| Author |
Message |
(Unregistered Guest)
Unregistered guest
| | Posted on Monday, December 07, 2009 - 05:02 pm: |    |
We have a contractor asking to install the un-insulated precast prior to the interior backup (which is either CMU, or a stud wall with sheathing). I can see no long-term "up side" for this: at the very least, how is exterior airbarrier and flashing installed? (the CMU is to be parged, and an airblock fabric is to be installed on the sheathing).
I have used insulated tilt-up, but only for warehouses and non-institutional buildings. I have never had un-insulated tilt-up installed before the backup wall.
Has anyone had experience with this? |
Tim Werbstein, AIA, CSI, CCS
Senior Member
Username: tim_werbstein
Post Number: 18
Registered: 09-2006
| | Posted on Tuesday, December 08, 2009 - 07:45 am: | |
I had a similar request once. When asked the questions you raised, the contractor withdrew the request. I believe the request was driven by the precaster, with no serious review by the General Contractor. |
John Bunzick, CCS, CCCA, LEED AP
Senior Member
Username: bunzick
Post Number: 1143
Registered: 03-2002
| | Posted on Tuesday, December 08, 2009 - 10:51 am: | |
Are these large precast panels? We have done this, installing foamed-in-place urethane insulation to the back of the precast. Since it performs as an air barrier (it has been tested), so no separate product is needed. It allowed simple access to the connections to structure. In our case, we had cold-formed framing backup, with no blanket insulation. |
Steven Bruneel, AIA, CSI-CDT, LEED-AP
Senior Member
Username: redseca2
Post Number: 211
Registered: 12-2006
| | Posted on Wednesday, December 09, 2009 - 01:29 pm: | |
In large cities where zero setback sidewalls are the norm, Contractors often develop a great deal of skill in "blind side" construction techniques. |
Wayne Yancey
Senior Member
Username: wayne_yancey
Post Number: 291
Registered: 01-2008
| | Posted on Wednesday, December 09, 2009 - 01:54 pm: | |
Further to Steven's comment, applicators are able to control the application rate at the nozzle in blind side locations to ensure they apply the correct amount for the R-value required.
I have seen this performed successfully on past projects.
However, subsequently Seattle DPD has tightened up their approval to use SPF in Type I and II construction. No longer permitted until such time as an ICC Evaluation Report is provided for the product, which has not happened to date as far as I know. At least not the Dow SPF.
Other jurisdictions may not be so restrictive. |
(Unregistered Guest)
Unregistered guest
| | Posted on Friday, December 11, 2009 - 10:00 am: | |
Why do you want to involve yourself with the "means-and-methods"? |
Ellis C. Whitby, AIA, PE, CSI, LEEDŽ AP
Senior Member
Username: ecwhitby
Post Number: 59
Registered: 03-2003
| | Posted on Friday, December 11, 2009 - 11:53 am: | |
I started this thread, and forgot to log-in when I did: hence the "Unregistered guest". Sorry.
I don't think that I am getting involved in "means and methods", so much as assuring myself that:
1) the Contractor understands the design intent, and the necessary performance requirements; and
2) that the "means and methods" the contractor proposes can meet the project requirements.
It appears that the contractor may not pursue this issue in any case. |
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