Concealed or through-fastened: picking the panel joint
One joint hides its fastener and gives you one finished face. The other shows the screw and gives you two. The wall height and the steel decide which.
Article
Insulated metal panels come with two kinds of side joint, and the choice changes how the wall goes up and what you see when it is done. In the Kingspan line they are the KS42 series and the KS45 series. Here is how we pick between them.
KS42: the concealed fastened joint
The KS42 is the commercial industrial panel and the industry standard for the outside of a metal building. Its offset joint has a small groove on the fastening side. A stainless clip goes in that groove, so it will not corrode.
The installer field drills with a matched bit, which makes a pilot hole through the clip, and runs a screw into the structural steel. The next panel covers it. No screw shows.
These panels go up to 48 feet tall on a 3.5 foot module. They go into clean rooms, food processing and cold storage.
KS45: the through-fastened joint
The KS45 has a stackable joint with two grooves that take a bead of butyl sealant, the vapor seal. The screw goes through the face.
The gain is that either face can be the finish. Flip it over and it still works. A partition can be stainless on both sides, or white on one side and stainless on the other. For a partition inside a plant, or a plant ceiling, Don likes the 45.
The KS42 cannot do that. You are married to its offset joint, and it has one face.
Where the screw has to show
Run an interior partition up past about 30 feet and you need an intermediate girt. With a KS45, that means a screw through the face of the panel at the girt.
If you do not want that screw showing, go with the KS42 and its concealed clip. That is usually how the choice gets made.
Sealing the joint
The long joint can take urethane or silicone caulk. The female joints on the top of the panel get set in a bead of butyl, which stays concealed and gives the wall its vapor barrier.
On architectural panels the factory pre-butyls that edge. We still field caulk it, or tell the crew to, especially in cold weather. When it gets cold, butyl stiffens up and does not move the way it should.
The girts are not a guess
How far a panel spans between girts comes off the manufacturer's load chart and the engineer of record, not a rule of thumb. A freezer wall has ambient on one side and freezer on the other, and that is not always on the chart.
We quoted a freezer wall once, four inch panel, about 34 feet tall. We told the design-build contractor it would not work as a clear span and needed an intermediate girt. It did not go in. In the end the whole wall assembly had to come down lower, and the owner lost pallet positions in a building he paid for at full height.
We will not do a job if we cannot sell it properly. Our name is on it.
Bring us the drawings, the wall heights and the steel. We will tell you which joint fits and where the girts have to be talked about before anything is ordered.
Watch it from the shop floor.
Concealed or through-fastened
How a KS42 panel fastens
The KS45 panel joint
Sealing a stainless panel joint
When the design is wrong
Sources
This piece is our own experience, from the shop and the job site. It cites no outside figure, so there is nothing here to source to anybody else.
Where this applies
- Kingspan panels and freezer floor board.QuadCore KS Shadowline and KS Flat cold storage panels, K-Roc mineral fiber panels and GreenGuard XPS freezer floor board, with Kingspan data sheets and quotes.
- Cold storage panels for coolers, freezers and cold rooms.Kingspan QuadCore insulated panels, 2 to 8 in. thick, foamed in place, R-32 minimum to -20°F, with trim and Jamison doors. Installed by us or material-only.
- Stainless steel FRP, and the stainless wall panel a wash-down room needs.FRP has no steel in it. For a caustic wash-down room, a 304 stainless insulated panel, KS42 or KS45, shown by Don Ross. For the look, a Silversmith architectural panel. Cleveland.
- Insulated metal panels for rooms that hold a temperature.Insulated metal panels 2 to 8 in. thick at about R-8 per inch, fire-rated mineral fiber walls and Kingspan cold storage panels. Installed by us or material-only.
- Food processing wall panels, chosen by the room.Insulated panels for food plant rooms held cold, FRP or UtiLite PVC for wash-down rooms at room temperature. CLEANsafe and stainless faces. Cleveland.