From the desk of Peter Downey

I've had a rash of questions lately about the need to install floor wastes in places outside the "usual bathroom areas." Architects have asked if they really need to provide a floor waste in the kitchen or the laundry, especially of their apartment development. To them, floor wastes are ugly in the middle of their imported polished timber floor so they want them eliminated.

It seems some territorial authorities believe that because the Acceptable Solution E3/AS1 asks for a floor waste to be provided in all areas containing sanitary fixtures and appliances, then that's the only way to satisfy the Code.

Of course, the Acceptable Solution is only one way to satisfy the performance requirements of the Code. But these days, thanks mainly to the leaky building crisis and its aftermath, it's becoming harder to find people in TA's that are prepared to look for some other way of meeting the Code's performance requirements. It's hard to get them to rationalise through a sensible solution outside the Acceptable Solution.So stipulating floor wastes is the easy way out for them!

I personally can't see the logic in providing all these additional floor wastes. Almost all of them simply will not work and do the job they were supposed to do and it's dumb to simply do things that will not work, just so everybody involved in the process can naively believe they have complied with the Code requirement!

I'm urging some discussion about the subject and want to lay the groundwork for that discussion in this column. As an industry, it's important for us to get this right, because the cost of all these additional floor wastes is going to be enormous.

What's generally going on now?
Most TA's seem to accept that floor wastes are not required in situations where the Sanitary Fixture/s can be provided with an internal overflow. Sanitary fixtures are the things we use to wash ourselves, or our utensils, generally in a manual way. It also seems to be generally accepted that even WC's can go in non-floor waste rooms, and that's mainly because they are designed to hold within their bowl the water from one full flush. So areas with only sinks, basins, baths or laundry tubs with internal overflow provision and WC's don't need floor wastes. This is a great precedent!

The difficulty seems to be in areas where sanitary appliances are installed. Sanitary appliances are things we use to machine wash things, like washing, dishwashing and glass washing machines. So, according to some TA's, as soon as we install one of these machines, we need to provide a floor waste. What I want to know is, how does this help?

What are we trying to protect against? When I ask this question, I am usually told that it's the possibility of a hose break. I believe that's a very remote possibility so let's look at it in more detail. The water supply hoses on most machines are pressure rated to over 1,000 kPa at 20 degrees C. Given that this is more than the pressure rating of the cold water reticulation pipes within the wall framing, why should I believe that the hose is any more at risk than the water pipe? The answer is that it's not.

Having pointed this out, I'm generally told that the connection is the "weak point". Again, if flexible, braided connections are acceptable on water supply pipes on sanitary fixtures in rooms without floor wastes, why should I believe that the same type of mechanical connection on a dishwasher hose is any more of a risk. And again, it's not.

I'm then told that the user of a frontloading machine might open the door when it's full of water. But most machines have lockout mechanisms that prevent this from occurring. If they then persist, well surely they deserve the consequences. You could take this point to the extreme, and ask "does this mean that I also have to make my design so failsafe as to provide a floor waste under every window, just in case the owner leaves the window open and it rains?!!"

Despite my explanations, I'm then told to comply with the Acceptable Solution, put in a floor waste and stop making trouble! But installing a floor waste is one thing. Making water flow to this floor waste is another. Most floors are not level but TA's and installers generally ignore this point. What's the point of installing a floor waste if it's at the highest point in the room? Consider the situation where the floor in the kitchen is 19mm tongue and groove, and the living room and remainder of the apartment is carpet. That means the top of the floor covering in these areas is 10 mm lower than the floor level in the kitchen. How do you stop water travelling across the "level" timber floor to the rest of the apartment, even if free-flowing water did occur? Again, the obvious answer is you can't.

And another thing, the area under the joinery unit will still be at structural floor level. The construction sequence is that the joinery unit goes in, and then the feature timber floor is cut around it. So the area under the carcase of the joinery unit is 19mm lower than the floor. Of course water will pool here before it weirs to flow on to the lower levels of the apartment. You can't put a floor waste in the floor outside the joinery unit and expect to drain the areas under the joinery unit to it. It's just dumb! And to put the floor waste under the joinery unit is even dumber!!

The point I'm making here is that there are inherent risks associated with any sort of living environment. An inherent risk with high-rise and multi level developments is the remote possibility of water falling from an upper level if certain precautions are not taken.

So I believe we need to be able to satisfy ourselves that we have been reasonable in our endeavours to stop this from happening. I believe the following meet those criteria.

I recommend that you:

• Provide all your sanitary fixtures with internal overflows if you don't have a floor waste in the room.
• Provide floor wastes to wet areas that contain sanitary fixtures without internal overflows.
• Provide floor wastes to bathroom areas with showers.
• Ensure any floor waste you install is in a location that allows water to flow into it.
• Ensure that all hoses used on sanitary appliances are rated to at least 1,000 kPa.

It is my opinion that if the above precautions are taken, the performance requirements of the NZBC will have been met. I'd welcome your comments and opinion. Write to me at peter@hsc.co.nz