Myths about ventilated façades
- Ventilated façades are very expensive
The initial costs of building a rendered façade with polystyrene foam are indeed lower. However, from the long-term perspective, building owners should evaluate foreseeable performance costs such as painting and repairing façades as well as removing possible mould infestations. A comparison of rendered and ventilated façades in the long-term reveals that ventilated façades are only initially more expensive and pay for themselves quickly as they do not require as much maintenance as rendered façades.
According to a study carried out by the Housing Energy Efficiency Agency, projected investment plan costs (for contracting services) were about 20% lower than the calculated market average, and the difference between external wall insulation costs for rendered and ventilated façades was about 30%. This data was collected for an analysis of contracting service procurements carried out in August of this year. The analysis presented a comparison of projected investment plan costs to real costs, i.e., what services actually cost in real life.
Data collected during the Housing Energy Efficiency Agency study:
|MEASURES/PRICING||Projected investment plan costs (per m2)||Real costs (per m2)|
|Insulating a rendered façade||LTL 300 – 320||LTL 230 – 250|
|Insulating a ventilated façade||LTL 380 – 400||LTL 300 – 330|
- The colour of ventilated façade panels fades
Saving money is a serious consideration for most building owners, thus they often choose to work with cladding materials of poorer quality or materials that are not certified. Regulations applicable in Lithuania demand that external walls are only designed and constructed using thermal insulation elements for ventilated façades that have European Technical Assessment (ETA) and/or CE marking. Cases of colour fading do not occur with certified high-quality materials because the products are tested and certified using scientific methods in accredited laboratories.
- Ventilated façade panels are too heavy
This myth only holds true when heavy materials such as ceramic or natural stone panels are used. HPL panels and aluminium composite panels are very lightweight. Fibre cement panels are the most commonly used type of material in residential block renovation. They are not heavy and come at a more modest price than engineered stone or ceramic panels.
- The layer of thermal insulation frequently gets wet underneath the ventilated façade.
Because of the natural ventilation that ventilated façades offer, moisture evaporates from the insulation material much more quickly without having any time to accumulate. The moisture is simply extracted by a draught wind. The important thing is to make sure that the insulation material is suitably secured in place, the ventilating gap is of an appropriate width, and the protective wind insulation has been appropriately applied to the thermal insulation material.
Water finds its way into the thermal insulation layer in one of two ways: when rainwater affected by wind and capillary action seeps into it through a gap between the cladding panels and when a dew point moves into the insulation material, thereby increasing moisture levels. However, the ventilated air gap does not allow any such moisture to accumulate by ensuring its rapid evaporation.
- Thermal insulation behind ventilated façades is prone to rodent infestation.
Rodents prefer to nest in polystyrene foam, but there have also been cases of rodents making their homes in mineral wool. This is easily prevented with the use of a special perforated base profile that protects the thermal insulation material from rodents and ensures adequate ventilation at the same time.
- Using a ventilated façade means creating many thermal bridges
The issue of thermal bridges is addressed by using special-purpose washers between the ventilated façade frame and the wall, and by using systemic frames that only have a small area of surface contact with the wall base. Such solutions limit heat losses to a minimum.
- Thermal insulation underneath ventilated façades slumps down over time.
Mineral wool will not sag or slump if work is carried out according to the appropriate method and in compliance with the manufacturer's recommendations.
Typically, such issues are the result of the wrong type of mineral wool being used or the incorrect use of wool for the purposes of saving money on work that is not visible to the naked eye. Mineral wool manufacturers clearly indicate which products can be used for ventilated façades.