I built this raised planter and placed it next to my house. There is around an inch and a half space between the wall and the siding of the box. Pictures are shown below.
Is there any reason why this would not be ok? I've looked up some information and everything I have found talks about putting the back directly up to the house without any separation.
Personally, I like the separation. It will keep the back of the bed from rotting due to moisture trapped between the house and the raised bed.
It looks like your siding could be wood, and putting wood up against other wood is never a good idea (insects, rot, and fungi can run amok in all that dark and damp). Even if your siding is vinyl or fiber-cement you'll have trapped moisture behind the bed, so your bed placement seems to me to be quite good.
One thing you'll want to watch for is weeds growing between the bed and the house - the narrow space may make it hard to get them out easily if you don't see them early.
I agree with Jurp. This is fine as long as moisture dries quickly in that bark mulch. Is this area covered by a roof? Is there a slope to the undisturbed soil from the house and away? To have put it any closer to the house would have been wrong in any construction sense.
The rule is to keep all mulch or soil or rock a minimum of 4" from the bottom of the siding, leaving an expanse of concrete foundation and keeping the siding high and dry. Slope of the soil away from the foundation is crucial. Is this in front of your patio doors or just windows? Is there a roof over this area? It looks as if this area is beneath a roof near a patio? This will dictate what you should grow in your raised bed and ultimately if that space is large enough to be easily kept dry.
Is this raised bed sitting on the ground or is it on a patio? Is it sitting on bark mulch on top of soil? Are there drain holes if this bed has a wooden floor?
Where is it that you live, do you have winters? What kind of soil have you used? Did you put anything between the soil you put in your bed and the garden soil beneath? Also, looks as if you've used pine lumber without pressure treating? Putting black plastic between wood and soil helps to protect your lumber. Best to not have any wood bottom or anything other than soil to soil contact. No gravel, no plastic. Slope away however from the house.
Hope this helps. It would be nice to get more information from you about the details of your raised bed and this area next to your home. That 'breeze way' between the bed and home was absolutely necessary. Whether or not you have problems later will depend on what you want to grow, think about how to clean the glass, how to protect roots of perennials during winters that you'd like to grow in this raised bed, how deep the shade is from the roof or how large that roof is or even if there is a roof, drainage near your foundation...is there at least a 4" space between patio and siding? Pictures from the side of your patio/door/windows to show slope away from the foundation? Water standing near your foundation will drastically weaken the foundation of your home as well as cause unhealthy molds in your home. Just a little more information and I think we can help you even more.
