Suggestions about building my own reptile terrarium

Me and my girlfriend recently decided on getting her 8 year old daughter a bearded dragon for christmas. After spending some time researching I've decided on building my own terrarium mainly because I want a big one and costs to buy one brand new are to high. I've seen alot of great do it yourself videos and pics of vivariums on the Internet but I have a few questions for the one I am going to build. I've researched that a adult bearded dragon needs about 8 square feet of living space which equates to a 4x2x2 terrarium. I am going to buy my dragon from a local breeder who has them with the German giant gene making them somewhat larger then regular dragons. That and wanting my reptile to have more then just adaquate living space I decided I was going to build a 5x3x3 terrarium. Researching has also told me the the wider your terrarium is the harder it is to regulate heat. Would a 5x3x3 terrarium be ok to use or should I make it a 5x3x2 to maintain heat from lighting. Another question that retains to this is in researching I've been leaning on using a mercury vapor basking light as it is said it produces more heat, has a longer life span, produces more uva, uvb rays and leads to a healthier pet. Is this true and is it a good choice for my larger terrarium? Last thing I'd like to ask about is the top of my soon to be built terrarium. I've read that you want proper ventilation to let moisture escape to keep the humidity down for your bearded dragon. I also know that to much ventilation can make it hard for you to keep temperatures up. I wanted to build a screen top with wooden framing across the whole top that can open up or slide open on half the top of the tank for easy access from the top if needed. So my last question is... with the top of the terrarium being open with the screen is that too much or not enough ventilation? Should I just make a solid wood top and cut holes for the vents and lights? Looking to get started on this project as soon as next week so any help greatly appreciated!

The heating and lighting is done in zones, so having a large terrarium isn't as hard to manage as it sounds. You want to create a zone with high temp/high uvb, low temp/low uvb, high temp/low uvb, and moderate temp/moderate uvb. It's easier to achieve this with a taller setup. A taller setup also allows you to put branches in so they can climb around. Here is an excellent example and explanation of lighting which was put together by one of the members here, Taterbug https://sites.google.com/site/thelizardmadness/photogradient

For lighting, I suggest using a T5 UVB tube that runs across about half to 2/3 the enclosure. That will allow you to create a nice wide zone of high UVB for basking. A basking light should be placed over this zone to create appropriate temperatures of about 100-110. These are great lighting options (just change the size to be appropriate for the dimensions of the enclosure you build but these will work in a 4' wide setup.)
This fixture http://www.amazon.com/Sunblaster-904296-NanoTech-Fixture-Reflector/dp/B00AKKUBDQ
With this bulb http://www.amazon.com/Zoo-Med-ReptiSun-10-0-Lamp/dp/B00AQU8HAO/

Or this combo set http://www.lightyourreptiles.com/22-t-5-ho-fixture-high-output-with-arcadia-d3-12-ho-bulb/

As far as ventilation goes, having the top open is good, but I'd put a couple of side vents in as well. You'll want air to be able to flow easily from one end to the other. There is a walkthrough of a 4x2x2 build that may be helpful with your planning https://beardies.dreamwidth.org/2145.html You may be able to get additional ideas by browsing the Enclosures section, especially the Viv Pics Only thread.

Thanks cooperdragon, I figure I'll order 2 of the 24 inch bulbs to cover most of my terrarium. What about a basking light for that sized tank though? Should I get a 100 or 160 watt bulb? And are mercury vapor bulbs a good choice?

I don't think you'll need two. The T5s are quite powerful, especially with a reflector. Depending on how long you wind up building it, you could get away with a 34'' but One should be plenty. You want to have an area with intense UVB and areas with lower UVB. Your dragon will self regulate and seek out what he needs so you want variety rather than full coverage throughout the tank.

You'll need to test out some different wattages for the basking bulbs. It also depends on if you set up basking platforms at different heights/distances. Generally a 150w (or 90w halogen flood) will do. It's a good idea to put them on lamp dimmers if they're fixed in place so you can adjust the power to get proper temps. You may need to try a few different wattages at the beginning to get it just right.

I wouldn't get an MVB if you're using the T5 tube. That would produce too much UVB. I'd go with one or the other. I prefer the tubes because of their nice wide distribution. It creates wide basking areas and nice gradients. If you decide to go with an MVB, it's worth buying a high quality one such as a MegaRay or one of the Arcadia bulbs with a good fixture from LightYourReptiles. These will create a circular basking area with a gradient as you go away from the bulb in a circle. They should also be mounted no closer than 12'' from the basking spot due to intense UVB output at close range. Because of this you may still need to use a heat projection bulb or a low wattage basking bulb to provide proper temperatures at that distance. The T5 tubes need to be about 12'' above the basking area as well but they aren't relied upon for heat so having a basking bulb in addition is a given.

I see now so the t5 bulb supplies enough rays on its own and all you really need a basking light for is the heat?

Yep. The T5 will put out proper basking levels of UVB (using a reflector) at around 12'' and there will be a gradient down to shade levels to the sides and down from there. You'll want to set the basking spot light to provide an area of 100-110f that is large enough for a dragon to fit his whole body in easily. There will also be a heat gradient down from there. He will just move around to get what he needs at any given time. There is more info about the UVB lighting and proper distances here https://sites.google.com/site/thelizardmadness/lighting-guides

Thanks that's really alot of help

The bigger your terrarium the more you need to plan for heat, but its not really that its harder so much as a little more work. In the end, if you have the budget and space/ability to set things up it will be a better living space for your dragon. I've found Pepper loves to climb, and uses all the height I give him, even up to the very top of his branches.

In my case (my enclosure is roughly 4x2x4 and based on the crossfire plans cooper linked) I use three basking lights (each with its own dimmer), one 22" T5 Reptisun and one 36" T5 Daylight bulb. You really should be ok with a shorter UVB bulb, but if you want to do a longer one you'll want to plan it so your dragon can get out of the sun so to speak. This gives me a lot of control over the environment, I have the three basking sites at different temperatures and the Daylight bulb helps keep things bright without over doing the UVB.

Multiple basking lights usually isn't possible in smaller setups, but it gives you more control over having a nice even patch of heat when you can have a bank of lower wattage bulbs than if you just have one bulb.

You could add an MVB if you wanted but I would personally only recommend to do so if you have a solarmeter to make sure your levels are safe. (meters are pricey but a pretty good investment for checking the health and use of your bulbs to get the most out of them) Personally, I just use the T5 in a reflector. I like that I can control the lighting separately from the heat, they give a much broader exposure area than a MVB (which is more of a focused 'beam') and the T5 bulbs last the same 12+ months the MVB do.

I have just side vents on one of my enclosures and just a front vent on my big one, no top vents. You want a fair amount of air exchange so that it stays nice and fresh inside. I probably wouldn't do a full screen top, but that will depend also on how warm your room is, since you will be loosing heat up and out due to convention. A solid top helps trap it a bit more, but if you make something adjustable that would be an option too. All my lighting is hung inside and its nice because then the top of the thing is like a shelf. Having the lights outside is fine too, it keeps them safely out of reach and maximizes your internal dimensions.