Fiber Cement Siding Installation Question
ac03806
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Project – Siding a 1913 craftsman style house using Fiber Cement clapboard
3 Floor House(In Connecticut) Baseboard water / oil / 2000sq ft of siding
Removing Stucco (bottom 1/2) Wood shingles(Top Half)
Plaster walls / No Insulation / 1X6 planks in good condition
Questions
- To insulate or not? – Id’ consider blowing in insulation or external but have gotten gun shy after reading articles about problems with moisture. I can’t seem to get an answer from anyone that gives me a good level of comfort one way or the other. Resale is more of a concern than heating costs or warmth since neither has been a problem. We will be replacing windows, doors and insulating the attic.
- What to apply the siding to? The planks are in good shape so I am not too concerned with the nailing surface.. Options I am considering..
- Tyvek and nail direct to planks
- Zip System sheathing and apply siding directly to that.. (This is the option that seems to make the most sense to me right now).
- Rigid foam board insulation then side over that? Would be an option if I decide to insulate. I believe the Tyvek would go on first then rigid foam over that.
Any advice would be greatly appreciated.
Replies
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Actually the FHB (#219) that just showed up shows a great way to do this on Page 43. I am looking at the same issue for my 1900 row house. I just also have the Historic reivew board to give me grief.
I would recommend putting in some sort of insulation, especially while the exterior is off and it can just be blown at the wall. Type would depend on the quality of the wiring. If there is modern Romex, I would put in the expanding foam while the exterior is off. If you have old wiring it would still be worth some fiberglass or cellulose insulation. The foam is expensive, but should help resale. The cellulose will allow for easier modification and some room for the old wiring to shed heat.
I would apply the siding to 1"X 2" strapping that you screw through tyvex, rigid foam and thin OSB. Nail on the OSB, Few nails to hold the rigid foam in place. Staple the tyvex to that and then go to town with 3" screws in the straps. Then put the siding on that. That keeps the rigid foam in where it will stay dry.
This will increase the thickness of the walls, so new doors/windows are going to have to go in anyway, but the house will be nice and tight and quiet. That should help resale.
The thing with the zip system is that they like to put the rigid foam outside the water proofing. Not sure that is a good idea. If you are looking at cost hard, I might go with zip instead of rigid foam, but not together. I suspect that if you use the zip system, since I could not find pricing information that it is expensive and may eat enough budget that there is not room for rigid foam.
In Connecticut I think I would try for foaming in the walls, and then zip and apply siding directly to that. Simple, easy to execute and gets it done and you on to the next project.
My only piece of advice is that nailing the siding onto foam panels can make the hardi plank wavy. It's not very solid backing and hardi can get waves in it easy since it's pretty flexible.
I sided my colonial in fiber cement last year. I installed 1/2" xps (the pink stuff) taped the seams and then used 3" nails into the studs. Fiber cement will follow telegraph any defects in the framing bowed walls etc. Even though it is only 1/2" foam greatly reduces thermal bridging and air infiltration/convection in the wall cavity. The 1973 house was far more comfortable afterwards. XPS is a vopor retardant (not a vapor barrier) at thicknesses less than one inch, I believe.