**The attic is often a manageable DIY project. Insulating brick-and-block walls is a substantial renovation**, especially if the plaster is applied directly to the block.

First, have the inspector confirm the actual wall layers. There may be interior furring strips, an existing insulation layer, or a drainage gap behind the brick. Those details determine your options.

For the walls, the usual approaches are:

- **Add insulation inside.** Install a designed insulation system against the masonry, then cover it with an approved interior finish, typically drywall. This reduces room dimensions and requires changes around outlets, baseboards, and window and door trim. Depending on the existing plaster’s condition, some removal may be needed.
- **Add continuous insulation outside, with new cladding.** This changes the house’s appearance and requires careful detailing at windows, doors, roof edges, and the foundation.
- **Fill an existing cavity only after confirming its purpose and suitability.** A gap behind brick may provide drainage; filling it can create moisture problems. Hollow concrete blocks also need assessment before considering injected insulation. [DOE’s insulation renovation guide](https://www.energy.gov/sites/default/files/2023-03/insulation_guide_0.pdf) explains masonry retrofit options and their limitations.

Interior insulation changes how warm the masonry stays and how it dries. Poor detailing can cause condensation, and cold climates can introduce freeze–thaw damage. Have someone experienced with masonry retrofits specify the insulation and moisture-control details. An experienced DIYer can then tackle much of the carpentry and finishing. [Building Science Corporation’s masonry retrofit guidance](https://buildingscience.com/documents/bareports/ba-1505-measure-guideline-deer-interior-insulation-masonry-walls/view) covers these considerations.

For an accessible, vented attic, the work generally involves sealing air leaks at the ceiling, maintaining ventilation paths at the eaves, and adding insulation to the appropriate depth. Follow required clearances around chimneys, flues, and light fixtures. [DOE attic guidance](https://bsesc.energy.gov/energy-basics/air-sealing-existing-attics) recommends air sealing before insulating.

**For cost, assuming U.S. dollars:** HomeGuide’s 2026 estimate puts professionally installed attic insulation at roughly **$1–$4 per square foot**, or **$1,000–$4,000 for a 1,000-square-foot attic**. Removal, repairs, and substantial air sealing can add to that. DIY costs depend on the additional insulation needed and equipment rental. [HomeGuide attic cost estimate](https://homeguide.com/costs/attic-insulation-cost/)

A whole-house masonry wall retrofit can reach **tens of thousands of dollars** once framing, finishes, electrical work, and trim are included. Treat that as a planning allowance: the description alone cannot support a reliable quote. Ask contractors to price the complete finished assembly, using **wall area**, rather than just the insulation material.

Before purchasing, I would ask for:

- Confirmation of wall construction and attic insulation type, depth, and condition.
- An assessment of leaks, damp masonry, and drainage.
- An energy assessment to identify which improvements offer the best return.
- Separate estimates for attic work and wall retrofits.

If the attic contains vermiculite, leave it undisturbed and get professional advice; it may contain asbestos. [DOE guidance](https://www.energy.gov/sites/default/files/2023-03/insulation_guide_0.pdf)

Your location, house size, and attic access would help narrow the budget considerably.