If a regular vinyl window is replaced, and the foam is applied from the inside around the window, should it be also sealed / caulked from the outside before the capping is done?



You should silicone the flange top and sides (not the bottom), and use flashing as wide as practical for the top and sides as well.

  • Foam is no substitute for weather-tight caulking and sealing against moisture intrusion. It serves as an air barrier and to replace lost insulation volume in voids only. – Fiasco Labs Nov 2 '12 at 2:19
  • @matthew-pk all contractors I talked to assure me that sealing from the outside is not necessary because there is also capping that protects from water / air to get in. I suspected this may not be true, and sealing from the outside is a must. Just to confirm: are you saying the one should always seal from the outside no matter what e.g. whether the capping is done? – tolitius Nov 2 '12 at 15:37

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