Floors for outdoors: Blurred lines between living spaces

It’s the time of year when we are spending a lot of time indoors, and if you’re like me you are looking forward to the days when we can put the winter coats and the snow shovels away. From that mindset I found myself this month thinking about floorcoverings for outdoor use.

I started in the business in the 1970s, and I remember doing a fair number of installations of “indoor-outdoor carpet” in my years as a floorcovering retailer. I also remember certain resilient flooring products such as the original Kentile solid vinyl tile (SVT) that was approved for outdoor use. I never did any outdoor SVT projects with that Kentile, although I always wanted to because I had done a lot of SVT work indoors, and I still do.

Fast forward to the last nine years or so that I have been on the commercial side as a manufacturer’s rep. I have come across several resilient flooring products being promoted for outdoor use, and even had the opportunity to work with some of them on projects. That could be an outdoor patio, playground, sidewalk, roof deck, or a covered or enclosed porch that’s relatively dry but unheated. Regardless, this is a different set of circumstances from an indoor floorcovering installation. As a result of working on a few of these projects, I have done a fair amount of Q&A, so I thought I’d share with my Coverings readers.

What products are being used outdoors?

Of course, there are many tile products such as porcelain and quarry tile that are suitable for outdoor use, and there are also some wood and bamboo products on the market that look like an indoor wood floor but are being used for outdoor decking. However, for this column we will discuss carpet and resilient flooring products since that’s more of a unique application.

My old favourite outdoor SVT products are long gone, but there are some manufacturers with sheet vinyl that’s being sold for outdoor use. Of course, vinyl is waterproof but not always colourfast, so that’s why these products are a little different from a standard indoor product and why not just any vinyl can be used outdoors.

Another option for outdoor use is recycled rubber. Standard vulcanized rubber is not colourfast enough for outdoor use, but recycled rubber can be, depending on the manufacturer and how its product is made. Recycled rubber is a combination of scrap tire rubber and colour chips made from polymers that are similar to the material often used for roofing. Both materials are colourfast, but the binding agent used to fuse the rubber and colour chips together may not be. Check with the manufacturer before you recommend a product for outdoor use. I have worked on a number of recycled rubber projects for outdoors — some in modular tile that’s loose-laid and some with glue-down sheet goods.

There are also some “poured in place synthetic” materials used outdoors. Some of these are made with rubber, such as for playgrounds. Others use stone chips or various polymer particles.

What type of adhesive should I use?

A number of waterproof adhesives can be used outdoors and will take the temperature swings we northerners are accustomed to. I have worked with single-part urethane adhesive on rubber installations, and there are also two-part reactive adhesives, such as epoxy and polyurethane. The floorcovering manufacturer will usually be able to guide you in this regard. The same holds true for outdoor carpet and synthetic turf. There are adhesives specific to the application. Make sure the adhesive is right for the backing and the substrate.

Can I install outdoors at any time of year?

Not really. Temperature at the time of installation is important for floorcoverings — whether it’s indoors or out. But for outdoors, it may be the most important thing. In cold temperatures, some flooring material can shrink slightly and adhesives will be a lot harder to work with. They’ll also take much longer to cure, or they won’t cure at all once you get below about 4 – 5 C. A recent modular rubber-tile installation I worked on had to be postponed several months because they just couldn’t get the job started before the cold weather set in. Very warm temperatures can also work against you — because the material can expand or stretch during handling (I often say “grow”) when it’s hot and the adhesive will cure very quickly. Your ideal temperature for installing any glue-down floorcovering — indoors or outdoors, is about 18 – 24 C.

Is there anything else I have to be concerned about?
Yes — moisture and substrate preparation. With floorcovering products designed for outdoor use and adhesives that are waterproof and temperature stable, it’s easy to assume that’s all you need worry about. However, if you are installing on concrete, it’s safe to assume there is not any kind of vapour retarder or barrier beneath the slab as there would be for indoors. The slab was probably not designed to be covered with an impervious floorcovering. And, make no mistake about it — no matter where you are; in the desert or on the water, moisture from the ground is passing through that slab. Just because the adhesive is waterproof doesn’t mean that moisture vapour emissions won’t cause an adhesive bond failure. An “action-back” outdoor carpet might let moisture pass through it, but anything with an impervious backing will not.

Trapped moisture can cause the adhesive to separate from the slab and bubbles will be everywhere. There may be adhesives that can handle this condition but if not, apply a moisture-mitigation coating to the slab first. This ensures all that moisture from the ground stays put. Very few moisture-mitigation products are geared for outdoor use, so specify the right one.

If you are going over a wood substrate such as plywood, beware of “pressure treated” wood, the adhesive may not be comparable with the chemicals in the wood. It’s a good idea to do some research. Maybe call the adhesive manufacturer, have a chat about the conditions you are dealing with and do an adhesive bond test.

And, as with any glue-down floorcovering, the substrate needs to be smooth or irregularities will telegraph. If you use a patching compound to smooth the substrate, make sure it can handle temperature extremes that are sure to be present with an outdoor installation or an unheated indoor space.

Outdoor installations are a unique growth area for our industry. As with any specialty floorcovering, a little extra care needs to be taken to do the job right. 

Christopher Capobianco is a flooring expert currently working with Forest Hill, Md.-based Spartan Surfaces, a distributor of commercial hard-surface flooring. Chris’s family lineage in floorcovering goes back for generations. His career includes time as a retailer, architectural sales rep, technical support manager, consultant, instructor, columnist and active volunteer in several organizations.