I am on a committee currently figuring out whether we want our new play structure installed with a "surface mount" or with concrete footings. We have placed an order for the equipment and have been asked this question by the maker. I didn't even know a surface mount existed. If we use footings, we have to go four feet down to go below the frost line (we are in northern Vermont), and will need 75 holes to install all of the equipment. A surface mount is a concrete ring that you bolt the equipment to, but "floats on the ground like a slab under a house. Does anyone have experience with this? Is one way better than the other considering our harsh climate? The surface will probably cost more in concrete, but I am not sure. I do not have access to an auger for the holes if we go that way. I guess we'll rent one. 75 is a lot of holes! Anyone?
Ruth in VT
The decision about what type of install will depend on two main factors: 1) what type of playground safety surfacing you intend to use, and, 2) what type of surface on which you are building. A third factor to all of this may be your budget, but that is a different issue.
If you are using a unitary playground safety surfacing (rubber tiles, rubber mats or poured in place rubber surfacing), you will need to have a concrete, asphalt or compacted base rock (compacted to 75%) subsurface on which you are building. If the sub surface is concrete, you will use a surface mount. Basically a surface mount means that you will order your playground with posts that have flat plates on the bottom. The posts are bolted to the subsurface through the plate. The rubber tiles, rubber mats, or poured in place surfacing is installed on top of the subsurface.
If you are using loose fill playground safety surfacing (engineered wood fiber, sand, pea gravel, etc.), you will be building the playground directly over dirt and you can punch holes in the ground, place posts in the hole (posts will be 2 or 3 feet longer). Concrete is poured into the holes around the post forming a concrete footer. Because asphalt is soft enough to punch holes through but has a smooth and clean enough finish, you may use asphalt under rubber surfacing and punch holes through it for a direct bury. You may not do a surface mount on an asphalt subsurface because the asphalt cannot hold the bolts with the weight that the playground needs to bear.
Note: Loose fill surfacing is never placed over concrete or asphalt because if the loose fill gets pushed a way and a child falls headfirst, he/she will sustain much more serious injuries.