Njerwa zomangira ndi mtundu watsopano wazinthu zapakhoma, zokhala ndi mawonekedwe a hexahedron amakona anayi komanso midadada yosiyanasiyana yosakhazikika. Njerwa za block ndi zinthu zopangidwa kuchokera ku konkriti, zinyalala zamafakitale (slag, ufa wa malasha, etc.), kapena zinyalala zomanga. Iwo ali ndi makhalidwe a kukula muyezo, maonekedwe wathunthu, ndi kumanga yabwino, ndi kukwaniritsa zofunika kusintha khoma pa chitukuko cha mafakitale zomangamanga. Miluko ndi midadada ikuluikulu imagwiritsidwa ntchito. Posankha zida zamakina omata okha, sankhani zida zokhala ndi zodziwikiratu, zomwe zimathandizira kwambiri kupanga.

Mwachitsanzo, khoma chipika njerwa, kudzikonda kutchinjiriza njerwa, njerwa olimba, etc. ntchito pomanga nyumba, madzi otsetsereka miyala, mtundu (permeable) misewu pamwamba njerwa kwa municipalities lalikulu landscaping, midadada kukongoletsa, curbstones, curbstones, ndi mokwanira basi chipika zida zomangamanga kubzala ndi kukhazikitsa akavalo siliva akhoza kudya zinyalala zambiri zomangamanga. Kupanga njerwa zamatabwa monga zomangira zobiriwira zimakhala ndi zabwino zingapo monga kuchepetsa kuwononga chilengedwe, kupulumutsa ndalama zopangira, kuonjezera mtengo wa nyumba, kuchepetsa kukana kwa chivomezi cha nyumbayo, ndi zina.