I think its best not to have your specs depend on other's opinions, experts or otherwise. Specs should describe the minimum level of acceptability.
Its a common misconception that specifications should describe the methods used to arrive at an acceptable result rather than the standard of acceptability that will be used to measure the results of the work. They should never specify a particular method the contractor can or, in anybody's opinion, should be used to acheive the specified results. If you do specify a construction method, you are actually working for the contractor and you are really writing a "constructin method statement", not a specification. Let the contractor decide on the methods to be used. He supposedly has the knowledge and equipment to construct according to the methods within within his relm of experience in which he is competant and probably planned to use when he made his winning bid.
Actually, its also much better not to allow any choices in a specification at all. Why do that? What's the purpose of a specification anyway? If your specification is adequate, it shouldn't matter which method is used to produce the results you require. Furthermore, it allows the contractor to do this in the most competive manner he can. For example, when I specify an offshore pipeline project, I do not attempt to specify that the pipeline must be laid using a J-lay rig, or from a standard S-lay barge, or welded up onshore and floated away to be sunk in the final position, nor do I really care (from a specification perspective). I only want that the pipeline be finally laid within a certain right-of-way on the ocean floor, from A to B and that it doesn't overstress the pipe in the process. Actually, I don't care if he sends divers down one-by-one to weld the pipe up in a hyperbaric chamber. Keeping it simple here, basically I give them the drawings showing the R-O-W and a spec telling them that the pipe must not be overstressed at any time during the laying, nor in its final position. Let the contractor use his S-lay barge, if he can or develop some other construction method, if he wants to. If you specify that a particular method be used, you assume 100% of the risk of non-performance. I'm sure you don't have to be told who's pocket repairs will be paid from, if the final result using your specified methods, are not within the acceptable results of your specification. Any smart contractor knows this and happily accepts specifications that tell him exactly and precisely how he must go about building something. That's the absolute best CYA 100% coverage insurance policy. Specify the minimum acceptable results and let the contractor take the risk of using any methods he believes will permit him to produce the results to the minimum (specified) acceptable level at a competive cost.