Dense-pack cellulose

clls blwn IV         The North St. Louis County (NSLC) affiliate uses a dense-pack cellulose process to insulate their walls. Below are some pictures and descriptions of how they do it.

clls blwn I         This wall is ready to fill. Mesh material is stretched between vertical studs. The mesh is anchored with horizontal strapping – this keeps the mesh from bulging out too far when filled. The strapping also holds the interior wall stud out from the exterior wall framing – this creates a space for cellulose insulation at the intersection behind the interior stud, where normally it would just be less-insulating wood (wood can create a thermal bridge in a wall). Preparing the mesh can be accomplished with trained volunteers.

clls blwn III      Small cuts are made in the mesh to fit the insulation hose through. Just like blowing cellulose into an attic, the operator holds a switch box to control the flow, and ideally wears a mask. The operator can use a large hose to quickly fill the cavity, then come along with a smaller, more manageable hose to pack it tight. Filling the cavity can be accomplished with trained volunteers…

clls blwn VII            But be prepared for a mess until they get the hang of it.

clls blwn II          Again, just as with an attic, an insulation blower is used to break down the cellulose blocks and send the material out through the hose. Volunteers can perform this work…

IMG_0914            But let them know it gets real dusty.

Once filled, it is ready for drywall. No plastic in this wall; NSLC uses an airtight drywall method and vapor retardant paint. In addition and as noted in the wall section below, NSLC has 1″ of extruded polystyrene (XPS) rigid foam board on the exterior, as well as a sub-slab passive depressurization scheme. Finally, the affiliate also uses a Heat Recovery Ventilator to keep air moving in and out of the house. These factors can work together to facilitate successful drying of the wall to the inside. NSLC Wall Section

For greater detail on how dense-pack cellulose works in a Habitat home, consider a visit to the North St. Louis County HFH to volunteer.


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