What I'm Seeing Now


Best Practices - Shower Stall Waterproofing

On pre-drywall inspections it isn't often that you see best practices - shower stall waterproofing.

Shower stalls are one area where so many installation mistakes are made, or the wrong products used, you just know it is a problem waiting to happen.  When it comes time to have to repair those problems, it is difficult, costly and you are without a shower for a long time!

This shower is a two-person stall beside a large master bath tub. 

There will be a glass surround for the shower.

On the walls and around the bath tub, I was told, will be ceramic tile glued onto a barrier of concrete board, a product called Durock.

Durock is an aggregated Portland cement slurry with polymer- coated, glass-fiber mesh which completely encompasses all edges, and the back and front surfaces.

It is an excellent product because it is WATERPROOF. 

It doesn't swell, expand or contract, or move.  It installs just like drywall.

In the olden days we used a special drywall called green board.  It was a drywall product with a little more water RESISTANCE.  It was NOT waterproof.

But it was the best we had at the time.


But even Durock has seams and gaps that must be sealed.  This is where the synthetic rubber membrane comes into play, which you see in the photo.  This will be a seat at the end of the shower.

However, the membrane has special installation techniques, which, if followed, will MAKE SURE it is providing a water barrier.

What makes this installation a

Best Practice


>  Often I see this membrane installed with drywall screws!  Drywall screws are for drywall, and not for any application near water!  This installer has used stainless steel, wide-head nails.  They are 1" long.
>  The membrane is stamped IPC and IRC.  Those are where building codes are found and this stuff is code acceptable.  The knock offs do not have such a stamp and are OFTEN used.
>  The membrane is a SINGLE PIECE and there are no cuts, splits or gaps lower than 4".
>  Areas where the Durock will be seamed and there will be stress are double protected with a properly-glued special secondary membrane made for that purpose.  It is similar in thickness to bicycle tire inner tubes.  It is installed with a special glue.

All in all, this contractor, and supervisor who is watching what is done, knows what he is doing.  This is likely to be a dry shower and dry for a long time.

My recommendation:  on pre-drywall inspections you have to look for the little things.  These little things make HUGE differences in the final outcome of any construction!  And it is ALWAYS good to see those little things done well!



Jay Markanich Real Estate Inspections, LLC  

Based in Bristow, serving all of Northern Virginia.

Office (703) 330-6388   Cell (703) 585-7560


Comment balloon 25 commentsJay Markanich • October 16 2011 06:11AM


Sounds like the people were doing real estate right and you agree..

Posted by James Dray, Exceptional Agents, Outstanding Results (Fathom Realty) over 8 years ago

Just goes to show that new home buyers serve themselves well if they have a pre-drywall inspection by an experienced new home inspector. 

Then the challenge is finding one.


Posted by Lenn Harley, Real Estate Broker - Virginia & Maryland (Lenn Harley, Homefinders.com, MD & VA Homes and Real Estate) over 8 years ago

This is the same builder who put in the doors well, on a previous post James.  I enjoyed the inspection!

Lenn - I agree and I'm still looking...

(My daughter tells people I am "obnoxious" and "annoying."  Just doing my job.)

On such inspections, when I see this kind of stuff, I like spending time with the buyer to explain why I like it.  And that helps reinforce their purchase and all feel good!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

Good morning, Jay. I have to agree with Lenn. Sadly, only 1 out of 100 folks do a pre-drywall inspection...

Posted by Michael Thornton, Nashville Area - Photography & Videography (RadnorLake Video) over 8 years ago

Michael - of the two, pre-drywall and final just before closing, I don't know which is the more important one!  I find stuff on both!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

Looks like blue has made a huge improvement over green !

Posted by Sally K. & David L. Hanson, WI Real Estate Agents - Luxury - Divorce (EXP Realty 414-525-0563) over 8 years ago

Yes Jay in my last old house (1820 old) they put the tile right on the drywall without any durock...it was not fun when that side wall to the attic gave in...some contractors are fools...

Posted by Ginny Gorman, Homes for Sale in Southern RI and beyond (RI Real Estate Services ~ 401-529-7849~ RI Waterfront Real Estate) over 8 years ago

Jay - amazing how many little details you have to keep track of, like using drywall screws only in, um drywall appropriate areas. I would *think* this would be second nature, but apprarently, it's not.

Posted by Carol Zingone, Global Realtor in Jax Beach, FL - ABR, CRS, CIPS (Berkshire Hathaway Home Services Florida Network Realty) over 8 years ago

Yes bathrooms are definitely tricky business.  We've seen all sorts of things when ripping them up.

Posted by Debbie Gartner, The Flooring Girl & Blog Stylist -Dynamo Marketers (The Flooring Girl) over 8 years ago

Nice post Jay! You taught me something as well, almost every inspection I do has some type of problem in this area, whether it be caulking, grout, or... TOO LATE!! Have a great day!!

Posted by Fred Hernden, CMI, Albuquerque area Master Inspector (Superior Home Inspections - Greater Albuquerque Area) over 8 years ago

I always learn so much from you, Jay!    Love the lessons, - we did a new bath last year - and I think it was done with that cement board.....

Posted by Dagny Eason, Fairfield County CT, CDPE Homes For Sale and Condo (Dagny's Real Estate) over 8 years ago

Jay, I have seen so many homes with issues stemming from water damage caused by improper shower installation that your post is so welcome.

Posted by Chris Smith, South Simcoe, Caledon, King, Orangeville Real Esta (Re/Max Chay Realty Inc., Brokerage) over 8 years ago


Good to see that being done. Unfortunately I have seen many showers done wrong. Good tilers are worth their weight in gold.

I really like the Kerdi system and like type systems.  For those who have not seen this here is a link. ( http://www.schluter.com/143.aspx ).


Posted by Donald Hester, NCW Home Inspections, LLC (NCW Home Inspections, LLC) over 8 years ago

Jay, Durock is a great product and I think that since it came out in the early/mid 80's most "better" tile layers have never looked back.  While the rubber liners are great there is also a product that many tilers use called Ultra-set that is essentially the rubber membrane in liquid form---tile can be laid right in the stuff---very tough and flexible.  It is very expensive---and certainly fits the definition of "best practices."  I see the price for a two gallon can has come down to around $150.00---it used to be considerably more.

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 8 years ago

S&D - good point!  Well, in this case!  This looks like a good job in the making.

Wow, Ginny.  Sounds like a fun problem to have to clean up.  And expensive...

Carol - there are so many things to look at, hundreds really, and with people talking and asking questions all the time, sometimes things can get overlooked!

Debbie - I bet!  Especially around the toilets and near the tubs.


Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

Great Fred!  Yes, and usually those problems are because of installation or materials.

Dagny - I would be surprised if anyone was to use another product.  There are probably grades of the Durock, though I have not investigated that.

Chris - that is the biggest spot for problems, and when they crop up they can be really, really bad.

Don - I have heard of the Kerdi stuff, which seems very top notch, but have never seen it.  That would probably be used only by custom builders.


Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

Charlie - sounds like a latex glue would have to be used.  I have never seen that stuff at all, and certainly builders, at that kind of price, would never use it.  It certainly could be considered best practice though!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

Jay - As a former builder, I was always aware of the potential for problems with showers and paid particular attention to their construction. And I always had my tile contractor (who was a stickler for quality), not the plumber, install the shower membrane to help protect against damage during construction. (In those jurisdictions that required a water test of the drain system, we just replaced the old membrane prior to tile installation. . . and we never had call-backs for leaky showers.

Posted by John Mulkey, Housing Guru (TheHousingGuru.com) over 8 years ago

Beautiful.  It's nice to see stuff done right.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 8 years ago

That's how it's done John.  Leave the different parts to the people who do them best.  The other shower in this house was just as well done.

Right Reubs.  There are so many things to look for in bathrooms.  This is a really important one.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

Nice, I was waiting to see a post where you found some items that were up to snuff for a change.

Posted by Justin Dibbs, REALTOR® - Ashburn Virginia Homes for Sale (Pearson Smith Realty) over 8 years ago

Jay - It is good to know there are some builders doing it right.  Have a great week!

Posted by Steven Cook (No Longer Processing Mortgages.) over 8 years ago

Justin - that's why I started my new group!   http://activerain.com/groups/bestpractices

Join up!

Steven - there were a couple of things on this house, but not many!  And I think the supervisor is right on the job!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

Nice post per usual Jay, love reading your "adventures"   Myself, I have been using the Schluester Kerdi membrane that gets thinsetted onto the walls and absolutely love it, not cheap but never a leak ever.

Posted by David Niles (Niles Real Estate Investments www.NilesREI.com) over 8 years ago

Thanks David.  Kerdi is really good stuff and mentioned above, but builders are not going in for something that expensive.  They should consider stuff like that, however, to try to set themselves off from the pack.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

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