Nobody shops for carpet padding. People shop for carpet, and the pad is a line on the quote that gets about four seconds of attention. That is a mistake in an understandable direction, because the pad is invisible from the day it goes in. It is also the part of the job that decides whether the carpet above it looks good for fifteen years or flattens in six.
This guide covers what carpet padding does, what the two numbers on it mean, and what we would put under carpet in each part of a Central Ohio house.
What the pad actually does
Carpet pad, which the trade calls cushion, has four jobs:
- It absorbs impact. Every footstep compresses the floor. With a good pad underneath, the pad takes that load. With a poor one, the carpet backing flexes with every step until the fibers break down from underneath, and the carpet wears out from the bottom up
- It makes the carpet feel the way it felt in the sample. Much of what people describe as a soft carpet is a good pad
- It insulates. Pad adds warmth over a cold subfloor, which you notice in a bedroom over a garage in January
- It quiets the house. Carpet over a proper pad takes a noticeable amount of footfall noise out of the rooms below, which matters in the two-story homes and split-levels common around Heath, Newark and Granville
The two numbers: density and thickness
A pad is specified by its density, in pounds per cubic foot, and its thickness, in fractions of an inch. Density is the one that matters more, and the one fewer people ask about.
Density is how much material is packed into the pad. A low-density pad feels wonderfully soft when you press it with your thumb in a showroom and bottoms out under an actual person, which means it is doing nothing in the traffic lanes where it is needed most. A denser pad feels firmer in the hand and supports the carpet for years.
Thickness is where the instinct goes wrong. Thicker feels more luxurious for about a year. After that, a pad that is too thick lets the carpet flex too far with every step. That stresses the backing, works the seams, and lets the carpet loosen and ripple. The carpet industry's own installation guidance caps residential pad at 7/16 of an inch for exactly this reason.
For most residential rooms with a cut-pile carpet, the target is a pad of about eight pounds density, no thicker than 7/16 of an inch. Six pounds is the usual minimum the guidance allows, and the difference in price between six and eight is small next to the difference in how the carpet wears.
Thinner and firmer for loop carpets and stairs
Low-profile carpets, such as Berber and other loop piles, and thin commercial-style carpets need a thinner, firmer pad: no more than 3/8 of an inch, at eight pounds density or more. These carpets have a stiffer backing, and too much give underneath lets that backing flex and crack.
Stairs want the same treatment for a different reason. Traffic on a staircase lands on a strip a few inches wide at the nose of each tread, which makes it the hardest-worn carpet in the house. A thick, soft pad there wears out fast, lets the carpet shift on the tread, and makes footing less certain. A thin, dense pad holds the carpet tight to the step. Carpet on stairs is its own subject, and how we fit stairs covers the installation side.
The main types of pad
Rebond. The multicolored pad most people picture, made from bonded scraps of recycled foam. It is the most common residential pad because it performs well for its price, and it comes in the full range of densities. A good rebond at the right density is a perfectly sound choice.
Memory foam and other premium foams. These are generally made from new foam, not bonded scrap, which makes them denser and more uniform. They feel noticeably more comfortable underfoot and recover better after compression. This is a genuine upgrade in bedrooms and family rooms, where the floor is walked on barefoot and sat on.
Fiber or felt. A dense, firm, flat pad with very little give. It is what goes under Berber and loop carpets, and it is sometimes used over concrete.
Rubber. Flat rubber is very dense, very durable and the most expensive. Waffle rubber, the rippled kind found under a lot of carpet from decades ago, is mostly air and has largely fallen out of use.
Moisture-barrier pad. Any of the foam types can come with a film layer on top that stops liquid soaking through. That layer is what matters in a house with pets, which gets its own section below.
Pets: the barrier is the point
A pet accident on carpet is a cleaning job. A pet accident that soaks through the carpet into the pad is a different problem, because a saturated pad cannot be cleaned from above, does not fully dry, and holds the smell. From the pad it reaches the subfloor, and at that point the odor is in the structure of the house.
A moisture-barrier pad keeps the liquid on top of the pad, where it can be extracted through the carpet. It does not make carpet waterproof and it does not help an accident nobody finds for a week. What it buys is time, and the chance to actually get it out. Paired with a solution-dyed carpet fiber that tolerates aggressive cleaning, it is the specification we recommend for a house with dogs or cats.
Basements
Carpet works in a finished basement if the slab is dry and has never taken water, and the pad has to be chosen for the location. Over concrete that means a synthetic pad that will not hold moisture or break down if the humidity runs high, and it is not the same roll that goes in the bedrooms. The rules for basement flooring apply to what is under the carpet as much as to the carpet.
Why builder-grade carpet fails at the pad
In a production-built house, the pad is one of the first places the budget was trimmed, because no buyer ever sees it. The thin, light pad under builder carpet bottoms out in the hallway and on the stairs within a few years. After that the carpet above it is taking the full force of every step, and it mats down. People blame the carpet, and the carpet was only half of it.
It is the main reason builder-grade flooring tends to look worn at six to eight years, and it is why new carpet over the old pad is never worth the saving.
Can the old pad be reused?
No, and we would not recommend it to anyone. A pad that has spent ten or fifteen years under carpet is compressed in every traffic lane, has absorbed whatever was spilled on it, and will not support a new carpet the way a new pad will. Carpet manufacturers also set minimum pad requirements, and a new carpet laid over a worn-out pad may not be covered by its wear warranty.
The old pad comes out with the old carpet. On most of our projects that removal is already in the price, along with the new cushion.
The warranty angle
Carpet wear warranties are conditional on the installation, and the pad is part of the installation. The manufacturer's documents specify the minimum density and the maximum thickness for that carpet. A pad outside that specification can void the warranty even if it is a more expensive pad. This is the practical reason to let the carpet decide the pad, not the other way around.
What this costs
Less than people expect. The pad is a small share of the cost of a carpeted room, and the step from a minimal pad to a good one is smaller still. Our carpet pricing is all-inclusive: the cushion is in the project price and on the proposal, not added afterwards.
We also currently upgrade qualifying residential carpet purchases, with professional installation, to a selected premium memory foam cushion at no charge. Product and minimum-purchase requirements apply, and we confirm them at the consultation.
The short version
- Most rooms, cut-pile carpet: about eight pounds density, no more than 7/16 of an inch
- Berber, loop and low-profile carpet: firmer and thinner, no more than 3/8 of an inch
- Stairs: thin and dense
- Pets: a moisture-barrier pad
- Basements: a synthetic pad chosen for concrete
- Never: the old pad, or the thickest, softest pad in the showroom
For the carpet that goes on top, how to choose carpet covers fiber, pile style and density, and how to care for carpet covers the vacuuming and cleaning that keep it looking new.
If you are planning new carpet, book a free in-home estimate. We bring the samples to the house, measure the rooms and the stairs, and give you one written price with the pad, the removal and the installation in it.
