My senior neighbor needs her roof replaced. Because she has composite shingles over original wood shingles, the roofer plans to remove all the old shingles, but not the wood laths to which the wood shingles are attached. The roofer plans to install radiant barrier decking over the laths. However, another opinion is that the radiant barrier is more effective if the laths are also removed and the radiant barrier decking is installed directly to the rafters. Please advise whether the laths should be removed before the radiant barrier decking is installed.
You pose an interesting question that relates to the ROI of the two installations. First, I’d need to know the spacing on the laths and their dimensions. Perhaps you can do a calculation of the amount of the total roof area that is covered by the laths. Wherever the radiant barrier is in direct contact with another surface, direct conduction of heat will take place. Without question installing the radiant barrier over the trusses is the best thermal option, however, the cost of removing the laths and other attendant costs must be included in calculating the ROI of the total job. I suspect that the house is in California, perhaps near Stanford? The more exposure the roof to the sun there is, the more effective a radiant barrier is. If cost and ROI isn’t a concern, I’d definitely remove the laths.