Footing Loads

[John M. Zirzow]

GREAT INFO !!! Thanks for sharing Randy.

[Jeffery L. Haynes]

Still the loads in both cases exceed 2000 psf........ the problem for the most part is soil bearing capacity and/or in NC are the expansive soils we have here.....add to the fact that very few homes are properly drained........the results are foundations cracks etc.

I love stick built roofs....often cheaper and greater versatility.

I am currently building a large custom home with a very complex roof system......LVL's everywhere including the ridges. Will have to pics and post.

[Randy L. Mayo, PE]

Jeffery

That footing load is per linear foot not square foot. If your footing is 2 foot wide then the soil load would be 2000/2 = 1000 psf

[Jeffery L. Haynes]

Im saying that soil bearing capacity is measured at per square foot.
As stated earlier, many times its the soil and improper drainage around same.

If memory serves me, most clay soils are around 2000 psf, sandy gravel around 5000 psf and bedrock over 10,000 psf.

Still with expansive clay soils it becomes problematic.....

Understandable why a simple carpenter told the story about a wise man building his house upon a rock......

[Mark S. Tyson]

Randy,
As always excellent information.
Being in SE Florida and always concerned with uplift can i spin this a different way. Does it stand to reason that the uplift connections at the roof member to the wall would then have too be more substantial for a conventionally framed roof as opposed to a truss framed roof in that the conventionally framed roof member has less down load at the exterior wall?

[Marcel R. Cyr]

http://search.yahoo.com/r/_ylt=A0oG7...onnections.pdf


Although designed primarily to resist roof uplift forces, the hurricane clips increased the peak lateral resistance of the roof-to-wall connections by approximately a factor of two. The unit resistance of specimens that included hurricane clips (configurations 3 and 4) was between 545 lb/joint and 584 lb/joint compared to approximately 280 lb/joint for toe-nailed-only specimens (configurations 1 and 2). Therefore, the hurricane clips can be successfully used to enhance the lateral resistance of conventional roof-to-wall connections. The system with 22 toe-nails and 9 hurricane clips (configuration 3) exhibited lower peak load than the system with 4 toe-nails on end trusses only and 9 hurricane clips (configuration 4). This observation indicates that toe-nails are incompatible with engineered hardware and the addition of toe-nails does not improve the lateral resistance of connections assembled with hurricane clips. The displacement at peak load of 0.6 inches observed for toe-nailed-only connections versus 1.1 inches for connection with hurricane clips further supports the evidence than the two connection types have different stiffness characteristics and achieve capacities at different deformations. Therefore, resistance of toe-nails can not be superimposed with the resistance of hurricane clips.

[Marcel R. Cyr]

http://search.yahoo.com/r/_ylt=A0oG7...douts/B-91.pdf

[Mark S. Tyson]

Originally Posted by mcyr

http://search.yahoo.com/r/_ylt=A0oG7...douts/B-91.pdf

Marcel

Could you add an addendum too your will leaving me your bookmarked technical links

[Marcel R. Cyr]

I thought pages 4-6 would be of help Mark.
In my opinion, the attachment for conventional framing is just as critical if not more than trusses due to the weight of the imposed load is all on the exterior walls vs. that of conventional that bears down on exterior walls as well as interior walls. The weight load on the exterior walls are that much lighter at the exterior and with the overhang, needs just as much tie down for uplift.
That is why the use of H1 or A35's hurricane anchors are still required.
Our sustained winds up here max is only 90 mph, in which I have never seen, so probably no match for your area. But tie downs at the roof to wall juncture is pretty much the same for conventioal or trussess.

Pardon my French.

[Mark S. Tyson]

Marcel,
Here is the most specified attachment down here

roll over images below to see larger image META with TSS
DETAL20
U.S. Patent 7,987,636
HETA20
(HHETA similar) HETAL Typical HETA20
Installation
Typical META Installed with TSS
Typical DETAL
Installation

Straps may be installed straight or wrapped over to achieve listed loads
Typical Installation with two METAs

[Marcel R. Cyr]

Nope, not up here.

[ROBERT V. YOUNG]

Love it.Thanks Mr. Mayo and the rest of you guys.

[Kenton H. Shepard, CMI]

Originally Posted by mtyson

Marcel

Could you add an addendum too your will leaving me your bookmarked technical links

I think it's headed for the Smithsonian.