Window insulation

For all those Replacement Window decisions - just read, review or post a question. You will be helped!
Post Reply
Posts: 4
Joined: Wed Oct 07, 2020 8:00 am

Window insulation

#1 Post by Window2728 »

When installing windows is it common practice to put fresh insulation around the new windows during installation? If so, does it make a big difference whether its fiberglass insulation or the low expansion foam? Which is better insulation to use? Most of the videos showed low expansion foam, while some use fiberglass. I'm thinking foam is better. Any opinion on pro or cons of each one? Thanks.

User avatar
Delaware Mike
Posts: 902
Joined: Mon Jan 30, 2006 1:32 pm
Location: Delaware, New Jersey, Philadephia Area

Re: Window insulation

#2 Post by Delaware Mike »

Most pros that have adopted pro guns and reducer tips for them prefer foam over fiberglass. Applied correctly, it's superior to fiberglass in every aspect. When the jamb depth is filled with foam on a window or door one can remove the fasteners and the door/window is locked in place as a continuous shim (no one would remove the fasteners, just making a point). It's an extra water/air barrier too, fiberglass not so much.

You can spend over a $100 bucks on a Hilti type gun or as little as $15 on Amazon.

Posts: 1791
Joined: Sun Feb 22, 2009 5:52 pm
Location: SE PA & NJ; CT

Re: Window insulation

#3 Post by TheWindowNerd »

Foam is the best.
Caution: do not completely fill the void, even low pressure foam can destort windows and doors.
As Mike alluded a pro gun is the best way to handle.

wayne theWindowNerd

User avatar
Windows on Washington
Posts: 4648
Joined: Wed Apr 04, 2007 11:21 pm
Location: DC Metropolitan Area-Maryland/Virginia/DC

Re: Window insulation

#4 Post by Windows on Washington »

+1. Low pressure, window and door specific, foam.

You can spritz the opening with a bit of water before hand and that will help it cure.

User avatar
Posts: 2593
Joined: Tue Feb 16, 2010 6:14 pm
Location: Milwaukee, Madison, Northern IL

Re: Window insulation

#5 Post by HomeSealed »

Another vote for foam. Even most of the old-timers that were holding out are using it these days. Works great and its easy to use if you know what you are doing.

Post Reply