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Wall detail – old house renovation

builder49 | Posted in General Questions on

I will be replacing old double hung windows in an old (1790’s) house with numerous siding and wall issues. New construction windows will be installed due to exterior moisture issues, sill rot and clapboard failure necessitating the complete replacement of clapboards. Existing wall assembly:

1. Cedar clapboards
2. Old Felt paper
3. 2″x16″ pine planks installed vertically (stockade fence style). These planks 
     sit on an 8″x8″ sill with a similar beam above (post and beam style)
4. Split lath and plaster installed directly to the 2″x16″ vertical planks.

     Proposed assembly: due to small roof overhand extending exterior not an option.

1. Replace existing clapboards with new cedar clapboards over a rain screen/barrier product nailed to “plank sheathing:
2. Demo lath and plaster walls to planking. 
3. 1″ foil faced rigid insulation 
4.. 2×4 interior wall.
5. Dense pack insulation.
6. 1/2″ drywall

     Any feedback greatly appreciated.

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  1. GBA Editor
    Brian Pontolilo | | #1

    Hi John,

    I have a couple of thoughts about your assembly. First, consider using a self-adhering WRB over the sheathing. This will go a long way towards air sealing. With air sealing taken care of outside of the wall, skip the interior rigid foam. Instead, hold the new stud wall away from the sheathing and have the dense pack cellulose fill that space for more R-value and a thermal break. You didn't say where the house is located, so I can't comment on actual R-values to shoot for or vapor control. But air sealing should be a priority and I don't see the need for the polyiso inside the wall.

  2. builder49 | | #2

    Thanks Brian, that's a better idea. Is there a particular type of WRB you suggest? Since I'm installing CVG red cedar back primed would a WRB/rain screen system be better.

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