In TDC, TDF and Ductmate fittings there’s usually an open gap of remaining V Notch in between where the duct is joined with the corner.
This gap needs to be sealed, otherwise it can become a point of leakage when TDC, TDF or Ductmate is used as the transverse joint connection. The Duct Shop is typically tasked with sealing off this gap during assembly of the fittings so that the field crew receives a fully sealed product.
There are different methods each shop has for patching this opening; these are some of them:
Brushing Duct Sealant over the Gap:
Many shops use Duct Sealant with bucket and brush.
Loop more Butyl Gasketing to press down into the Gap:
Other shops loop extra Butyl Gasketing into the gap.
Butyl Corner Patches:
Ductmate’s 2″ x 2″ Corner Patches of 3/16″ Butyl Gasket can make it such that the shop can avoid having to determine how much product to loop for excess and it’s cleaner looking.
Pressure Sensitive Rolled Mastic Tape:
One emerging trend in Duct Shops is to use 2″ Mastic Tape .The ease of tearing off short pcs of this Mastic Tape and putting on both sides of the fitting’s gap makes the job faster , provides an immediate seal with Zero VOCs and meets pressures Classes all the way to 10″ WG.
It’s been used for years in residential jobs and has a growing use in the Spray Foam encapsulation market . It’s 2″ or 3″ wide and Looks like Red Letter Alum Foil Tape. But this Mastic Tape has a backside of Butyl adhesive once the strippable film is peeled off.
