Polyglass Sheet Membranes

MEMBRANE WATERPROOFING:

1. What are membrane waterproofing products?

Membranes can be in the form of a liquid, a sheet or even an admixture. Bitumen is the most well known waterproofing material applied as a sheet, liquid, hot-roll or bog. A waterproof membrane needs to be a continual seamless barrier across the area. Fortecon or builders plastic is not considered waterproof.

2. Where can membrane products be used?

Membranes are designed to waterproof bathrooms, roofing, foundations, practically anywhere in construction. The choice of membrane is crucial, choosing the wrong membrane can be detrimental to your project. For example, bitumen-based products are suitable for external areas but not for internal areas such as bathrooms. For further information and recommendations, please contact our office.

 

A. Slated membrane maintenance

Self-protecting slated mineral membranes are often chosen for visible waterproofing in order to avoid painting maintenance. These membranes, apart from ensuring water tightness thanks to the layer of mineral slate on their surface, are not subjected to UV rays and therefore the bitumous mass does not suffer.

The granules are usually made with flakes of natural slate therefore a slight chromatic difference can be seen due to the nature of the product. The quantity of slate applied is approximately 1kg per m² and an initial granule loss at the beginning of a project is perfectly normal, normally there is a tolerance of up to 15%, which occurs because not all the slate flakes manage to penetrate the bitumous mass during production.

1. What can appear on slate surfaces?

Immediately after the laying the membranes, especially in very hot weather, oily marks can appear on slate surfaces due to the natural bitumen mass migration. Such marks usually disappear after rainfall which effectively washes the surface. If these marks should persist it is possible to wash the surface with a medium pressure hose, taking care to avoid aiming the water at the end laps (to avoid accidental peeling). However it should be remembered these marks do not affect the product’s efficiency in any way.

2. What is it necessary to periodically check for on the membrane surface?

Immediately after the laying the membranes, especially in very hot weather, oily marks can appear on slate surfaces due to the natural bitumen mass migration. Such marks usually disappear after rainfall which effectively washes the surface. If these marks should persist it is possible to wash the surface with a medium pressure hose, taking care to avoid aiming the water at the end laps (to avoid accidental peeling). However it should be remembered these marks do not affect the product’s efficiency in any way.

3. What is it necessary to periodically check for on an unfinished granule covering?

In the case of an unfinished granule covering it is necessary to periodically check the overlap seal, particularly in the most stressed parts (corners or expansion joints of the building). Over a period of time some overlaps may come unstuck for various reasons; for example a small amount of water may not cause immediate seepage but could, due to overnight frost, cause eventual lap peeling and lead to seepage.

4. Is lap peeling normal?

ATTENTION: Lap peeling over time is normal as the covering is applied in segments and this is why periodical maintenance is necessary.

5. Do I have to check that vents are clear?

It is necessary to check the working order of all ventilation systems. The vents should be dust free and free from obstructions such as wasps nests etc.

6. What do I need to check?

Check the cleanliness of the overflow pipes.

B. Walking on bituminous membranes

Polymer bitumen membranes whether smooth (non-self-protecting) or slated, ARE NOT TO BE WALKED ON. In summer the bitumous mass tends to become softer, therefore it is easily damaged (especially on slanting roofs).

1. What happens if I want to walk on the roof?

The membranes are not walk able, as previously stated. In order to walk on them a protected pathway must be created using “washed gravel squares” placed on the correct supporting bases or with a concrete floor foundation.

2. What is it advisable to do if I should need to walk on the waterproofing covering?

If it should be necessary to walk on the waterproofing covering it is advisable to avoid doing so during the hottest hours of the day in summer (and equally during the coldest hours of the day in winter). It is advisable to avoid wearing footwear with big soles (like Vibrams) and choose footwear with smooth soles in order to avoid overstressing the membrane.

3. What happens if there are mechanical structures present on the roof?

If there are mechanical structures such as air conditioning systems present, it is important to check that these machines do not emit oily liquids (such as petrol or solvents) which would damage the bitumen membranes. These structures should not be in direct contact with the membrane but placed on sufficiently large bases made of the correct material.

4. Is it possible to place heavy objects on the covering?

Do not place any heavy (or sharp) objects on the covering if a uniform distribution of load with a wooden board or other appropriate instruments has not been already organised.

C. Roof waterproofing surface curling

Polymer bitumen membranes applied with traditional methods (propane gas flame torch) can be applied in different ways, depending on the surface they need to be applied to. These surfaces can be:

  • “totally free” (independent laying)
  • “Partial laying” or partially glued
  • “Total adherence laying” (all surfaces).

In all three cases both the overlap and the perimeter of the covering are soldered to the support.Depending on the type of laying used the membrane will be more or less free to move for any eventual temperature or insulating system changes etc.

1. Is a certain amount of cover movement normal?

In summer and winter, as during the day and at night, a certain amount of movement is normal due to temperature change. Movement generally occurs near the corners of the building, since these are the critical areas where the movement converges.

2. How do non-soldered membranes move?

Completely supported non-soldered membranes tend to move in opposing diagonal corners.

3. What can happen if the membrane has not been properly laid?

Bitumen polymer membranes reinforced with non-woven polyester have a 50% stretching to breaking point. Therefore it is difficult to imagine a membrane breaking but an end lap could come away if it has not been installed properly.

4. What can new buildings do to membranes?

Where new constructions are concerned the settling movement of the buildings can cause abnormal tension to the roofing cover.

5. What is it that moves frequently?

Quite often it is not necessarily the waterproof cover which moves, it is the insulating panel under it. Relatively low temperatures (70°C) can create dimensional stability problems for some insulation. Therefore it is necessary to check both the presence and the perfect hold of the mechanical fixings (on average 4 per m²).

D. Water or air bubbles on roofing surface

The presence of water or air bubbles on waterproof covers is a fact that can occur in some particular circumstances, such as in the case of thermal insulation and the absence of an adequate vapour barrier. In the latter case the vapour may rise up and meet the membrane (notorious for being scarcely breathable to water vapour) and bubbles can form, at low temperatures, which then condense into water. Another problem can occur when the concrete is not left to set long enough and being waterproofed immediately it holds on to the water still present inside it.

1. What should be checked?

Check the presence and working order of the water vapour barrier.

2. What are the functions and presence of air vents for?

Check the working order and presence of air vents as they are always useful with or without an insulating panel.

3. What should be done to the bubbles?

Any bubbles should have a cross cut into them and then, after having waited for them to evaporate/dry out, a patch of the appropriate material should be applied.

4. Why are the bubbles more obvious when it is hot?

The bubbles may be more obvious when it is hot; this is due to the increase in the amount of water vapour compared to the amount of water.

5. What should be checked inside the building?

Check that the inside of the building does not have any damp marks; which might not necessarily be due to a leak but due to dampness present in the foundations. As this humidity cannot be released externally (because the membrane is not very breathable) it may manifest internally.

6. When does condensation happen?

Condensation normally only happens at certain times of the year, or when there is humidity and particular temperatures. Therefore the problem occurs in cycles throughout the year and often can be caused by thermo-igrometric phenomena and not by seepage.

E. The effect of hail on bitumous membranes

Hail is a meteorological phenomenon which concentrates on one area and is often very violent. It occurs due to large temperature differences in air masses. Sometimes hailstones can be of ample dimensions, in these cases hailstones cause an intense mechanical degradation to the membrane. Hail is often accompanied by a rapid and violent drop in temperature which can make the membranes more fragile. In circumstances like these hailstones can break the membrane itself. Choosing a technically higher quality membrane eliminates or reduces the destructive effects of hail. The high quality membranes or elastomeric (SBS) are much more resistant to dynaminc impact.

1. What should be checked?

Check the state of the bitumen membrane, which should not be too stiff.

2. What should be done in the case of damage?

If the membrane is damaged an intervention with reinforcing pieces should be carried out.

3. What should be checked after a hailstorm?

After a hailstorm the state of the roofing should be checked immediately in order to highlight any imperfections in the shortest time possible

F. Torch On Membranes

1. Can you torch over sticky back Spider P membranes?

Yes you can, but we suggest applying an SBS torch on using low heat.