I’m in the process of siding my house. The first floor was originally built in 1960 w/concrete blocks w/simulated brickface finish that will not come off. The second floor I recently added is stick built w/plywood sheathing. I have elected to use premium vinyl cedar shingle siding. On the block walls I have installed pressure treated 5/4 x 6″ deck boards as vertical firring strips 24″ o/c directly to the facing using premium exterior adhesive and 3″ charge activated nails w/washers, one every 8″ after having pressure washed off the paint. 3/4″ exterior plywood followed by house wrap will go on top of the firring strips to become the nailing surface for the siding. The question: should I put 1″ foamboard in the cavities between fir strips and seal the bottoms w/expanding foam to keep the critters out and pick up a little R-value, or leave hollow and fill bottoms w/cobra ridge vent material to let air in, keep critters (moths, bats, etc) out? The house is in southern NY and does not receive direct sun, humid summers, moderate winters.
Thanks in advance for any advice offered – Daveyboy
Replies
Are the treated furring strips made with ACQ treating material or CCA?
If they are ACQ then your PAF fasteners will need to be specifically labeled as being compatible with ACQ or you will find that the ACQ will corrode your fasteners away in a few years. Likewise all your other nails and screws will need to be at a minimum of hot dipped galvanized to prevent corrossion and failure of those fasteners also.
.............Iron Helix
Are the treated furring strips made with ACQ treating material or CCA?
Will you talk more on these two treating materials?
Is one new? Is one old?
Corosive? Non corosive?
Common? Uncommon?
Are they gonna start this race today or what?
Jack
Trigger go to the Advanced Search in the upper left corner of the message screen.
Type ACQ and hit search or search for mesage 43048.1 and read tge thread.
If you need more info drop me a note again................Iron Helix
Davey,
With the system you are using in that climate, I would use 3/4" foil backed foam and Cobra vent. Put the foil to the outside. Add foil over the 5/4 furs, taped to the foams' backing, for a superlative deserving job.
Use a waterproof, vapor flowing housewrap. I think 15lb felt is ideal in this application.
Do not vapor proof the inside of this wall. If the inside is already vapor proofed, omit the foil on the outside.
SamT
Iron Helix - thanks for PT fastner tip. I hadn't thought about it and switched my fasteners after calling Ramset to double check.
SamT - your helpful answer yields another question regarding the inside wall. I'm not sure I'd call it vapor proof, but it may be close enough to cause problems down the road if foiled rigid foam is applied to the outside as you suggest.
The interior side of the block wall was coated with thick black somewhat tarry looking paint which looks like an effort at moisture control. 3/4" firing strips are mounted to the wall w/3/4" rigid foam board against the block between the fir strips w/ 1/2" gypsum.
My guess is I should skip the foiled rigid foam on the exterior and go w/uncoated rigid foam followed by 15#felt or tyvek. Any thoughts?
BTW - We've decided to change the gameplan a bit from the original posting last week by omitting the 3/4" exterior plywood sheathing in favor of thicker foam.
The application sequence now looks like this: original cement block wall w/cement brickface now has vertical 5/4" PT fir strips 24"o/c glued and PAC to the block; rigid foam in each bay to fill void; horizontal 1 x 4" fir strips to be nailed to vertical fir strips 13" o/c to become nailing base for shingle; 3/4" rigid foam in these bays to fill void; tyvek housewrap; vinyl shingles (Nailite Rough Sawn Cedar)
Thanks again, Daveyboy
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