Hi Al welcome to the community from Sheffield.
I've not seen anyone on here mention having Starlings nest in a box so will be interesting to see what they say, the only thing you have to watch placing boxes on fencing or sheds is Cats being able to sit above the box, even if they don't catch anything it will put the birds off.
It has been mentioned on here about House Sparrows getting confused with the terrace box with all the holes being at the front so I would go for one with holes at either end.
Hopefully the others will give you better advice.
I’ve tried lots of combinations of nest boxes on the house with varying amounts of success. We have a Blue Tit box on the back of the house [facing northwest (ish)] which has been used every season since we put it up. It’s positioned around 12 feet up and just above and to the side of the back door, although this doesn’t seem to bother the birds in the slightest. We also have Starling boxes under the eaves but they were only put up at the start of this year and haven’t had any nests in them yet. We have a decent sized loft in the house so this year I removed a vent at the end of the house and built a nestbox inside the loft. This had Starlings going in and out of it within a few days of being put up which makes me wonder if perhaps they prefer a hole on a flat surface (wall, tree etc.) instead of a protruding box, but I’ve also found that some nestboxes can be in place for a few years before there seems to be any interest in them.!!
I put up a Sparrow terrace with three holes in the front and for the first few years I found the beginnings of nest building in all of the compartments but no completed nests. I watched a Sparrow take nesting materials into one of the end compartments and then come out of the box and go straight down into the garden for more material. It then flew back up and took the material into a different compartment of the box. This made me think that the birds were getting confused about which part of the box they were using. I came up with an idea of marking the front of the box to see if this would make a difference and although the Sparrows did still seem to be going into different compartments (very difficult to keep track of) we did have a successful nest the same year as I marked the front of the box. The results are inconclusive though because we were having work done to the outside of the house last year so all the nestboxes were taken down before the breeding season. For this season I decided to try a Sparrow terrace with one hole in the front and a hole at each end but there didn’t appear to be any interest in this box at all. I wonder if they just do it just to confuse us.!! :-) I also have an open fronted box around 10 foot up in one of our trees but this has never been used either. A teapot ‘nestbox’ installed (with much difficulty) in the middle of our big Holly bush had a Robins nest in it within a few weeks but doesn’t seem to have been used at all this season. I don’t know if any of this information is of any use to you as it seems that the birds are fussy in some years yet easily pleased in other years. I’ve added a few photos to help show my successful attempts at encouraging them to nest.
Starling box (inside loft). I drilled some holes in the top of the box inside the loft which still allows air to circulate within the loft. This box has had many birds fighting to use it and I think they're using it to roost in as I'm still seeing birds going in and out of it. It has a hinged access at the rear so I go into the loft to clean the box out.
Sparrow Terrace with markings on the front to perhaps help the birds find the specific box they've been using.
This box had no succesful (fully built) nests in the first three seasons it was up. The season I marked it had one succesfull nest in it. Perhaps this was just coincidence though. After the work to the outside of the house I replaced it with the end/end/front type of terrace so I may have to wait another few seasons until they get used to the new boxes.!!
Thanks for your answers both.
I've now installed the Blue Tit box on the side of my shed and may put some prikka-strip, trellis or similar above to deter cats from the roof.
Will be putting the Starling box in the tree and a Blackbird Open Nest Box on the fence soon and after looking at the advice online have decided to put a Schwegler Woodcrete Avianex on the side of my house instead for Great Tits or House Sparrows.
Will be interesting to see if anything gets used next year!