Installing insulation under siding


Old 10-31-17, 08:09 AM
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Installing insulation under siding

I'm going to be replacing my siding in a few weeks and have been thinking about doing some upgrades in the process. I'll be doing it myself, am considering adding insulation under the new siding. My house is a 70 year old wooden bungalow in southern Florida, so there's basically no insulation right now.

I have a few questions:

Would you guys recommend doing this?
What is a good brand you recommend at a reasonable price?
What's your recommended method of hanging? I'm not sure if I do house wrap first and then insulation, or the opposite.

Thanks for your help.
Old 10-31-17, 09:09 AM
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I would. Can't comment on brand or price down there. Dow blue board is one. Assuming you are talking rigid foam and not the vinyl siding styrofoam insulation (if vinyl siding).

Insulate and then house wrap. The rigid foam boards expand and contract so seams will move.
To attach: cap nails. Make sure you mark the stud locations. I use 3M All Weather Flashing Tape 8067 for the seams.

For 1 inch foam board, I cut long strips of window screen about 6 inches wide. Then I nail standard drip rail and the screen to the bottom of the wall with half the screen hanging down, sit the foam board on it, wrap the screen around it and nail through the screen and foam. Protects the bottom of the foam.
Old 10-31-17, 11:56 AM
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Be mindful of the insulation thickness and how it will affect your siding install. Mostly this pertains to trim around doors and windows. If using 1/4" thick you usually don't have to get fancy around windows but if you go thicker you'll have to somehow address the additional thickness since your siding may protrude more than your window/door trim.
Old 10-31-17, 12:17 PM
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Since you are replacing your siding have you considered blown-in insulation? With old siding off it becomes an easy job to drill and install cellulose or fiberglass into each stud cavity. Net result would be better than adding an inch of rigid and less expensive. Plus, some insulating companies can do the job for about the same price you would pay for the insulation.

Add some DIY air sealing before the house wrap and new siding.

Old 11-01-17, 08:35 AM
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Blown in

Thanks for the advice on blown in, I think I'm going that route.

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