Build a Better Bathroom Faster with KERDI-BOARD
**Our honesty policy: This post may contain affiliate links and I may be compensated if you make a purchase at no extra cost to you. Some are, some aren't--I do some comparison shopping. The important thing is you will know exactly what we are talking about. Drop a note/comment if you have any questions on the products as these are materials and tools we use on our own projects.
Why should you pay hundreds of dollars for a shower waterproofing system when you can install cement backer board yourself for $75 and throw some Red Guard* on the walls?
This logic is VERY tempting in the middle of a remodel where the dollars are going out and you feel like an open checkbook.
#1: It is not as cheap as you think.
#2: The problem isn’t Red Guard, it is how it is applied (AKA user error, which may be why you are ripping out your current shower?).
#3: There are newer, better products that make waterproofing your next shower foolproof (I’m sure it can be done, but if you are reading this article I think you are the kind of person who will not prove me wrong!).
Actual scenario that inspired this post–maybe you are here because you can relate:
A friend pulled me aside and asked for my opinion about their deteriorating bathroom:
- The grout is falling out–water behind the tile is guaranteed.
- I know my tile was (as of almost ten years ago when I gutted them) attached to drywall with no water barrier and our houses are from the same builder.
- Their bathtub/ shower combo serves the four people living in their house.
My immediate answer: “So we’re gonna tear this all out…”
Of which the next question was, “any ideas” which in my book also implies, “how fast and how much.”
My answer: Schluter KERDI-BOARD.
You want this.
It is a lightweight board made out of polystyrene foam and the felt webbing pioneered from Schluter’s KERDI product, creating tileable surface a waterproof barrier.
A closeup of the texture of the fleece webbing on both sides of KERDI-BOARD.
Once in place, all screws and seems are covered with strips of KERDI, called KERDI-BAND. As soon as the last KERDI-BAND is in place you start tiling. There’s no 24-hour grace period needed. You can cut it with an everyday utility knife.*
You can see the white foam core on this 1/2″ KERDI-BOARD.
It comes in several thicknesses (3/16″, 3/8″, 1/2″, 5/8″, 3/4″, 1″, 1-1/2″, and 2″) with the intention for you to build other fixtures throughout your bathroom. For instance, you can build a pony wall between your shower and bathtub with two 2″ KERDI-BOARD sheets glued together–no framing needed. In fact, without framing or porous cement backer board in the walls there is nothing for mold to grow on.
Before KERDI-BOARD you had two options:
Install cement board, patch any seams with mesh and thin-set mortar, wait for that to dry, and roll on two coats of Red Guard with drying periods.
–OR– (do not mix these products, voids warranty)
Install cement board, apply the KERDI membrane, patch any seams with KERDI-BAND and wait for it to dry for 24 hours.
A time argument.
Let’s analyze them even further by breaking them down in terms of the amount of time each option takes to do a standard 32” x 60” bathtub surround. Included in this time estimate are items like: mixing mortar, cleaning tools, cursing, etc., but not trips to the store:
99% of bathtubs (maybe less after this article?):
- Install cement board –3 hours
- Patch any seams with mesh and thin-set mortar and wait for it to dry –3 hours
- Roll on one coat of Red Guard and wait to dry –2.5 hours (depending on drying conditions)
- Roll on a second coat of Red Guard and wait for it to dry –2.5 hours
= a long day
Applying KERDI:
- Install cement board –3 hours
- Apply the KERDI membrane (I love watching Schluter videos. For real. They make it seem so easy–like watching Olympic volleyball. I’m certainly not a pro and a second pair of hands was required for the level of quality I wanted–hung straight, the least number of seams, with minimal divots from me–like what happens when I realize I am not as good as Olympians playing volleyball. In my defense, when you look at the pictures above, I also did not cut KERDI down to the width of one wall. I over analyzed it like a good engineer. I figured if the cement board meets in the corner, and the KERDI meets in the corner, and then the tile meets in the corner–what is the one place where water is most likely to infiltrate? The corner. So I intentionally made the KERDI turn the corner. Second, I chose the overlapping method. Instead of butting edges of KERDI and applying KERDI-BAND, I wanted less seams–cutting possible points of failure in half–and overlapped at least two inches** (pictured at the end of the post). A second pair of hands was essential to make the corner turn, maintain a straight overlap, and keep the evenly spread mortar…well…evenly spread.) –2 hours X 2 people
- Patch the seams with KERDI-BAND –2 hours
- Wait for it to dry for 24 hours –24 hours (you could tile right away, but you run the risk of moving the KERDI)
= a long day and a down day
Now the time estimate for KERDI-BOARD:
- Install KERDI-BOARD –2 hours
- Patch the seams with KERDI-BAND –2 hours
= a morning
KERDI-BOARD allows you to create a tub surround in a quarter of the time by combining all of those previous steps into two.
- As a contractor you are tiling when you used to be still waterproofing. This time savings can double the number of installations you do per year effectively DOUBLING your income! Also consider what happens when you have virtually zero callbacks…
- As a DIY homeowner you are shortening the amount of downtime you have in a bathroom.
Back to my neighbor’s scenario:
With four family members relying on a single bathtub enclosure, how fast can we do a tub surround? One thought is to pre-plan an amazing tile design that also lends itself to a quick install. After we have all materials on hand we can pick a weekend to make it happen. On said weekend, it will be all hands on deck, preteens included, to demo out the old enclosure the night before on Friday night. It would be amazing if we could start installing the KERDI-BOARD Friday night, but it might be more realistic to start the next morning. Next we would, rent a saw as my beloved DeWALT wet tile saw is currently out of state. We would tile Saturday, bleeding into Sunday if needed. So worst case we are grouting and caulking on Monday night (having mixed the grout with sealer). Allow another 24 hours for drying and they could be back in business by Wednesday at the latest. With showers at my house in the interim, we are all motivated to move this job along at full speed.
A cost argument.
It’s not just a time saver either. If we actually read the labels on products you might be surprised how similarly priced KERDI-BOARD is in comparison to the first solution the average person thinks of (liquid membrane on cement board) when they tackle a bathtub surround.
This is where I’m going to get technical and call out that both Red Guard and KERDI-BOARD are rated for ANSI A118.10 (again, for Load Bearing, Bonded, Waterproof Membranes for Thin-set Ceramic Tile and Dimension Stone Installation). I want to provide you with a full on apples to apples comparison:
Hardie-Backer @$15 x 5 = 75
Red Guard = 40 sq ft/ 1 gal as waterproof membrane meeting ANSI A118.10 standards @$50 (65ish sq/ft divided by 40 = 2 gallons) = $100
self-adhesive alkali resistant fiberglass cement board mesh tape = @$7
A decent 3/4″ nap paint roller so you don’t end up with castoff lint creating “texture” in your Red Guard = @$7
= $189 + tax
–VERSUS–
KERDI-BOARD $99 x 3 = $297
KERDI-BAND 33 ft roll = $32
KERDI-BAND 16 ft roll = $18
KERDI-BOARD-ZT/-ZS (40 screws and washers/package) $12 x 2 = $24
= $371 + tax
Shared purchases just to round out what all you need to set up for tile. Both scenarios need these so I’m excluding them from our expense comparison:
KERDI-FIX = $25 <–you still need to seal the gap between the tub flange and the Red Guarded cement board
KERDI-Seal-PS Pipe Seal with 3/4in. Opening (for the tub and shower head plumbing) $6 x 2 = $12 <–you still need some way of sealing off these protrusions.
KERDI-Seal-MV Mixing Valve with 4-1/2in. Opening = $7 <–see previous line
thin-set mortar <–to set the mesh tape and KERDI-BAND
Shared materials aside, we’re at a difference of $182 plus tax.
What is $182 worth to you? Making sure Red Guard is even so it meets the same waterproofing standards of KERDI-BOARD? An extra day of setting up the walls of the shower? No pain in your back?
Also note, we are not factoring in the cost of labor here since we are clearly talking about DIY. However, if you aren’t going that route and you are searching for an idea for a general estimate, you’ll have to factor that more labor costs more. From a point and pay perspective, it might be equal, or more likely, cost less to install KERDI-BOARD.
I’m going to admit I was a bit surprised as I saw the numbers adding up for the traditional scenario. I think of cement board being economical, but all in it wasn’t as economical as I thought. I KNOW how hard it is to install cement board. For that amount of work I was expecting it would cost about $100. The thing about KERDI-BOARD is it is an all-in-one board-and-foolproof-waterproofing solution so you don’t have to go through all that work. I am sold!
Dropping the install time for a watertight, mold fighting bathtub surround is only made possible with a product like KERDI-BOARD. It makes a project of this magnitude over an extended weekend a guarantee**, not just a pipe dream.
KERDI-BOARD is a waterproofing membrane
It ensures water stays in and does not escape behind the cement board into the framing. If you end up with mold growth behind the wall, it’s going to be because of some other problem from the other side of the wall, not the shower side.
Lightweight
A 3’ x 5’ x ½” cement board runs 39 pounds. Compare this to a 4’ x 8’ x ½” KERDI-BOARD at 6.54 pounds. KERDI-BOARD is 37.5% larger than cement board and weighs only 17%? Yeah, I can handle that–with one hand.
Durability and longevity
Because of waterproofing, the shower will last a lot longer than if no waterproofing or improperly applied waterproofing were used.
Added insulation.
The polystyrene foam in KERDI-BOARD adds R-value (2.2 for a regular 1/2″ board to be exact) to your exterior walls. My master bathroom is already temperature sensitive due to sub par ducting, a large window and a skylight. Adding KERDI-BOARD instead of cement board would have added some appreciated insulation in the walls.
Dust free.
I’m not gonna lie. I didn’t end up with the knack for scoring cement board. I have a turbo blade on my grinder, a pair of goggles and a respirator. I know how to use them. It’s not to say I can’t improve, but why put down the sledgehammer when it is effective? Plus, I’m going to need them anyway when I need to cut a bump out, not just a straight line.
Me and my dad sporting safety equipment and wielding power tools getting our subfloor on!
In any case, when I am cutting cement board I’m creating a dust cloud. That is not going to happen with a utility knife and KERDI-BOARD. You can skip the goggles and respirator too.
Did I mention it is light AND dust free?
I can throw a few sheets in the back of my Mazda3 hatchback guilt-free! It won’t mess up the interior of the car and I don’t have to worry about the weight limit. I’d have to rig up some protective measures with plywood or 2×4’s for transport, but it would not be a big deal.
You don’t need as many tools.
Put away the grinder, turbo blade, googles and respirator.
Pre-made KERDI-BOARD shower niches are also available.
If you don’t opt for corner shelves Schluter has a pre-made KERDI-BOARD option for a 100% waterproof niche. Quick to install with a KERDI-BOARD shelf that can be set at any height–you decide!
Warranty
If the product is defective it is probably going to show up sooner than later. Just in case, if you follow all of the installation instructions and keep your receipts for proof of purchase, they will warranty your shower with a 10 year guarantee (limited lifetime if you use their thin-set and register the project within 90 days of installation). Check out all the warranty details here.
Mike Holmes uses it.
Not only is he handsome, but his attention to detail and his insistence on doing things the right way is unquestionable. Doing an install right the first time is my mentality too. I started looking into Schluter products, as I am sure other people have, after seeing him use it on his rebuilds.
Marketing works! But it’s not just hype. The product is solid!
More pros:
- As a DIY lady with no muscles (like me), you can install an entire waterproof shower by yourself.
- As a person who fears power tools, if you choose the right tile design you can get away without any power tools for the entire project (although I’d still highly suggest using a drill to sink in the screws and mix the mortar).
- As the main installer, you don’t throw your back out hauling around cement board. Not only are you saving yourself muscle pain, perhaps you are also saving on medical bills if you injure yourself with unwieldy cement board.
Other considerations:
There are times when you really need to plan well in advance before installing KERDI-BOARD.
Installing safety or other weight bearing fixtures.
KERDI-BOARD is foam. Anything load bearing, such as grab bars, need to be planned ahead of time in the framing stage. If a stud is not in the exact spot, you’ll need to install additional framing to support the fixture. Then, make DAMN sure you know EXACTLY where the framing is and write it down in multiple places.
Consider your tile choices.
Thinking about glass tile? Schluter asks you to contact them before deciding just in case you need special materials for installation. The same goes for moisture-sensitive stones, such as green marble, or resin-backed tiles.
Schluter KERDI and KERDI-BOARD does not uncouple tile from the wall.
The ability to uncouple your tile from the walls, creating a floating structure, ensures grout does not crumble and tiles do not pop off due to movement of the base structure. KERDI–and likewise KERDI-BAND–has limited crack bridging capabilities, but it is mostly for the gaps where backer board pieces meet. Or where the wall meets the floor. It is not a crack isolation membrane according to ANSI A118.12 standards.
It is certainly better than nothing and I put it on my custom window ledges as such, but DO NOT count on it for warranty purposes.
I want Schluter KERDI-BOARD! Now where do I buy it?
Schluter KERDI-BOARD isn’t necessarily on the shelf at your local big box store. Home Depot has 4′ x 8′ sheets on the website, but it does not have it in stock within 100 miles of me in Phoenix and probably due to the lightweight, yet massive size, they don’t deliver it either. Lowe’s only offers it online in 32″ x 48″ pieces. It is a start into mainstream big box stores, but I’d rather have the full sheet for cleaner installations. Instead, look to places like Floor & Decor or your local tile store. Here is the Schluter store locator.
When I went to take photos of the Schluter products at Floor & Decor the knowledgeable associate (thanks again, Tim!) said KERDI-BOARD is flying off the shelf. Call ahead before heading over to make sure they have it in stock.
I really considered not including an link to the Schluter-KERDI-BOARD-KIT where Schluter puts everything you need all together in one package. It includes KERDI-BOARD, all the gaskets, two tubes of KERDI-FIX, etc.
Why not mention it?
Because I wouldn’t buy one.
Instead, I would buy three full sheets of KERDI-BOARD. In this bathtub surround we are considering, the two walls that are 32″ x 80″ will be full sheets. Then the third wall that is five feet across will have an full sheet across the entire bottom along the tub as a 4′ x 5′ sheet. The rest can be pieced together on top with the leftovers. –Yes, piecing together your own shower can also qualify for the lifetime warranty as long as you follow all installation directions with all the proper Schluter materials (verified by the Schluter sales team).
The Schluter-KERDI-BOARD-KIT comes with 8 panels that are ½”x 48” x 38”. Which means you’d have to splice more pieces together. I’m not going to knock that because I can only imagine what the box of three full size panels would look like on my front doorstep. Seriously, if a shipping service drop kicked a tank-less water heater at the build site last week…
A 4′ x 8′ package that weighs only 20 pounds would look like a folded lawn chair. It’s foam. It does it’s job on the wall–not as a punching bag.
However, it is worth mentioning because not everyone lives in a huge metro area with access to dedicated flooring stores. Not splicing is a nice to have. No Schluter in a nice new bathroom is just wrong.
You can check out the Schluter-KERDI-BOARD-KIT here.
Our products cannot be sold. They have to be understood. -Mr. Werner Schluter
I wholeheartedly agree with this sentiment. Until you understand what you gain by using a Schluter products, you probably won’t want to spend the extra money. However, if a watertight, mold proof shower sounds good to you, it is money well spent.
It is not just about what the tile looks like on the outside. Grout is porous and all water needs is time. Water will eventually find a way behind the tile. This is why it matters what is BEHIND the tile.
I don’t want to think about how long my neighbor’s shower has had issues. The problems in my house were probably showing up well before I bought it in 2009. Faulty showers and bathtubs are plaguing the entire neighborhood.
It is not just in my neighborhood, though. Substandard materials and poor installation are a problem everywhere! It might be immediate or take a while for problems to appear, especially when they are covered up (in this case with tile). What I do know is when we are done my neighbor’s new tub surround will be solid for decades to come with KERDI-BOARD.
*This is not a bash on Red Guard. It has done very well by establishing itself as an easily recognizable household name brand for a reason and it most certainly has its uses. The concern is how it is applied in the real world–which is totally out of Custom Building Products’ control.
Is it thick enough? Is it too thick? Either direction has problems. Likewise, did you put on two coats with enough time for it to completely dry in between? Did you use the 1.6 gallons needed for that standard shower? Did you honestly?
This is why when it comes to showers, we fell in love with Schluter. You put it on and don’t second guess the thickness or application. In all fairness, though, you can still mess up a Schluter installation with thin-set that is too wet or not wet enough, or applied too thick or thin, or not pushed in enough, but the thickness of the waterproof membrane is no longer a factor.
We have and will continue to use other Custom Building Products other products. Their offerings, Red Guard included (and we have used it in the past), are good quality.
**Again, with a preplanned, easy to install tile design. Nothing complex. We aren’t talking about plumbing changes either.
Some of you may be wondering, “This is a post on KERDI-BOARD. If you love it so much, why don’t you have pictures of it in your showers?”
I used KERDI instead of KERDI-BOARD.
I started on the first bathroom at the end of 2010 with a huge roll of KERDI (you can tell because the pictured KERDI does not have the handy metric grid it now displays for easy cuts and lining up tile). Schluter came out with KERDI-BOARD in 2010, but I did not know about it. The roll was enough for the bathtub surround and the master walk-in shower. So when 2013 came around and it was time to do the master walk-in shower I went with KERDI because I already had it. I didn’t know about it then either as I had a watertight solution so I wasn’t looking.
Now if I was starting over I’d definitely use KERDI-BOARD as I will on any future bathrooms.
