| Author |
Message |
Jeff Williams RA
Senior Member
Username: architectjw
Post Number: 27
Registered: 10-2013
| | Posted on Monday, August 07, 2017 - 01:05 pm: |    |
On a single-ply roof, is high density wood fiber a good cover board over polyiso?
Thanks,
Jeff |
David G. Axt, CCS, CSI ,SCIP
Senior Member
Username: david_axt
Post Number: 1590
Registered: 03-2002
| | Posted on Monday, August 07, 2017 - 01:09 pm: | |
On single-ply roofs (PVC, TPO, KEE, EPDM) I always specify primed coated moisture-resistant gypsum board (Georgia-Pacific DensDeck Prime).
David G. Axt, CCS, CSI, SCIP
Specifications Consultant
Axt Consulting LLC |
Jeff Williams RA
Senior Member
Username: architectjw
Post Number: 28
Registered: 10-2013
| | Posted on Monday, August 07, 2017 - 01:54 pm: | |
I am comfortable with moisture-resistant gypsum board and Glass Mat sheathing. Glass mat and Fiberboard are listed as a acceptable choices in a spec that I am reviewing. I don't recall any roof manufactures promoting fiberboard and I have no experience with it. I was just wondering if there is a reason not to use it. |
Ronald J. Ray, RA, CCS, CCCA, CSI, AIA
Senior Member
Username: rjray
Post Number: 161
Registered: 04-2004
| | Posted on Monday, August 07, 2017 - 02:31 pm: | |
Jeff, high density wood fiber board is generally an acceptable product for cover boards. Many would consider it near the bottom of the list of cover board materials, with ASTM C1177 and ASTM C1278 gypsum board a better choice. Another option is high density (80 psi) polyisocyanurate insulation. |
Jeff Williams RA
Senior Member
Username: architectjw
Post Number: 29
Registered: 10-2013
| | Posted on Monday, August 07, 2017 - 03:18 pm: | |
Thank you for the information. |
J. Peter Jordan
Senior Member
Username: jpjordan
Post Number: 985
Registered: 05-2004
| | Posted on Monday, August 07, 2017 - 04:14 pm: | |
I am making my clients aware of the high-density polyiso products. There are several manufacturers offering boards with 100 - 110 psi compressive strength (not density) and one that offers a 1/4-inch thick product with a 140 psi compressive strength.
Incidentally, there were some studies done in the early 2000s that indicated using a coverboard improved the hail-resistance of single-ply roofing products. The manufacturers that I talk to currently are unanimous in supporting this.
J. Peter Jordan, FCSI, AIA, CCS, LEED AP, SCIP
|
Steven Bruneel, AIA, CSI-CDT, LEED-AP, EDAC
Senior Member
Username: redseca2
Post Number: 593
Registered: 12-2006
| | Posted on Monday, August 07, 2017 - 05:18 pm: | |
To circle the wagons, Firestone markets a hail resistant poly-iso roof insulation, "HailGard" that consists of polyiso with a glass reinforced mat facer on one side and 7/16-inch OSB on the other side. |
David J. Wyatt, CDT
Senior Member
Username: david_j_wyatt_cdt
Post Number: 206
Registered: 03-2011
| | Posted on Monday, August 07, 2017 - 05:27 pm: | |
Good call, Peter Jordan. Had to switch to this product to overcome a supply chain problem with other types of polyiso composites. The 100-110 psi iso cover board appears to live up to the marketing claims. |
4specs.com Home Page