Adding Insulation


Old 10-09-05, 04:53 AM
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Adding Insulation

I recently had a 14' x 18' room addition added onto my house. The walls were insulated with R-19. The exterior will be vinyl siding with 3/8" fan fold. However, the R rating of the fan fold is only rated @ R-1.5.

I was considering adding or substituting a higher rated rigid type of insulation prior to completing the siding. Lowe’s has rigid insulation board measuring ½”, rated @ R-3.3 and 1" @ R-6.5

The windows have a built-in J channel which has a width measuring 1".

Can I add ½” rigid to the ⅜" fan fold or a full 1" without the fan fold, or would the 1" not work with the siding because of the 1" window J channel limitation?

Because of higher fuel costs, I would like to maximize the R rating.

One contractor indicated that going beyond R-19 for the walls is not cost affective, that anything beyond R-19 would not save on heating cost. What would you do?

Thanks for your reply.
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Old 10-09-05, 09:37 AM
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Location: Eastern USA
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I use Tuff-R 4x8 foam, it gives the highest R value of any of the equivalent thickness foam sheets. Lowes carries that around here.
Old 10-09-05, 01:30 PM
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Originally Posted by Hellrazor
I use Tuff-R 4x8 foam, it gives the highest R value of any of the equivalent thickness foam sheets. Lowes carries that around here.

Thanks Hellrazor for your reply. That’s just what this insulation is, super turf from Lowe’s, however, my question is... in view of possible increased utility costs, should I add the additional insulation beyond the R-19 insulation factor?

I live in Northeastern PA where the winters are quilt harsh and the summers are not usually very humid, therefore, if I decided on the additional insulation, should I use faced or unlaced; the exterior sheathing is currently covered with felt? The interior is completely finished and has faced R-19 in the walls.

Considering the 1" limitation on the window’s J Channel, would I be able to install(“squeeze”) the additional 1" of rigid insulation along with the siding into that 1" space, or should I go with a ½” rigid board by itself or in combination with the fan fold, or nothing at all?

Thanks for your expert opinion.
Old 10-10-05, 10:42 AM
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Apparently, everyone is busy or doesn’t know the answer to my posed question(s). If someone knows of another site in regard to proper insulation installation techniques [boy, is that a tongue twister], I would certainly appreciate it if you could direct there as the contractors are coming tomorrow to install the siding.

Thank you in advance.

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