SETTING UP FOR SHRINK WRAP
Setting Up Scaffolding For Shrink Wrapping
Shrink wrap is adaptable and can be used to cover structures of any kind of shape and dimension. The tips given below will make it more convenient to install shrink wrap on the scaffolding structure and give it a professional appearance. While these are general guidelines for shrink wrap sheeting, for more complex projects it is recommended to seek the guidance of a professional shrink wrap installer and scaffolder to ensure to get the best results whilst comforming to designs and health & safety regulations.
When any scaffold needs shrink-wrapping its installation must meet NASC’s TG20:13 requirements. Since June 2014, it is accepted norm as per the Health and Safety Executive. TG20:13 is the standard in accordance with BSEN12811-1 applicable to all types of scaffolds and tubes. When containment or weather protection is needed shrink wrap would need a support structure. For the structure, complete boarding access and handrails are a must for all areas that need to be shrink wrapped. Before shrink wrapping the installed scaffold has to be inspected and verified (Scafftagged). The scaffolder bears the responsibility to ensure the shrink wrap can withstand severe weather conditions.
Protrusions not only impact the look of shrink wrap it also delays the process if there are a number tubes to cut through/around. Getting the sheet straight is a challenge and while cutting around a protrusion is relatively easy, resealing and taping can be a time intensive. An ideal scenrario is having a flush scaffolding with sheeting rails that can make the daily installation much swifter and optimising the final finish. The price of shrink wrapping installation can sometimes be subject to how flush or straight forward a strucure is.
The ledgers have to be level with the main scaffolding structure. While it is possible to cut sheeting wrapped around a scaffold tube or board (and reseal it) it takes extensive time and does not look too good. Another risk is that despite resealing complete weather protection or containment is not guaranteed.
These have to level with the main structure of scaffolding. A handrail may also be needed when a horizontal join is required between sheets.
All boards used in scaffolding have to be lined up with the main structure and must be secured down with clips, not left loose. Boards on roofs must be positioned every 2 metres in runs of 3 to allow ample walkways for safe access whilst moving around to install a temporary roof.
Installing a sheeting rail improves the look of the wrapped sheet as it keeps the sheet away from fittings of the scaffold. While the shrink wrap is “drum tight” to mould firmly over fittings, when kept for an extended time in windy areas it can loosen eventually leading to formation holes. While they can be patched up with patch tape, having a sheeting rails helps to prevents damage in the long term.
This is needed for those locations that need complete containment. For this, the scaffolding must be lined up with minimal protrusions to minimuse the number of potential holes. A shrink wrap skirt is glues/taped/welded to the wall/ceiling/floor with an adhesive or wooden batten. Another alternative is to have scaffold boards on the floor with a scaffold on top. To seal it effectively the sheeting is battened and sealed on the boards at ground level.
Horizontal joints between sheets
Shrink wrap sheets come in 7m x 15m rolls. While it can be hung up the norm is using 7m width to cover 3 lifts of the scaffold. This is the largest drop. Depending on the types of projects you may have to reduce it to 2 lifts or a single lift in windy areas. For scaffolding higher than 6m, having a horizontal joint in between sheets is a must. The ideal way to do this is to have a double scaffold tube around the scaffold where the join is needed (around 6m).
The double tubes must be in close proximity (5-10 cm). At times the double tube of the handrail is used as a joining point for the sheets. As guardrail or handrail tubes may be up to 47 cm separate, it would take extra shrink wrap. Therefore using the double tube as a joining point is a better option. In this manner, every part of the shrink wrap is separately attached to the structure and fitted behind each other.
Temporary Roof Structures
Shrink wrap structures serve well as temporary roofing. Some of the things to consider are
When constructing scaffolding for the roof it should allow the easy drainage of rainwater from the roof. The minimum pitch for the shrink wrap on the roof should be 1:10 or 10% and no more than 20%. Installing a temporary roof of shrink wrap requires access to the top of the roof. Having a handrail on the perimeter of the roof is necessary. It offers both protection and the possibility to attach safety tension lines between handrails (if needed).
If safety lines are used operatives must be aware of a rescue plan and in using casualty recovery equipment.
Installing a handrail at the roof edge does not impede shrink wrapping the roof. It is always best to wrap the scaffolding sides first and overlap the sheet by about 35-40 cm on the roof. It results in having to cut the side sheet 35-40 cm from the sheet’s edge to wrap around the stanchions. When the shrink wrap is unfolded on the roof it should overlap the roof edge onto the sides by approximately 30 cm. That will entail only cutting the roof sheet by 30 cm around the stanchions. Both the roof sheet and side sheet are heat welded to join. Lastly, patch tape creates a seal on the bases of every stanchion.
Size Of Your Temporary Roof
Canopies / Small roofs (up to 5 metres wide)
If there is a small roof within arms reach access to the roof underside, you do not require extra boards installation. It is the same where a canopy is needed over the top lift of the scaffold. If the installers have access to the canopy underside from the top lift there is no need for extra boards.
For medium size roofs a temporary roof must have scaffold boards that allow the installer to gain easy access to all parts of heat shrink film and weld sheets comfortably. Also having boards works like a support for the shrink wrap film on the scaffold. After the shrink wrap is attached to the temporary roof an installer battens the film on to the boards at a gap of 1-2 m. Therefore the board must be firmly attached and secure to remain firm in windy conditions.
For large roofs that make it impossible to have a temporary roof using boards, 3 metres in width, every 2 m is the minimal requirement for roof boards around the edge of the roof.