I don't know if it's common or uncommon, but installing a layer of rigid foam above your roof sheathing in order to interrupt thermal bridging is always a good idea, and is preferable in all respects to a roof assembly without any rigid foam above the sheathing. If you decide to install rigid foam above the roof sheathing, you shouldn't use closed-cell spray foam under the sheathing; either use open-cell spray foam (which is vapor-permeable) or a fluffy insulation like cellulose, mineral wool, or fiberglass (any of which will allow the roof sheathing to dry to the interior).
Most flat roofs are not perfectly sloped, causing water to puddle in some areas, in particular around the drains and scuppers. Many roof coatings are not rated or warranted for "ponding water", and thus might fail pre-maturely if exposed to standing water over long periods of time. Serious consideration should be given to the performance and limitations of the coating being selected. Some manufacturers will warranty their coatings including ponding water. Typically, manufacturers for acrylic roof coatings do not include warranties for ponding water, while some polyurethane and silicone roof coatings manufacturers will.
Water-based acrylic coatings have more than 30 years of proven performance over a wide range of substrates. It is the coating of choice for metal roofs since it is highly reflective, can be easily tinted and is not extremely slippery when damp. When used with our rust primer, even rusted roofs can be saved. TIP: If you have a metal roof or a low slope roof that doesn't pond water, consider acrylic coatings. https://www.youtube.com/attribution_link?a=ggLAUsiuI_o&u=watch?v=XXXXXX&feature=share
Although spray polyurethane foam has many advantages over other types of insulation, spray foam installation isn’t foolproof. Some builders have reported problems with sloppy foam insulation. For example, some installers have been known to begin spraying before the chemical components are up to temperature, which can affect component mixing and foam performance. When components are poorly mixed, or mixed in the wrong ratio or at the wrong temperature, cured foam has been known to shrink away from rafters or studs, leaving cracks. Some installers rush through their spraying, resulting in voids.
Porch urns are an excellent way to add seasonal curbside flair. However, tall items such as twigs, birch stems or even pumpkins can sway in the breeze and make a mess of your carefully planned decor. To prevent things from shifting, place your items in the container and spray around them with expanding foam to create a comfy nest that will keep your urns looking great. Place a layer of moss, hay or greenery on top to finish the look.
Spray Foam Under Mobile Home
The local foam installer that I used here in Hilton Head told me he looked for some peeling back of the foam. This was ensuring that it was at the perfect temperature which helped them maximize their yield (profit). I have open cell foam and it pulled away a little, and did so immediately (within minutes). They went back after they were done to any spots that pulled away too much and filled them with the touch up kit; they were looking for the top edge to roll just a little bit.
This tropic heat actually is the cause that the steel structure, which most roofs in that part of the world are built on, expands and contracts all the time. By doing so, the sun-battered steel structure causes the roof tiles to dislodge and slowly creates small openings between the roof tiles, through which rain water can run into, creating leaks that can cause much damage to plastered ceilings and electric wiring. https://youtube.com/watch?v=ggLAUsiuI_o
In the case you have above the installer wasn't reading his foam. They must be trained to do that as they spray. Temps and conditions are constantly changing thru out the day. Either he wasn't properly trained or if he was,he wasn't doing his job! This is a serious problem with people jumping in to the foam business. A lot of homeowners and builders are looking the best price and end up with someone who doesn't know what they are doing. Hope this info helps. Foam insulation is a great product. It just has to be done right by someone who knows what they are doing.
Spray Foam House
Thoroughly clean the roof surface. Roofs collect oils from asphalt, chimneys, and cars plus lots of dirt and dust. Coatings don’t stick well to any of these. We recommend cleaning with an inexpensive solution of TSP or TSP Substitute in a bucket of water (follow label instructions). Use a broom to scrub ponding areas and areas of peeling coatings. Work a section at a time and hose off the dirty water. Sweep away puddles to promote drying. Do not allow wash water to dry on walls, furniture, windows, and visible surfaces.