The room you already paid for

Because concrete is permanently damp and fiberglass holds that moisture against the wall while letting air move straight through it. Within a few years you typically have wet insulation, mold on the paper facing and no measurable thermal benefit. It’s one of the most common things we remove. Batts work fine in a dry framed wall above grade — they’re simply the wrong material against concrete.

Only if you genuinely want the basement to stay cold and it has no mechanicals in it. Insulating the ceiling separates the basement from the house, which means your furnace, water heater and ductwork are now outside the heated envelope — and pipes down there get colder. In most homes here, insulating the walls is the better answer. The exception is a basement that regularly floods, where you don’t want to bring it inside at all.

In an occupied or finished space, yes — IRC R316.4 requires a thermal barrier over exposed foam, and half-inch gypsum board is the standard way to meet it. In an unfinished utility basement the requirement is generally lighter, and some assemblies use an approved intumescent coating instead. We tell you which applies to your project at the estimate and price it in, rather than leaving you to discover it at inspection.

If the dampness is condensation, usually yes. Warm humid summer air meets cool concrete, and water forms on the wall — closed-cell foam stops that air ever reaching the cold surface. If the dampness is water coming through the wall or up through the slab, no. Those look similar to a homeowner and are completely different problems, which is why we check before quoting.

Often, and it’s common in Bucks, Hunterdon and the older parts of Mercer County. Foam conforms to irregular stone in a way rigid board never will, which is a real advantage. It needs more care though: these walls were built to dry inward, and sealing that path without thinking it through can push moisture into the mortar and the sill. We assess these individually rather than applying the standard detail.

Partly. Once the walls are insulated, heat already escaping from the furnace, ductwork and the floor above stays in the space instead of going into the soil, and most basements come up noticeably. Whether that’s enough for a room you’ll sit in for hours depends on the house. If you’re finishing it as living space, plan on a supply register or a small dedicated unit, and size it after the insulation is in rather than before.

They stay accessible and working — we don’t foam over a sump lid or block a drain. If anything, a sealed basement makes a sump easier to keep sealed and vented properly. Where a radon system is present or planned, tell us at the assessment so we detail around it rather than compromising it.