Consider planting a Hornbeam tree. they are durable and long lived trees with roots that will not damage your sidewalk. Just do web searches on the American hornbeam and the European Hornbeam trees. Of the European Hornbeams, the Carpinus betulus 'Frans Fontaine' is a narrow less formal looking tree which grows tall but continues to stay narrow even after reaching maturity. The Carpinus betulus 'Fastigiata' grows into a more formal, narrow, oval to vase shaped form. Near maturity it will begin to spread wider into a more oval canopy form than the 'Frans Fontaine' Mature height is 40-50 feet. The tree does not drop litter other than leaf litter when it enters its winter dormancy. The tree grows fine in shade or sun exposure. Hornbeams do well in alkaline soils especially where the soil becomes more alkaline due to leaching from cement sidewalks and foundations. It is considered a good street tree, provides good shade, and can be very effective when planted in a group to create a screen. They have crisp, green summer foliage and smooth gray bark. They do not suffer from common insect or disease problems. They grow best in well draining soil, but will tolerate a wide range of soil conditions; even in clay soils. They are hardy down to USDA Zone 5 and do fine growing in my local 6b/7a zone.

Yeah, Tom has it right. Nothing is too small. Let me tell the story of my "dixie cup" tree. Near the town of Hyattstown, MD--not to be confused with Hyattsville, MD, there was an old house with two Norway spruce trees planted in front as traditional German "bride and groom" trees. These two trees, when I first saw them, made me think of the giant conifers of the Pacific N.W. I visited these trees from time to time just to see how they were doing and to admire their magnificence. One of the last times I saw these trees the house had been abandoned and it was spring, so I thought I would scrounge around and see if I could find any seedlings. Well, I found a few, but they were so very, very small--really just seeds that had germinated just about a week before. No green except the little ring of cotyledons. I put them in little plantic coffee cups that I found by the roadside (not actually dixie cups) and took them home and planted them in my garden. One soon died. Another lived for a little over a year, and the third I have growing now at my place in Winchester. After it grew in my garden in Arlington for about 4 years, I moved it to my timberland place where it grew for three more years and then I moved it to my place in Winchester. It almost died from my fertilizer mistake three years ago, but is now in full recovery mode. I really treasure this little thing--maybe not so little now. So--nothing is too small, even for transplanting. The other two seedlings died, probably because they were not the product of cross pollination. A pair of trees NS growing alone is usually not a good source for seed that will produce good strong trees. But these trees were so magnificent, I had to try to find something. I say "were" because the one that was slightly smaller has died--and I have not seen the other one for more than 10 years now. --Spruce

Im just taking a stab at this. I'd say that given the appearance of the tree and where it's planted, it was originally the rootstock of a flowering quince (ornamental shrub), which I THINK is often grafted to a pear rootstock. So what you may have is a "wild type" pear tree. At any rate, it's too close to the house and I would move it. It might not be worth the trouble of trying to save it, especially since you are not sure what it is. You might wait a year and see what it looks like in the spring, if it blooms, etc. But it is too close to the house...you'll have trouble with the siding staying damp and if the trunk gets much bigger, you wont be able to get around it to do maintenance.

Peach rootstocks are not about dwarf or standard. It is more about how well it could tolerate your soil type It is not difficult to train peach low for peach should be pruned to an open center shape. Your need to buy a bare root peach so you can cut a tree trunk to be as low as two feet above ground. Once a tree has branches, train those branches to go out, not up. Your can prune your tree to be 10' tall that way. This is quite late to order bare root fruit trees. Rootstocks such as Lovell, Guardian, Halfotd are good for many soil types.