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RE: New Simpson Holdowns - Recommendations

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From my understanding the new HDU type holdowns should be your first choice in deciding a Simpson holdown.  They look similar to the older PHD holdowns and have similar capacities but they have less deflection (per the catalog).  They are also cheaper for Simpson to make (the way they stamp the steel to form the shape) so that means it should be cheaper to buy.  As for the ‘SDS’ designation they have always been there for the HDU and PHD holdowns.  I don’t think you can install them with anything but Simpson’s own screw (if you want to use the catalog specified capacity).  As for the HD holdowns, I never use them because they are hardier to install properly and their eccentricity with the post is greater.  They are an old holdown that for some reason Simpson still makes.


A warning with the HDU holdowns is that they do not have code approval yet and you may run into problems if the building department you are going through wants one.  I know Simpson backs this holdown and will have a code report soon.  You can also contact your local Simpson rep. and they will do the leg work of working with the building department to get them approved for your project. 


Joseph Goldbronn

Crosby Group

3444 Marconi Avenue

Sacramento, CA 95821

Phone - 916-563-7600

Fax - 916-563-7610

From: Dennis Wish [mailto:dennis.wish(--nospam--at)]
Sent: Monday, January 22, 2007 11:22 AM
To: seaint(--nospam--at)
Subject: New Simpson Holdowns - Recommendations


I have been updating my analysis and design software (including AutoCad ADT 2007) for schedules that including Holdowns. I have noticed many new connectors from Simpson that go beyond the traditional HD’s or Pre-deflected PHD’s. What I don’t see is a cost or availability index on any of their catalog pages. These include HDUx-SDS2.5 series; HHDQxx-SDS2.5 series; PHDx-SDS3 series and HDQx-SDS3 series. Most of these have overlapping capacities and there are differences in connections to studs/posts. I know that most of the builders in the area won’t be familiar with the newer versions and some of these may hold cost savings.

Does anyone have any suggestions or recommendations to limit my choices to availability and economical products?  I’m not interested in their straps that embed in concrete and nail up the face of the panel or framing below. We have a problem in this area of the desert with spalling and heavy mineral corrosion. I’ve yet to see straps installed correctly where they don’t rot out in less than five years. So if you can make a recommendation for the more traditional eccentrically connected Holdowns and threaded anchors through sill plates, I would appreciate your comments