Concrete countertops the most unique, personal countertop option because they are made from scratch for each client. To determine whether concrete is right for you, think about whether you believe that:
If so, concrete countertops may be right for you.
What are the advantages and disadvantages of concrete compared to other countertop materials?
How much do they cost?
Even though it is a completely custom material, concrete is competitive in price with standard countertop materials. The price is competitive with high end granite, ranging from £80 to over £100 per square foot. We are happy to work with you and your designer to give you an estimate on your project, and we can help you with options to fit your budget.
What colours are available?
Any colour! Concrete can be made in hundreds of colours including every colour on the spectrum. Any colour can be produced in a solid, speckled or variegated pattern. And, you can specify embedded stone, glass, or other objects. You can specify the colour, size and density of embedments. Coupled with the many colour choices, you have myriad design options.
What is the process for custom colours?
PCNI specializes in custom colour development. We can customize existing colours or match the colour of an item such as a paint chip or fabric. The process takes about 3 weeks. We produce two or more 150mm x 150mm samples and submit them for your approval.
How much colour variation can occur?
Concrete is a natural, handmade material. Many factors such as humidity, sand lot and cement lot can affect the final appearance of the concrete. All of our colour formulas record the type of sand, type of cement, and exact measurements of pigments to 1/10th of a gram, and we use specially developed software to calculate mix design. However, colours can still vary because of the aforementioned factors.
Another factor that contributes to perceived variation is simply the size of samples. A 150mm x 150mm sample will look different than a whole countertop simply because the small sample does not capture all of the natural, random variations that will occur over a large surface. The colour in a 150mm x 150mm sample may appear completely uniform, but a whole countertop in that exact same colour will not appear as uniform. The same situation occurs with other natural materials such as granite. If you are looking for perfect uniformity, you might not be right for concrete, and you should choose solid surface instead.
What edges are available?
For concrete, edging is formed and cast rather than cut like granite or solid surface. Therefore, edge choices depend on the availability of appropriate trim molding. For example, PCNI can do pencil, beveled, concave, bullnose and reverse cove edging, and other custom edges may be available. Edging may be placed on top or bottom of the countertop.
What kind of sinks can be used with concrete countertops?
PCNI countertops can accommodate all types of sinks including drop-in, undermount and apron front. The minimum lip of concrete around all sides of sinks is 75mm. Concrete can also accommodate drop-in cooktops. The minimum lip of concrete in the front of a cooktop is 75mm. We recommend 75mm for the back also, but 50mm will suffice.
PCNI can make integral concrete sinks of almost any shape. Bathroom vanity tops are an excellent application of integral concrete sinks.
We do not recommend integral concrete kitchen sinks for engineering reasons. Kitchen sinks are deep and have angles that would put large stresses on the concrete and have high potential for cracking. Also, the size of kitchen sinks generally dictates a very thick concrete bottom that would be a problem with standard plumbing and cabinetry.
Concrete vessel sinks are also possible, and concrete’s versatility means that the sink can be any colour and shape.
What about backsplashes?
Backsplashes are cast and finished separately and deck mounted after the countertops are installed. Backsplashes are nominally 25mm thick and can be from 75mm high to full height. Outlet openings are cast in, not cut on site.
Will concrete countertops stain?
Bare concrete is very porous and will readily stain. Virtually all concrete kitchen countertops are sealed to prevent staining; however the degree to which these sealers works varies significantly. Commonly used sealers include wax and penetrating acrylic sealer. Both of these are inexpensive and easy to apply. However, neither offer significant stain or heat resistance, and both require frequent reapplication to prevent the formation of a “patina”.
PCNI’s sealer is different. We use a high-performance sealer that is exceptionally durable and provides excellent resistance to incidental contact with staining agents such as red wine, lemon juice and olive oil. Complete care instructions are included in your Owner’s Guide. Touch-up of any marks that do occur is simple and easy.
Will they scratch?
While the sealer is durable, it can scratch if cut with a knife or subjected to heavy, sharp objects dragged across the surface. Cutting on the concrete may compromise the integrity of the sealer and allow stains to permeate the concrete matrix. Cutting on the concrete will also ruin knives, requiring a professional resharpening to reshape the damaged edge. Remember, concrete is made with stone, the same thing used to sharpen knives (and will therefore dull them just as easily). If you do scratch a countertop, you can easily repair it yourself using your Touch-Up Kit.
Can I put hot pots on the countertops?
As with almost all types of countertop surfaces, it is best to use trivets. Concrete can microcrack if exposed to high heat, and the sealer is not elastic enough to “absorb” these microcracks. The surface will appear “crazed”. However, the Touch-Up Kit can be used to minimize the appearance of these microcracks, just like it is used to touch up scratches.
How are concrete countertops made?
All of the slabs are precast in our shop and fully finished and sealed prior to installation.
When it comes to concrete countertops, there are two basic processes: cast-in-place and precast. Cast-in-place involves building forms and pouring concrete in place, directly on the cabinets. While this avoids the hassles of transporting heavy slabs, it does tie up the site for many days (or weeks), and it involves a messy process. In addition, cast (or pour) in place provides fewer options and less control over the finished product. Generally the only finish available is a trowelled surface, which is either acid stained or coloured with pigments. The quality of the concrete, the finished appearance and ultimate performance of the countertop are all hampered by the fact that it’s all being done on site under a rushed time schedule.
Precast concrete, on the other hand, moves all of the processes off site into a controlled environment. In the structural engineering community, it is well known that precast concrete is superior to cast in place concrete, mainly because tighter quality control can be exercised. Curing, which is a critical step that is commonly misunderstood, can be closely monitored. Moving the process to a shop allows greater flexibility in terms of the look of the concrete. Glass, stone and other objects can now be embedded; these require extensive wet grinding with diamond power tools to reveal the embedded objects and hone and smooth the resulting surface.
There are 2 methods of precasting: wet cast and glass fiber reinforced concrete (GFRC).
Wet cast uses a more traditional concrete mix of sand, aggregate and cement poured into forms. Our formula uses specialized admixtures to achieve the ultra-high surface quality needed for interior kitchens and bathrooms. We use local ingredients whenever possible.
Because of our education with The Concrete Countertop Institute, we are able to properly reinforce wet cast concrete to prevent cracking. Proper steel reinforcement is essential to combat the large stresses placed on a long, thin slab of concrete such as a countertop.
GFRC is concrete that is structurally reinforced with a large loading of alkali-resistant glass fibers instead of with steel. It is built up in 2 stages: a thin “mist coat” that is sprayed into the forms and provides the surface appearance, followed by a very fibrous “backer coat”. GFRC is extremely strong, flexible and light compared to wet cast concrete.
PCNI will work with you to determine which type of concrete is best for your project, depending on the look and shape you want to achieve.
What is the lead time?
Although countertops are one of the last items to be installed, concrete countertops should be selected as early as possible. Here is an outline of the process:
1. Colour selection
How are templates made?
Concrete countertops are templated just like quartz and granite. Templating is done after any existing countertops are removed, or after new cabinets are fully installed. Your contractor needs to arrange for existing countertops removal. Almost all concrete countertops require physical templates from the finished and installed cabinetry.
In some cases, such as small or freestanding pieces, we can fabricate from CADD drawings instead of physical templates. We will advise on templating requirements for your project, and we provide your contractor with a templating checklist to help him prepare. All fixtures that penetrate the concrete, such as sinks and faucets, must be available at templating time.
How are the countertops installed?
Concrete countertops are handled and installed just like quartz and granite. Seams are caulked with a colour-matched acrylic caulk. Your contractor needs to arrange for plumbing and electrical hookup no earlier than 24 hours after the countertops installation.
Are there any seams?
Often concrete countertops can be designed without seams. Seams may be located around sinks and cooktops, or wherever required for structural reasons. Or, seams may be necessary due to the logistics of getting the slabs into the house if stairs or corners are involved. PCNI will work with you to design seam placement that is both structurally sound and aesthetically pleasing.
Seams are typically 1/1150mm wide, similar to tile grout lines. However, it is important to realize that concrete countertops are handmade and hand processed; they are not machine cut, so tolerances for seams are more generous than with quartz or granite. Seam appearance is minimized by using colour-matched acrylic caulk.
Are there any special structural considerations?
No. Standard precast concrete weighs about the same as quartz or granite of the same thickness., and glass fiber reinforced concrete weighs half as much. Typically, no special considerations are necessary for standard kitchen or bathroom vanity tops. Cantilevered slabs, bartops on kneewalls and similar situations sometimes require brackets or other structural supports. PCNI can advise on support requirements.
Do you offer a warranty?
Yes. PCNI warrantees the structural integrity of the concrete for one year after installation. Concrete will of course last a lot longer than a year, but if any problems were to occur, they would occur in the first year. We subject the concrete to much larger stresses while handling it than clients ever could once it is installed. In addition, PCNI provides each client with an Owner’s Guide and a direct phone number for support.
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