Sealing Things Up


 Sealing Things Up — Foam and caulk

So if you have an old house like mine you probably have a lot of air leaks though hopefully not as bad as mine was.   It is amazing how much how much air flow there is.   So here is some suggests about want to do about it.

What you need

Great Stuff Foam

First you are going to want several cans of  Great Stuff foam insulating sealant.  There is actually 5 different versions depending on what you are doing.

  • Great Stuff 16 oz Gaps and Cracks Insulating Foam Sealant is the standard foam sealant and is  good for most applications.
  • Great Stuff 16 oz. Big Gap Filler Insulation which is for holes bigger than 1 inch.  I have not used this since the regular Gaps and Cracks seem to do just fine as long as the hole isn’t too big and if it is you may want to consider filing with wood or cement then use the Gaps and Cracks to seal it up.
  • Great Stuff 16 oz. Window and Door Insulation Foam Sealant.  The idea here is to have foam that doesn’t expand as much and there fore does not put so much pressure that it warps the window casing or door jam.
  • Great Stuff 16 oz Pestbock Insulating Foam Sealant.   I used several cans of this around the foundation wall because I had some holes that mice and rats were getting in.  It is supposed to taste bad to rodents and bugs.  It seems to have work well for me so far.
  • Great Stuff 16 oz. Fireblock Insulating Foam Sealant.  This is for sealing around things like pipes, cable and duct penetrations.  It is a orange color so the inspector can see it more easily.   As for as I can tell it is a orange version of Gaps and Cracks.

Great Stuff Foam Gaps & Cracks

Gaps & Cracks

Great Stuff Foam Big Gap Filler

Big Gap Filler

Great Stuff Foam Windows and Doors

Windows & Doors

Great Stuff Foam Pest Block

Pest Block

Great Stuff Foam FireBlock


Nitrile Gloves Along with the Great Stuff Foam you are going to want some Nitrile Large Disposable Glove (100-Count). The pack is around $13 and you can use them for all kinds of things.  Trust me no matter how carefully you are you are going to get that foam on your hands and you don’t want that.  You will want to use them when you are working with the caulk as well.  BTW if you do get Great Stuff Foam on you skin spray some WD-40 on rub the area until free of the Great Stuff then wash your hands.  If it is really bad use Carburetor cleaner.  Or just use the gloves so you don’t get it on your hands to begin with.


Silicon Indoor/Outdoor Sealant

You also are going to want some caulking and a caulk gun.  I like the DAP Dynaflex 230 10.1 oz. Premium Indoor/Outdoor Sealant.  You can get it in Clear, White, Almond, Black, Gray and  Tan.  I usually just get white.  The DAP Dynaflex 230 combines latex and silicone so you get the flexibility and durability of silicone with the paint ability, low odor and water clean-up of latex.   The main thing you want in a caulk it that it will not shrink.   And once again don’t forget the Nitrile Gloves.  This caulk will wash off with warm water but still the glove are nice. One other thing if you haven’t used caulk before you are going snip the application nozzle with scissors then there is a wire on the bottom front of the caulk gun that you flip out and jam down the nozzle to break the seal.  Then put the caulk cartridge in the caulk gun.

Theory of operation

So we are trying to block heat transfer from either the outside in (summer) or inside out (winter) and slow down heat transfer between floors in you have more than one.  Heat move by one of three methods: conduction, convection and air flow, and radiant.  In this case we are working on the convection or airflow. So we want to find all the place where air is flowing and block it with foam or caulk.

Which to use where.

This is really your chose but I will give you some suggestions.  I would use foam if the hole is larger than a ¼ wide and you don’t have to look at it much.  I would use caulk in place where you or other see it a lot.  I would use it up to 1 inch wide in some application but generally around ¼ inch or smaller.  Why do I say this?  Because while foam is general cheaper per area covered it is harder to control the flow rate and you are likely to end up with something that doesn’t look that great.  Another thing to consider is caulk weathers a lot better that the foam.  If for example you are sealing in the basement  around the sill I would do it from the inside if possible.  Here are some pictures so you can see what I am talking about:


Finding the right place to seal up:

So we are looking for air flow.  The three easiest ways of doing this are:

  1. Get the inside as dark as you get it on a sunny day and look for light coming through. Then seal both  the inside and outside.
  2. When it is cold outside run you hand around windows, doors, cracks in wall, basically any gap you can see and feel for cold air.
  3. Look for holes from the basement/crawspace to the first floor and from the attic down into the top floor.

You will be surprised how many you find.  If you don’t find any you either have a relative new house or you are not looking hard enough.  You will most like find some seal them then find more.   I find a set that I think a can of Great Stuff Foam and/or a tube of DAP caulk will fill and then try and use the whole can or tube.  I have seen people us part of a can or tube then try and seal the tube or can up for later use then have trouble with it being stopped up.  It is better to just use a complete tube or can and be done with it.  If you find more holes get another tube or can.

Where to purchase

So where can you get the Great Stuff and Sealant and which brand are best?     Go to the What You Need page for a full list of where and what to buy.

Let me know what you think in the comments below.

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