One seller says that a factory-made module is always more airtight. Another insists that only a masonry home is truly reliable because its walls are heavy. Both claims are too broad. Airtightness depends on the planned layer, its junctions, openings and workmanship. The construction's name does not show whether all these locations have actually been completed and checked. A modular home can be more airtight than a masonry one, but this must be confirmed by data for the particular property.
It is more useful for the buyer to compare not advertising adjectives, but what is included in the proposal and how the result will be checked. This text is specifically about comparing proposals. We do not declare one construction type the winner or assign invented general airtightness scores to different materials.
Airtightness is not insulation thickness
Insulation material and the airtightness layer may perform different functions. Thick insulation does not in itself confirm that air cannot leak through junctions or openings. Equally, low air leakage does not describe all heat losses: the envelope's properties, windows and ventilation matter. These indicators must not be combined into one unexplained list of advertising features.
If a proposal focuses heavily on wall thickness, ask for the airtightness solution to be shown separately. Where is its continuous line? How does it connect to the floor, roof and windows? Which details are used for services? A clear section and junction details say more than one large number in centimetres or the general term 'energy efficient'.
Factory advantages have limits
Controlled production conditions can help repeat recurring details consistently. However, the home will still be transported, assembled and connected to external services. Module joints and site work will follow. The quality of the factory process therefore does not replace a check of the final property. It is necessary to know what was assessed before dispatch and what was assessed after assembly.
For example, testing one module does not cover a water inlet opening made later on site or the joint between two modules. That result can be useful, but its scope must be described correctly. The buyer should receive clear responsibility for the completed home, not several unrelated promises, each ending where another contractor's work begins.
Masonry junctions also need work
The mass of masonry does not eliminate openings around pipes, electrical penetrations or other junctions. Plaster or another specified layer must be continuous and coordinated with the rest of the envelope. Locations behind equipment and in inaccessible voids are not automatically airtight because the surrounding wall is called masonry. This is checked against the particular solution.
The DOE explanation of pipe penetrations draws attention to hidden airflow routes in various building constructions. The principle is common: the opening and its completion matter, not just the wall's label. This source's general recommendations are not Lithuanian certification rules, but help explain the physical nature of the problem.
Pipework can change either home's result
Water supply, drainage and ventilation pass through the envelope, so their installation must be coordinated with the airtightness plan. An opening must be in the correct location and completed with compatible materials. If the system is altered after testing, the earlier result does not describe every new penetration. The documents must remain clear about which version was checked.
The pro clima gasket overview shows products for particular pipe openings and dimensions. This is one example of a technical solution, not an instruction to use the same brand everywhere. Assess actual compatibility and the installation instructions. A proposal including openings alone and one including their completion as well do not have equivalent work scopes.
How should two testing proposals be compared?
Check at which stage the home will be tested, by what method and who will provide the report. An interim search for air leaks and a final assessment may have different objectives. It also matters who will repair defects found and pay for the necessary repeat check. These conditions must be clear before the contract, not only on the day of an unsuccessful result.
When comparing numbers, their definitions and measurement conditions must match. Do not simply copy the lower number from an advertisement into your selection table. If the units, test-pressure condition or version of the property assessed are not given, ask for the report. An actual document allows you to check whether the number is suitable for direct comparison at all.
Contractor questions in one table
| Question | Why both construction types need it |
|---|---|
| What forms the airtight layer? | To establish the continuous envelope line |
| Who completes pipe openings? | To avoid a responsibility gap |
| What changes after transport or installation? | To avoid treating an earlier test as final |
| Who repairs identified leakage? | So the outcome is more than report delivery |
| Which documents reach the owner? | So later changes can be verified |
The purpose of these questions is not to complicate purchasing, but to make proposals comparable. If one contractor provides the whole route to a verified result and another only an undefined structural supply, their prices cannot be assessed as the same service. The missing scope will still have to be provided later.
Airtight homes still need ventilation
It is worth including coordination of later service work in the contract too. If additional equipment is installed after handover, the owner must know where the airtightness layer is and whom to inform about a new opening. The initial good result will then be protected as the home's use changes.
The aim of airtightness is not to leave the resident without air. A planned and properly operated ventilation system is needed. Random gaps are not a reliable replacement, because their behaviour depends on weather conditions and they do not allow the airflow route to be controlled. Read more in the heat-recovery ventilation and fresh-air guide.
When choosing a modular or masonry home, ask for the design, work boundaries and evidence of the final test. The construction type will then remain one factor in the choice, rather than an unfounded airtightness guarantee. A good home is recognised by coordinated and checked details, not by one appealing-sounding wall name.
Information sources
You can read the explanation without leaving this page. The original document opens only when you choose its link.