On the face of it, installing carpet over carpet does have many advantages. It saves on the cost and labor of pulling up and disposing of the existing carpet, keeping carpet waste materials out of the landfill. When the existing carpet is glued down, not tacked, this can be a huge time-saver, since glued carpet is expensive and time-consuming to pull up. Finally, leaving existing carpet provides one extra layer of insulation for cold floors. Installing a pad is not necessary, as the existing carpet acts as padding.
But carpeting industry professionals advise that installing carpet over carpet is not a good idea for many reasons.
Tack Strips Are Difficult to Install
By leaving a layer of carpet, you make it that much harder to nail down the tack strips (those long, wooden strips around the perimeter with upward-pointing spikes). Nails on tack strips run about 3/4-inch long, which is far too short to penetrate carpet plus a pad (if the carpet has one) and into the subfloor. In fact, the difficulty of placing tack strips may be the single factor that prevents you from putting carpet on carpet.
Carpet Is an Inadequate Base
Carpeting needs a solid base for installation. Carpet installed with an improper base will wear out quickly. There are many aspects to this, but consider just this one: traffic patterns worn into the existing carpet will be transmitted to the new carpet.
Old Carpeting Harbors Dirt, Mold
Studies show that mold and mildew in carpeting are exacerbated by the presence of dirt. Dirt and moisture, with high temperatures added, equal mold and mildew. It is virtually impossible to clean an old carpet enough to remove all of the dirt. Yet if you go the route of professional carpet-cleaning, you're already spending money that could have been spent on removing the carpet in the first place.
Creates Additional Floor Layers
By adding an extra layer to your flooring, you are effectively lowering your ceiling. If this is a basement or any other height-challenged room, every inch counts. Don't forget that adding height to your carpet will mean that doors will scrape and thus need to be cut at the bottoms. Also, trim will have to be removed and reinstalled.
You Lose a Chance to Check the Subfloor
Ripping up carpet lets you assess the status of your subfloor. This will provide you with an opportunity for repairing damaged subfloor. Keep in mind that if a previous owner has installed low-quality carpet, this may signal problems underneath, particularly problems that are difficult to deal with, such as rot or mold.
Carpet on Carpet: How to Make It Work
If you still feel, after reviewing your options, that installing carpet over existing carpet is the best route, here are some tips for that strategy:
- Go Low: Extremely low-pile carpet is the best kind that will work. The lower the pile, the better.
- Keep It Temporary: At best, carpet-on-carpet is a short-term solution. So, if you are house-flipping or intending to stay in your home for a short while, this option may be for you. In fact, placing an area rug on carpeting is perfectly acceptable.
- Using Failed Glue to Your Advantage: Have you ever tried removing glued-down carpet? It might not be as hard as you think. Even though glued-down carpet can be notoriously hard to remove, some old carpet adhesives have essentially failed over the years and broken up. Test a corner of the carpet and see how hard it is to pull up. You might get lucky.
- Carpet Recycle Options: Concerned about dumping carpet in landfills? There is a non-profit consortium called Carpet America Recovery Effort that helps plug homeowners into companies that recycle carpeting.
- Use Power Tools to Scrape up Carpet and Glue: When you do need to laboriously scrape up glued-down carpet, don't do this by hand; it's simply too difficult. Instead, recruit the services of a power tool, such as a multi-tool with a scraper attachment. It's also helpful to have a heat gun to loosen up the stubborn glue. Be very careful when using a heat gun near textiles and carpeting, though.
- Using a Thin Underlayment: Thin plywood underlayment atop low-pile carpet is better than just putting the new carpet straight onto existing carpeting. The underlayment will a rigid base for the new carpet.