SIP Builder's Blog | Foard Panel - Part 3 Blog – Page 3 – Foard Panel

First Parish Church of Stow and Acton

Foard Panel worked in the cold of this past January to put on the SIP roof of the First Parish Church. There is a great video of the process of building the new church. Foard Panel Worked with Murray Brothers Construction to complete the process.

We also have a few of our own Pictures of the Process.

Siding and Roofing Details

Hilltop 140402_16Most of Foard Panel’s experience and customer base is in the northeast. The best practices outlined here are based on a combination of our experience and our best understanding of building science. Since our geographical range of experience is regional, these recommendations should be taken as guidelines and only applied in areas with roughly similar climate and weather.

We’ve learned that some amount of liquid water will get everywhere in any building’s envelope/weather-protection assembly. The sources of water vary from extreme wind driven rain, imperfections in flashing details, and many other sources. (We’ve seen cases where there was liquid water behind the synthetic building-wrap high up on a gable wall, above all ROs, and under an overhang with no sign of air exfiltration.)
Wet wooden sheathing dominantly dries toward outside. In conventional/pre-IECC construction, there is plenty of air movement within stud bays and through sheathing to encourage the water to move from the sheathing to the outdoors. Additionally, low- and moderate-performance buildings have a meaningful amount of heat heat loss, from inside-to-outside, during the winter. this provides energy to evaporate the liquid water in the sheathing into a vapor, allowing it to pass through vapor-open building-wraps easily.

The Conventional Building Wraps Do NOT work with High Performance Systems Like SIPs.

When the envelope is much higher performance, like SIPs, the “drying dynamics” change dramatically. SIPs have no stud-bays nor in-wall or in-roof caveties so there there is no air circulation to help the drying process. Also, the huge reduction in thermal bridging and full-thickness “continuous insulation” integral to SIP envelopes reduces the heat flow (BTU/sqft/hr) through the wall/roof assembly. This removes most of the energy required to evaporate water in or near the sheathing, rendering “liquid-tight/vapor-open” membranes much more likely to retain water within wood components.
For these reasons, Foard recommends traditional #15 or #30 tar paper over any synthetic building-wraps or roofing underlayments. We have evaluated the properties of each house wrap and roofing underlayment suggested by our customers. Comparing these properties with our on-site investigations and other evidence, we expect the best of the synthetic building-wraps may approach the protection and durability provided to wood-based/low-heat-loss envelopes by tar paper.stowe rotton panel 021
We’ve yet to document a tar paper covered SIP envelope with a building-wrap-driven durability problem. On the other hand, we get a tragically high number of calls and emails each year from owners of synthetic/hydrophobic building-wrapped buildings, SIP or otherwise.
From our analysis of all of the site visit information and consultations with well respected building science engineers, we’ve been able to amass the following list of recommendations:
• All sheathing eventually gets wet. Encouraging it to dry rapidly is the key to durability.
• Liquid water can reach the sheathing either from the outside or the inside, but outdoor water penetration is most common by far.
• Liquid water management is at least as important as water vapor management.
• To reduce wetting the sheathing from the inside, the most effective air- and vapor-control layers must be on the warm side of the envelope. Everything to the cold side of these retarders should be of increasing permeance.
• To reduce wetting the sheathing from the outside, use the most proven and durable flashing details, use “rain-screen” siding and vented or “cold” roof designs, reduce water concentration as much as possible, and understand that large overhangs are cheap insurance.
• Use house wrap and roofing underlayments that allow water vapor AND liquid water to slowly pass through.
• Provide a 1/4” or greater vent-space/capillary-break between the roofing or siding and the sheathing. This is among the most effective durability enhancements we’ve found. Capillary breaks can be made with strapping or furring strips or with a super-porous mesh product like Home Slicker or Cedar Breather.

The following picture illustrates an example of the long term effects of hydrophobic roof underlayments direclty applied to the exterior sheathing. The roof on this 18 year old house was covered with Grace Ice & Water Shield, a material that is hydrophobic and has a maximum permeance rating of 0.05. The permeability rating of SIPs is about 0.2. rotten panel
Because of the difference in partial pressure of water vapor between indoors and outside, water vapor always diffuses outward during New England winters. The “peel & stick” membrane stopped the outward diffusion of water vapor and, being on the cold-side of the assembly, condensed into liqued water at the wood sheathing. This diffusion rate ws slow but, over time, the moisture content of the wood rose to the level where it supported fungal growth. The water had no ability to migrate anywhere else so it stayed in wood sheathing and rotted it. The rate of water accumulation is relatively slow as it is limited by the cumulative permeance of the envelope assembly interior of the Ice & Water Shield.

The following is a list of siding and roofing layups that have proven to be among the most durable:
Clapboard siding:
SIP, #15 tar paper, 1×4 or 2×4 vertical strapping, clapboard -or-
SIP, #15 tar paper, Home Slicker, clapboard.
Traditional shingle, shake, or vertical board & batten or ship-lap:
SIP, #15 tar paper, 1×4 or 2×4 horizontal strapping, shingle -or-
SIP, #15 tar paper, Home Slicker, shingle.
Stucco, brick, stone, or fake-stone veneer siding:
SIP, #15 tar paper, 2×4 strapping/furring, PT plywood or fiber-cement panel, masonry finish, functioning top and bottom vents.
Asphalt shingle roofing:
SIP, #30 tar paper, 1×4 or 2×4 strapping/furring, T&G sheathing, any roof underlayment, asphalt shingles
Standing seam metal roofing:
SIP, tar paper, standing seam metal roofing -or-
SIP, tar paper, standing seam metal roofing w/ vertical spacers between each seam to create a vent space
Wood shingle roofing:
SIP, tar paper, Cedar Breather, wood shingles -or-
SIP, tar paper, horizontal wood furring strips, wood shingles
Pre-formed, ribbed metal roofing panels:
SIP, tar paper, steel roofing panels
For other siding and roofing types, please contact your Foard Panel project manager or Foard Panel engineering.

Our Current Project at Hilltop Montessori School is now being sided. They are using our recommended layup for clapboard siding. Here are some pictures of SIPs with #30 Tar Paper, Homeslicker and Clapboards.

Hilltop Montessori Barn

One of our big winter projects. Our part of the work is nearing completion so we did a round of inspections to make sure we are building to our own high standards and make a list of the details left to tighten up.

How to Choose Your Core

Beginning in the 3rd quarter of 2012, Foard Panel expaned from two to four different foam core materials. Our original core foams, EPS and XPS, will continue with no changes. We added polyiso (PIR) & Neopor (NEO) cores.
This bulletin provides guidance to help specify the core best suited to your project.
Structural and thermal examples are listed to help illustrate the differences between cores under differing conditions. To ease comparison to other technical information, this document complies with federal regulations1 and SIPA guidelines2. Consult the Foard Panel Data Sheet for the panel of interest to find more details.


Pro: Structural properties – EPS is the most mature, most heavily tested, and best documented of all core materials. Only EPS-core SIPs have IBC/IRC-level code listings in the US.
Pro: Very high R-Value per dollar ratio.
Pro: Easiest core to work – Edge rout with panel routers, hot wires, & foam-scoops.
Con: Moderate R-value per inch, about the same as most conventional infill insulation.


Pro: Structural properties – XPS has the highest shear, tensile, and compressive strength of all cores.
Pro: High R-Value per inch ratio.
Pro: Easy to work – Edge rout with panel routers, hot wires, & foam-scoops.
Pro: Available in 6 specific thicknesses.
Con: Lowest R-value per dollar ratio.

Polyiso3 (Urethane3)

Pro: Highest R-Value per inch ratio.
Pro: Very high R-value per dollar ratio.
Con: Structural properties – Polyiso and Urethane have the lowest structural properties of all available core materials, based on all available test data. For this reason, Foard Panel doesn’t recommended polyiso or urethane SIPs transverse load conditions.


Pro: Structural properties – Similar properties to EPS. Foard is qualifying Neopor for the exising EPS code listing.
Pro: Higher R-value per inch than EPS.
Pro: Just as easy to work as EPS – Edge rout with panel routers, hot wires, & foam-scoops.

Core Type EPS XPS Polyiso (PIR) Neopo (NEO)
Max roof span for 8.25” SIP 80 lb/sqft load @ L/240 11 ft 14 ft 4 ft 11 ft
Max pressure for 4.5” SIP wall 8' vertical span L/240 52lb/ft2 75lb/ft2 30lb/ft2 52lb/ft2
6.5” SIP whole-surface R-value R-23 R-30 R-35 R-26
SIP Thickness required to meet R-494 ceiling spec. in IECC code 10.25" 8.25" 6.5" 8.25"
Available SIP Thicknesses Any Thickness 3"-25" 3.0 4.5 6.5 8.25 10.25 112.25 3.0 4.5 6.5 8.25 10.25 12.25 Any Thickness 3'-25"
R-Value Range Min. R-10 R-12 R-14 R-11
R-Value Range Max. R-93 R-58 R-70 R-110

Contact & Technical Support

If you have any questions about any of these items, please feel free to contact me or any one of the Foard Panel project managers.
Paul Malko
Technical Director
Selecting SIP cores pdf

1 US Code of Federal Regulations Title 16, Part 460
2 Structural Insulated Panel Association, Published R-Value Guidelines,
3 Polyiso is a nickname for polyisocyanurate foam and urethane is a nickname for polyurethane foam. Polyiso and urethane foam of the same density have basically the same thermal and structural properties, according to chemistry suppliers that serve the SIP industry. For more information see Foard Panel Technical Bulletin “Why Polyiso/Urethane SIPs are Non-Structural”.
4 The IECC-2009 assumes light wood frame & infill style construction and allows other building systems with equivalent performance of a light wood frame & infill assembly with the stated R-value of insulation in the cavity. The reason SIPs can use much lower R-values and still meet this requirement is because the IECC assumes that a large portion of it’s surface area as thermal bridges where SIPs do not. See Foard Panel Technical Bulletin “SIPs and the IECC”

Haystack Baselodge

Foard Panel Inc. has been working all this cold and snowy winter to help create the new base lodge for the Hermitage club. The luxurious timber framed base lodge will be completely wrapped in Foard Panel SIPs.
Here are some recent pictures taken during our inspection on March 24th

Here is a photo from the Live Web Camera on March 21st 2014

Click on the Picture to see the current action!

Here is a Photo From The live camera on site at the Haystack Base lodge March 28th 2014

The Hermitage Club’s new Ski Area has been in the news recently

Here is the recent story of the new exclusive ski area.

WCAX.COM Local Vermont News, Weather and Sports-

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