---
title: "Air Sealing Gaps And Cracks"
url: https://betterhomebetterplanet.com/catalogue/air-sealing-gaps-and-cracks/
description: "Closing the small unintended openings that let outside air move through the shell."
---

# Air Sealing Gaps And Cracks

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| »Categories[Building Envelope](https://betterhomebetterplanet.com/catalogue/building-envelope/)5[Heating, Cooling & Water](https://betterhomebetterplanet.com/catalogue/heating-cooling-water/)6[Water & Outside](https://betterhomebetterplanet.com/catalogue/water-and-outside/)4[Materials & Finishes](https://betterhomebetterplanet.com/catalogue/materials-and-finishes/)3»Project Types[Sealing and draughtproofing](https://betterhomebetterplanet.com/catalogue/air-sealing-gaps-and-cracks/)[Insulating](https://betterhomebetterplanet.com/catalogue/attic-and-loft-insulation/)[Water and pipework](https://betterhomebetterplanet.com/catalogue/hot-water-pipe-insulation/)[Planting and drainage](https://betterhomebetterplanet.com/catalogue/drainage-and-ground-levels/)[Surfaces and finishes](https://betterhomebetterplanet.com/catalogue/low-voc-paints-and-finishes/)»Quick FindJump straight to the entry that covers a common complaint.[Lower electricity bills](https://betterhomebetterplanet.com/catalogue/how-to-reduce-electricity-bill/)[Draughts](https://betterhomebetterplanet.com/catalogue/air-sealing-gaps-and-cracks/)[Cold rooms](https://betterhomebetterplanet.com/catalogue/wall-insulation-choices/)[Condensation](https://betterhomebetterplanet.com/catalogue/secondary-glazing-and-films/)[Damp at low level](https://betterhomebetterplanet.com/catalogue/drainage-and-ground-levels/)[Noise between floors](https://betterhomebetterplanet.com/catalogue/floor-underlay-and-acoustics/)[Slow hot water](https://betterhomebetterplanet.com/catalogue/hot-water-pipe-insulation/)[Summer overheating](https://betterhomebetterplanet.com/catalogue/planting-mulch-and-shade/) | BE-01Straightforward · Cool, still weatherClosing the small unintended openings that let outside air move through the shell.Section[Building Envelope](https://betterhomebetterplanet.com/catalogue/building-envelope/)ReferenceBE-01DifficultyStraightforwardSeasonCool, still weatherTypical scopeA weekend, room by roomWhat it affectsDraughts, heating load, comfort near wallsWhat this isAir sealing means finding the unintended openings in the shell of a house and closing them with a material that stays flexible. It is not the same as insulation. Insulation slows heat moving through a solid layer; air sealing stops air carrying heat straight past that layer. A wall can be well insulated and still feel cold if air moves freely around the insulation, which is why sealing is usually the first thing worth doing.Telling whether your home needs itThe openings are rarely obvious. They collect where different materials meet: around loft hatches, at the top of internal walls, behind skirting boards, where pipes and cables pass through, around recessed light fittings, and at the frames of windows and doors. On a cold, windy day you can find many of them by moving the back of a hand slowly along those junctions. Dust staining on insulation or carpet edges marks places where air has been moving for a long time.What the job involvesWork from the top of the house downwards, because warm air leaves highest. Larger gaps get a backing material pushed in first so the sealant has something to grip. Narrow cracks take a flexible sealant; wider openings around pipes take an expanding filler cut back flush once cured. The loft hatch itself is usually worth treating as a small door, with a compression seal around the rebate and insulation fixed to its upper face.Things to watchA house needs a controlled supply of fresh air, so sealing should go together with keeping deliberate ventilation clear: trickle vents, extract fans and air bricks stay open. Never seal an air brick serving a room with a fuel-burning appliance. Around flues, chimneys and recessed fittings that get hot, use a material rated for high temperature rather than a general-purpose filler.**More in Building Envelope:** [Attic And Loft Insulation](https://betterhomebetterplanet.com/catalogue/attic-and-loft-insulation/) · [Wall Insulation Choices](https://betterhomebetterplanet.com/catalogue/wall-insulation-choices/) \| [All Building Envelope entries](https://betterhomebetterplanet.com/catalogue/building-envelope/) \| [Catalogue index](https://betterhomebetterplanet.com/catalogue/) | »Catalogue StatusThis catalogue holds **18** entries across **4** sections.Entries are written to be read and worked from. Nothing here is ordered, priced or supplied.»Start Here[Air Sealing Gaps And Cracks](https://betterhomebetterplanet.com/catalogue/air-sealing-gaps-and-cracks/)[Attic And Loft Insulation](https://betterhomebetterplanet.com/catalogue/attic-and-loft-insulation/)[Weatherstripping Doors](https://betterhomebetterplanet.com/catalogue/weatherstripping-doors/)[Thermostat Settings And Zoning](https://betterhomebetterplanet.com/catalogue/thermostat-settings-and-zoning/)[Radiator And Baseboard Care](https://betterhomebetterplanet.com/catalogue/radiator-and-baseboard-care/) |
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|  | BE-01Straightforward · Cool, still weatherClosing the small unintended openings that let outside air move through the shell. |  |
| Section | [Building Envelope](https://betterhomebetterplanet.com/catalogue/building-envelope/) |  |
| Reference | BE-01 |  |
| Difficulty | Straightforward |  |
| Season | Cool, still weather |  |
| Typical scope | A weekend, room by room |  |
| What it affects | Draughts, heating load, comfort near walls |  |

4 sections · 18 entries · 5 index pages

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[Building Envelope](https://betterhomebetterplanet.com/catalogue/building-envelope/)

[Heating, Cooling & Water](https://betterhomebetterplanet.com/catalogue/heating-cooling-water/)

[Water & Outside](https://betterhomebetterplanet.com/catalogue/water-and-outside/)

[Materials & Finishes](https://betterhomebetterplanet.com/catalogue/materials-and-finishes/)

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