Merits of Rooftents
Will,
Maybe I can help shed a little insight on this subject. It seems we are bringing in brands and such when we should be talking about design and what you plan to do with the tent and whatconditions you plan to encounter, and maybe and a little what your budget is. Let me give you some thoughts.
If you are looking at a rooftent, it means you generally are going into rugged conditions, most all rooftents are four season, they have to be. I've found that a rooftent will allow me to go places and do things I wouldn't be able to do without one. I prefer a rooftent over something like a Westphalia because they can be moved to many vehicles and tend to be designed for one purpose, to protect you from the elements and allow you get a good night's sleep. If you can't sleep, you are worthless for an expedition, and its no fun, comfort is critical.
Cold weather, this is where a rooftent comes into its own. Smaller tents tend to be more comfortable, think alpine tents. less area to heat up, low roofline to keep the heat down low. Insulation is critical, the hard shelled tents are great here, fiberglass is excellent because it can be made into insulating composites. ABS plastic and metals don't insulate, so probably not the best material. Even fiberglass needs added insulation because water will condense inside the roof and drip on you or worse, condense under your mattress and you sleep in a puddle. The outside fabrics have to be engineered to let out a lot of moisture to keep you dry but still keep out the rain and not allow water to condense, Goretex, Airtex or something like this is what you are looking for. Waterproof fabric is not good when you have the tent closed up and cotton canvas can wick.
Hot weather, again, a rooftent excells. Trying to sleep when everything is 90 degrees is ugly. The nice thing is air cools off first, the ground may be 85 and radiating heat but the air up high will be much cooler. Also, up high you get a breeze. Look for a tent that opens up well, windows or doors on all sides to catch the wind. There are a couple tents that are triangular and are designed to actually direct the wind. One other neat feature of rooftents is that they will shade your vehicle's roof during the day keeping you much cooler when you are driving. When it rains in tropics or sub-tropics, it really rains, unbelieveable, I've seen over four inches an hour. Again, you need breathable fabric because you will be closed up when this happens, high winds usually accompanies.
The folding tents are good when you need a big tent, or one that will fold up small. Again, look for strong breathable fabric, the fabrics need to be much thicker because they take more abuse. The ridge poles need to be insulated for condensation and if you can get one with a winter hood for cold conditions, it is a plus. Check the ladder system, some of the ones on expedition tents are designed for dirt and slide on pavement, not good.
Weight, expedition tents tend to be heavy. Probably the best rooftent in the world is designed in Italy but made in Germany. Incredible design but you can't get it here in the US, weighs over 250 pounds. Light is good, rooftents help, because you pack your light fluffy stuff like bedding up high. I like the rugged African expedition look with the integrated expedition basket but don't think it is practical here in the US. You first have to mount the basket, 75 - 135 pounds, then the rooftent, 100 -150 pounds. You can seriously overload your vehicle. Land Rover Discovery has a specification for 165 pounds on the roof, but their engineers recommend 140-145 pounds. Look for rooftents with an integrated subframe so they can use sport bars like the ones for Thule ski racks. My rooftent weighs about 115 pounds and is mounted on Thule bars but we have had five people up there without a problem. I don't notice the tent's up there.
Summary, think about what you plan to do, and rather than get a tent because someone says, Oh, brand X is good, sweat the details and you will be really happy you got a rooftent. I've had several and used them in Europe and North America, from Alpine snow blizzards to tropical heat, none of them have let me down.
Cheers,
Rich