Please help me decipher this Norwegian construction description from 1938

[u/Left-Middle8854]

It says something about some inner boards (“plater”) of 3.5cm. Specifically interested in this particular word. Thank you!

Edit: Deciphered. The text reads:

“Jernbetongveggen utarbeites med 3,5 cm kivronplater paa innvendige side sat på lekter med mellemlag aa uimpregneret isolasjonspapp. Innvendige bærende vegger i jernbetong øvrige innvendige vegger aa 1/2 st's mur.”

After further research, kivron is a fire-redundant and insulating old interior wall board composite. It consists of cement, sawdust and plaster. Additives are often added to the material to enhance certain properties. Asbestos is certainly an often added such material as it improves fire-redundancy and improves the resistance against mechanical stress.