Structural insulated panels (SIP’s)

[Cancertomnpdx]

Has anyone purchased in Costa Rica or imported SIPs into the country for use in building their new home? I am interested in the concept of the panels in home construction, but they might be over kill for my mountain lot in Palomo, Cartago.

Any thoughts or ideas?

Thanks,
Tom in Portland, Oregon

[gzeniou]

We finished building a solar house in NC about a year and a half ago. We used the standard “Green” SIP’s 4 inch. They have a true R value (unlike stick build) of 24, roof of 6 inches gives a true R value of 40. IMHO….SIPS are an over kill in CR and an unnecessary expense, the climate just isn’t that extreme to get the benefit. Concrete block would do the trick, Perhaps the only think I would go with is Double pane windows if anything and better quality sliders. The construction grade windows and sliders down here are poor quality in my view, pay a little extra and upgrade. Solar Hot Water would also be a savings in a few short years.

Windows:

Single Pane: R .85
Double Pane: R 2.0
Double pane with Argon gas R 2.7-3.5

I assume you will have a lot of windows to maximize CR views. This is why I would go with upgrading windows.

Just for fun:

stick build home R factors:

2 x4 R-13 (however this it not true R-13 as there are thermal breaks along the studs)

2 x 6 untrue R-19

Concrete Block, low R value but it heats and cools very slowly (probably because of the high mass), perhaps that is why its used in Florida. I have seen studies that have shown there is a little sayings if you insulate the concrete block, In one study in Miami it had a payback time of 30 years. Of course Miami is typically much hotter then CR, thus your payback time would even be longer in CR.
http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/94/940311.html

[DavidCMurray]

Designing a house to be built with SIPs wouldn’t be difficult, and the panels themselves could readily be transported in a forty-foot shipping container. A twenty-foot container might do. Container costs would be a minimal part of a building project. Customs duties might be an obstacle, however.

But I have my doubts . . .

First, I’m skeptical that the oriented strand board or plywood skins on the panels would stand up to the humidity and insects here.

Second, I wonder how you would finish the interiors. Drywall walls are not typical here, and common drywall, at least, is also subject to degradation from excess humidity.

Third, who would you get to assemble and finish this house? When we researched building with SIPs on the Outer Banks of North Carolina early this decade, the builders there all took one giant step backward when the matter of the SIPs came up. You need a knowledgeable crew to build with panels and I’m skeptical that you could find that crew here. When building, it’s better not to be a pioneer.

Fourth, as stated immediately above, I think SIPs’ insulative value may be an overkill unless you live in a very, very hot climate where the cost of air conditioning will eat you up. Clearly, the energy you save is the least expensive, but the additional cost of the SIPS, transporting them, erecting the structure and finishing it may not be justified by the energy savings.

Fifth, you would have to be certain that the design of the house would meet Costa Rica’s earthquake-resistant building code or you could not get a permit. There’s no doubt that SIPs will stand up to hurricanes, as we learned, but earthquakes may be a different matter altogether. On the Outer Banks, we had to go through a lengthy process of educating the local building department before they would even consider letting us use SIPs. Are you prepared to undertake that project in a language (maybe Spanish, likely “engineering”) you don’t speak?

Sixth, your planning would have to be spot-on perfect with regard to the additional parts and materials you would need. The special adhesives and screws needed to secure the panels and the structural lumber used in the joints are not likely to be found here at any price. All those things would have to be imported, too.

And finally, it’s my understanding that Costa Rican Customs is extremely picky about the importation of wood products. They require documentary proof that the wood does not come from virgin or threatened sources. Proving that for the OSB, 2 x 4s, etc could be a bureaucratic nightmare.

I think the advice above to stick to block construction is good. The local builders know the technology and it’s proven reliable for many years. In the right situation, SIPs offer a very attractive alternative, but I don’t think this is the right situation.

One final note: The recommendation above to install a solar hot water heating system is excellent. We’ve had them on our houses since 1980 and wouldn’t build again without one.

[gzeniou]

David does bring up a lot of good points but I would also like to shed more light on SIPs. I am not a SIP Expert but I can answer a lot of these questions having build with them.

First….The OSB is sealed with a house Wrap, Good quality OSB stands up much greater then regular Ply wood in high humidity. If done correctly, no need to worry about high humidity. SIPS in nature have less issues with insects, fungus etc.

Second….You don’t need to use drywall, There are other finishes including tongue-and-groove clad panels which are really nice. If you are doing a Timber Frame house, this gives it a nice feel. We used it for the entire ceiling which connected direct to the SIP. It is of course more expensive then drywall.

Third….This is a good point but it’s not very difficult to build with it, but I wouldn’t want someone doing it unless I really trusted them or had previous experience with it.

Fourth….Yes SIP’s would be very expensive in CR, typically the material and manufacturing is very expensive but in the states you make up a lot of the cost in savings in labor, this is not the case in Costa Rica with labor being hugely less compared to the states.

Fifth….SIPS are considered Earthquake resistant, The structural characteristics of SIPs are similar to that of a steel I-Beam. In Japan several SIP buildings went through a 7.2 earthquake, they were basically the only buildings that were left intact.

I could have sworn last year that I heard of a builder or supplier in CR that was doing SIPs but just don’t remember who it was.

In the states I would not build with anything but SIPS (insulation, strength value). Of course because of the tightness of construction with SIPS, you will need an ERV to bring in fresh air from the outside. In CR again it just doesn’t make sense to me, It would be just so costly for insulation you really don’t need. With all the windows that most people put into their CR house, it really doesn’t make sense as you lose a lot of the R value from the windows that you would gain from the SIPS. It’s all in the windows….LOL

[Cancertomnpdx]

Thanks for the feedback, I appreciate the feedback. I can see how SIPs might be overkill in Costa Rica, just thought I would ask for thoughts on the idea.

Again thanks,
Tom in Portland, Oregon

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