I recently moved to a home (new to me). One thing that is bothering me quite a bit is a gap between wall and window trim. You can see the picture below. How do I get rid of this? What are the basic steps involved?

Click photo for full size enter image description here

  • 1
    Actually the gap shown in the two photos is between the jambs and the casing. The casing could have been removed for an energy program to insulate between the jambs and RO. Is the paint seal also broken at the joint between the wall and the casing?
    – mike
    Aug 13, 2013 at 4:57
  • You may be on to something. I can't tell what the material is in the crack on the second picture. But If the seal is broken on the wall side, it could be insulation.
    – John Smith
    Aug 13, 2013 at 5:44
  • No, it is only broken towards the window. I checked outside and it seems alright.
    – user16983
    Aug 13, 2013 at 14:26
  • I just noticed the paint seal is also unbroken at the casing's miter joint. Was there an A/C unit in the window? Or were the sash removed so that the opening could be used to toss out demolition debris? or haul in sheet rock? or move a piano in/out? or large bed or other furniture?
    – mike
    Aug 13, 2013 at 18:52
  • Is there a gap at the top?
    – mike
    Aug 13, 2013 at 18:55

2 Answers 2


You will want to clean the area first. Scrape and moderately sand any peeling paint. Afterwards use a latex caulking which you can find at any home improvement store. This caulking is paintable which is the main reason I would use it and also shrinks and expands with temperature and moisture changes. Once the caulk is completely cured according to the directions on the tube, you can paint over the area. The better caulk products tend to have more flex giving them better longevity and decreases there chance of pulling away from the wood/molding.

Also, one more thing to add; What is the cause for the cracking in the first place? You may get more cracking if there is insufficient insulation between the rough opening and the window frame. Usually this can be solved easily by spraying foam insulation in between the two. This would be a more time consuming and difficult task, but may solve the root cause since this type of foam both insulates and seals the gap eliminating moisture and decreasing temperature change, both common causes of major expansion around windows and doors. The process for this fix would start with removing your trim, insulating with the foam, re-installing your trim and then following the steps above. This may not be worth the work depending on where you live, etc.... but it is a notable option.

  • I live in Calgary, Alberta and in winter it can get quite cold here. I'd be concerned if it is related to poor insulation. Here is another picture I took that might show the size a bit better. I might remove trim for one window first and see what is going inside. I own this home now and need to take care of things. So, I am ready to put in effort.
    – user16983
    Aug 13, 2013 at 4:32
  • If you do use foam insulation, the foam will expand and can cause issues opening the window. The link provided is Great Stuff's least expanding one designed around this issue but I'd still fill the depth of it in with multiple layers.
    – Jason
    Aug 13, 2013 at 16:36

It is hard to tell from the picture how wide it is. If it is 1/8 inch or less I would caulk it. If it is bigger than I would go over it with wood putty. You can paint over each. Also if you use wood putty chances are it will eventually form a small crack (expansion) and need to be caulked.

  • Here is another image that might give you better idea about the gap size. It seems less than .125 in but still quite wide though.
    – user16983
    Aug 13, 2013 at 4:27
  • I would just caulk it. If you use anything else it will form a crack after a given time that needs to be caulked anyway. Use something like DAP or any painter's caulk. Caulk then sand down the area the next day and paint.
    – DMoore
    Aug 13, 2013 at 4:34

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