4 Ways To Winterproof Your Home

How do you winterproof a home and keep the heating bills down?

Keeping a house warm in winter is mostly about stopping cold air getting in, not about generating more heat. Four measures below, and the first one — sealing gaps — is the one that pays back fastest, because every gap you seal is heated air you stop losing.

1. Check for gaps and draughts

Holes and gaps are a welcome entryway for cold air. Inspect the house thoroughly, paying careful attention to skirtings, walls, architraves and even light fittings — particularly older downlights.

The Selleys No More Gaps range is a quick and easy solution for most gaps in architraves, with products for both inside and outside. A door snake handles the gap under a door, which is the one you cannot caulk.

Which product depends on where the gap is:

• Interior joints — skirtings, architraves, cornices, the wall-to-ceiling line. No More Gaps Interior Multipurpose gives a smooth finish with superior flexibility and low shrinkage. Interior Fast Dry does the same job if you want to paint the same day: semi-gloss immediately, gloss and low sheen at 10 minutes, flat at 100 minutes and ceiling paint at 120 minutes, against 60 and 180 minutes for the Multipurpose version. Both handle a maximum gap of 10mm wide by 5mm deep.
• Exterior — No More Gaps Exterior, with ±25% movement capability (ISO 9046), weather, mould and UV resistant. Paintable once skinned, at around 30 minutes; allow 24–48 hours before oil-based paints.
• Brick and mortar — No More Gaps Bricks & Mortar for repairs in brick and cement, with a mortar-like finish.
• Wet rooms — No More Gaps Bathroom & Kitchen, ±25% joint movement, with superior water and mould resistance.
• Timber floors — No More Gaps Timber Floors, for gaps around and between tongue and groove flooring and between other timber panels and fittings. 25% movement capability (ISO 9046).

A caution about light fittings. Gaps around older downlights are a genuine source of heat loss into the roof space, but downlights have clearance requirements for a reason. Do not pack or seal around a light fitting without checking what the fitting itself requires — this is one gap where a licensed electrician is the right answer rather than a caulking gun.

2. Pull out the rugs

If you have hard floors — timber or tiles — winter is the time for rugs. They help retain heat and they feel better underfoot. It is the cheapest measure on this list.

3. Thicker window coverings

Sheer curtains look good on a balmy summer night but do very little in winter. Thick window coverings, particularly curtains that reach the floor, are a good way to keep cold air outside — glass is the least insulating surface in most rooms, and a heavy curtain effectively adds a layer to it.

4. Clean out your air conditioning

Keep the air filters clean through the season. If your home gets dusty or has pet hair — most do — clean them once or twice per season. Airflow improves, the system runs more hygienically, and you save on the energy bill.

Why sealing gaps works better than it looks like it should

A 3mm gap running the length of a skirting board is a slot several thousand square millimetres in area. Air moves through it continuously, driven by the temperature difference between inside and out. Sealing it is not about draught-proofing one visible spot; it is about closing the total open area of the building envelope, which is why doing all of the skirtings and architraves in a room makes a noticeable difference where doing one does not.

The reason a flexible filler is specified for these joints is that they move. A skirting board and a wall are separate elements that expand and contract independently, so a rigid filler bridging them cracks — and a cracked filler is a gap again. Flexibility is what makes the seal last past the first summer.

Limitations — where these fillers should NOT be used

• Maximum gap size. The interior products and No More Gaps Exterior are all rated to 10mm wide by 5mm deep. Beyond that, shrinkage during cure becomes visible and paint over the top can crack — most noticeably with low binder flat and ceiling paints. For larger voids, use No More Big Gaps or an expanding foam.
• Application temperature. No More Gaps Exterior is not to be stored or applied below 10°C — a real constraint in winter, which is exactly when you want to use it. Bricks & Mortar and Timber Floors have a 5°C floor. Work on a mild afternoon rather than an early morning.
• No More Gaps Bathroom & Kitchen — not for outdoor use or constant moisture exposure, and not recommended around bathtubs, showers and sinks, where a wet area silicone is needed instead.
• No More Gaps Exterior — not for sealing around bathtubs and kitchen sinks, and not for areas prone to frequent water immersion.
• No More Gaps Bricks & Mortar — not for areas of frequent water immersion, not for replacing mortar in construction, and not for moving cracks.
• No More Gaps Timber Floors — not for exterior use, not for gaps larger than 3mm wide in trafficable joints, and not for gaps between tongue and groove boards or weatherboards.

Safety: sealing a house up in winter works against what one of these products needs

The No More Gaps range used for measure 1 is mild. Interior Multipurpose is not classified as hazardous at all; Interior Fast Dry, Exterior, Bathroom & Kitchen and Timber Floors are each Warning with H317 (may cause an allergic skin reaction) and nothing more. Gloves, and wash your hands.

The product named for larger voids is in another category. No More Big Gaps is an isocyanate-based polyurethane foam, signal word Danger, with H222 (extremely flammable aerosol), H229 (pressurised container, may burst if heated), H334 (may cause allergy or asthma symptoms or breathing difficulties if inhaled), H351 (suspected of causing cancer — suspected, not established), H372 (causes damage to organs through prolonged or repeated exposure) and H362 (may cause harm to breast-fed children), plus H332, H335, H315, H317 and H319.

The conflict is specific to this guide. You are doing this work in winter, in a closed-up house, with the heater on — that is the whole premise. The foam's own requirement is active ventilation, not an open door, and no work in a confined space. Those two things cannot both be true in the same afternoon. If you use foam, open the room up properly and accept losing the heat for the duration, or do it before the cold sets in. H334 is why: respiratory sensitisation is generally permanent once acquired, symptoms can appear hours later, and afterwards much smaller exposures trigger it.

H222 and the heating are the second conflict. An extremely flammable aerosol discharged around skirtings, architraves and light fittings sits in the same rooms as a gas heater, a flue or a wall furnace. Turn the heating off before you spray and let the room air before you turn it back on. H229 also means the can must not be stored in a roof space or a car, and never above 50 °C.

Do not let the cold push you into the wrong product. The temptation this page creates is real: No More Gaps Exterior cannot be applied below 10 °C, and foam is not similarly limited. That is not a reason to substitute. Wait for a mild part of the day and use the water-based filler, which is what these 10 mm by 5 mm joints call for anyway.

And the page is right about downlights — that gap is an electrician's call, not a caulking gun's, and certainly not a foam can's. Poisons Information Centre — 131 126 in Australia, 0800 764 766 in New Zealand.

Common questions about winterproofing

Where do the worst draughts come from?

Skirtings, walls, architraves and older light fittings are the places worth inspecting first, plus the gap under external doors.

Which gap filler for architraves?

An interior flexible filler — No More Gaps Interior Multipurpose, or Interior Fast Dry if you want to paint the same day.

How soon can I paint over the filler?

Interior Multipurpose: 60 minutes for gloss and sheen paints, 180 minutes for flat and ceiling paints. Interior Fast Dry: semi-gloss immediately, gloss and low sheen at 10 minutes, flat at 100 minutes, ceiling at 120 minutes.

Can I use exterior gap filler in winter?

Only above 10°C. No More Gaps Exterior is not to be stored or applied below that, so pick a mild part of the day.

How big a gap can I seal with these?

Up to 10mm wide and 5mm deep. Anything larger needs a big-gap product or an expanding foam.

Should I seal around downlights?

Not without checking the fitting's own clearance requirements. Older downlights in particular have specific installation rules, and that is an electrician's call rather than a DIY caulking job.

Why did last year's filled gap crack open again?

Almost certainly because the joint moves and the filler used was rigid. Flexible gap fillers are specified for these joints for that reason.

Do heavy curtains really help?

Glass is the coldest surface in most rooms. Thick window coverings, particularly floor-length curtains, are a good way to keep cold air outside, where sheers do very little.

How often should I clean the air conditioning filters?

Once or twice per season if the home is dusty or has pets. It improves airflow and hygiene and saves on the energy bill.

What else should I look at while I am sealing?

Gaps around windows are usually worth more than gaps in architraves — see how to fill gaps around windows and how to prevent draughts in your home.