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Re: MBR Tie-Down System

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What's the answer I wonder?

Thor Tandy  P. Eng
Victoria  BC

Subject: RE: MBR Tie-Down System


>Thor,
>You are correct that even holdowns that anchor floor to floor will loosen 
>from shrinkage because floor joists will experience much more shrinkage 
>than the vertical stud portion because of wood grain direction.
>
>I agree that TJM products shrink less than sawn lumber, but depending on 
>the environment, swelling will occur between when the TJM's are produced 
>and when it makes it to the job site (especially stored outside in a moist 
>environment!).  So over time, shrinkage will occur and holdowns will surely 
>loosen again.
>Subject: RE: MBR Tie-Down System
>
>
>>Ron,
>>I've seen a building in the Seattle area which is a five story condominium 
>>that suffered extensive exterior wall water intrusion because of some
>>flashing and sealing issues around the windows.  When the General
>>Contractor opened up some shear walls, he found the holdowns were loose.
>> The threaded rods were pretty much sloppy in the stud bays.
>
>
>The problem occurs even if you anchor floor by floor.  I have usually 
>specified that the anchors be tightened regularly during construction (I 
>never specifiy full buildng height anchor rods because of shrinkage) with a 
>final turn and nut-locking immediately before closure.  By that time (often 
>a number of months) I estimate less than 1% remaining shrinkage.  Over the 
>depth of a floor (10" +/-) I figure the amount of slack will be minimal? 
> With TJM products there is almost no shrinkage.
>
>Thor Tandy