Flat roofs
Roof Paintings
REPAIRS AND MAINTAINING COATING ISOLATION AF FLAT ROOFS
By painting systems on cold bitumen base
From time to time we come across with questions how correctly maintain the waterproof isolation of flat roofs made from classical hydro-isolation sheets from oxidized bitumen. Not each owner of building whose flat roof has waterproof isolation done like this, has enough wherewithal on its repairs by modern maintenance-free modified bitumen sheets and hydro-isolating sheets.
Most of us remember the time when only hydro-isolation sheets from oxidized bitumen were used such as SKLOBIT, BITAGIT and IPA (therefore today the non-professionals distinguish all the bitumen sheets as IPA). These products were delivered without protective coat that supposed to protect them against unfavourable influences of UV radiation and high temperatures at summer. Hence the part of the hydro-isolation structure of these flat roofs used to be protective and reflective paintings that composed the final coat.
Domestic producer PARAMO, a.s puts on the market wide range of quality bitumen products that enables to realize reliable maintenace of these originals (in some cases also newer but prematurely aged) hydro-isolation bitumen coatings. Some of its products are also used for repairs of the existing hydro-isolations from bitumen sheets for its reconstruction.
Before any type of coating (painting) system application is applied, it is necessary the current hydro-isolation clean deeply and the original hydro-isolation expertly amend (remove blisters by cutting and sealing). Let me mention that lifetime of any coating (painting) system depends not only on quality of carrying on but also on conditions of the original roofing coat and on climatic conditions of the specific construction. For instance lifetime of the reflective coating REFLEXOL is usually shorter on south part of the roof. From these reasons are the following lifetime figures of repairs only informative.
It is necessary to warn that in case expired or too much damaged of isolation the coating (painting) system would not be a solution. Using of coating system for maintaining of flat roof either of family house or garage with waterproof isolation from bitumen sheets might be managed even by non-professional when necessary rules and security proceeding are maintained).
It is necessary to mention that for reliable usage of all mentioned bitumen material is necessary to maintain the minimal air and base temperature when its application and these coatings can't specific period of time got ranched. Bitumen lacquer might be freely used but only on dry bases in temperature above +3°C and basically the rain (depending on the air temperature) after 1 hour usually don't mind. Total flash time needed is minimal 24 hours and when temperature is under +5°C it might even multiplied. Empirical criterium for total flash of bitumen lacquer is that if we touch by finger on the surface that is dry the finger stay clean. If it became black, the surface is not sufficiently dry yet.
Bitumen adulterate suspensions might be used on dry surfaces at temperatures over +10°C and it can't get wet till desiccation and the chemical reaction stops. Desiccation of bitumen suspension coating (excepting GUMOASFALTU SA-23) to water indissoluble state might be easily recognized: wet coating is of fuscous colour and while it turn to black than rain do not mind and might be further painted (coated). In case of ferruginous suspension GUMOASFALT SA- 23 is again possible to use empirical criterium, when touch by finger on the surface that is dry the finger should stay clean.
Selection of suitable technology of coating system for roof reparation is also influenced by the fact if on the existing roof surface permanently occurs pools. In that case it is not advisable to use bitumen suspensions GUMOASFALT, which are swelling and subsequently cracking when instantly soused under water. If pools are occurred on the roof surface, it is, therefore, reliable to use coating systems on bitumen lacquer and cement basis or in case of bitumen suspension GUMOASFALT after application finish by bitumen painting.
In case of repairs of accidents of water-resistant isolation either in winter or after rain, the modified bitumen cement LUTEX MOAT might be used that in this case should be applied also only on dried surface.
Considering diffusion of water vapour through the roof coating we might say that paintings from asphalt lacquer RENOLAK ALN and RENOLAK MOAL or from asphalt cement LUTEX ATN and LUTEX MOAT are less vapour permeable than paintings from asphalt lacquer PENETRAL ALP or reflex paintings REFLEXOL and considerably less permeable than paintings from asphalt suspension GUMOASFALT.
Possible usage of coatings (paintings) from PARAMO Inc. Company offers for waterproof isolation from classical sheets:
A - Reparation of existing waterproof isolation by asphalt lacquer RENOLAK ALN + reflective painting REFLEXOL
Structure of waterproof isolation:
Concerned the most oxidized and relatively short-term solution of waterproof isolation fixes, when it will be used as a restoration painting (coating) asphalt lacquers RENOLAK ALN. This bitumen lacquer has high percentage of hard asphalt dissolved in organic dissolvent (lacquer petrol). Its consumption is 0.4 to 0.5 kg/m2. Recommended are 1 or 2 paintings. In the end on the surface of that treated and properly degasificated surface (with technological break 24 hours) is applied 1 asphalt-aluminium reflective painting REFLEXOL (with consumption cca 0,3 kg/m2). Lifetime of the entire introduced painting system is around 2 to 3 years. This variation is also suitable for treating GUMOASFALT that will be in areas with pools long-term under water. (See note in E variation)
B - Reparation of existing waterproof isolation LUTEX ATN + reflective painting REFLEXOL
Structure of waterproof isolation:
Asphalt cement LUTEX ATN is asphalt lacquer with organic diluent and with organic filler additive. This product doesn't contain SBS rubber and that is why compared to LUTEX MOAT cement it is more frangible, it easily cracks and has faster ageing process. While maintaining of waterproof isolation, they are usually applied 2 coats of paint with consumption about 0.8 kg/m2 per each coat. Finally on the top of so treated and properly degasificated surface (with technical break 24 hours) will be painted one asphalt-aluminium reflective coat REFLEXOL (with consumption around 0,3 kg/m2). Lifetime of this coating system layout is 3 up to 4 years.
C - Repairs of existing waterproof isolation by modified asphalt lacquer RENOLAK MOAL + reflective coat of paint REFLEXOL
Structure of waterproof isolation:
Modified asphalt lacquer RENOLAK-MOAL consists from asphalt dissolved in organic dissolvent with SBS rubber, but do not contain any fillers. It generates relatively thin coat on the surface of the asphalt sheet and, therefore, its application does not have long-term effect. Consumption of lacquer RENOLAK MOAL per one coat of paint is around 0,4 to 0,6 kg/m2.
Finally on the top of so treated and properly degasificated surface (with technical break 24 hours) will be painted one asphalt-aluminium reflective coat REFLEXOL (with consumption around 0,3 kg/m2). Lifetime of REFLEXOL is 3 years and bottom coat of paint 5 to 6 years. This variation can be considered as the most suitable for treating GUMOASFALT that will be in areas with pools long-term under water. (See note in E variation)
D - Repairs of existing waterproof isolation by cement LUTEX MOAT + reflective coat of paint REFLEXOL
Structure of waterproof isolation:
Modified asphalt cement LUTEX MOAT is basically asphalt lacquer with fibrous filler additives, organic fillers and SBS rubber. It has cold-working properties; it is workable at temperature above +5°C. Hence the material contains lacquer petrol, it is guaranteed that when application will be carried on the surface of the aged asphalt sheet and, therefore, the solid connection of this cement and the underlay will be created. While fibrous fillers together with SBS rubber provides flexible bridging of cracklings in the original waterproof isolation. When maintaining the waterproof isolation are usually painted 3 coats with consumption of 0.8 kg/m2 per each coat.
Finally on the top of so treated and properly degasificated surface (with technical break 24 hours) will be painted one asphalt-aluminium reflective coat REFLEXOL (with consumption around 0,3 kg/m2). Its protective ability is around 3 to 5 years. After that period is always necessary to renovate the reflective coat. However before creating the new reflective coat is necessary to check if the underlay coat LUTEX MOAT satisfactory. When well-timed renovation of the reflective coat we might count that the lifetime of the underlay coat LUTEX MOAT will be extended to two up to tree times of the reflective coat lifetime.
E - Repairs of existing waterproof isolation by asphalt bentonic suspension GUMOASFALT SA-12 (or ANTIVIBRAL TH 12) + surface finish GUMOASFALT SA-23
This variation might be used only for roofs with waterproof isolation with relatively good condition.
Structure of waterproof isolation:
Asphalt penetration coating PENETRAL ALP has good cohesion to all the construction materials (concrete, metal, walling etc.) Its consumption is 0,3 kg/m2. It intrudes up to 5 mm deep to the pores of the underlay and ensuring tight connecting with other isolation layers. If the penetration asphalt lacquer is separately used it is not fairly resistant.
Asphalt suspensions are water dilutalbe panting substance that creates disseminated bentonic with asphalt in water. It is ecological painting substance, which is vapour permeable. As underlay are used 3 coats of asphalt suspension GUMOASFALT SA-12 with consumption of 0,7 kg/m2 per each coat. Instead of using GUMOASFALTU SA 12 it is possible to use, especially on wide surfaces, asphalt water-suspension ANTIVIBRAL TH 12 that contains in addition also fibrous filler - consumption of this coating is also 0,7 kg/m2. Asphalt ferruginous suspension GUMOASFALT SA-23 with consumption around 1kg/m2 will be used as a finishing coat.
Lifetime of such reparation is around 5 years. Please, keep in mind that ferruginous suspension GUMOASFALT SA-23 is not sufficiently hydro-isolating material - its main objective is to protect bottom hydro-isolation layers against UV radiation and it has also aesthetical function.
Note:
In case there are some pools on the roof it is necessary after deep desiccation of asphalt suspension from GUMOASFALTU SA-12 replace with (from esthetical reasons on the entire surface of the roof) ferruginous suspension GUMOASFALT SA-23 by asphalt lacquer RENOLAK ALN (possibly RENOLAK MOAL) + reflective coating of REFLEXOL (See the variation A or C). Asphalt lacquer RENOLAK ALN or modified RENOLAK MOAL closes the surface of the asphalt suspension in so far that it won't be swollen. While REFLEXOL would be directly applied on asphalt suspension that closing would not be provided as the reflection coat is too slurry.
F - Repairs of existing waterproof isolation by two-coated reinforced by asphalt bentonic suspension GUMOASFALT SA-12 (or ANTIVIBRAL TH 12) + surface finish GUMOASFALT SA-23
This variation is possible to use in case of worse state of waterproof isolation with demand on longer lifetime.
Structure of waterproof isolation:
Lifetime of such reparation is up to 10 years and after 4 to 5 years it is necessary to renovate the upper coat by ferruginous suspension GUMOASFALT SA-23 (around 1 kg/m2). Instead of GUMOASFALTU SA-23 might also be used REFLEXOL providing the necessary delay from the last coat of SA 12 needs to be at least 10 days. This reflective coat needs to be renovated each after 3 years. In case of slops on roof see Note in E variation.
For repairs of waterproof isolation from asphalt sheets that are of worse condition the only suitable variations are D and F.
Necessary to successful realisation of above mentioned products is not only careful treatment of the existing underlay but also a quality and careful application of individual coatings. As above mentioned it is necessary to provide repairs of the existing waterproof isolation and skilled repairs of sensitive details on roof. Anyhow careful coating system would not prevent leaking into the roof cladding in the place of connection of waterproof isolation with the rusty attic edge and the over-roof walling or a chimney from zinc-coated metal (that still appears on older flat roofs). For details attachment it is convenient to use GUMOASFALT SA 27.
The most steady and long lasting solution always is a professional reconstruction of an existing waterproof isolation with quality modified asphalt sheets used. All the above mentioned coating systems enables, if needed in the future also depending on the roof cladding condition (mostly on the existing waterproof and thermal isolation) reconstruction of existing waterproof isolation with laying new asphalt sheets. By reason of embedded or inflow moisture in the current waterproof isolation structure it is not possible full-area smelting of new asphalt sheet but only a sheet with expansion ply.
We recommend to consider the straining by blow on the roofing and possibly to add anchoring components or use some additional loads (e.g. concrete tiles).
The surface of the current waterproof isolation treated by above-mentioned coatings is needed to be coated with PENETRAL ALP (asphalt penetration lacquer) with consumption of 0,3 kg/m2 (of course before it the necessary repairs and removing blisters by cutting and sealing should be done)
This asphalt penetration lacquer ALP has better underlay cohesion than the above mentioned but also then more commonly used RENOLAK ALN (asphalt lacquer coating). Because of used dissolvent - lacquer benzine, it is important before melting of new asphalt sheet to let the ALP coating to let the coating at least 24 hours to aerate after the application.
On such a treated surface of coating system it is of course possible to stick an additional thermal isolation if requested (of course with the new waterproof isolation). Because this thermal isolation is not attached on the entire surface but usually by strips of adhesive, we recommend considering the reliability because of the straining by blow and possibly to add anchoring components or use some additional loads (anchoring possibilities depends also on bearing capacity of roof construction).
We sometimes meet requirement of roof repair whereon is waterproof isolation from modified asphalt sheets SBS with protective strewn from milled slate that was from particular reasons has been released from the surface of the asphalt sheet. Such a bared black surface of the asphalt sheet is then exposed to UV radiation and at the same time it is heated in summer that causes ageing of asphalt sheet. However its lifetime might be extended by a suitable protective coating system. Of course the same repair of the surface might be done on classical hydro-isolation sheets from oxidized asphalt, which are today supplied also by producers supplied with strewn from milled slate.
G - Repair of roof with tumbled protective strewn from milled slate
If it is necessary to repair a roof those upper sheets have tumbled strewn from milled slate, to extend the lifetime of bared asphalt sheet it is possible to use below mentioned surface coating systems. Current surface of waterproof isolation, however, needs to be properly mechanically cleared so as to remove from the surface of the asphalt sheets not only released laminas of strewn slate, but also fouling of dust and fly-ash from air. We recommend that you splash water on such a treated surface of waterproof isolation in the end. Before first coating application the surface needs to be completely dry anyway.
a) Flat roof (up to 5° slope)
b) Sloping roof (from 5° < up to < 45° slope)
Instead of ferruginous suspension GUMOASFALT SA-23 is of course possible to use the reflective coating REFLEXOL. If this slopping roof is under surrounding objects with windows it might cause, especially in summer, very unpleasant sun blindness due to the glint from reflective coating of REFLEXOL.