Monday, December 20, 2010

Relocating Hold Down Anchors

Here is a common issue that can arise in the placement of hold down anchors.  In this picture, two cast in place anchors interfered with the installation of the hold down anchors.  The easiest fix from the Framer's perspective is to move the hold down to the nearest stud for a clean installation.  This presents several items that the Engineer needs to consider prior to approving this change. 
  • As you can see in the picture, the fasteners provided with the anchor are too long for one stud.  Hold down anchor manufacturers generally require an attachment to a minimum of two studs.  Additional studs may be required to meet the manufacturer's specifications.
  • If the hold down anchor is relocated away from the edge of the panel, does the shear wall diaphragm boundary element change? The tension load needs to be transferred into the stud pack with the hold down anchor.  I recommend requiring the specified edge nailing be used to fasten the sheathing to the new stud pack at the relocated hold down anchor.  
  • By relocating the hold down anchor, the length of the shear wall changes.  This may be critical in a high wind or seismic area.  The design of the shear wall should be verified based on the field changes.
Merry Christmas and Happy New Year. 

Monday, December 6, 2010

At First Glance

One of the things I quickly learned in the field is that not everything is what it appears to be.  Whether it is an epoxied anchor bolt that you can pull out by hand or a hurricane clip wedged between two pieces of wood with no nails, the closer you get to see and touch the structure the more confident you will be with your field observation.  The girder truss in the above picture looks to be properly supported.  A stud pack below the truss and hurricane clips on each side of the truss are standard fare in a region with a low wind design speed.   If I stood across the room and looked up at this condition, I would feel satisfied.  Walking further into the structure, however, I saw that the stud pack may not be adequate.   Have a look at the picture below.  

When observing the framing in apartment complexes or housing units, the framing quickly becomes redundant.  Continuing to walk through each room in each unit is still important to not miss the problem conditions that exist isolated to specific units.   

Thursday, November 18, 2010

Beat to Fit - Part Deux

On this episode of "Beat to Fit, Paint to Match", we have this dandy plate washer that was bent to allow the sheetrock to be attached to the wall.  The stud wall in question consists of 2x4's at 16.  The plate washer, if I remember correctly, is 2"x2".  You can see that the problem is the location of the anchor bolt, which barely fits behind the edge of the sill plate.  For a 3 1/2" wide sill plate, there is a tight tolerance for locating the anchor and placing a 2" plate washer.  Had this been a 3" plate washer, there would be a 1/4" tolerance each way from the center of the plate.  

I have to ask, at what point would it be better to use post-installed anchors instead of cast-in-place?  From conversations with two different Contractors, a Titen HD is about twice the material cost of an L-bolt.  For a job with 50+ housing units, that would be a substantial impact on the overall cost.  In my opinion, labor savings may cover the cost difference, especially when bolts and/or studs have to be replaced when they align with each other (see previous posts).  If the framing crew is working on contract, and not by the hour, then the labor savings may not be seen by the owner.     

Friday, November 5, 2010

Beat to Fit

I woke up last Monday morning in a hotel in Mississippi.  It was one of those almost cool, humid Southern mornings with an overcast sky and the promise of rain.  I was excited to get to the job site and get to work.  My excitement was more about getting finished so I could make it home to my first Preparing for Parenthood Class than it was for being on-site.  I do enjoy being on-site, but for that day it was trumped by thoughts of the arrival of my first child.  Anyway, I should at least say that I was pleasantly suprised by the framing conditions I found.  I am not that pessimistic, but problems often arise in wood framing construction. 

I was on my 20th, and last, house when I discovered the beauty below.  I can understand the need to cut a stud because the anchor bolt is in a bad position.  I have seen that happen many times now.  This may be the first case where someone decided to beat the stud into submission rather than use a power saw.  Maybe it was early in the morning and this guy was full of extra energy.  Maybe he was just wielding his authority with his all-mighty hammer.  Maybe the wiley ole-timer did this and had the panel set in place before the young thinker could get the saw out of the tool box.  I just could not help being reminded of the old saying "Beat to fit, paint to match."  

Wednesday, October 27, 2010

Plumber versus Window Jamb - Take #2

Here for Take #2 of the Sawzall Massacre*, someone did a fine job carving up another window jamb.  Reminds me of the Dim Mak scene from Jean Claude Van Damme's Bloodsport:  
Official: "Cut stud with saw"
Sawzall Frank: "Okay, which stud?"
Official: "The two in the middle!"

I have to wonder if the window manufacturer counted on the frame to transfer the load from the header into the single remaining stud below.  Maybe this will not affect the opening and closing of the window in the future. 

*The Sawzall Massacre has been filmed live at a jobsite near you. 

Tuesday, October 19, 2010

Plumber versus Window Jamb

It is amazing what someone can do with a reciprocating saw.  Here you can see where someone cut the studs of a prefabricated wall panel to fit around the pipe cast in the slab.  Three support studs were cut to allow the pipe to stay in its location.  This is not good.  Thankfully, for a small opening and a one story structure, the single stud would probably never fail.  That was before the plumber decided to core the 3 1/2" studs with a 2 1/2" hole saw.  Let's just hope this opening was reinforced before it was covered with sheet rock.  It is usually best to review the framing AFTER the rough plumbing installation.