Drafty? How to Seal Your Windows and Doors From the Cold

With temperatures dropping, you don’t want to let the outside in. There are various easy ways you can seal tight your leaky windows and doors. The DIY experts at Stack Exchange tell you how.

Question:

I currently live in a rented apartment and the windows in my shower are not sealed, so it gets pretty cold there. The front door of the house also has a sealing problem.

The thing is, I’m not going to stay in this apartment more than a couple of months.

So, what are some good, cheap, fast solutions to seal my windows and front door as much as possible?

Answer: Stripping & Film

If your leaking problem is from loose fitting window sashes or a poor fitting door, the simplest and cheapest method would be to purchase some self-adhesive foam weather stripping . This rolled product can be easily installed at the bottom of a window or around the outside edge of the door frame. Select the smallest size that will help seal the gaps, then just peel and stick. Too large and you may have difficulty closing the door etc.

Another good window treatment is the clear plastic window film that mounts to the frame of the window. Use a hair dryer to «stretch» the film, thus sealing any air leaking in around the sides or through poorly glazed panes.

All these products are cheap and avail at any hardware store or box store like Lowes or Home Depot. Stay warm!

Answer: Window Insulator Kit

Get a window insulator kit . It is made of a clear, plastic material that goes over the window, with double-sided tape around the edges to seal it. It’s easy to set up and helps a lot with drafty windows . (Pictured to the right.)

Answer: Foam & Sillicone

If you can actually see the gaps in the windows, a can of » Great Stuff » would probably do the trick. It’s an expanding foam that you spray into gaps.

Or you could use a squeeze tube of » DAP Silicon II » and run a bead of it around the window. I’m going to assume that if you’re in an apartment for the short term you either don’t have a caulking gun or don’t want to buy one (don’t need yet ANOTHER thing to move when you do move), so the link goes to a «squeeze it yourself» tube of Silicon II.

As for the door, if it’s just a short term thing you may want to just wad up a bath towel and put it along the bottom of the door as a draft blocker for the short term.

Beware «Great Stuff»

Don’t use «Great Stuff» behind window casings and door jambs. It and its triple-expanding cousins can just about blow 1″ lumber off the house framing, severely warping window casings so windows won’t slide, and mucking up door jambs in a similar manner.

Low expansion foam, which is specifically labelled for door and window installation, should be the only product you use here. I had to help un-DIY a door installation. It involved a long bread knife, a long straight edge and cutting long thin wedges out of the foam until the door casing lumber was straight again.

Did we miss something? Do you know a better way to seal your windows and doors? Bring your expertise to the question at Stack Exchange — a network of Q&A sites on diverse topics from software programming to Apple & Android to bicycles . and plenty in between.

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DISCUSSION

unless your windows are ridiculously old and drafty AND you pay a lot for your heat, you’re going to pay more for those 3m kits then you were out in bills. I’ve run the numbers many many times in past years. Its a great idea but those things are just too pricey to be justified, especially if you’re going to remove it at the end of the season to open the windows.

Other suggestions above work as well.. another good one is painters plastic dropcloth. This is like $3 for enough footage to do multiple windows. Get whatever tape you feel like springing for. Avoid masking tape as its meant to be temporary, and that which stays leaves a horrible residue. Clear packing tape can be ok, but tends to fall off after a few monthes. Clear duct tapes works pretty well. Don’t leave on for more then a few seasons or once again you get residue.

Air Sealing Window and Door Rough Openings

Air seal the rough opening around doors and windows prior to installing trim to minimize air leakage.

• Fill the rough opening around windows and exterior doors with caulk, canned spray foam, or foam backer rod. If spray foam, use a low-expansion foam designated for doors and windows.
• Do not rely on fibrous insulation alone to block airflow; it will not air seal.

See the Compliance Tab for related codes and standards requirements, and criteria to meet national programs such as DOE’s Zero Energy Ready Home program, ENERGY STAR Certified Homes, and Indoor airPLUS.

Window and door rough openings are essentially big holes in the building envelope, and while these holes get filled with window and door units, the gaps between the units and the framing rough openings can be major sites for uncontrolled air leakage in a home (DOE 2000). However, by sealing these rough opening gaps, this air leakage can be significantly reduced. A study conducted at Oak Ridge National Laboratory’s Buildings Technology Center on window air sealing showed that windows with 3/4-inch rough-in gaps had an equivalent leakage area of 28.2 cm2/ m2. When the gap was sealed from the interior side of the wall, the equivalent leakage area was cut to 0.5 cm2/m2 (Baechler et al. 2010).

Sealing the gaps between window and door units and the framing rough openings requires care and precision. Unlike other parts of the air barrier on exterior walls, which have layers of redundancy, the seal around a window and door unit stands on its own: usually only a single closure separates the indoor air from the outdoors (BSC 2009).

Window and Door Sealing Materials

Too often, an attempt to seal around a window or door unit is made by stuffing the gap with fiberglass insulation. However, fiberglass is not an air barrier; air can readily seep through the insulation fibers. Instead, the gap should be filled with one or more of the following materials (DOE 2000):

Backer rod comes in both open- and closed-cell varieties. Only closed-cell products (usually made of polyethylene foam) should be used for sealing window and door rough openings, as open-cell foams can absorb and hold moisture. Closed-cell backer rod is typically stocked at hardware stores in 1/4 to 1-1/2-inch-diameters, and sold by the foot from a reel. Larger diameter backer rod (up to 4 inches) is also available in 6- or 7-foot lengths. Always use backer rod that is wider than the gap, so it can be pressed firmly into the gap and create a tight seal.

Figure 1 — Closed-Cell Backer Rod for Air Sealing Window and Door Rough Openings.

Air Sealing Window and Door Rough Openings

Air sealing window and door rough openings is typically done by the insulation contractor, but in some cases it may be done by the window and door installer or by the finish carpenter prior to installing window and door trim.

With the window or door unit permanently installed in the rough opening, air seal the opening as follows:

1. Trim back the shims securing the window or door unit to the wall framing. If possible, try to cut these back behind the interior face of the wall and jambs, so that sealant can be applied over the shims for a tighter seal.
2. Apply the sealant toward the interior edge of the window or door unit. Using this approach, the gap to the exterior can drain freely and will be pressure equalized with the exterior, which limits the potential for an air pressure difference to force water into the joint (BSC 2009).
   • With backer rod: Press the backer rod into the gap between the wall framing and the window or door unit. Use a flat bar to push it in. Apply even pressure; don’t force it in, or the tool will tear the backer rod. Push the backer rod to an even depth. If caulk will be applied over it, take care to create an even surface that will provide a uniform substrate for the caulk.
   • With caulk: If the gap is less than 1/2 inch wide, apply caulk over the backer rod for a tighter seal. Caulk should always be applied against backer rod, not just squeezed into the gap. Tool the bead against the backer rod. This will create an hour-glass shape (see Figure 3 below), which allows the sealant to expand and contract over time without cracking. Without the backer rod, the bead of caulk would be too thick and would be prone to cracking when it cures, and it would be resistant to flexing with movements in the building materials of the wall system as they change dimension with seasonal changes in temperature and humidity.

Figure 3 — Caulk Applied Against the Backer Rod to Seal a Window Rough Opening. When tooled, a bead of caulk (light blue) should have an hour-glass shape when applied against backer rod (dark blue). This profile allows the caulk to expand and contract over time without cracking.

• With nonexpanding foam, wear gloves when applying spray foam; the foam has an especially aggressive bond that will adhere to skin. Insert the spray nozzle about half an inch into the gap between the wall framing and the window or door unit. Keep the spray nozzle moving at a steady speed while applying the foam: Too slow and the foam will fill too much of the cavity; too fast will result in gaps in the bead.

Visual Inspection

Visually inspect the seals between the window rough openings and the window and door units prior to installing interior finish materials. The seal from caulk or nonexpanding foam should be uniform without any visible gaps.

Blower Door Testing with Smoke Pencil Diagnostics

Blower door testing, conducted as part of whole-house energy performance testing, may help indicate whether windows have been successfully sealed. With the blower door pressurizing the house, use a smoke pencil to check for air around windows. A smoke trail moving away from the smoke pencil into the wall around the window or door unit indicates a leak that should be sealed.

National Rater Field Checklist

Thermal Enclosure System.
4. Air Sealing (Unless otherwise noted below, “sealed” indicates the use of caulk, foam, or equivalent material).
4.6 Rough opening around windows & exterior doors sealed. 28

Footnote 28) In Climate Zones 1 through 3, a continuous stucco cladding system sealed to windows and doors is permitted to be used in lieu of sealing rough openings with caulk or foam.

The map in Figure 1 shows the climate zones for states that have adopted energy codes equivalent to the International Energy Conservation Code (IECC) 2009, 12, 15, and 18. The map in Figure 2 shows the climate zones for states that have adopted energy codes equivalent to the IECC 2021. Climate zone-specific requirements specified in the IECC are shown in the Compliance Tab of this guide.

Figure 2. Climate Zone Map from IECC 2021. (Source: 2021 IECC).