Bill has a problem about the installation of a hob-less shower. - his question and our answer.

Hi,

I'm currently investigating the installation requirements of a hob-less shower.

Your website has been an invaluable resource and I would like to extend my thanks and gratitude on behalf of all DIY'ers.

Obtaining the correct information for proper installations certainly helps planning such activities.

Anyway, what I wanted to ask you was why you stipulate (in capital letters) on your drawings that the external tray for a hob-less shower should extend a minimum of 5mm above the floor tiles.

My problem is that the section of aluminium used by the shower manufacturer does not accommodate such an protrusion.

Would a similar result be obtained if the shower frame sat directly on top of the tray (i.e. not cut 5mm above the tiles but flush with the files) and a bead of silicone applied to the external and internal edges?

If not, what how would this practice compromise the external tray and it's waterproofing capabilities?

Thanks again and good luck,

BMc

Bill,

The requirement for the extension of the vertical above the tiles is based on our experience over the last twenty or so years.

Hobless showers look great but one must remember that looks are one thing, but to make the shower serviceable, you must make some decisions that favour functionality over aesthetics.

Most leading frameless screen contractors have provision for protruding membranes.

Stegbar, Topline, Erina Glass, Impressions, are some of the manufacturers that we deal with that cater for the detail that you are considering.

To seal the glass to the membrane is great in theory, but what do you do at the door opening ?

Since the mid 1990's both myself and my co-director have been members of the Standards Assn. committee that is constantly upgrading the Wet Area Std. (AS 3740) and the latest edition which is about to be circulated for public comment actually recommends that the protrusion above the floor tiles be 10mm.

Furthermore the committee voted to classify frameless shower screens as "unenclosed showers" in their categorization.

We have found that designers that incorporate frameless screens usually also incorporate large floor tiles and small floor waste fittings.

The large tiles slow the flow of water towards the waste and the small waste cannot handle the volume of water that flows from the average shower head.

This quite apart from the fact that the smaller outlet is more easily blocked by feet, dropped face washers, etc.

Water falling into a shower fitted with a 50mm grate will build to 20mm deep in less than a minute under normal flow conditions.

It is all to do with the available cross-section of the grate and the flow pattern of the water.

Floor grates should be at minimum an 80mm fitting, but 100mm is preferable.

Hope this helps,

Bob Hearn

Hi Bob,

Thanks for your reply.

I'm now convinced that although the hob-less do look great they may be more trouble than they're worth.

As a result I will incorporate a 50mm hob into the desgn to avoid any leakage problems.

I have traked down a "p" trap that has a 100mm riser (and therefore grate) suitable for a 50mm waste pipe (seems to be the standard dimension).

I will use this to aviod ponding within the enclosure (although I realise the 50mm waste pipe is the bottleneck).

Thanks again for your comments.

BMc

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