Am in the process of renovating an old plank farm house and am wondering how to best increase R-value in walls. Am wondering about using “Bubble wrap” type insulation over planks (not sure what R-value you get from this) and framing with 2×4 with R13 fiberglass due to wavy/out of plumb walls. Anybody with a better way please speak up
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story

The crew discusses finding rot when remodeling, challenges installing custom shower panels, and how to prevent subs and suppliers from sabotaging builds.
Featured Video
Builder’s Advocate: An Interview With ViewrailHighlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
Look at my recent thread on vapor barrier on John's Manville Spider (in Construction Techniques) - I think blown on 'glas might just work, and seal infiltration best.
Forrest
I think blown cell does a better job or air sealing than blown 'glas - fibreglass doesn't restrict airflow that well at all. Cell needs to be a sufficient density (56 kg/m3 or 3 1/2 lb/cu.ft) ... but I agree, getting a good air seal on the walls will make a much more comfortable space than insulation alone.
Don't take this personally as an insult, but the two types of insulation you are considering are the two least efficient performers in general terms.
The probelm with the bubble foil is that to achieve the claimed R-ratings, you must have an inch or so of free air facing it for the radiant function to perform. This rarely happens. There are good applications for this material, but walls are not amoung them, IMPO.
The problem with FG batts is that they allow convection currents within the stud cavity transferrring heat to outer walls and increasing drafts within the house. Test show that the effectiveness of FG batts is reduced with greater temperature differentials and with higher wind sppeds - the two instances where insuylation is most needed.
The better insulation choices are denspacked cellulose ( Cells) and similar chopped fibreglas (BIBBs - blown in blaket systems) and sprayed in place foam such as Corbond. ( Icynene is also applied as a spray but produces c. half the R-value of the R-7 Corbond)
The above are listed in terms of increasing cost and IMO effectiveness.
Hybrid systems can also be used. Your idea of combining two products is an example, but not an effective one.
use the advanced search function here - see left column at top - to search for these products discussed here and also for Mooney walls
One hybrid addition is to use foam panels such as a foil faced Polyisoanurate like Thermax 1" thick across the face of the studs with blown insulation in the stud cavities behind it. Then furring strips over the foam to attach SR to and to provide a thermal break where the solid stud material would otherwise transmit heat to the exterior.
I prefer the sprayed PUR ( Corbond) foam when the budget allows. it provides a vapour barrier and eliminates convection loss when installed well. it also eliminates dew point condensation that encourages molds.
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!