HomeShape AI — How-to guide
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HomeShape Repair Coach
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Interior Finishes · Air Sealing & Weatherproofing
Windows, Caulk & Weatherstripping
Windows and doors account for roughly a fifth of a typical home's total air leakage — and almost none of it comes from the glass itself. It's the failed caulk bead and the flattened weatherstrip around the frame doing the damage, and both are among the cheapest, most DIY-friendly fixes in the entire house.
All 9 zonesLifespan: caulk 5–10 yrs, weatherstrip 3–7 yrs~21% of home air leaks are windows & doorsInterior Finishes
Whole-house re-weatherstrip
$130–$470
DIY materials, all doors/windows
Whole-house re-caulk
$200–$500
DIY materials, exterior trim
Share of home air leaks
~21%
from windows & doors combined (ENERGY STAR)
DIY-able tasks
~75–80%
of routine maintenance
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Exterior window caulk — the sealant bead where the window frame meets the siding, trim, or masonry. Typically a paintable acrylic-latex or a more flexible siliconized-acrylic/polyurethane hybrid, rated for 5–10 years outdoors before UV and thermal cycling cause it to crack, shrink, or pull away from one side of the joint. This is the single most common building-envelope air leak point in an average home, and one of the cheapest to fix.
Maintenance tasks
| Task | Cadence | Skill | Time | Consequence if skipped |
|---|---|---|---|---|
Inspect the caulk bead for cracks or gaps UV exposure and seasonal expansion/contraction are the two things that break a caulk seal down | Annually, spring or fall | 1 · Beginner | 15 min (whole house) | Water intrusion behind siding and rising energy bills go unnoticed for years |
Cut out and remove failed caulk Old caulk must come out clean or new caulk won't bond | As needed, per failed joint | 2 · Confident | 10–15 min per window | New caulk applied over failed caulk fails again within months |
Clean and dry the joint before recaulking Dust, mildew, and moisture all prevent adhesion | Same visit as removal | 1 · Beginner | 5 min per window | Poor adhesion and premature re-failure |
Apply new exterior-grade caulk Choose a paintable siliconized-acrylic or polyurethane, not pure silicone if painting is planned | Every 5–10 years or as failures appear | 2 · Confident | 10 min per window | Continued air and water leakage at the frame |
Check for gaps at corners and the sill Corners and the bottom sill see the most movement and water exposure | Annually | 1 · Beginner | 5 min per window | Sill gaps are the most likely spot for water to reach the wall sheathing |
Tool the bead for a clean, sealed finish A poorly tooled bead leaves pinholes that still let air and water through | Same visit as application | 1 · Beginner | 2 min per window | A cosmetically fine-looking bead that still leaks at microscopic gaps |
Troubleshooting
Symptom
Likely cause
Action
Who
Caulk looks fine but a draft is still felt near the window
The leak may be at the interior trim or between the frame and rough opening, not the exterior bead
Check interior trim and use a smoke pencil or the back-of-hand test to locate the actual gap
DIY ok
Caulk has pulled away from one side of the joint but not cracked
Normal thermal-cycling adhesion failure, common on south/west-facing windows
Remove and replace just that section — no need to redo the whole bead if the rest still adheres
DIY ok
Paint or caulk is bubbling or peeling right after a fresh application
Caulk applied over a damp or dirty surface, or incompatible caulk-over-paint chemistry
Remove, let the surface fully dry, clean again, and reapply with a paintable-rated product
DIY ok
Water staining or soft trim appears below a window despite caulk looking intact
The leak is happening behind the visible caulk line, at the flashing or sill pan
Stop — this is a water-intrusion issue behind the wall, not a caulk issue; get it inspected before more damage occurs
Call pro
Recommended tools & materials
Weatherstripping — the compressible seal (foam tape, felt, vinyl bulb, or door sweep) between a moving window sash or door and its frame. Unlike caulk, this seal has to survive repeated compression every time the window or door opens and closes, so it wears out faster — typically 3–7 years depending on material and how often the opening is used.
Maintenance tasks
| Task | Cadence | Skill | Time | Consequence if skipped |
|---|---|---|---|---|
Inspect weatherstripping for gaps or flattening Compressed, cracked, or gapped strips no longer seal | Annually, before heating/cooling season | 1 · Beginner | 10 min (whole house) | Drafts and energy loss at every operable opening |
Do the dollar-bill or light test A simple way to confirm the seal is actually compressing | Annually | 1 · Beginner | 10 min | Passing this test with a gap means the seal isn't doing its job even if it looks fine visually |
Remove and replace worn weatherstripping Adhesive-backed foam and vinyl strips are made for easy DIY replacement | Every 3–7 years, or when compression fails | 2 · Confident | 20–30 min per opening | Continued drafts even after new caulk is applied elsewhere |
Adjust or replace the door sweep The bottom seal on exterior doors sees the most foot-traffic wear | Every 3–5 years or as it wears | 2 · Confident | 15 min | Visible daylight gap under the door, pest entry, and the single largest single-point draft in most homes |
Clean tracks and channels before reinstalling Debris in the track prevents new weatherstripping from seating correctly | Same visit as replacement | 1 · Beginner | 5 min | New weatherstripping fails to seal evenly |
Lubricate window and door hardware Stiff hinges or sash locks can prevent full closure, defeating even good weatherstripping | Annually | 1 · Beginner | 10 min (whole house) | A sash or door that doesn't close all the way negates any weatherstripping |
Troubleshooting
Symptom
Likely cause
Action
Who
Draft persists after installing new weatherstripping
The sash or door isn't closing/latching all the way, so the new seal never compresses
Check and adjust hinges, strike plates, or sash locks so the opening closes fully
DIY ok
Foam weatherstripping keeps falling off within weeks
Old adhesive residue or a dirty/cold surface prevented proper bonding
Clean the surface fully with rubbing alcohol and apply in a warmer temperature for better adhesive set
DIY ok
Door sweep drags or won't let the door close
Sweep installed too low, or the threshold has settled/warped
Adjust the sweep height; if the threshold itself is warped or sunken, that's a carpentry fix
DIY ok
Ice or heavy condensation forms on the inside of a window sash in winter
Warm indoor air leaking through a poor seal is condensing on the cold glass/frame
Improve the weatherstripping seal; persistent heavy condensation can lead to wood rot at the sill if unaddressed
Call pro
Recommended tools & materials
Glazing and insulated-glass seal — for older single-pane windows, “glazing” is the hardened putty compound holding the glass into the sash; for modern double- or triple-pane windows, the “seal” is the sealed gap between panes (an insulated glass unit, or IGU) filled with air or argon. The two fail completely differently: putty glazing dries out and cracks with age, while an IGU seal fails once and cannot be re-sealed — only the whole glass unit can be replaced.
Maintenance tasks
| Task | Cadence | Skill | Time | Consequence if skipped |
|---|---|---|---|---|
Inspect old-style glazing putty for cracks or gaps Putty dries, shrinks, and separates from the glass or sash over decades | Every few years on older single-pane windows | 1 · Beginner | 10 min per window | Glass can loosen or rattle, and air/water gets behind the pane |
Re-glaze cracked or missing putty A traditional but learnable skill for single-pane wood windows | As needed, per failed section | 3 · Advanced | 30–45 min per pane | Loose or falling glass, and a major air leak at the pane itself |
Check insulated glass units for fogging or condensation between panes This is the tell-tale sign the factory seal between panes has failed | Annually | 1 · Beginner | 5 min per window | A failed IGU seal cannot be fixed after the fact — only replaced, and the failure gets worse over time |
Inspect exterior glazing/glass stops for paint failure Peeling paint on wood glazing stops signals moisture getting into the wood | Every 2–3 years | 1 · Beginner | 5 min per window | Wood glazing stops rot, requiring full sash repair rather than a simple reglaze |
Get IGU replacement quoted once fogging appears Replacing just the glass unit (not the whole window) is usually far cheaper than full window replacement | Once fogging/condensation is confirmed | 3 · Advanced | 1–2 hrs (pro), per unit | Continues losing insulating value and looking permanently foggy while cost of full replacement climbs |
Troubleshooting
Symptom
Likely cause
Action
Who
Foggy or cloudy haze between the panes that won't clean off
The IGU seal has failed and moist air has entered the gap — this is permanent, not dirt
Get the glass unit itself replaced; cleaning will not fix it since the moisture is trapped between panes
Call pro
Putty is crumbling and falling out around a single-pane window
Age-hardened glazing putty has dried past its flexible working life
Remove loose putty, prime bare wood, and reglaze with fresh compound
DIY ok
Glass rattles in the frame
Glazing points or putty holding the glass have failed or gone missing
Reseat the glass and secure it with new glazing points before reglazing over them
DIY ok
Water is visibly pooling or trapped between the panes of a double-pane window
A more advanced IGU seal failure allowing liquid water intrusion, not just humid air
This unit needs replacement — continued use risks mold growth inside the sealed unit
Call pro
Recommended tools & materials
Storm windows and interior insulation — a secondary layer added over or inside an existing window rather than replacing it: exterior storm windows/doors, interior storm window inserts, or shrink-film window insulation kits. These are the lowest-cost way to cut window-related heat loss without full window replacement, and are especially common as a stopgap on older single-pane windows.
Maintenance tasks
| Task | Cadence | Skill | Time | Consequence if skipped |
|---|---|---|---|---|
Inspect storm window frames and seals Aluminum storm frames and their gaskets weather over years outdoors | Annually, before winter | 1 · Beginner | 10 min per window | Reduced insulating benefit and potential water intrusion between storm and primary window |
Clean storm window tracks and weep holes Weep holes let condensation drain out; clogged ones trap water | Annually | 1 · Beginner | 5 min per window | Trapped moisture between the storm and primary window can rot the sill |
Install or refresh interior shrink-film window insulation A seasonal, low-cost DIY air-sealing layer using a hair dryer to shrink clear film taut | Annually, each heating season | 1 · Beginner | 15–20 min per window | Missing out on one of the cheapest per-window heat-loss reductions available |
Check interior storm window inserts for fit Compression-fit acrylic or magnetic inserts lose effectiveness if the frame warps or the gasket compresses | Annually | 1 · Beginner | 5 min per window | A loose insert provides little more than the primary window alone |
Switch storm window panels between glass and screen seasonally Traditional combination storms swap a glass panel in winter for a screen in summer | Twice yearly, spring/fall | 2 · Confident | 10 min per window | Reduced ventilation in summer or reduced insulation in winter |
Troubleshooting
Symptom
Likely cause
Action
Who
Condensation or frost forms between the storm and primary window
Blocked weep holes trapping humid air, or the primary window's own seal is the actual leak source
Clear the weep holes first; if it persists, the primary window's air seal likely needs attention
DIY ok
Shrink film has gaps or won't stay taut
Incomplete double-sided tape adhesion around the frame, often from a dusty or cold surface
Clean the frame surface fully and reapply tape before rehanging and re-shrinking the film
DIY ok
Storm window won't latch or close flush
Frame has warped, or the track has debris or corrosion buildup
Clean the track first; a warped aluminum frame usually needs replacement rather than repair
DIY ok
Interior insert traps visible moisture against the primary window glass
The primary window itself is leaking humid indoor air into the sealed gap
Improve the primary window's own weatherstripping/caulk seal — the insert is exposing an existing leak, not causing one
DIY ok
Recommended tools & materials
Relevant In Your Zone
The Deep Freezer
Sealing drafts matters when it is this cold outside.
The High-Altitude Hybrid
Thermal swings between sun and cold crack seals fast.
The Windy High Plains
Wind-driven moisture finds every gap in siding and windows.
The Humid Hotbox
Sealed entry points keep humidity and pests out.
The Dry Scorcher
UV exposure breaks down caulk and weatherstripping over time.
Related Guides
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