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Jason Ezell
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New Member
Posts:1
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| 09/11/2000 11:51 PM |
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I've been doing alot of reading about SIP homes and I am very interested.I plan on building a SIP home in the near future,but I have one question that I can't find an answer to so maybe you can answer it for me since you're the pro.What is the difference between polyurethan and EPS SIP's? I have seen a few distributers/manufactures selling the polyurethane panels and both panels had the same warranty.The only thing I can find on polyurethane sips is some R value numbers(the R values are about 10 points higher for the polyurethane than the EPS with the same thickness) and a note on a building prouducts web site saying "stay away from polyurethane sips there bad stuff".He did'nt even explain why they were "bad stuff",so when I came across your site I knew some one here would have to know the pros and cons of both SIP's.
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Steve Andrews
Registered Users
Basic Member
Posts:334
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| 09/18/2000 10:36 PM |
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Jason, normally when I ask some industry pros to help out with a question, they chime in. Not this time. Must be too hot a topic....
In my assessment, both EPS and urethane panels are fine building products, as long as they are made with good quality control and testing during and after the manufacturing process. I wouldn't agree with the negative statement (re urethane panels) you noted from some website.
Some random points for your consideration, regarding the differences:
--EPS panels don't require as sophisticated a manufacturing process as urethane panels and are produced in many more factories (probably by a 10-to-1 ratio).
--Urethane panels provide a huge service temperature buffer when used in roof panels, whereas EPS panels in roof applications can reach up close to their rated service temperatures.
--EPS panels tend to cost a little less, but the market is competitive.
--When properly installed and covered with drywall, both products have shown excellent resistance to fires and natural disasters.
--Your right about the issue but a little off on the numbers: To get the same R-value, you have to use slightly thicker EPS than urethane panels. A 4-inch urethane panel will give you about an R-23 to R-25 wall assembly (depending on the number and type of splines and posts and window/door bucks in the wall), whereas a 6-inch EPS panel will give you about an R-21 to R-23 assembly (based on the same factor).
--The cost increase for thicker jambs for doors and windows in an EPS house tends to somewhat level out the cost difference between the two types of panels.
--I would be comfortable using either product in a home I either specified for others or built for myself. (I happened to use EPS panels in my own SIP home I built last fall; in part, that was a function of geography and working with the factory across town instead of across the country.)
--Manufacturer warranties are more a function of individual companies than they are a function of the types of foam used.
Level of manufacturer's service, type of quality control, cost of panels: these are more significant differences than type of foam.
There are other differences--absolute differences (in the type of foam and its service characteristics) and perceived differences in subtle items. I've written a fair amount about those differences in a 275-page publication "Foam-Core Panels and Building Systems."
I invite the various product manufacturers to add their perspectives. Sorry for the delayed response. I hope that helps.
Steve
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SIPsmart
Registered Users
New Member
Posts:23
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| 10/14/2000 1:02 PM |
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Jason - I recently built my first Urethane panel home after using EPS panels on all other projects. I liked the idea of having the 2x window and door bucks in place when the panels arrived on the job and the increased R values were a bonus for the client. I struggled with getting the electrical plan in finished shape before the production order was signed. There were areas where switch wires needed to go to ceiling fixtures so boxes needed to line up with chases and they are much more difficult to modify in the field.
Because the panels are injected with liquid foam and expand in the panel I had heard that they can have some distortion and bowing in the panels. The ones I received were definitely not as flat as a typical EPS panel. The sag in a couple of roof panels caused problems in connecting them because the splines did not want to engage. Some facia and trim problems developed which involved furring with tapered shims to make them look right.
Urethane panels are more difficult to field modify. Using routers to relieve foam is no fun. There are some rotary relief tools out there but I didn't have one here.
The biggest problem was that the electrical chases are 3/4" blue " smurf " conduit attached to boxes and there is a plug and socket connection between panels for continuous runs. The plugs and sockets missed sometimes. The expanding foam collapsed the conduit in the panel in numerous places preventing wires from being able to be pulled. I had to spend 14 hrs. before the electricians came on the job pushing a fish tape up each conduit until it jammed and then, using a big holesaw cut into the panel and cut out the collapsed section. It was a real headache.
My experience was negative and I will use EPS panels for the forseeable future. No names but this was a national, reputable company's panels.
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