Roofing

Published on July 10th, 2014 | by Henri

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Getting best value when replacing siding and roofing

Q.    I am soon having my split-level house re-roofed, while also installing new siding and gutters. The enclosed picture shows my home, which faces South.

When the contractor strips off the old (original) aluminum siding, he will be injecting Airkrete into the wall cavities all around the house (also the brick). The lower roof on the right (East) side of the house covers a cathedral ceiling which is over the front living room and a few steps up, to the dining room. The far North side of this lower roof covers the kitchen which has a regular 8-foot ceiling.

The contractor will also be injecting the Airkrete into the cathedral ceiling, and adding additional blown-in insulation above the kitchen. There are two can vents over the kitchen area. Airkrete will also be injected into the walls and ceiling in the attached garage.

On the top roof, you can see the front gable vent, there is also a matching gable vent on the North side of the house. There are also four can vents on top of roof. I have a 1500 cfm. powered attic fan on the East side of the top roof.

Fifteen years ago, I re-insulated the attic using Owens Corning R-25  batts (I think it was called Easy Touch. Has a thin sheathing all around the batt). First layer laid in the floor joists, 2nd layer laid perpendicular over 1st layer.  I also installed soffit vent chutes in all rafters at the soffit area.

For the siding, my contractor will be installing Mastic Structure foam-backed Dutch lap siding over Tyvek housewrap. For the roof, he will be installing GAF Timberline Architectural shingles with 6 feet of ice and snow shield.  The 4-inch gutters will be replaced with 6-inch gutters and downspouts. The wood railing and posts above the garage will be replaced with Azek board material.

I would greatly appreciate your opinion and suggestions to make sure this is being done correctly so I can get the most value for the money I am investing in this major renovation. My location is a Northwest suburb of Chicago. Thank you.

A.    Everything you are having done seems fine. The only comments I would offer are as follows:

  • Power roof vents have serious drawbacks. Unless there is enough net, free ventilation area (NFVA) in the attic itself to satisfy their CFM rating – which is seldom the case – they will draw conditioned air from below. This is a waste of energy both summer (assuming that you have central air-conditioning) and winter.
  • A better approach is to insulate the attic as you did, and make sure that you have adequate passive ventilation by means of continuous soffit and externally-baffled ridge vents. You also must have an uninterrupted air flow between the soffits and the ridge.
  • However, if there are no moisture problems in the attic, it would indicate that the two gable vents are doing the job, in which case there is no need to change anything.
  • Roof can vents are not effective, and it is best to eliminate them in favor of the passive ventilation described above. But, as mentioned above, if you have no problem, don’t change anything.

Otherwise, you are doing fine. I am glad that you are replacing residential gutters and downspouts with commercial ones; it’s a winning combination.

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