should be your first choice for concrete refinishing (concrete grinding and sealing and/or Polished concrete). Whether it be a bar, restaurant, shop, kitchen, lounge, patio or whatever. We can grind and seal or polish your concrete to get a smooth attractive finish and seal it with the best suited sealer for your application. We have repaired too many jobs done by inexperienced “tradesmen”. (free tip, if a “tradesman” mentions polyurethane and concrete in the same sentence, run away). Experience has shown us that 95% of problems with sealed concrete involve polyurethane.
Why have a concrete floor?
Concrete is a great flooring medium that is unsurpassed by other flooring options in many aspects.
- Concrete has great thermal properties – concrete floors are thick and do not change temperature quickly or dramatically. On the other hand, tiles are thin (10mm) and change to the air temperature in minutes.
- Diamond Polished concrete saves on lighting costs – Mitre 10 Mega estimate that their highly polished floors save them about 80% on their lighting bill because of the light reflection.
- Concrete is robust – under normal use concrete will outlast virtually all other flooring options. Polished concrete is even harder, with greater abrasion resistance. There is nothing to come off, warp, suffer water damage or be cut by a devious child.
- Concrete is affordable – Lets face it, you’re probably going to have a concrete slab anyway.
- Concrete is attractive – It is certainly very popular at present. It can be coloured and/or have different coloured aggregate etc.
- Concrete is timeless – Unlike flower print wallpaper or terracotta tiles.
- Concrete will suit most home styles and furnishings.
- Concrete can be used inside and out, allowing that indoor outdoor flow.
- It’s very easy to change to a different style of flooring in the future (you don’t have to pull anything up).
- Concrete floors can easily be dressed up with rugs that are easy to clean or change. (tip, swap rugs between rooms to change the feel of the room)
- Concrete floors are easy to clean and very healthy because they don’t hold dust mites and everything else dropped on them.
- You have options. You can colour your concrete, or stain it. You can choose what colour and size aggregate you want, add coloured glass or crushed shell (if it’s not an existing slab). It can be cut into a large tile pattern, with or without grout (2mm deep by 6 or 10mm wide lines). You can have very little or a lot of aggregate showing. It’s your floor and we can help you make all the decisions that are right for you.
There are two ways to finish a concrete floor.
1) The previously most common and initially the cheapest way is to “Grind and Seal” the concrete. This involves grinding the concrete to about 120 grit with metal bonded diamonds and applying a surface sealer to the concrete. This will give a good finish that is easy to clean. It is the only way to complete external concrete as an antislip additive can be added to the sealer to prevent slipping. The surface sealer should be reapplied every 3-5 years to keep it in optimum condition and maintain ease of cleaning. The use of a mat in entrances will help reduce sealer wear.
We usually use Acrylic Concrete sealers because they do not scratch as quickly as epoxies and have a reasonable life span. A waterbased concrete sealer will give a lighter finish to the concrete, while a solvent based concrete sealer will darken the concrete (wet look). The solvent based concrete sealers can be Matt or Semigloss. The waterbased concrete sealers are semi-gloss or gloss only.
2) The latest advancement is “Diamond Polished Concrete” DPC (warning some people refer to grind and seal as polished concrete, the difference is like the difference between a gold plated ring and a solid gold ring). This involves grinding to 120 grit with metal bonded diamonds, applying an integral sealer (Creteshield DN), that penetrates the concrete and through chemical reaction forms a gel that swells, blocks the pores, then hardens. The result is a floor that is very hard (approx 42% improvement in abrasion resistance) and will not allow the penetration or escape of dust etc. This is then polished with resin bonded diamonds in various grades until the desired finish is obtained. This gives a natural shine to the concrete. Grades include 50, 100, 200, 400, 800, 1500 and 3000. DPC-200 is a matt finish, DPC-3000 is a gloss finish. Every concrete slab is different, what an 800 grit finish looks like on one floor may differ on another. Gloss has 2 elements, light reflection and clarity of reflection. The results can be similar to a granite bench top (if finished to DPC-3000 grit).
At Floor Masters we have developed our own system DPC. The DPC system is a result of our own experience and over 10 year experimentation here in New Zealand with local concrete floors. It is important to understand that most systems are formulated in other countries, where they have different sand stocks, that result in different concrete characteristics – some methods don’t work the same.
The major advantage over the other systems is that the DPC system does not need to be polished to the 3000 grit gloss finish (other systems require polishing to 3000 grit). This means we can do a matt, semi or gloss finish to your floor. Not only does this give you more control over the look, but can save you $ if we don’t need to do finer polishing. We have also sourced a great waterbased stain resistor (Creteshield SR) that we apply to the finished floor to give added protection from common staining agents. Creteshield SR also increases the slip resistance to greater than .05 Co-efficient of Friction required by OSH.
Our experience is that most people prefer a semigloss finish “DPC-800”. At this level the aggregate gains colour clarity and the sand starts to reveal it’s beige tones rathen than the grey of the cement. About 70% are finished to DPC-800(semigloss), about 20% are finished to DPC-400 (matt) and about 10% to DPC-3000 (gloss)
Summary – Grind and seal is the best option for external surfaces because an antislip additive can be used in the sealer. Polished concrete is the best finish for all internal floors as the concrete is hardened and a lot more scuff and scratch resistant. Shower bases can be sealed with an antislip additive.
Price is determined by the size of the area and the gloss level chosen. Big open areas attract a lower rate than small jobs and areas with more obstacles. Contact us for a rough estimate or for a written site quote. We can also quote from plans. Quote request
It is only fair to warn you about the unpredictable finishes attained when grinding concrete. We are always limited by a number of key factors. These should be taken into account when deciding to have a ground concrete finish.
1) What is in the concrete mix – If you want white stone and there was never any white stone in the concrete mix, guess what? – You’re clever! Things like leaves, bits of stick, bits of wood or worse, polystyrene can really detract from the finished floor if they are allowed to fall into the mix. Any patching will never be a perfect match.
2) How the surface is finished. The more concrete is worked and finished the more the stone or other goodies will sink below grinding level. Stone is heavier than sand. Grinding will normally only take off 2-3mm. More grinding will cost more. With highly finished commercial floors (ones that are slippery even when dry) when ground may not show any stone at all. It is also worth noting that if the slab is not finished well enough, you will have air pockets in the slab (little holes). We can slurry your floor to fill the majority of these holes during the grinding process. If you are wanting a “salt and pepper” finish, the floor with need to be highly power floated and very flat to ensure there are no high points to be removed as these will increase the likelyhood of larger aggregate being exposed.
Floor Masters has formulated the best process for reducing/eliminating aeration holes in a finished floor. I guarantee we do it better than anyone else. If the finish is important to you – call us.
3) Protect the slab until sealed – something as minor as a contractor spilling a cup of coffee on the slab can leave a lasting impression that won’t be noticed until the floor is finished. Concrete is porous, it will absorb most liquids that are spilled onto it. Painters, builders, gardeners or anyone with any form of liquid could ruin your idea of a perfect floor. Applying a sacrificial sealer after the concrete is laid is one option.
Ok so now you are thinking that ground concrete was a bad idea. Maybe not. A realistic expectation is all you require to enjoy the finished result. If you are building from scratch, plan for the above issues, choose your mix. Consider sealing the slab initially before building begins. The slab must cure a minimum of 14 days prior to sealing. If you are dealing with an already laid slab, keep in mind that you may not find any aggregate whatsoever and count anything better than that as a bonus. (to find no aggregate in a domestic slab is almost impossible, I’ve never seen it yet).
Concrete Staining – Staining is another option after grinding. (We only use water based stains due to environmental and health risks of using acid stains, and the fines if you allow them into storm water drains). This is an effective way to add colour to a ground concrete floor. We have a wide range of blendable colours available. The finished look is still largely influenced by the content of the slab. Staining is generally a mottled finish with the colour taking more strongly in some areas than others. This is then sealed for lasting results and ease of cleaning. If you are wanting a polished floor, then the colour needs to be in the concrete when it is laid. The process of Concrete Polishing and the penetrating sealers prevent the concrete stain from remaining in the concrete.
Questions & AnswersQ – At what stage should I get the floor done?
A – The best option is to grind the slab about 10 days after laying. This will be the first cut. Then after the framing and roof is in place we do our next step (inc grouting if required). Then apply a sacrificial sealer or 250 Micron Polythene to protect the floor during the building process. If you get all the building done and the plastering and painting out of the way, then we can come back and remove the plastic and grind and seal or polish the concrete. If you are carpeting sections of the floor, carpet should be done after concrete is ground. (note) skirting boards may need to be touched up after the floor is done.
Q – What are the options for sealing?
A – We have a variety of concrete sealers and coating available. Each has specific benefits best suited to particular applications. Gloss levels can be Matt, semi gloss or high gloss. Low odor sealers for public areas or occupied homes. Ask us for our recommendation.
Polished concrete uses Creteshield as an internal sealer. The advantage of this is that it is a permanent part of the concrete and can not be worn off and does not need re applying. It also hardens the concrete by about 42%. This is very scratch and scuff resistant, a lot more so than a surface sealed floor. A surface polish also can be used for added protection and buffed periodically.
We have a number of grinding machines that allow us to quickly and proffesionally complete your project.
Call us about your grind and seal or polished concrete project 0800 733 566