Floor joists insulation suggestions (no room underneath)
robbyve
| Posted in Energy, Heating & Insulation on
Hello guys, I’m going to build a house addition above piers. The clearance from the ground would be a little more than one foot, so no room to put insulation from underneath. How can I insulate the floor from above? I’ve been suggested to put plywood underneath, but still the same problem, no room to nail it. Do you have any suggestions? Thank you very much.
Replies
fasten 1x strips to side of each joist, at bottom. Place 1/4" ply in between joists to support insulation - all from above.
Thank you. I appreciated your suggestion.
Use these: https://www.homedepot.com/p/Simpson-Strong-Tie-15-1-2-in-Insulation-Support-100-Pack-IS16-R/314837644?MERCH=REC-_-pipsem-_-302672566-_-314837644-_-N&
They are made for this type of situation. Inexpensive and easy to put into place.
Thank you very much!
If you're planning on using some kind of fluffy insulation, you're probably going to want to put some kind of air barrier on the bottom of your insulation anyway. Wind washing can really reduce the r-value of fluffy insulation and it needs to be enclosed on all sides to get the rated r-value.
That issue is discussed in this article:
https://www.finehomebuilding.com/2012/09/06/two-ways-to-insulate-attic-kneewalls
I like the idea of attaching 1x strips to the bottom of the joists before installing then add thin plywood from the top to support the insulation. But I would go further and caulk all the plywood to joist joints to create a nice air seal.
The plywood will also help prevent critters from getting into your insulation...mice seem to love fiberglass.
Thanks man! I appreciated!