Analysis of the roof layers

In the third step, the roof structure or its condition should be documented and possibly analyzed.

For this purpose, roof openings can be made, preferably in different places. They will provide information on:

the actual construction of the roof,
connections between individual layers (which is important for assessing the stability of the arrangement),
previous or current dampness and water absorption,
the condition of the layers (rotten, wet), waterproofing (stresses, contractions).
Earlier dampness of hard foams (e.g. polystyrene) can be easily recognized by the discoloration caused by washing out substances from bituminous membranes, while soaking in mineral insulation results in a loss of fiber cohesion. Thanks to this, the soaks have quite clear boundaries.

By applying pressure to the roof with your hand or foot, you can tell if water is coming out of it under pressure.

Long-term exposure to water may cause possible softening of the binder and, consequently, loss of toughness.

Roof renovation after prior analysis

Depending on the slope and design, long-term leaks at the lowest points can manifest themselves elsewhere - water may spread over the airtight layer and seep into remote areas.

Sometimes the water lying between the layers can be simply sucked off.

The type and amount of thermal insulation adhesive used, its adhesion to the substrate, adjacent layers and the supporting structure should also be carefully checked.

On older roofs, you can also meet gluing with the use of hot mastic, which - as the excavations made show - usually had a temperature either too low or too high. Both of these conditions are disadvantageous because when the adhesive is too cold, which is manifested by its shiny, smooth surface, it does not have adequate adhesive properties.

When it is too hot, it can melt the top layers of heat-sensitive polystyrene.

But earlier solvent-based adhesives can also damage heat insulation and cause loss of functionality. And let's also mention the workmanship, which both in the past and today may be at least incorrect, inaccurate, i.e. too little binder, inaccurate mixing, etc.

Outcrop in the roof. The insulation is dry, with no signs of mold, but not sufficiently stuck to the substrate

This results in poor fastening of the insulation to the ground, shifting of the roof layers, gaps in the thermal insulation, excessive load on the waterproofing, increased level of condensate in the insulation, gradual loss of functionality through the roof. Just degradation in installments.

That is why it is so important to check the connection between the individual layers of the roof.

When sampling the roof, the importance of information such as the presence and condition of a vapor barrier is often underestimated.

It is extremely important to the physics of the original roof and the new layers.

It is worth paying attention to this, because it is the leaky vapor barrier foil that can cause the presence of moisture in the roof or leaks in internal rooms.

Internal drainage system. The supporting structure requires urgent replacement

Step 4 - End and Joint Analysis
Taking samples from the corrugated end areas of the waterproofing and its connections to other parts of the structure can provide insight into possible thermal bridges. Practice proves that they are often caused intermittently with warming. Gaps with a size of 0.5 to 1 cm may of course not be taken into account, but those 5–15 cm wide do not always indicate inaccurate arrangement, but that they appeared after the boards were laid - it means that they were left behind. poorly adhered to the substrate and shifted.

Check whether the edge profile (often aluminum) is permanently connected to the roof waterproofing, or whether he is sunk into it.

If this is the case, the waterproofing at the joint with the profile often cracks. This is due to the thermal expansion of the metal profile.

If the edge profile is replaced, the condition of the wooden plank underneath should also be checked. Its condition and anchoring to the ground are important for absorbing wind forces acting on the roof edge.

The connection heights should also be noted and compared with those recommended by regulations or guidelines.

Detail on the renovated roof - the connection between the insulation and the door is too low

Particular attention should be paid to doors and their frames, the joints of which with the waterproofing must be of an appropriate height, if no other solutions are provided to prevent water penetration. In these places, I encounter rather experimental solutions that do not work in practice.

It also happens that these details, made as a wall connection, soak up moisture from the plaster and become leaky.

When checking connections with vertical objects, both the connection itself (e.g. for tightness) and the top closure should be checked.

The condition of the object itself is also important, as its cracks mean the possibility of soaking with water, not to mention soaking of fired bricks, facade cladding or ETICS insulation systems.

If in doubt about the condition of e.g. drain pipes, continue with the inspection or contact someone with more experience. I have already encountered cases where pipes placed in a concrete ceiling corroded due to the alkalinity of the concrete.

Detail on the renovated roof - the glued triangular profile will expand under the influence of temperature, the roofing felt will crack

The decision on the choice of given solutions is made by the investor or the owner of the facility. The contractor should, however, provide him with all possible repair options.

Step 5 - condition of adjacent, piercing and connected
objects Moisture in the chimney is caused by the lack of a lining or a cap. Moisture in combination with sulphated deposits can clog the chimney, which manifests itself in brown stains on the walls of the rooms adjacent to the chimney.

At domes, skylights, roof hatches, first of all, it is necessary to check their technical condition (whether they have suffered mechanical damage) and tightness.

In terms of the physics of the structure, it is necessary to find out whether the dome has a single or multi-layer structure and whether its flange is insulated or not.

Breaks between insulation intensify the formation of condensation in the roof.

Bituminous felt paper directly, without separation, passing from the horizontal plane to the vertical wall. Cramps are likely to appear here, papa may slip off. Incorrect mounting. Machining with silicone is not a permanent solution

Roof lightning protection systems are necessary, but the bases of the air terminals are usually in a deplorable condition.

Vibration of motorized vents, blowers, etc. may cause the waterproofing to peel off or damage at the connection with the vibrating element. In such places "vibration compensators" should be designed.

The condition of the roof and its waterproofing is influenced by all objects, parts of the building adjacent to it, even if they are not integrated with it: attics, chimneys, roofs, machine rooms for elevators, etc. Their condition should also be taken into account when assessing the roof. Possible new cladding of these objects may be necessary for the roof renovation to take effect.

The roof after renovation. Plastic, bitumen felt and liquid foil were used on the eaves. But has anyone preceded this with a compatibility analysis?

Step 6 - security assessment.
Roof areas where there is a risk of falling should be secured. If they are not present, e.g. around skylights, they should be included in the renovation project and installed.

Step 7 - documentation of the roof structure
Information on the roof structure is important for the behavior of the layers resting on it. They are also important for the analysis of the building physics of a given layer system.

If the structural substrate is unknown, the pits should extend deeper than the roof layers themselves. If, for example, it is possible that the load-bearing substrate is made of moisture-sensitive materials, e.g. chipboard, combined systems or unprotected metal profiles, their condition should be checked at least visually.