Wood: The quality of the frame will determine how long the sofa will last without losing its shape. The best frames are made of kiln-dried hardwood. Frames made out of softer woods like pine will be less resistant and warp more easily, and if the wood has a lot of knots it can crack and break.
Also check the thickness of the wood. If you can reach under the front part of the sofa you can feel the frame. It should be at least 1 inch thick.
Construction: As I mentioned in Is it a good deal? Quality checklist for wooden furniture, the joinery is very important. To find out how the frame is built, ask the salesperson, or if they have one of those store models that is cut in half, take a look at the joints. Ideally they should be mortise and tenon or dowelled joints; these will be more resistant. Screws are okay, but stay away from those that are stapled together. Also take a look to see if the frame has reinforcing blocks — these will help keep the shape of your sofa.
Take a look at the legs. Built in legs are stronger than those that are screwed in. And while you are lifting the front corner to check out the legs, take a look at the other front corner — if you are lifting more than 6 inches, it should be lifting too. If it is not lifting, the frame is not as strong as you want it to be.
Springs: There are different types and qualities of springing out there, so if your sofa has springs, find out what type of springs they are. The best quality sofas will have eight way hand tied springs, but there are also some good quality sofas with sinous springs (s-shaped wires that that run from front to back). Remove the cushions and feel the springs. When you push on them they should feel very strong and sturdy.
Cushions: Ask about the cushions' filling. The top-of-the-line filling is down, but often manufacturers will use foam and Dacron. If you can, you should lift the cushions and feel how heavy they are. There is a quality/weight relation. If they are nice and heavy it probably means that they used either down or a mix of down, better quality foam and Dacron. (Note: if the cushions are sewn to the frame, the manufacturer skimped on that extra bit of material, which is a sign that the sofa is probably not the best quality).
Fabric: As you know, there are given many options to choose from when selecting your sofa cover, and depending on what you choose the price point varies greatly. If you are going with fabric, look for one that is heavy and that would be best suited for your lifestyle. If you have pets, a very tightly woven fabric would be best, and if you have kids and expect to have a lot of stains, choose an option that is less likely to stain — a good bet would be anything with synthetic fibers. If you are getting a leather sofa, make sure you are getting top grain leather. This is the best quality and will last longer.
Tailoring: If you are paying more for a sofa, expect the best tailoring. All seams and welting should be straight. If you have a patterned fabric, the pattern should line up on all seams — if should flow over the sofa.
And one last tip: If you live in an apartment, when you have measured the room and the sofa to make sure it's the right size, don't forget to also measure the doorway, stairway and halls!
(Image: Natalie Espinosa)