The attic is often a manageable DIY project. Insulating the exterior walls usually involves substantial renovation, and the options depend on whether the plaster sits directly against the block or has a usable cavity behind it.

Have the inspector confirm how the walls are built. A neighbor’s experience can give you a clue, but it doesn’t establish what’s in this house.

There are three possible ways to insulate the walls:

- From inside, you can add a properly designed insulation and air-sealing layer, followed by framing or furring and drywall. You’ll lose some room space and need to adjust window trim, baseboards, outlets, and possibly radiators or cabinets. A skilled DIYer could do much of the carpentry and finishing, though this amounts to remodeling each room.
- From outside, you can add continuous insulation and new cladding. This preserves indoor space but covers the brick. The details around windows, doors, and roof edges need careful planning, and the work generally calls for a contractor.
- If there’s a suitable cavity, you may be able to fill it. First, confirm that it can safely be insulated. A gap behind brick may be needed for drainage, and filling hollow block cores won’t necessarily provide the same benefit as continuous insulation.

[DOE’s masonry retrofit guidance](https://basc.pnnl.gov/resource-guides/seismic-and-insulation-retrofits-solid-masonry-walls) describes the first two approaches. Interior insulation makes the masonry colder and limits its ability to dry inward. Depending on the climate and rain exposure, a poorly designed installation can cause condensation or damage from freezing and thawing. Before choosing insulation or a vapor barrier, have someone experienced with masonry retrofits specify the wall assembly. [DOE masonry insulation guide](https://www1.eere.energy.gov/buildings/publications/pdfs/building_america/enclosure-retrofit-masonry-walls.pdf)

I would start with the attic, assuming it’s accessible and unfinished. The usual sequence is to seal air leaks through the ceiling, keep ventilation paths open and maintain required clearances around heat sources, then add blown cellulose or fiberglass, or unfaced batts. ENERGY STAR estimates 1 to 3 days for a DIY attic project, although access and preparation can make the work harder. [DIY effort guide](https://www.energystar.gov/saveathome/seal_insulate/determine-effort-required), [installation guidance](https://www.energystar.gov/products/energy_star_home_upgrade/attic_insulation)

For 1,000 square feet of attic, rough budgets in U.S. dollars are:

| Work | Approximate cost |
|---|---:|
| DIY blown insulation, including materials and equipment | $700 to $1,200 |
| Professionally installed blown insulation | $1,500 to $4,500 |

These are broad estimates. Insulation depth, air sealing, access, removal, and repairs all affect the price. [DIY cost estimate](https://costofowning.com/guides/attic-insulation-cost/), [installed cost estimate](https://www.remodelingexpense.com/costs/cost-of-attic-blown-in-insulation/)

For a whole-house wall project, I would budget a provisional five-figure amount until you get quotes. Finishing, trim, electrical changes, and moisture repairs can account for more of the cost than the insulation itself. Calculate wall costs using the exterior wall area, rather than the home’s floor area.

Before purchasing, ask for measurements of the attic’s insulation levels, evidence of wall dampness, and an energy assessment to help prioritize improvements. If the attic contains vermiculite, leave it undisturbed until a professional assesses it, because it may contain asbestos. [EPA guidance](https://www.epa.gov/asbestos/my-attic-has-vermiculite-insulation-it-am-i-risk-should-i-take-it-out)

Your location, house size, and plans for remodeling the rooms would help narrow the wall options and budget.