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Old-House Online » Old-House Tips, Restoration Stories, & More » Repairs & How To » 7 Ways to Weatherize

7 Ways to Weatherize

Quick tips on tightening up old houses for better cold-weather comfort. By the OHJ Editorial Staff

    A few smart moves can keep your old house snug all winter long.

    A few smart moves can keep your old house snug all winter long. (Photo: Elenathewise/

    When cold weather sets in, old houses tend to feel it first. Given their seasoned construction, some lose heat through conduction (transfer through materials), but even more escapes via infiltration (air movement through cracks and joints). The secret—if there is one—to making an old house more thermally efficient and comfortable in cold weather is limiting the opportunities for these losses. It’s picky work, but low-tech in terms of skill and materials. Plus, it more that pays for the minimal materials costs. As you work your way around the building this fall, look to improve the following key weatherizing areas’and keep your caulking gun handy.

    1. Seal window and door exteriors.

    Caulking all around the frame, especially where trim edges meet shingles or clapboards, helps prevent air and water infiltration through these joints and gaps in the building envelope. (It improves the paint job too.) Also caulk joints between dissimilar building materials, such as where wood meets stone. However, do not caulk the undersides of windows or doors, or where clapboards lap. These spaces are important exits for moisture vapor. Clear silicone or polyurethane caulks are good for this work; where the surface will be painted choose good-quality acrylic-latex caulk.

    2. Point up foundations.

    Inspecting existing weatherstripping and sealing gaps around windows and doors will help keep drafts at bay.

    Inspecting existing weatherstripping and sealing gaps around windows and doors will help keep drafts at bay. (Photo: Karen Smith)

    Many old houses sit on stone, brick, or concrete block foundations. As this masonry settles slightly or wood sills shrink, gaps can appear at the sill line. Before addressing any large air leaks with caulk, trowel them closed with mortar.

    3. Inspect weatherstrips on doors.

    If your exterior doors have surface-mounted weatherstrips, such as rubber bulb seals along the jamb or sweeps along the floor, check their seal by looking for drafts with a lighted stick of incense. Then adjust if necessary. Inspect integral spring-metal weatherstrips for bent or missing sections and repair.

    4. Check fireplace damper.

    Most fireplaces built since 1900 have dampers just above the firebox that close off the flue to limit heat loss when it’s not in use. Make sure the damper is not damaged by age or stuck open (or shut) because of fallen debris. Call in a chimney sweep for major problems.

    5. Insulate unheated crawlspaces.

    Install rolls of batt insulation in the bays between upper floor joists. Staple wire mesh or rabbit fencing to the joists to hold the insulation in place. Though it’s been said many times before, place the vapor retarder (foil or other facing) towards the living space, not towards the ground. Also, install batts so there is an air space between the vapor retarder and the subfloor, and block the ends (to prevent moisture from entering the air space). Finally, lay medium-weight polyethylene sheeting across the ground (to block moisture migration) and tape joints.

    Chimneys, attics, and crawlspaces are all likely areas of cold air infiltration.

    Chimneys, attics, and crawlspaces are all likely areas of cold air infiltration. (Photo: Nathan Winter)

    6. Check storm windows and sashes.

    Storm windows not only protect the main window from winter rain and snow, they slow heat loss by creating a dead-air space – however, only if they are tight enough to limit air movement. Make sure storms fit snugly all around the window frame, leaving only a small weep hole to permit moisture vapor to escape. Loose storms are not only ineffective, they promote frost on the indoor window surface. Sashes should be equally tight, or they will lead to frost on the storm window. (Are your old windows not holding up through the winter? Learn more about sash window repair.)

    7. Seal all attic penetrations.

    Pipes, vents, hatches, recessed lights, and cracks that penetrate the second-floor ceiling are easy avenues for heat loss. Even more important, they allow moisture vapor to migrate to the attic, where cooler temperatures cause it to condense into liquid water that saturates insulation or freezes into frost. Close off large penetrations with plywood or wallboard, then seal all joints and cracks with clear caulk.

    Published in: Old-House Journal November/December 2000


    Catherine Brooks September 30, 2011 at 1:17 pm

    Regarding improvement in window seals: If seals are poor and the glazing putty is compromised, a longer-term solution may be needed: reglazing the windows. The composition of putty used in older homes is not standard. After decades of exposure, it often seriously hardened, cracked, and even fell off completely.
    The challenge is how to remove the often concrete-like, dry putty without breaking glass or damaging the wood. Heat has long been the preferred method to soften the putty sufficiently so that it can be chiseled off the wood without gouging it. Traditionally, high heat guns or torches were used. But their 1000+ degree heat focused only on a short strip of putty had to be moved frequently to prevent scorching of the wood. This created different temperatures across the glass; where the different temperatures met, the glass would break. The radiant, infrared heat from the Speedheater is evenly-distributed across the length of the 12″ bulbs. This softens the putty with little danger of cracking the glass and allows smooth chiseling to gently release the putty from the glass and from the wood.
    See and

    John Mattson February 2, 2012 at 4:21 pm

    Love the Speed Heater/Silent Paint Remover for many things. However, I have been working for the last several months to re-putty my 1903 windows, and the best solution has been STEAM. Yes, a plain $100 clothes steamer and lots of patience. The bad news is that century old, wavy glass, one-eighth inch thick is DELICATE stuff, and even at steam temperatures, sometimes the glass just cracks for no apparent reason. This is tricky business, and slow. I am only getting about 75% of the windows out without breaking.

    K&A Cameron February 27, 2013 at 4:07 pm

    A more subtle sales pitch from Catherine from Eco-Strip on this one. She never quits.

    Steve Smits February 27, 2013 at 6:36 pm

    I have found an effective technique to avoid cracking glass when a heat gun is used to soften putty. Take a plastering trowel and place it between the putty and the glass. Working on small sections of the putty soften it with the heat gun while holding the trowel against the glass surface. Soften the putty just enough to pop it loose with your putty knife. You can’t avoid slightly scorching the paint on the sash, but this can be easily repaired with sand paper and repainting it.

    Meryl Logue February 28, 2013 at 12:11 am

    Regarding windows: The infrared device at is actually 100% effective IF you have patience. The only glass I’ve broken so far has been that which my TOOLS broke, not the heat. Mind you I DID break a thermal-pane in my house in Eugene when using a heat-gun. (It was my last window that I was stripping the interior woodwork on. Bummer!) But so far (knocking on my old wood!), I’ve removed glazing putty from 2 dozen sashe windows using the Speedheater at eco-strip. I ALSO bought the extra “sash” tools. I think it was an extra $100, but VERY well worth it. I keep them sharp with a whetstone (not often a file). I use a (sharpened) stiff window glazing too for putting the putty in. I am getting excellent results. Do be aware, though, that the IR tool will heat up the paint as well as the putty. You have to set the tool on the glass at a 45-degree angle right at the edge of the putty, to let the aluminum baffles shield the glass, and that directs the heat to the wood/paint. It’s a good idea to reprime and paint anyway, but be aware.

    cheryl coull February 28, 2013 at 11:57 pm

    To remove old, dried out putty simply rehydrate it by liberally applying linseed oil and let it sit. Linseed oil was one of the original components of the putty. Apply as many times as needed, and have patience. Very little danger of breaking the glass.

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