Envelope Penetration Sealing System

Every service entering or leaving a building makes a hole in something that was continuous. A flue passing through a roof interrupts the covering, the insulation, the vapour control layer and the deck in one movement, and each of those interruptions is a distinct problem with a distinct remedy. What this system does is put each plane back, separately.

The assembly exists rather than a repair because the penetrating element will not hold still. Pipes lengthen and shorten with what they carry, ducts pass on vibration from plant, cable bundles are pulled and rerouted, and structural members deflect under load. A seal formed against a moving object either moves with it or is progressively defeated by it, and a rigid smear of sealant is a temporary illusion.

The nearest neighbouring entry is the rooflight kerb and upstand system, and the pair are separated by asking what the opening was made for. A penetration weathers something that passes through and keeps working afterwards, still carrying water, air or current. A kerb trims the structure to form an aperture that a manufactured unit will later sit on. The observable test is whether the opening was cut for a service or built as a hole in the structure.

Fire-resisting penetration sealing is a regulated determination made against tested systems by qualified professionals. It is named here only so that a reader knows it exists and is a separate subject; no rating, class, product or arrangement for it is given anywhere in this reference. Roof, wall and floor penetrations are gathered on this page, with the roof-specific concerns of falls, ponding and proximity to outlets treated as part of it.

The sleeve and the seal solve different halves of one gap and neither is useful without the other. The sleeve gives the building a clean, stable edge that a bond can hold to; the seal closes the remaining annulus around an object that will not stay still. Sealant applied straight into a rough perforation is being asked to be both at once, and it lets go at whichever edge moves first.

Each interrupted plane needs its own return, and the returns are directional in different ways. A bond to the drainage plane has to be lapped so water passes over it; a bond to the air barrier only has to be unbroken; a bond to the vapour control layer has to be unbroken on a particular side of the insulation. Making one good return and calling the perforation closed leaves the other planes open, and the symptom then appears wherever the open plane mattered rather than at the pipe.

Movement, temperature and future replacement all bear on the same joint. A pipe that lengthens as it warms drags the seal with it, so a rigid seal bonded to both the pipe and the sleeve is loaded on every cycle until it splits, and the split is hidden beneath the collar. That same rigidity is what makes replacement destructive: cutting a bonded service free takes the returned planes with it, which is why how a penetration is expected to be maintained is an input at the start rather than a discovery later.