Replies

1. 
   BossHog | Oct 24, 2002 02:47pm | #1

   I think "hurricane clips" are a good idea. Every lumberyard I've been in keeps them on hand. But that could vary from one region to the next.

   Unfortunately, they're virtually NEVER installed correctly. Just nailing them to the inside of the top plates isn't enough. What keeps those top plates on? Mostly just a few nails driven into the end grain of the studs.

   Installing the clips on the OUTSIDE, where the nails go through the exterior sheathing (Assuming it's plywood or OSB) will at least hold them down to the walls.

   But what holds the walls down?

   People forget how fast you did a job, but they remember how well you did it.

1. 
   Nails | Oct 24, 2002 07:27pm | #4

   Boss "but what holds the walls down" 10 yrs ago I used to run the sheeting on the exterior all the way down and fasten to the foundation plate/mud sill and make sure the foundation bolts were 4ft o.c. and the only reason that I can think of for not doing it today is because nobody else is ...........really dunb reason huh?

1. 
   BossHog | Oct 24, 2002 08:11pm | #5

   Don't know why more people don't take that seriously. Wish they did.

   I guess - Like you said - If "We've always done it that way" it must be O.K.The answer, my friend, is blowin' in the wind. -- Peter, Paul, and Mary

2. 
   TimGoins | Oct 24, 2002 10:55pm | #6

   So it is alright to nail them through my sheathing? (OSB) On the out side. I would not have to aks this question if I did'nt jump the gun and put my sheathing up. So either side of the wall is O. K. ? In my case it is the out side of the wall. Thanks Hat  

1. 
   BossHog | Oct 24, 2002 11:17pm | #7

   My opinion is that they go on the OUTSIDE of the wall. That way the OSB that's nailed on the walls helps hold them down.

   On the inside, the OSB doesn't really have much effect. The top plates can pull loose from the studs and twist fairly easily. Headline: Suicidal twin kills sister by mistake

2. 
   Catskinner | Oct 24, 2002 03:45pm | #2

   Taking Boss's well-substantiated observations under advisement, you might check out the Simpson H-2. This clip goes from the truss, around the top plate, and onto the stud.

   This is NOT the H-2.5 (the little single-twist clip that hooks to the top plate).

   You didn't say who told you you could do either or both. If clips are not required by code in your area because of low anticipated wind speeds, you're probably OK on the rest of the connections.

   However, Boss's comments on uplift resistance throughout the structure are worth keeping in mind -- it's just as important as load path.

   DRC

1. 
   BossHog | Oct 24, 2002 04:30pm | #3

   Dave, you're right about the H2 clips - I really like them. The only drawback is that they require that the trusses line up with the studs.

   Her's some info from the Simpson website, and it shows both the H2 and the H2.5:

   http://www.strongtie.com/products/Connectors_List/H_1.htmlThe brain is a wonderful organ; it starts working the moment you get up in the morning, and does not stop until you get to work.

1. 
   Catskinner | Oct 25, 2002 05:17am | #8

   Thanks for the link, Boss. I never noticed that H8 before. I might have to give that one a try.

   On the subject of what holds the rest of the wall together, I've been using construction adhesive under the bottom plate, and between the decking and floor joists. I figure if that lets go, we're really in trouble.

   DRC

1. 
   RalphWicklund | Oct 25, 2002 07:41am | #9

   Without having the benefit of having an engineer required to calculate uplift for you and proscribe a fastening system I think you should take another look at the components of your structure and how they work together.

   When you bolt the bottom plate through to the foundation you can be pretty sure it's not going to fly off in the next wind storm but then you start adding some vertical sticks with two 16's in the end grain at the top and bottom and you've changed the formula. I'll bet any one of you could grab hold of a stud in a stick wall (no sheathing yet), lift straight up and pull it and a couple of its neighbors right off those two 16's. So, when the wind comes along and grabs the roof overhang and lifts, those hurricane clips (H2.5, etc.) get to hold the trusses (rafters) to the top plates and take it right off the 2 16"s in the end grain of each stud. Ignoring the effect of the sheathing for now, you can see that the weak points are the end grain connections to the top and bottom of the studs.

   In the really windy areas (also seismic) the sheathing alone is not allowed to take on the whole task of keeping the structure together, although the sheathing and nailing patterns contribute heavily. Additional tiedowns, whether simply a length of perforated strap extending several inches both down from the top plates and up from the bottom on every or alternate studs or lengths of all-thread with nuts and large washers extending from foundation embedment through the top plates are used to ensure that the studs do not separate from the top and bottom plates. Think of the 2 16's in the end of each stud as just an alignment tool to raise the structure until you get to the serious business of keeping it all together.

   In many parts of the country there is no wind <G>, hence no added steel requirements. The sheathing alone now becomes the means to hold the top and bottom plates together. Unless, of course, an inadequate, two nails per panel policy is used. Sheathing, without added tie downs, is completely suitable for the job as long as the panel, or panels, are truly nailed off to the top plates and the bottom (and/or the rim joists for those not building on slabs). There's more to the process than the above but it's a place to start.

   Get a Simpson catalog as a start for information on available fasteners. Even if you can build with no or minimal oversight (what building department?) you can only benefit if you have the means. The catalog is free and so is the CD. Online you can download a copy of NER-272 (National Evaluation Service, Inc), an evaluation report covering fasteners and alternatives. For instance, the building code you follow specifies 8d common nails, 2 1/2" long, but you have boxes of 8d, 2 3/8", .113 gun nails or something else. This report, 43 page long, shows the substitute values.

1. 
   BossHog | Oct 25, 2002 02:10pm | #11

   ".......when the wind comes along and grabs the roof overhang and lifts........"

   That's not actually what lifts the roof up. The wind passing over the roof makes it act like a big airplane wing. People say crazy stuff during sex. One time I called this girl mom.

2. 
   BKCBUILDER | Oct 26, 2002 01:01am | #15

   Couple of problems from here in Ohio.

    1) trusses don't line up with studs, because the walls are framed 16 oc and the  trusses are   24 oc.

   2) if you are using precuts in 8' ceilings and you run the plywood all the way to the sill, your top plates are held to the studs by a piece of plywood 12" wide, or your sill to bottom plate is, either that or you are wasting one he77 of alot of plywood.And 9' plywood is to freaking expensive either way, plus most houses I've been doing have 9' ceilings, so it hoots either way.( I hate running the sheathing to the sill plate)

   3)  most foundation to sill connections use straps, which are only bonded between the 4" or 8" block and the brick band, either way, they are for looks, cause I could pull one out with a hammer. Bolts aren't much better, since they only make it into the core of the first block. That plus, I've never seen a house sitting in the road anyway, and even if it was picked off the foundation and set down easy, would you really want it back anyway?

3. 
   BossHog | Oct 26, 2002 02:08am | #17

   "trusses don't line up with studs, because the walls are framed 16 oc and the trusses are 24 oc."

   True - But every other truss could hit a stud. You don't need to tie each one down to do a lot of good.

   On ther plywood thingy - You can either use straps to hold everything together, or tie it together with the plywood. Either one could work.

   "most foundation to sill connections use straps, which are only bonded between the 4" or 8" block and the brick band"

   Virtually ALL foundations around here are poured. (Guess it's regional) If yours are block, they should probably be tied together well enough to resist uplift forces. Never seen one, so I don't know how they could do it.The sex was so good that even the neighbors had a cigarette.

4. 
   FrankB89 | Oct 26, 2002 04:02am | #19

   "...virtually ALL foundations around here are poured..."

   Same around here, although block foundations are not uncommon (OK, not ALL are poured).  But block foundations here are required to be built with vertical rebars on, at least, 4' centers and horizontal bond bars tied to the verticals every 4th course and ALL the cells filled with concrete.  Part of that has to do with being in a zone 4 seismic zone and part of it has to do with being able to install solidly imbeded J-bolts as is done with a poured foundation.  I've always felt that block walls are inherently weaker than a poured foundation, but, properly done, they have a good track record.

   Personally, I prefer to just pour a solid concrete foundation, but I have done some with block at customer's request (Common on additions, where it's necessary to match, say, a split-faced block foundation to the existing for appearance purposes).  Actually, costwise, it's about a push, but block foundations require a few more steps and more time than building forms so they can kind of slow a project down a little IMO.  However, a block foundation or wall constructed by a skilled mason is usually dead-on square. plumb and level to work from.

   Since I'm rambling on on a side-track to the original thread,  I've noticed several comments that referred to sheathing issues.  Some time back there was a thread that got into whether to install sheathing verticall or horizontally and, eventually it was determined that either way is correct depending on what forces are to be resisted by the sheathing.

   In my area, it's almost always installed horizontally (the strength axis of sheathing is along its length) to resist horizontal wind shear.  But the other advantage of horizontal application is that it makes it a lot easier to tie the entire wall structure together from mudsill to top plate, using 4X8 sheets and off-setting the courses.

    

   Edited 10/25/2002 9:32:42 PM ET by Notchman

5. 
   xMikeSmith | Oct 27, 2002 02:35am | #21

   we're now working with the UBC code and a lot of what you are talking about is covered in that..

   but one thing to keep in mind.. the plywood sheathing CAN tie the entire wall assembly from the bolted sill to the top plate.. just lay out your sheathing to make it so.. wether you do the horizontal sheathing or the preferred vertical.. you can still get the tie strength ..

    once you  have tied the wall, then you can tie the truss to the wall.. either inside ...or outMike Smith   Rhode Island : Design / Build / Repair / Restore

6. 
   FrankB89 | Oct 27, 2002 05:36am | #22

   I agree.  I was just making a long-winded response mostly to some commentary by those who didn't run their sheathing all the way to the mudsill.  That seems a little odd to me, but DW accuses me of having halfheimers disease and so maybe I'm missing something.   

3. 
   FrankB89 | Oct 25, 2002 08:29am | #10

   Ralph Wickland has it right.  If I remember right, you're in the S.F. Bay area and I would think you're in the class 4 seismic area which prescribes specific structural guidelines, at least with foundation reinforcement and structural tiedown to foundation.  This should have been flagged out on your approved permit planset if it wasn't on the submitted drawings.

   And Boss Hog has it right on the hurricane clips being to the outside;  think about it...the closer to the ends of the trusses that they're secured, the less purchase the wind can have on them.  And if your studs are on layout with your trusses, you're in great shape for grabbing solid wood.  If not, and you're worried about it, you can nail in some blocking between the studs up next to the plates to catch the hangar nails, but for that to be totally effective you'll want to nail in the blocking through the studs to overcome the endgrain  nailed weakness Ralph and others described.

   And nailing sheathing from the mudsill up is pretty much standard practice around here.  Actually, we (me, anyway) usually hold the lower edge of the  first course of sheathing about 1/2" below the bottom of the mudsill to cover that seam between the concrete and the mudsill  (check the discussion in the thread on "sill sealer").

    

1. 
   BossHog | Oct 25, 2002 02:10pm | #12

   ".....the closer to the ends of the trusses that they're secured, the less purchase the wind can have on them."

   Not sure why that would have anything to do with it...........You can do it anyway you want to as long as you do it my way first.

1. 
   UncleDunc | Oct 26, 2002 12:34am | #14

   >> Not sure why that would have anything to do with it.

   It shortens the lever arm the uplift force has to work with. The effect is probably negligible, certainly less than the advantage of getting the roof firmly connected to the sheathing.

   >> I called a girl Mom once.

   Snork. Got a source on this one? I'd like to read more of his stuff.

1. 
   BossHog | Oct 26, 2002 02:03am | #16

   "It shortens the lever arm the uplift force has to work with."

   Not really. The truss is picked up like an airplane wing - It's not just the overhang picking it up. The mind is never blank. If it were, how would you know?

1. 
   DLightbourn | Oct 26, 2002 02:19am | #18

   Boss, I have always installed H2.5 type hangers diagonally opposite each other on a 2x member ie/ L inside, R outside.  This reduces the chance of the wood splitting.

   Just as an aside, it can be very difficult to find 8d x 1½" nails around here, I have seen 4d nails used on countless jobs :-(

4. 
   booch | Oct 25, 2002 04:42pm | #13

   The Hurricane clips as well as bolts to the foundation are required in all new house plans. My 80+ year old building inspector in northern Wisconsin even thinks they are a good idea.

   Further you need to review the stress panels on your prints. Normally the corners of the building are built into a torsion box by having a rigid nailing schedule with OSB or plywood secured to the sill plate and all the framing up to the roofline. It isn't just code, it makes sense. The rigidity this provides is awesome. Get a simpson catalog from a lumber supplier and sit down with it for a few nights. It'll keep one out of the bars and I felt more comfortable with the design afterward. Simpson has hundreds of options many of which you can put on before or after sheathing.

   PS. Stay away from staples for securing sheathing. A couple of years ago FHB reviewed some new Florida home construction techniques after a big hurricane and found the staples acted like perforations on roof sheathing.

   
   

   ---

   Edited 10/25/2002 4:53:22 PM ET by Booch

5. 
   FramerJay | Oct 26, 2002 10:52pm | #20

   Dear Hat:

   I am assuming you have trusses that are 24" OC and studs that are 16" OC. In that case, only every third truss will fall directly over a stud, which precludes using simple "clips". Here in Alabama we use a similar system of construction, and our hurricane tie requirements are met by using a 16"-24" strap nailed into the truss (or rafter), the top plates, and the studs. We strap every rafter, as this reduces the load on any individual strap (versus the every 4' idea proposed by some). Whether you nail them on the outside or inside is not nearly as important as is that you nail into the studs, in addition to the top plates. If you do chose to nail them on the outside, again, ensure you're not just nailing into the sheathing; 1/2" plywood/OSB has very little withdrawal resistance on its own. And as far as nailing sheathing is concerned, nails and staples are both approved here; my crew uses 1 1/2" 1/2" crown staples and we've found through experience that stapled sheathing is much harder to dislodge than is nailed sheathing.

1. 
   BossHog | Oct 27, 2002 01:29pm | #23

   "....every third truss will fall directly over a stud........"

   Actually, every second truss will land over every third stud. And that's only if they're laid off from the same point. There's a hole lot to see at the Grand Canyon.