Amapangidwa ndi PVC yapamwamba kwambiri, magolovesiwa amapereka chitetezo chapamwamba ku mankhwala, zotsukira mwamphamvu, ndi madzi otentha, zomwe zimawapangitsa kukhala abwino kwambiri kutsuka mbale, kuyeretsa zimbudzi, ndi kuchapa zovala. zosanjikiza zomwe zimazungulira mkati, zomwe zimapatsa kutentha ndi chitonthozo m'miyezi yozizira.Chosanjikiza ichi sichimangopangitsa manja anu kukhala omasuka, komanso amayamwa thukuta ndi chinyezi, kuteteza manja anu kuti asamamve bwino komanso osamasuka.