Why this is not a place for poly foam sealant.
Poly foam is an open-cell foam material that comes with various end results - very expansive to minimally expansive. It's used for weatherization, to seal gaps around windows, doors, siding members, various holes or gaps, vents, and even plumbing, electrical junction boxes, and the like. Poly foam is used anywhere air leakage might result. Very good energy efficiency can be achieved cheaply and easily. Some foams are made for fire blocking applications.
The cans look a lot like shaving cream cans, and come with straws to ease installation. These "canned" foams are ideal for small do-it-yourself projects. (Don't get it on your skin!)
However, one thing that happens to poly foam outdoors is UV degradation and discoloration.
It will literally fall apart and turn an ugly, rusty brown.
When used outdoors ( IF YOU READ THE INSTRUCTIONS ON THE CAN!** ) it should be trimmed and painted flat black.
Why black? Because flat black paint is more UV resistant, and protective of the foam.
Around siding penetrations like AC lines, electric service cables and gas lines like you see in the photo, there is a special putty that can be applied to seal the gap. The putty is made for outdoor applications and very UV resistant. This putty will last 15 or 20 years, even in direct sunlight.
The poly foam above was used to seal a gas line, on the sunny side of the house, and this is new construction. The builder apparently felt that this bulging, ugly bubble was an appropriate way to finish this location and present it to the buyer.
My opinion - UGLY at best. And the WRONG material to use in the WRONG place at worst. This stuff is fine to seal the gap from the inside. The perfect sealant actually. But from outside this location could be made to look a lot more professional. And this is the west side of the house, so the foam bubble will deteriorate rapidly.
My recommendation: sometimes the small and simple can be wrong and ugly. Not much more can be said about what you see in the photo. But this is a very expensive house, and to pass this gas line off as finished, professional and proper is over the top. It is an unthinking and unprofessional application. Well, 'nuff said.
** But that would require actually reading the instructions...
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560