How To Seal Around Metal Building Windows (No More Leaks)

  • By: homeshacks
  • Date: March 30, 2023
  • Time to read: 5 min.
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On older metal buildings, window air leaks are a major source of heat loss. The door section is generally the largest leak, but the windows are certainly significant in their own right. When you wrap your building in storm windows, it can be difficult to seal these leaks by wrapping any further around them. Don’t worry, there are a number of things you can do.

The easiest way to seal the gap is with a series of overlapping metal flaps that slide down over the window and then overlap. You can attach these curtains with sheet-metal screws into the framing around the window or simply tack them in place from the inside with a few nails.

You can also use metal tape or roll roofing to seal the seams between the window and the surrounding cladding. Most metal buildings come with a vapor barrier under the metal sheeting on both sides of each wall section; you should leave the paper-backed foil on one side of each panel and tape the other sides over the joints with a rubberized, adhesive-backed, or foil tape.

How do you install vinyl windows in a metal building?

Many people like to install vinyl windows in their metal buildings. This helps with energy efficiency and overall looks. There are several different ways of installing them though, depending on if you want inside or outside frame color.

One way is to use the standard installation method where the rail is permanently outside of the building and then you remove the sash to work on it. This has 2 pieces of rail with a parting bead between them located inside the wall cavity, so the sash does not have to be painted after installation.

Another way is to use an outside frame color that will blend into your building. The rail is then located inside the building and the sashes are removed for cleaning or other maintenance. This uses the same rail as the previous method so it will match for future replacement.

A third way is to use an outside frame color that matches your building but has the sashes removable so you can paint them. The rail is then located inside the wall cavity to keep it protected from the elements. If you are worried about security from metal theft, you can use a steel security bar to make it a little more difficult.

Manufacturers offer many different options and considerations for vinyl windows in a metal building. One of them is the ability to have an outside frame color that will blend with the exterior of your building. Another way is to be able to remove the sashes for easy cleaning and maintenance. This will also allow you to paint them if desired without repainting the rails.

You can also use a removable steel security bar for more security from metal theft. Many manufacturers offer options and considerations for installing vinyl windows in a metal building.

How do you fill gaps in a metal shed?

If you’ve got a metal shed that’s suffering from gaps, whether they’re between the roof and the wall or just along with one of the panels then filling them will help keep your storage items safe and dry. It’ll also stop water from getting in if it starts to rain.  

There are a few different options for filling metal shed gaps depending on what they’re made from and cost can vary. We’ll take a look at the options below.

  • Silicon: There are two different types of silicon – one for metal and another for plastic so before you start check the label to make sure you’ve got the right stuff. Simply squirt the silicon into the gaps, wipe off any excess with a piece of cloth and leave it to sit overnight. We recommend this silicon from Amazon, however, you will be able to find similar at your local DIY store. Another option is to use expanding foam, you don’t need any special skills or equipment so if you’re not sure about doing it yourself have a chat with one of the guys at your local DIY store.
  • Metal tapeA roll can be as cheap as $6 and is great for gaps that are more than a couple of inches wide. Simply cut off about 12″ to 18″ of metal tape, fold it over itself by 1/2″ or so and stick it in the gap. Make sure it’s dry when you do so and doesn’t have any particles on which could scratch the paintwork.
  • Joint sealant: Not to be confused with silicon, this is a special type of sealant designed for metal roofs and walls. It comes at a high price but works well to prevent water from getting in. Just follow the instructions on the tin – it’s fairly easy to apply but you might need a partner or an extra pair of hands to hold something! This joint sealant is recommended best for any cracks that need sealing.
  • Expanding foam: If you have gaps that are more than half an inch wide then expanding foam is probably your best option. It’s more expensive than silicon but can fill gaps of up to 3″ so is ideal for bigger holes. It’s easy to use but you’ll need to leave it for 24 hours or so before you do anything else, don’t touch it while it’s not wet, and avoid using your shed for a few days after applying it.

Please note: This is an article about filling gaps in metal sheds. It may also be relevant for other types of storage buildings but if you have any doubts about what type of shed you have it’s best to check with the manufacturer or supplier before doing anything.


In conclusion to filling gaps and sealing your windows on metal type building, we hope we have answered your questions. As mentioned, the correct type of silicon or expanding foam can really make the difference on small metal projects but on larger scale solutions you may have to look into more secure ways of sealing around metal building windows!

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