![The attic was insulated with fiberglass](https://cdn.treehouseinternetgroup.com/uploads/photo_gallery/medium/422397-6304f398614c1_before.jpg?v=)
The attic was insulated with fiberglass
The problem is that fiberglass will not protect from mold growth. In addition, it takes a lot of fiberglass for the insulation to be effective.
![The attic did not have ventilation mats](https://cdn.treehouseinternetgroup.com/uploads/photo_gallery/medium/422398-6304f3e0deb66_image-21.jpg?v=)
The attic did not have ventilation mats
And these are very important to have as they allow air circulation in the attic and reduce humidity.
![Brick chimneys must be insulated with non-flammable insulation](https://cdn.treehouseinternetgroup.com/uploads/photo_gallery/medium/422399-6304f410d5ee2_image-22.jpg?v=)
Brick chimneys must be insulated with non-flammable insulation
Air leaks around are sealed with polyurethane foam.
![Electrical light boxes must be insulated](https://cdn.treehouseinternetgroup.com/uploads/photo_gallery/medium/422401-6304f4b5bda4a_image-9.jpg?v=)
Electrical light boxes must be insulated
In this case, there was already a protective box on top, so we added polyurethane foam around it to seal the joint properly and prevent air leaks.
![We blew 16" of cellulose](https://cdn.treehouseinternetgroup.com/uploads/photo_gallery/medium/422402-6304f4f0d0614_after.jpg?v=)
We blew 16" of cellulose
Cellulose is very effective as insulation and is safe.