departments, lenders, insurers, and appraisers. You should attempt to determine whether repairs, renovation, remodeling, additions, or other such activities have taken place at this property. Property conditions change with time and use.