While the iguanas want to spend most of their time 'outdoors', they also need a place to stay dry, and warm, if necessary. Also a place to find their food consistently, which is also out of the weather. While living in Orlando, the winters are typically mild, we do occasionally get into the 30's, and possibly even lower. The house I am providing, will be able to be sealed up much tighter come winter. It currently has a roof mounted heat lamp, and I will monitor the temperatures and see if I wind up needing auxiliary heat. For now, being summer, it is not an issue.
The frame is 2x4's, the floor and roof 1x8's. The house is about 2 feet by 4 feet long. It is screwed together. The roof is curved plastic; which is old solar panels from my pool. Perfectly water proof, flexible, and non-affected by the suns UV rays. Also being black, it will attract as much heat into the 'house' as possible.
On top of the 'ceiling', but under the roof, is space for the 'workings'. Here you can see the PVC line which is the outlet from the pond pump. The bio filter will be fitted here. Also is room for the heat lamp, UV, electrical outlet, X-10 controls, and whatever else needs a dry place to sit.
The PVC is glued up to the last couple of pieces, which are just pressed in. When I put the UV there, I can easily slip them out, put in a T, and go about my installation. All the slipped on pieces are over the bio filter, when it is placed there, so a leak doesn't hurt. The bottom of the 'cross' pipe, leading up to the end 90 degree angle, has many large holes drilled into it, facing down, for more even water distribution - as well as more beneficial aeration.