Car Interior Tips: Ultimate Guide to Carpet Underlay and Carpets

Maintaining your car to even remotely resemble the condition that you got it in from the showroom, takes a lot of effort and time. Sure, you’ll observe regular servicing intervals, and frequent car washes to get the best shine, but what about the interior? Vacuuming and polishing can help, and changing seat covers or adding a few rubber mats can keep things clean, but only up to a point. The longer you have your car, the more damage there’ll be to your car carpet. Carpets are the most overlooked part of any car. How often do you gaze to check the condition of the carpet? If you’re a smoker, then quite a few times, but for the rest of us, we’ve got our eyes glued to the road.  

Carpets are the most abused areas of any vehicle. We’re constantly treading on them, scrapping them, spilling coffee and drinks, and letting them indulge in what’s left of our drive-thru takeaways. But it’s not just food and drinks that sticks and damages it, it’s also the exposure to the sun that makes carpet slowly but surely fade. Then there’s dirt, mud, water, or anything we wipe off of shoes. Tradies know what I’m talking about. You’ll have remnants of your cup of coffee, the combo meal, and all the mud from a day’s hard work partying on the car carpet.  

I’m exaggerating here, but you get the picture. Over time, mould, mildew and nasty smells coming from the floors mean it’s time to act. For a spotless interior, you can rip out your old one and buy automotive carpet in the colour, design and fabric you like. And while you’re at it, check the condition of the carpet underlay. If there are visible signs of damage, this needs to be replaced too.  

Reasons to Buy New Carpet and Carpet Underlay 

You’ll notice a difference in soundproofing between luxury and budget vehicles. This is largely due to the added layers of insulation between you, the driver, and the areas that generate the most noise. Obviously, this is the engine and exhaust, with added insulation in the firewalls and the body floor. Insulation also shields from radiant heat, meaning more comfortable driving conditions. A protective insulation underlay will keep wiring safe and clear from spills, and all metal parts free from rust.  

Carpet underlay is one of these insulative products. It not only serves as a non-slip surface for your new carpet and carpeting, but also provides waterproofing, soundproofing and acts as a protective layer.  

Types of Carpet Underlay 

Older vehicles have a jute or cotton shoddy underlay that deteriorates with prolonged exposure to heat and moisture. It forms clumps leaving large areas unprotected. If you’re restoring an older car, this needs to be removed. You can replace it with several newer, more high-tech yet affordable materials. The first consists of a thin vibration dampening mat made of a noise absorption butyl rubber bottom layer and an aluminium heat resistant top layer. This stops engine, transmission and exhaust noise from entering the interior. It is easily cut to shape and with an adhesive lining, sticks to the floor. Mats are sold in packaged sheets, and one pack should insulate the entire floor in most vehicles. You can also get them in different colours.  

This serves as a base for the next layer, the one just under your carpet. Here you have more options. Acoustic liners consist of foam in two layers. The bottom layer is open cell foam, to dissipate noise and heat, and the top layer is closed-cell foam, which is also water-resistant. Combined with adhesive dampening mats, this cuts out sound and also insulates against accidental spills. Another choice is to go with a mass loaded underlay consisting of a vinyl bottom and closed-cell top layer. With a total thickness of 8mm, this insulation layer is premium and used in luxury cars. It deadens sound, and provides for the best thermal protection. This type of carpet underlay is non-stick, meaning it can be removed at any time. Applying mass loaded vinyl is easy, simply cut it to shape with a pair of scissors. For vehicles with high heat generation (like diesel utes and 4WDs), and excessive sound this is the underlay to get.  

Car Carpet 

You can buy automotive carpets in two major types. The first is stretch carpet, used for sound and thermal insulation in areas other than the floor. Wheel arches, firewalls, boot lids and roofs are common places where the stretch carpet is applied. It consists of quality, cut pile carpet, which is also flexible and pliable, sticking to different surfaces. Its durable, UV resistant fibres are good for maintaining texture and colour in vehicles with longer exposure to sunlight. Stretch carpet sticks to the underlay with contact adhesive and can be ordered in the sizes best suited for your vehicle.  

Moulded carpet  

You can buy automotive carpet for your particular car make and model. Carpets can be ordered both for new or older cars. Moulded carpets come in older loop piles, with a more pronounced texture, or newer cut pile designs with a smoother look. Different materials can also be optioned. Popular choices are nylon, polypropylene, polyurethane and polyester. These are durable materials, more so than traditional fabrics like wool and cotton. Also, various colours will fit seamlessly with the rest of the interior. Moulded carpets can have integrated rubber inserts for the driver, to provide for a safer, non-slip surface.