A home's airtightness layer may be installed properly in the factory, but water supply, drainage or another service is passed through it later. Every opening must then be completed again as part of the particular building element. The fact that a hole is visibly filled with material does not yet prove a suitable, durable connection. The check is needed when pipes are in position but the details are still accessible for repair.
It is important to distinguish two concepts from the start. A building airtightness test checks the envelope's properties under defined conditions. A water supply pressure test checks pipework leak-tightness according to its procedure. One does not replace the other: a watertight pipe can pass through a leaky opening, while an airtight envelope does not confirm the quality of the water connection.
First locate the airtight-layer line
The drawing must make clear which layer provides airtightness and how it continues through floor and wall junctions. The decorative board in a modular home is not always that layer. The actual design detail must therefore be sealed, not just the visible hole from the room side. Otherwise, attractive finishes may conceal an airflow route that remains.
DOE educational material emphasises that pipe openings often remain hidden beneath baths, inside cabinets and in structural voids. This explains why checking before final covering is worthwhile. Repairing a small detail later may require removing a disproportionate amount of finish, even though the opening itself was fully accessible during installation.
One opening may serve several requirements
A detail may fulfil air, moisture, vapour, water or other design requirements. One product does not automatically perform all of them. For example, an airtight sealing collar is not automatic evidence of bathroom waterproofing or fulfilment of a fire safety requirement. It must be clear for which location and purpose the product is intended and with which surface it is compatible.
It is therefore worth listing the openings before work and identifying the applicable detail for each. Pipe movement, temperature changes and penetrations through several layers must be assessed. A rigid filler chosen spontaneously will not always accommodate the detail's behaviour. The decision is based on the instructions for the particular system, not just the material's name.
Match sealing products to the pipe
Diameter, surface, substrate condition and installation conditions matter. The Pro clima ROFLEX documentation classifies collars according to pipe dimensions and specifies their sealing purpose. This is a practical example of why randomly taping an opening is not equivalent to a properly assembled detail.
If other products are used, their documentation must be checked. Do not transfer one manufacturer's compatibility promise to another product's tape or sealant. The pipe material must also be protected from incompatible products. Where chemistry or surface preparation is doubtful, it is better to seek advice before installation than later investigate why the material is not adhering in a concealed location.
Document preparation for testing
The specialist conducting the test determines the applicable method and building preparation according to the brief. It is necessary to record what is closed, sealed or left operating during the test. Temporarily closing an intended opening during the procedure is not the same as permanently completing its detail for operation. That distinction must remain clear in the report.
It is worth the owner obtaining a pipe-penetration list before the test. This helps check whether a newly made opening has gone unnoticed behind equipment. If work remains unfinished, the limits of the result must be clear. An interim search for air leaks can be very useful, but must not be presented as automatic confirmation of every final certification condition.
How should an air leak be understood?
During the test, specialists choose suitable detection tools and establish the airflow route. Its visible exit must be distinguished from the actual cause. Air may move through a structural void and emerge further away from the faulty connection. Applying filler only to the surface where movement is felt does not always complete the required layer.
Mark the defect on the plan and in a photograph, stating the agreed repair. After correction, check the result using the applicable method. A photograph of new tape after the work and an assumption that the problem is solved are insufficient. The aim is restored performance of the detail, not merely a visually hidden opening or the removal of a temporary draught sensation beside the finish.
Example: a drainage stack in a cupboard corner
Suppose a new stack is installed after delivery, making a larger opening through the airtight layer in the floor. The finisher later covers the location with a cabinet. If the check is carried out before furniture is installed, the detail remains accessible and its sealing can be completed clearly. If the check waits until occupation, furniture and equipment will obstruct access.
A good work sequence at this location is an agreed opening, a suitable pipe and envelope detail, a photograph, an interim check and only then covering. This is not a specific installation recipe, but a clear control sequence. It distinguishes what the module manufacturer did, what the installer did on site and who confirmed the final condition.
What should the owner receive?
If some details are concealed already
Provide the photographs available and state what was covered and when. A specialist will decide which diagnostics remain useful and whether a particular location needs opening up. The suitability of an entire hidden detail cannot be confirmed from its remaining visible edge. The report must distinguish the checked section from an assumption. This boundary matters even if the overall test number looks good: the result must not be expanded into a guarantee of unassessed material compatibility or construction durability.
Keep the test report, preparation description, list of repaired locations and photographs of final details. Add information on the sealing products used. If new holes are drilled after the test, this must be reported and the need for another check assessed. The earlier result is not a guarantee for every later alteration.
Read about pipework in the water and heating pipe article. Also remember planned ventilation: airtightness is not a reason to leave a home without planned air exchange. Properly completed penetrations allow the building to be controlled according to the design, rather than depend on accidental gaps.
Information sources
You can read the explanation without leaving this page. The original document opens only when you choose its link.