Armchair Builder

Draft Stop Your New Home

How to Build a Home, Step 38

Did you know there is an actual building activity we call draft stop?  Also called draftstopping or air seal, the draft stop activity is important for creating a comfortable, efficient living space.  By sealing up all the nooks and crannies in your new home, we effectively keep the drafts and cold out, while creating a more air tight building. This is step 38 in our blog series, How to Build a Home.

Draft Stop Wall Plate

Who Does it?

So you’ve heard of plumbers and rough carpenters…but a draft stop company?  In many cases, your insulation company offers this service.  If you look at the Armchair Builder Scopes of Work and Specifications, we have added the draft stop activity to insulation.  There are also companies in the residential energy field that provide this service.  Sometimes called air sealing companies, these folks can also typically perform energy testing on your home to see if it meets specific requirements.  Have you ever heard of a blower door test?  This is where a big fan depressurizes your home to see how effectively the house was sealed up.

Draft Stop Scope

Many builders call it draft stop, but it actually covers quite a few activities.  Have you heard of a fire stop?  This is where we seal up the wall or floor cavity to keep fresh air from getting to it.  So basically, if a fire gets into the wall, we don’t want to create a chimney effect where the fire can easily spread.  By using a heat resistant foam or caulk, holes/gaps in the wall assembly are sealed up.  One example would be around electrical wires going up through the top of the wall.  When the electrician drills a hole through the top of the wall and pulls the wire through, a gap is leftover between the wire and the edge of the hole.  By filling in this gap, we slow down the spread of the fire at the top of the wall.

Many codes also require floors made with open web trusses to be sealed off.  A common requirement is to section off the floor every 1000 square feet of area.  To achieve this, drywall board can be applied to each side of the floor truss along its entire length.  So if a fire gets up into the floor framing, it will be contained to that space.

A few more items to include in the draft stop scopes of work and specifications…

  • return after drywall to caulk all electrical boxes to drywall
  • apply expandable foam behind all exterior wall outlet boxes
  • all penetrations/holes in exterior wall assemblies shall be sealed
  • any dead space below attic shall be sealed
  • check all cantilevers for gaps or holes


You will want to hold off on the draft stop activity until all drilling and cutting in the walls are complete.  So basically, all plumbing, electrical and ductwork rough-ins should be 100 percent complete.  This will allow the draft stop company to seal up all holes and gaps created while running mechanicals through the walls.

Spray Foam Insulation

Spray Foam Insulation

If you decide to go with a spray foam wall and ceiling insulation, your draft stop work will be minimized.  With expandable spray foam insulation, the entire wall cavity is filled with the insulation so there is no need to add any additional foam or caulk.  All of the other items in the draft stop scopes of work will remain the same.

With a little extra work, the energy efficiency and comfort levels in your new dream home will be greatly improved.  For more builder tips on building a tight home, check out this article called Energy Efficiency.  Have you checked out our latest video on Owner Builder Savings Today?  You can save 20 to 25 percent on your new home so check it out!  And be sure to stop by our ESTORE to see our latest promotion…we are offering a free rough cost estimate for a few more days.



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