“Of course I guarantee it! After we’re done here, I’ll ask you if you felt any pain. Then I’ll ask my assistant if she felt any pain. And then I’ll see if I felt anything and I guarantee the majority of us will be without pain.” Not quite reassuring.

Although my answer is not intended to be humorous, some clients are less than fully assured by it. “I do not give guarantees but always perform services in a professional manner to the best of my abilities. I have a long list of satisfied clients and I carry professional liability insurance just

in case.”

Most engineers, architects and consultants do not give specific guarantees, but a few do. If you’ve ever worked a job in which you were constantly being watched, and possibly had to tear out and redo walls and ceilings, then you can bet that job had some kind of guarantee attached to it. What are the pros and cons of guaranteeing acoustics?

Ironically, guarantees are readily given by inexperienced and less talented consultants who are less capable of performing. Their lack of quality service only reinforces the clients’ opinion that all acoustics should be guaranteed.

Recalls one such client, “Speaking as a customer, yes we did define acoustic targets for a new facility, yes we got the acoustic consultant to sign a performance guarantee, and yes he had to pay for a lot of extra work to be done. Personally, I am surprised that more people don’t put a performance guarantee into their contracts—after all, every other part of the building has to meet a spec, why not the noise?”

All the president's men

“Only once, early in my career, did I ever give anything close to a guarantee of a specific result at the request of a client. In that case, I did more testing and analysis than I normally would, charged the client for it, and made sure I had a margin of safety in the design.

“A few years ago, Laymon Miller gave a day-long lecture to NCAC recalling many of his experiences over his career in acoustics with Bolt, Beranek and Newman. He told a story of an industrial client who wanted a guarantee on noise reduction of a fan. Now, if any consulting firm was ever in a position to give a guarantee, it was BBN.

“If I remember correctly, he said he explained to the client the economics of consulting, the extra effort he would have to put into the project, the extra margin he would put into his recommendation that would itself cost more money in implementation and that he would have to charge a premium above the cost of the extra time to consider such a guarantee. The client recognized it was not worth it.”

In a typical job, the acoustic consultant recommends to the architect modifications to wall, ceiling and floor design to achieve the desired acoustics. The architect decides what modifications are within the project’s budget and revises the drawings accordingly. These are then passed to the general and sub- contractors who interpret the drawings and build the project. To guarantee the acoustics, the acoustician would have to be given full oversight of the project. This extra effort means that a job that would normally only require 20 hours of the consultant’s time may now require more than 100 hours.

To ensure successful sound isolation, the consultant will likely make each structure heavier than he or she would normally recommend. The project cost will grow accordingly. The consultant will want to inspect every part of the construction to make sure, for instance, that drywall screws are driven at 4-inch intervals, or that glue is being spread evenly between layers of drywall. (I know of one consultant that will reject wood 2 feet by 4 feet if they don’t “sound” right.)

Mr. Stewart also points out that express warranties and guarantees of any kind are excluded from coverage under typical professional liability insurance policies. This is the catch 22 statement for most clients—“I can guarantee the job, but it won’t be insured or I can insure a good job, but there’s no guarantee.”

You're gambling when you guarantee

“I have been giving churches written guarantees for years for acoustics but they are always on my terms,” says De Buglio. “If the builder, sound contractor or architect fail to follow through on my specification, they pay. That is in writing. I always recommend the parties involved take out liability insurance. Now, if I write a spec and it fails, then I pay. So far, in over 50 projects where I had given a written guarantee, I only had to pay once.

“If I specify ... a room, it also includes details of how that room is to be built. If there are any changes to what I specify and what is built, I’m off the hook. Oh, and one more thing: Giving a guarantee comes with a price. It is usually two and a half times more for that extra service.”

I asked De Buglio how he protects himself from variations in acoustics associated with the quality of construction, such as the variation of absorption of gypsum walls caused by the rigidity of the wall frame.

De Buglio explained, “I tell the client that in order for me to give the guarantee, it includes me supervising the construction of the building and I ask for authority to have all aspects of the building changed as needed to achieve the goal. That means weekly, biweekly or monthly visits to the site while under construction. Yes, that is an extra cost to the client, but if they are serious about wanting a good space, then they have to be willing to pay for it.”

Another variable that affects the consultant’s ability to predict the acoustics of a building is the quality and consistency of building materials. For example, how well does this week’s run of acoustic ceiling tile meet the manufacturers’ published performance data that was used to design the project?

De Buglio has that covered too.

“As to performance of acoustical materials, I ask for a guarantee from the manufacturer of a product that if the quantities, placement and installation are according to their product information sheet, then they carry the cost of any changes,” he says. “Most agree. Some do not, and the client then gets the product from another source. Either the product literature is truthful or it is not. What I have also found is that many of these manufacturers are not always aware of how their product actually performs in the real world—especially in large assembly halls. As a result, if there is a product that I think will serve the client best, then I get samples and test the product (myself). This makes predicting the final outcome very accurate. If the client is willing to pay for all of this support, I will guarantee the work.

“I would never offer a guarantee without follow-up support and the fees to carry that kind of support. If the follow-up is not included, then there is no guarantee whatsoever.”

Although “satisfaction guaranteed” sounds good, those words can easily be used to increase the cost of a project while providing less protection against errors and omissions. Guarantees always come with the condition that the consultant’s every command must be followed and so the unscrupulous can always get out of the commitment by specifying some expensive type of construction that the budget can’t support. Responsible construction involves balancing the needs and budget of the client with project cost.

Giving sole consideration to the acoustics needs of the client is only an option if the budget is unlimited.