The Complete Guide to Home Insulation and Winterizing Your Older Home

When most people think about keeping their home comfortable, the focus tends to be on the thermostat or the furnace. In reality, the biggest difference makers are usually hidden, your insulation, your air sealing strategy, and how well the home prevents heat loss through gaps and cracks. In this guide to insulation & winterizing older homes, we will cover the things you want to know about protecting your home in the winter months.

Done well, insulation and air sealing can make an older home feel dramatically less drafty, cut heating costs, protect pipes and finishes, extend the life of your heating and cooling system, and reduce moisture issues while improving overall comfort.

How Insulation Works, R Value and Air Sealing

Insulation slows heat flow. The higher the R value, the better the material resists heat moving through it. Two principles matter most.

Energy efficiency programs consistently recommend sealing air leaks first, especially in attics and crawl spaces, before adding insulation so you get the full performance you are paying for.

Main Types of Home Insulation, Pros, Cons, and Typical Costs

Costs vary by market and project complexity, however most residential insulation work falls somewhere in the range of approximately one to four and a half dollars per square foot installed. Basic materials such as fiberglass and cellulose tend to be at the lower end, while spray foam and complex detailing usually fall toward the higher end.

Fiberglass Batts and Rolls

Pros

• Relatively low cost
• Widely available and familiar to most contractors
• Do it yourself friendly in simple open attic areas
• Non combustible glass fibers

Cons

• Performance drops if batts are compressed, crooked, or loosely fitted
• Does not air seal, leaks still need caulk or foam
• Can irritate skin, eyes, and lungs during installation, protective gear is recommended

Best use, Straightforward attic or wall installations combined with careful air sealing at gaps and penetrations.

Blown In Fiberglass

Pros

• Fills irregular spaces better than batts
• Excellent choice for topping existing attic insulation to reach current R value targets
• Non combustible fibers

Cons

• Requires blowing equipment and usually professional installation
• Needs proper air sealing at the attic floor to perform as rated

Best use, Upgrading under insulated attics in existing homes without major demolition.

Cellulose Insulation

Pros

• Excellent coverage, fills small voids well
• Very good sound deadening
• High recycled content and often seen as an eco friendly choice
• Solid R value per inch, generally in the range of a little over three to nearly four per inch, depending on product and density

Cons

• Must be kept dry, moisture can cause settling or damage
• Performance depends heavily on correct installation density
• Usually requires a professional crew, especially for dense pack wall work

Best use, Older homes where you want to insulate closed walls and create a deep blanket over the attic floor without removing interior finishes.

Spray Foam Insulation

Open cell spray foam

• Softer and lower density
• R value generally in the range of about three point five to four per inch

Closed cell spray foam

• Higher density and more rigid
• R value often around six to seven per inch
• Adds some structural strength and improves moisture resistance

Pros

• Excellent air sealing combined with high R value per inch
• Ideal for irregular shapes and tight spaces
• Closed cell foam can help with moisture control

Cons

• High upfront cost compared with other materials
• Requires trained professional installation
• Difficult and expensive to remove once installed

Best use, Rim joists, complex attic rooflines, and situations where you need insulation and air sealing in one step and space is limited.

Rigid Foam Board Insulation

Pros

• High R value per inch, especially for polyisocyanurate
• Can create a continuous insulation layer that breaks thermal bridges
• Seams can be taped and edges foamed for good air sealing

Cons

• Requires careful measuring and cutting
• Must be protected as required by code where exposed
• Some products use blowing agents with higher environmental impact

Best use, Exterior retrofits, basement and crawl space walls, attic kneewalls, and insulated covers for attic hatches.

Mineral Wool Insulation

Pros

• Excellent fire resistance
• Good sound control
• Fibers shed water and dry quickly
• R values similar to or slightly higher than standard fiberglass batts

Cons

• More expensive than basic fiberglass
• Heavier and stiffer, can be a little more work for do it yourself projects

Best use, Fire sensitive areas, sound control applications, and as a premium upgrade over fiberglass in walls and attics.

Radiant Barriers and Reflective Insulation

Pros

• Can reduce radiant heat gain into attics in hot, sunny climates
• Works well when combined with standard insulation materials

Cons

• Does not replace thermal insulation in cold climates
• Benefits are modest where winter heating demands dominate

Best use, Hot summer regions where roof heat gain is a major concern and where it can be paired with regular insulation.

Rigid Fiber Board for Ducts

Rigid fiber boards made of dense fiberglass or mineral wool are typically used to insulate duct systems in unconditioned spaces. They handle higher temperatures than foam and help reduce energy loss and condensation on ducts, however they are a specialty product that is usually installed by heating and cooling professionals and not used for general walls or attics.

Specialty Green Insulations

There are additional niche products such as recycled denim batts and sheep’s wool. These options can be attractive from a sustainability or marketing standpoint, but they are often more expensive and less widely available. In many cases, performance is similar to fiberglass or cellulose at a higher price point.

Winterizing Your Older Home, A Practical Checklist

Older homes have unique weak points, vented crawl spaces, decorative dormers, drafty windows, gable vents, and uninsulated transitions in the attic. The following winterizing steps focus on the major areas where heat is lost and cold air sneaks in.

Close Foundation Vents in Cold Weather

Closing vents in cold weather can reduce cold floors and help protect pipes, especially in older homes.

Attic Gable Windows and Louvers

Many older homes have small attic windows or large gable louvers. In winter, you want to limit uncontrolled wind while maintaining any required roof ventilation.

• Make sure operable attic windows are fully closed, latched, and weather stripped
• For large louvers, confirm whether soffit and ridge vents already provide the required ventilation
• Where wind is blowing directly onto insulation, consider adding rigid backing and air sealing on the attic side while leaving appropriate vent area

Decorative Dormers and Attic Kneewalls

Dormers and half story rooms in older homes are often charming on the outside but poorly detailed on the attic side.

Seal Attic Perimeter Gaps and Penetrations

Attics are often the single largest source of unnoticed air leaks in a home. Look carefully at the attic floor and roof penetrations.

• Seal gaps along the top plates of exterior walls
• Block and seal open chases around plumbing stacks and vent pipes
• Use metal flashing and high temperature sealant around flues and chimneys where required
• Seal wiring holes, bath fan housings, and recessed fixtures rated for insulation contact
• Add insulation dams to keep loose insulation away from hot flues and clear around the attic access opening

Attic Hatch and Pull Down Stairs

These details turn a major weak point in the thermal envelope into a better performer.

Temporary Winter Protection for Older Windows

If you are not ready to replace older windows, there are simple temporary steps that can improve comfort during cold weather.

• Use interior shrink film window kits to add a clear interior layer and create an air space
• Add foam or rubber weather stripping where sashes meet the frame
• Press removable rope caulk into narrow gaps around the frame
• Use thermal curtains or lined drapes on cold nights to reduce radiant heat loss

Seal Drafts Around Outlets and Switches

Outlets and switches on exterior walls can be a surprising source of drafts in older homes.

Seal Around Pipes, Wires, and Utility Penetrations

Anywhere a pipe, wire, or vent passes through a wall, floor, or ceiling, air can follow the same pathway.

• Look under sinks where plumbing goes into walls or floors
• Check the attic for gaps around pipes, wires, and vent boots
• Seal with caulk or low expansion spray foam, using metal and fire safe sealants around hot flues as required
• In the attic, watch for dusty or discolored insulation that can mark air movement

Doors, Baseboards, and Trim Gaps

Many small leaks together can equal one large leak. Doors and trim areas are simple places to improve comfort.

• Weather strip exterior doors so they close snugly without visible light
• Add or replace door sweeps to block air at thresholds
• Caulk along baseboards on exterior walls where you feel cold air at floor level
• Seal cracks where window and door casings meet the wall

Exterior Pipes and Hose Spigots

Exterior faucets and exposed pipes can be vulnerable to freezing, even in milder climates during a cold snap. At a minimum, disconnect all hoses, use insulated faucet covers, and insulate any exposed pipes in crawl spaces or along exterior walls. For more detail on this topic, JoJo has a dedicated guide to winterizing outdoor faucets and hose bibs that can be referenced from this article.

Winterizing Your Home If You Are Leaving for the Season

If your home will sit empty for part of the winter, extra precautions can help prevent frozen pipes, leaks, heating and cooling failures, and general damage.

Keep the Heat On

Light Plumbing Preparation With Heat Left On

• Open sink cabinet doors so warm air can reach pipes on exterior walls
• Wrap vulnerable pipes in crawl spaces, basements, or unheated areas
• Shut off water to washing machines or ice makers if they are near cooler spaces
• Confirm that crawl space vents are addressed and pipes are insulated

Full Plumbing Winterization for Long Absences

For longer absences or more extreme cold events, many homeowners choose a more complete plumbing winterization. This is optional in some climates but can be wise if the home is older or has pipes in exposed locations.

Use only RV or marine antifreeze that is designated for plumbing systems. Do not use automotive antifreeze inside a home’s plumbing.

Treat Toilets, Drains, and Traps

• Add RV or marine antifreeze to toilet bowls and, if drained, to toilet tanks
• Pour antifreeze into sink and tub drains to protect P traps
• Add antifreeze to floor drains and shower drains where water may sit

This approach is widely used in vacation homes and cabins to protect fixtures from freeze damage when a home is vacant.

Protect Appliances

• Run dishwashers and washing machines empty to clear internal water where possible
• Add a small amount of RV antifreeze to floor drains and standpipe drains serving appliances
• Turn off ice makers and any appliance water supplies that are not needed
• Unplug sensitive electronics and small appliances to protect them from power surges

Water Heater Settings

• If water remains on, set the water heater to vacation or low mode to save energy while still protecting the unit
• If you have shut off the water and are fully winterizing, consider draining the water heater tank according to manufacturer instructions

Inspect Vulnerable Areas Before Leaving

Before you lock the door, do a slow walkthrough of the home, paying special attention to:

• Crawl spaces, basements, and mechanical rooms
• Attics and attic access points
• Pipes on exterior walls, especially behind cabinets
• Exterior hose bibs and any exposed piping
• Utility rooms with plumbing or mechanical equipment

Prepare for Possible Power Outages

General House Preparation

• Bring in or secure outdoor items that could be damaged
• Remove perishables from the refrigerator and pantry as needed
• Check batteries in smoke detectors and carbon monoxide alarms
• Set interior lights on timers if desired for security
• Lock all windows and doors tightly to reduce drafts and improve security

Putting It All Together

A smart winterizing plan for an older home follows a logical sequence.

Handled in this order, your home becomes warmer on cold mornings, less drafty along the floors and around windows, and more energy efficient, all while preserving the character and charm that drew you to your older home in the first place.

Disclaimer

The information provided in this article is for general educational purposes only. Every home is unique and conditions can vary significantly based on age, construction methods, materials, prior renovations, and the current state of plumbing, insulation, and mechanical systems. Homeowners should consult a licensed contractor, plumber, HVAC professional, or other qualified specialist before making changes to insulation, exterior pipes, sprinkler systems, heating settings, or any other part of the home that may impact safety, structural integrity, or energy performance.

Weather related recommendations, freezing precautions, and winterizing steps are offered as general guidelines. They are not a substitute for professional evaluation of your specific property. Joanna “JoJo” Jones and her team do not assume responsibility for any actions taken based on this article. Always use caution, follow all manufacturer instructions, and seek professional assistance when needed.