If I'm building a wooden bookshelf for my living room, which adhesive should I use to ensure the joints are strong and durable? I've heard mixed reviews about both types of glue and want to make sure my project lasts. Can you provide insights based on experiences with these adhesives in similar woodworking projects?

As stated many times, all professional wood glues, when used properly, can provide joints that are stronger than the wood.

Keep in mind that maximum surface area also contributes greatly. Mortise and tenon is better than a butt joint because of the greatly increased surface area.

Many glue failures are not a glue failure as much as they are a joinery failure.

I prefer to go with a wood glue over the polyurethane type glue simply because of clean up being so much easier. If this bookcase is going to stay inside, you could use elmers white glue (remember 1st grade) and you would be amazed at how strong it is with good clamping. As stated above, good joinery is paramount when it comes to longevity of a piece.

The only time I think about using polyurethane glue is when I need waterproof joinery. I might use it for a panel on an exterior door.

It's messy to use, it expands and foams and can get everywhere. The life in the bottle is shorter than yellow PVA.

It has it's use. But for normal use I prefer PVA.

Wood glue. Gorilla glue is best with with oily woods such as teak.

For building a wooden bookshelf, regular wood glue is the better choice compared to Gorilla Glue

PVA or polyvinyl acetate generally known as wood glue is more appropriate for woodworking because it is formulated to be used with wood and produces a strong, flexible bond when dried. Gorilla Glue, a polyurethane adhesive, is stronger than epoxy adhesives and moreover resistant to water, but is messier when it comes to wood joints as it expands as it dries. In fact, for all the woodworking projects, most people recommend the use of a wood glue.

For building a wooden bookshelf, PVA glue (polyvinyl acetate) is often recommended for its strong bond and ease of use. It's specifically designed for woodworking, dries clear, and is easy to clean up with water. Titebond III, a popular PVA option, is waterproof and has a longer open time, allowing you to adjust pieces as needed.

Epoxy is another excellent choice for joints that require extra strength or are exposed to moisture. It creates a very strong bond and can fill gaps well, making it ideal for challenging joints.

In general, PVA glue is sufficient for most bookshelf projects and offers a great balance of strength, convenience, and durability. If you’re looking for added moisture resistance or are working with complex joints, consider using epoxy. Both adhesives have proven reliable in similar woodworking projects, so your choice may depend on your specific needs and preferences.

Wood glue like Titebond or Gorilla Wood Glue is an excellent choice, as it creates a bond that's often stronger than the wood itself. From experience, a combination of screws or dowels with good wood glue is must.

Gorilla glue (poly) has been found to be among the weakest of the wood glues. It has the advantage of being water proof instead of water resistant like most modified PVAs

If screws and dowels along with glue are a must, then do the screws hold it together until the glue cures, or, does the screw hold if or when the glue fails? Or does using both point to a lack of a cohesive plan for joining wood?

If one wishes to use all wood, no fasteners, for solid wood doors, as I have for most of my 53 years as a professional, what would be my joinery plan? Very simple. Maximize glue surface area. This is done with mortise and tenon, cope and stick joinery.

No need, indeed, no place for screws. Several thousand doors, and not one failed joint. Never a dowel, never a screw.

PVA, aliphatic, urethane, epoxy or resorcinol, the glue type was almost immaterial to the joinery. ( Using brand names such as “Gorilla Wood Glue” is misleading - do you mean Urethane glue or the PVA marketed by Gorilla Company?).
Or are you just a smooth talking AI device?

Dowels on high use passage and exterior doors are a good idea because they do add strength. But other than that dowels, biscuits, dominoes are only used for ease of alignment for me 95% of the time.

A properly proportioned, well fit mortise and tenon joint will increase the glued surface area by multiples. It certainly has far more wood working than a few dowels. The best dowel joints with cope and stick profiling will be adequate, but I will always go to m&t first.

Do the math to determine the surface area. In fact, my book on doors has a nice little exercise showing the difference in joint areas.

Here comes the shameless plug, should you choose to avert your eyes : Small Shop Production of Custom Wood Doors.

Not disagreeing with you. But modern stuff is rarely mortise and tenon. I see 7/8" dowels in lots of low to mid priced doors for alignment and strength. On top of it most companies that manufacture doors rarely put glue on anything other than the dowels which is a big no no in my book.

I understand. I set my parameters on two things - what is the best way to do it? What is the sure thing - that will avoid callbacks and warranty problems.

I slept well, and never lacked work. Plus, I enjoyed the hell out of my work nearly every day.

A properly proportioned, well fit mortise and tenon joint will increase the glued surface area by multiples. It certainly has far more wood working than a few dowels. The best dowel joints with cope and stick profiling will be adequate, but I will always go to m&t first.

Do the math to determine the surface area. In fact, my book on doors has a nice little exercise showing the difference in joint areas.

Here comes the shameless plug, should you choose to avert your eyes : Small Shop Production of Custom Wood Doors.

To the original poster, I've never seen a glue hold better than Titebond 2 or Titebond 3. They have the same strength but TB3 is more waterproof. For something in your living room, either will do the job.

I would not use polyurethane glue. It's a fantastic glue but exceptionally messy and not one iota superior to Titebond 3 for 95% of the things you'll do in woodworking.

The only thing I would use a foaming polyurethane glue for is gluing up exterior slab panels. No real stress and the waterproof aspect is better than TB II or III.

I think TBII is more than fine for exterior work. I did a mailbox with #0 biscuits 20 years ago and it's still on the house and I've never had to do anything to it other than refinish it every couple years.