Would really like some advice here on putting a (villa/bungalow) right next to the sea (even over the water). External finish would be wood - like current construction methods here use. I guess this would be similar to log cabins that I have seen offered by some SIP companies. I was wondering about salt corrosion/rotting. Here, I am sure that moisture would get to the OSB and it would eventually rot. So can I still do SIP? What about SIP with fiber cement boards? Can I even attach wood cladding to that without water proofing/structural issues? I want the SIP to be structural also for the roof. I have seen SIP with external wood panel side, but the connections between panels dont look good. Please advise.

Posted By qna on 24 Feb 2011 06:37 AM
Would really like some advice here on putting a (villa/bungalow) right next to the sea (even over the water). External finish would be wood - like current construction methods here use. I guess this would be similar to log cabins that I have seen offered by some SIP companies. I was wondering about salt corrosion/rotting. Here, I am sure that moisture would get to the OSB and it would eventually rot. So can I still do SIP? What about SIP with fiber cement boards? Can I even attach wood cladding to that without water proofing/structural issues? I want the SIP to be structural also for the roof. I have seen SIP with external wood panel side, but the connections between panels dont look good. Please advise.

qna;

aluminum, painted galvalume and painted G-90 galvanized, stainless steel skins are also available and used often in coastal  salt evironments. Skins can also be coated with plastisol to prevent corrosion in all types of harsh environments
 
SIP wall/roof connections are engineered and tested, they can be designed to far exceed category 5 winds

Posted By cmkavala on 24 Feb 2011 07:14 AM

qna;

aluminum, painted galvalume and painted G-90 galvanized, stainless steel skins are also available and used often in coastal  salt evironments. Skins can also be coated with plastisol to prevent corrosion in all types of harsh environments
 
SIP wall/roof connections are engineered and tested, they can be designed to far exceed category 5 winds

Can I fix wood directly to this type of panel? Also, here even galvanized steel rusts. I assume thats when there is a scratch in the surface of it. So I would have thought that when we attach the wood panels as external cladding, this would create points in the galvanized steel which would rust. I would be reluctant to do that for that reason. I think the fibre cement (or something else rot and rust proof) would work, as long as I could easily put external wood paneling on the exterior wall.

If the osb sip panels would have problems in your area with what you want to do so would everyone else using an osb product in your area. Have you had an opportunity to talk with some panel companies about your concerns? Although most of them would love to sale you product most of the ones on this forum will tell you the truth. Please don't misunderstand, I am not trying to diminish your question or concerns but why are under the impression you would have a problem? When I built my sip house this forum had a different name but I see some post from the same people that helped me.  Good luck on the project, Sam 

Metal SIPs can still be used in an extreme marine environment with a wood siding finish. I would install a self healing self adhering bituminous roll underlayment over the metal panel prior to the installation of the siding. This would seal around the holes the screws for the siding would make and prevent wind driven sea water from corroding those points. I would also use needle point screws instead of drill point screws because they rip their way through the metal instead of cutting their way through thus mostly preserving the galvanization of the sheet metal SIP skin at that point. As for the metal panels themselves they in most cases wont rust because the base metal is high grade galvanized then primed then painted with a high durability exterior coating. All of these layers make it unlikely for the panel to rust with normal weathering. In my experience with metal building it is the fasteners that corrode before anything else. Make sure you upgrade to stainless steel fasteners.

Thanks. I will look into that idea with the galvanized SIP. I didnt know about the coating option, but that sounds do-able. I am still wondering about the fiber cement SIP (drilling into that to put up the wood exterior). So if anyone can answer that, I would greatly appreciate it.

qna;

fibercement has poor screw pull-out values for siding application, stucco works better over fibercement

If you don't mind using screws to put on the siding it will work but if you get to close to the edge of a panel it will crack. The fibercement panel is much like the siding you can buy from the big box stores under the name hardi plank and hardi panel. I did my on test in attaching various materials with different fasteners to  the  hadipanel and was not happy with the results.  You may  consider the fibercement panels with the exterior panel having the texture finish. Several panel companies do offer that. It looks like reverse board and batten or you can choose stucco.

I would consider SCIPs - basically a concrete/foam+steel/concrete SIP except that it is made in place. As long as the steel is galvanized and covered by the concrete, it should hold up well in a marine environment.

would it be reasonable to use pressure treated plywood for the exterior skins?

Posted By geruta on 31 Mar 2011 06:43 PM
would it be reasonable to use pressure treated plywood for the exterior skins?

I think PT ply is limited in size 4 x 8 ,   it would be tough to laminate  - extremely wet when first treated, warps but when dried out and has shrinkage issues