I managed to get the contractor I am working with (Robert Valitutti of P.C.L. Interior & Exterior Finishes http://www.pclfinishes.com/) to agree to installing R22 under the new siding. Work is in progress as I write this.
The insulation is Roxul (mineral) insulation. There is 2 by 6 inch strapping attached to the brick. Given that there are termites (and carpenter ants) in my neighbourhood I insisted on all wood being treated with insect repellent. He is using Blue Wood … the “Blu” is a brand name.
After the strapping and insulation are installed he will cover it with Typar (a vapour barrier) and finally the James Hardie fibre cement siding.
The problem with using 2 by 6 strapping (to handle the R22 insulation) is that it could be too heavy to support the siding. He resolved this problem by adding a bottom plate which will support the strapping and keep the siding from being in contact with the ground.
Another problem – there is insect damage to the wooden addition at the rear of the house. There had been a leak in the roof that had gone undetected – inviting insects to do their thing. I wanted all of the siding removed right down to the existing frame in order to determine the extent of the damage … it was not pretty. I wanted any damaged wood replaced.
This is happening right now. After the wood is repaired (the existing 2 by 4 is being replaced with more Blu wood) plywood will be added and then more 2 by 6 strapping and R22 insulation. The result will be that the addition will have R39 … R19 on the interior of the plywood and R22 on the exterior.
Removing the existing siding exposed a few gaps in the existing interior wall which explains why there were drafts there.
