# Rim joist insulation suprise



## rjwrightohio (Oct 3, 2011)

While insulating my rim joists with 2" XSP i found this little gem, where part of my home extends past the foundation. No surprise this is also one of the coldest portion of flooring....

How do i go about tackling this void? It extends way beyond arms reach.


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## algored2deth (Jan 7, 2011)

Vacuum out all the loose material. Get yourself a can of spray foam. Find some clear tubing that fits over the spray foam stray that fits fairly snug. You might also need a guide wire, like an old hanger or similar. Tape the wire to the tube, connect the straw of spray foam to the tube, stick it in the hole and then spray and seal it up. Beforehand, you could also try and cut a piece of XPS and see if you can fit and spray foam it in. this is what I would do.


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## Gary in WA (Mar 11, 2009)

That will work. If the soffit is easily replaced/re-installed, add rigid foam board to the joist bottoms also: http://www.buildingscience.com/documents/insights/bsi-009-new-light-in-crawlspaces/
otherwise you will only be getting R-value of 1.25 per inch of solid wood-- 9" joist= R-11, plus the thermal break. 

Gary


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## Windows on Wash (Aug 30, 2011)

Seal and insulated that entire cavity.

Do you have access to a 2-part spray foam kit?


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## rjwrightohio (Oct 3, 2011)

GBR in WA said:


> also: http://www.buildingscience.com/documents/insights/bsi-009-new-light-in-crawlspaces


Gary, fantastic link.. Once it warms up later this afternoon i plan to crawl under there and see what sort of access i have. 


I do not presently have access to a two part foam solution. Your suggesting filling the entire void solid with spray foam?


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## Windows on Wash (Aug 30, 2011)

If you had it, yes. That would be the easiest application as it is not that deep or big of a void to fill.


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