Closed Crawlspace Tips &Tricks

We hope at this point closed crawl spaces are a breeze. Just in case there are any lingering questions or concerns, we’re going to cover some tips and tricks. Remember – you can always visit, the crawls pace guide or the SystemVision training binder to familiarize yourself with the components of a closed crawl.

Just to review….

Upfront decisions to be made before beginning a closed crawl:
Will you…..

  • Insulate the floor or the foundation walls?
  • Use a dehumidifier or a supply air drying system?
  • Install a crawl space drain or a sump pump?
  • Install vents and closed them later or not include vents in the foundation wall?

Key concepts/components of a closed crawl space:

Site Drainage Keep water from flowing toward the home
Air Sealing Treat the crawl space like the inside of your home- seal all penetrations through the wall and make the access door air tight!
Sealed Vapor Retarder Keep moisture from finding its way into the crawl space
Insulation Locate our thermal barrier on the crawl wall or in the floor.  Check the R-values required here.
Drying Mechanism Install a supply that delivers 1CFM/30SF or a standalone dehumidifier.
Bulk Water Management Install a drain or sump pump at low point of crawl. We created a bathtub! We need a drain in case there is ever a plumbing leak.
Termite Inspection Strip Leave a 3” view strip from the top of the insulation or vapor retarder to the mud sill.
Combustion Safety Remember — no atmospherically vented appliances in the crawl.
Homeowner Education Make sure the homeowners understand the crawl and ensure they do not store mowers or gas in the crawl space.


On to the tips/tricks!
Floor System

Plan to hang wall materials before the floor system goes in
Plan for the crawl from the beginning! There is nothing more frustrating than trying to hang plastic and insulation from your knees or stomach. Plan to put the vapor retarder and/or insulation on the foundation walls before the floor system goes in.

Don’t forget the drain

A drain to daylight with a backflow preventer or a sump pump is required to handle bulk water. Planning for this is important, because it is a lot of work to install after the fact.

Powder actuated fasteners

Powder actuated fasteners are a quick and easy way to fasten furring strips or insulation to foundation walls. Do not forget to wear ear plugs!

Quick & Easy

Vapor retarder under water heater and/or air handler

If the water heater is to be located in the crawl space, have the plumber/HVAC technition put a piece of vapor retarder under the water heater and/or air handler before they are set. This will save the headache of trying to seal the vapor retarder to the water heater and/or the air handler.

Inexpensive backflow preventor

Backflow PreventerA dryer exhaust termination is a great option for the backflow preventor on your supply that is used as the drying mechanism. Make sure to include a manual damper to ensure the proper amount of air is delivered.

Test for radon

Better to be safe than sorry! A closed crawl does not seal out radon. Tests are about $8 to $20 and are very simple to do.

Install a reminder

Crawlspace ReminderPrint, laminate and hang the this sign near the entrance to the crawl to ensure the homeowners remember how to effectively utilize the benefits of a closed crawl.

Like anything in construction, without proper planning there will be lots of rework, money and time.  Plan as much as you can from the start and ensure all of the construction team members are on board.  Plan to complete as much of the crawl as possible before the floor system goes in to save time.  Plan to educate the homeowner.


Please send me your questions on closed crawls that you would like discussed in the webinar/conference call to follow! You must register from your computer but can call in from the jobsite to take part in the call Tuesday, October 25 at 11:00am.

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Category: Crawlspaces   


There is 1 Comment About This Post


PompanoBeachPlumber Says,

Good stuff, thank you for this. As a contractor this really helps keep me fresh…. Thanks Again…

on November 07, 2012 at 11:01 PM

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