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PAH (Polycyclic aromatic hydrocarbons)

Building Interior: Tar Paper

Tar Paper

Timber beams in old buildings are sometimes wrapped in tar paper to protect them against moisture.

Tar Paper

This wooden beam within an attic has tar paper attached to it. On top of the tar paper there is a cane lattice to support the plastering.

Damp-proof membrane

Broken floor screed with underlying damp-proof membrane (black). The damp-proof membranes of older building were tar based and therefore contained PAH. Today PAH-free bitumen products are used.

Tar Paper

Tar paper was once used to protect pipe insulation from moisture. This picture shows mineral wool lagging with tar paper wrapping.

Tar in Adhesives

Tar adhesives

Parquet flooring was once installed using tar based adhesive that is known to contain PAH.

Tar adhesives

Tar based adhesives for parquet floors were typically used until the 1950's. As with other tar based products high concentrations of Benzo[a]pyren (i.e. several 1000 mg/kg) may be expected. Subsequent to the 1950's tar based adhesives were gradually phased out and were replaced by today's polymer or solvent based adhesives. Nevertheless, tar based adhesive for stave parquet are known to have been used until the 1970's. Furthermore, some bitumen bases adhesives were blended with tar until the 1980's .

Tar adhesives

Some Floor-Flex adhesives were tar bases and therefore may contain PAH in addition to asbestos.

Tar in Wood Preservatives

Tar Wood Preservatives

Timber tenant storage compartments constructed in the 1970's. The wooden slats have been treated with a tar based preservative (see Section Wood Preservatives).

Tar Wood Preservatives

Close-up of previous photo.

Slag in Floors

Slag in floors

In this building slag and construction rubble has been used to fill the cavities between the floor joists (see next photo).

Slag in floors

Close-up of previous photo. In addition to brick fragments, mortar and slag the floor filling contains pieces of tar paper.

Slag and rubble filling between floor joists of attic.

Tar paper appears to have been used to cover the slag filling prior to putting the floor boards down.

Slag filling between floor joists of an attic floor.

Tar paper has been used to cover the slag filling.

Tar Cork

Tar cork insulation

Slabs of tar treated cork were once used in industrial and commercial buildings to insulate chill rooms and cold storage rooms. This photo show tar treated cork that has been mounted to the arched ceiling. At some places the cork slabs have become loose. In this case tar treated cork also lies behind the wall tiles. Sometimes tar cork may be found  between the brickwork within the wall itself.

Tar cork insulation

Close-up of ceiling shown on the previous photo.

Building Exterior: Roofing Felt

Roofing felt

Roofing felt is felt that has been treated either with tar or bitumen and is usually finished with a sandy surface.  Until the 1970's roofing felt was tar based and therefore contained PAH.

Modern bitumen based roofing felt.

One method of applying roofing felt involves heating bitumen to seal the edges of the  sheeting. Sometimes one layer of new roofing felt is placed on top of an older one so that a roof may have several layers of felting. Especially the lower layers are liable to be tar based and contain PAH. Tar based roofing felt is not a risk to the building occupants but requires proper disposal and implementation of health and safety measures during demolition.

Roofing felt

Flat roofs with gravel coverings sometimes have roof felt underneath the gravel.

Close up of roof covered with roof felting.

Roofing felt

Today, bitumen products are considered to be environmentally compatible and are only treated as hazardous when tar has been added to the bitumen. This picture taken in the east of Berlin shows roofing material that is reported to have been imported from eastern Europe. The roofing consists of coated aluminium foil (see next photo). Given its source and age a high PAH content is considered to likely.

Roofing felt

Close up of the previous photo. Roofing made of black coated aluminium sheeting. Its age and source indicate it to contain PAH.

Other Tar Containing Materials

Layer considered to contain PAH at a roof opening.

Tar containing materials

Close-up of previous photo.

Tar containing coatings

Tar containing coatings used to be used at the exterior of the building below ground to protect steel, concrete and brickwork from moisture

Tarmac surfacing

Tarmac was once predominantly made of tar as opposed to today's bitumen. In the old Federal States the use of tar in road construction was mainly phased out during the 1970's. It was ultimately banned in 1984.  The use of tar for road construction in the New Federal States was first banned with the reunion of Germany. Old tarmac surfacing dating back to the 1970's and older can contain high levels of PAH. Modern asphalt surfacing usually contains < 100 mg/kg PAH.

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