Bitumen puttying / Perimeter insulation WU-basement

Good day everyone,

Question regarding bituminous sealing on a waterproof concrete (WU) basement.

Currently, our basement is being poured on site with waterproof concrete. When asking the shell construction contractor on site, apparently only a perimeter insulation is being applied WITHOUT bituminous sealing (which is, however, specified in the tender documents [LV]!). He said that this is not necessary with waterproof concrete or for a waterproof basement.

Before I "bother" my general contractor with this, I would like to know whether this can indeed be the case (perhaps the tender documents [LV] are still very general and for a waterproof basement this is actually not necessary?), or whether this is simply a cost-saving measure.

Is perimeter insulation generally sufficient for waterproof basements? Is bituminous sealing advisable/necessary or not?

At which exact point do you want to have the bitumen layer? With us, the bitumen was used to glue the perimeter insulation to the watertight concrete as well as to seal the joint edges of all insulation boards with bitumen. However, there was no continuous bitumen layer in front of the perimeter insulation. Maybe the first-mentioned "adhesive layer" is also the bitumen coating you mentioned? It is important (and only then correctly executed) that the perimeter insulation is waterproof.

Alternatively, you can also install a studded membrane in front of the perimeter insulation. It also keeps water away from the insulation and can even be done as a DIY job if necessary.

At exactly which point do you mean to have the bitumen layer? At our place, bitumen was used to glue the perimeter insulation to the WU concrete as well as to seal the joint edges of all insulation boards with bitumen. However, there was no continuous bitumen layer in front of the perimeter insulation. Perhaps the aforementioned "glue layer" is also the bitumen troweling you mentioned? Important (and only then correctly executed) is that the perimeter insulation is waterproof.

Alternatively, you can also place a studded membrane in front of the perimeter insulation. That also keeps the water away from the insulation and can even be done by yourself if necessary.

No idea honestly... :D

I thought that there was still a bitumen layer under the perimeter insulation?

Our construction and service description contains the following:



Thus, I assumed that this is an "additional" waterproofing.

How do you understand that?

A dimple sheet is also still included in our construction and performance description - therefore it will also be implemented: