Fiber-cement siding is in almost standard use in home construction today.  It is a quality product which requires much less maintenance than other siding materials.  Since the introduction of this siding a common defect found in new construction is poor fitting of cornice work at the eaves of homes where cornice work interfaces the roof surface.  This is normally observed at the lower corners of the gables but may also be seen at dormers or similar configurations.  The gaps are often large enough for animals and insects to can gain access to the soffits and, in many cases, the attic area.

The reason for poor fitting of the cornice work appears to be builder’s strict adherence to the siding installation requirements for fiber cement siding which requires 1” to 2” of clearance to the roof surface.  Although I have not found this specified requirement in the cornice trim materials installation specifications, these clearances are enforced by quality assurance inspectors and are now a recognized standard in the construction industry in our area.

The problem with allowing gaps to exist is that they will, and do, allow animal access.  I frequently find evidences of animal access in new homes and those constructed in the last few years by major production builders.  Animals accessing the attic space damage insulation where they travel and nest in the attic insulation, damage wiring, plumbing insulation, roofing, and air handling equipment where they chew on these components. As well as damage, they can create a potential for the spread of disease. (see pest control blog article on this concern)

In trying to obtain clear information to determine if these clearances are required by the manufacturer to maintain the warranties on the products I have contacted James Hardie, a major provider of fiber cement products.  Although no statements or recommendations on the clearance were provided in their reply, I was provided with photographs showing a recommended flashing installation method to allow for clearance of the materials as well as to eliminate gaps.  I will assume this was intended to take the place of such requirements although this was not clear in the reply.  Here are the photographs I was provided which clearly detail a resonable correction or installation for such gaps:

	Facia Flashing Detail - Eliminates the gap often observed at the facia interface to the roof.
	Soffit Flashing Detail - Eliminates gaps between fit of soffit and roof.  Photo taken prior to application of fiber-cement soffit covering.
	Finished Detail - Shows application of both fashings after fitting of all cornice work.