Siding/ insulation project

[Speedman87]

Getting new siding on garage and house. Both the house and garage are cinderblock construction with furring strips. House built in 1954. Asked the contractor to install tyvek wrap and 1” rigid foam insulation under the siding. Today I did a popped up while they where doing the work. They are running the tyvek and insulation over the furring strips instead of in between. Is this correct? Will this affect the performance of the house wrap and insulation?


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[matt_i]

If they are leaving a mostly 3/4" airgap between the block and the insulation then no, its bound to have a lot of convection in that cavity which is going to really lower R-value.

The other thought is, if that's working OK then one could potentially get 75% more insulative value by adding a piece of 3/4" rigid foam in between, slightly more material cost but while the job is open...

 

[strutaeng]

Getting new siding on garage and house. Both the house and garage are cinderblock construction with furring strips. House built in 1954. Asked the contractor to install tyvek wrap and 1” rigid foam insulation under the siding. Today I did a popped up while they where doing the work. They are running the tyvek and insulation over the furring strips instead of in between. Is this correct? Will this affect the performance of the house wrap and insulation?


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Yes, you get better performance by using the rigid insulation over the furring strips to stop the thermal bridging of the strips vs. cutting between furring strips. What type of insulation? EPS, XPS or Polyiso? Are the furring strips 1x or 2x? I'm guessing they are in good condition?

In new construction the furring strips are installed over the rigid insulation. They would have to remove and install new furring strips in your case. What type of siding? You will need longer nails for the siding. I think most siding manufacturers have guidance on installing over rigid insulation.

 

[Speedman87]

Yes, you get better performance by using the rigid insulation over the furring strips to stop the thermal bridging of the strips vs. cutting between furring strips. What type of insulation? EPS, XPS or Polyiso? Are the furring strips 1x or 2x? I'm guessing they are in good condition?



In new construction the furring strips are installed over the rigid insulation. They would have to remove and install new furring strips in your case. What type of siding? You will need longer nails for the siding. I think most siding manufacturers have guidance on installing over rigid insulation.

Vinyl siding, Polystyrene Foam Board Insulation, 1x furring


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[strutaeng]

This might help:

https://www.greenbuildingadvisor.com/question/vinyl-siding-over-rigid-insulation