Storage Condo Site Design...the more you learn, the more you'll agreeSITE DESIGN AND LAYOUT Once I established the building design, I looked at how the site design and site improvements affect the cost, quality and overall value of the whole development. The site design involved the various topics covered below. As you become familiar with site design parameters, you can put that knowledge to use when determining how they “impact” the total project cost - even when you are in the site selection process! You will be able to discern rather quickly which properties are better than others and ones that simply won’t work. – especially, if you are trying to hit the 5.5 units/acre goal. (read on for how that is achieved) If you don’t get good at this process and find sites that yield a 5.5 units/acre goal, two things can happen.
Neither of these is very good so, do the work – get good at it! Building layout I started the design with a wide open space – no lot lines. I wanted to see what would be optimum. A typical cost effective residential subdivision design would be to put buildings on both sides of a main drive isle or private road. A private road is normally around 20 to 24. I then added space for parking, sidewalk, buildings and setbacks. Parking needs to be in front of each unit and the stalls are typically 8ft wide by 18ft deep. There needs to be some sort of walk way between the building and the parking to make them more functional. The buildings are 50 ft by 50 ft and have a 10 ft separation. In addition, there are setback requirements to the lot lines and those need to be determined from the zoning codes. Refer to a typical site plan as shown in appendix___. It’s important to note the separation from one building across the private drive to the other building. This distance has to be a minimum of 64ft. I like to see closer to 70ft if you have the room. The reason for this is that larger vehicles, boats, and trailers, need the space to back into their unit. The greater the space the more appealing it is to people. In fact, there are buyers out there that pick the unit location based only on how easy it is to get in and out of the unit. The goal is to start at the required front setback and fit as many units on the property as possible back to the required rear yard setback. This becomes the starting point to the design. The most efficient lot width then becomes the set back distance + the 50ft building depth + the walkway + the parking stall + the drive isle width + another parking stall + another walk way + another building + another set back distance. This usually adds up to 164ft plus both the side yard setbacks which are usually 10 to 25 ft per side. That means the lot width should range from 184ft to 214ft. If the lot is wider than this, it would be less efficient and therefore more costly. The only benefit is the extra space could be used for more green space or storm water ponds. This becomes the basic starting point for the “most economical design”. This design typically yields a density of 5.5 buildings per acre. What ever lot I analyze, the layout process will eventually reveal one thing. - the maximum number of buildings per acre. If the design yields less than the “most efficient” 5.5 ratio, then I look for other benefits or cost savings in selecting that particular site. I have had sites as low as 4.2 units per acre but offset that by a lower than normal land cost. The basic layout will give a starting point for the site selection process and it yields the “gross” buildings per acre. – not the “net” buildings per acre. Gross vs. net building/acre The gross buildings/acre is the preliminary number of units you think you can get on a property. It is used in the very beginning as you are qualifying sites to take a closer look at. The net buildings/acre is the number you get after all the other parameters that affect the site layout are explored. This is the number that you base the decision on to move forward with the project and clearly involves more knowledge and work to get to. The following parameters affect the “net” buildings/acre number:
Fire separation between units The commercial building codes are there to prevent the spread of fire. This is accomplished by using materials, creating fire walls, installing sprinkler systems, and through building separation. This will vary in each state and is rather complicated. In Wisconsin, there is a provision in the commercial building codes that state you can group separate buildings together as one (up to a total of 9000 soft). Within that grouping, you can have the buildings 10ft apart without any fire rated construction. The uses within that grouping have to be similar and fall within the specific “use classification”. Again, this is rather complex and I always refer to my architect. He reviews all my site plans, not just the building plans. The final site plans usually show several “groupings” and between those groupings we have increased the separation distance up to 20ft. I do group the buildings to minimize the required 20ft separations. Then, I utilize the extra separation space for drainage ways etc. In some instances, we need to reduce the distance from 20 to 15 ft in order to get an extra building (substantial benefit). I make sure the windows, doors and other openings in the exterior walls remain under 10% of the wall space. This allows us to install non fire rated windows and doors which are much more expensive. If we want to get closer than 15 ft it involves a substantial change in the class of construction, details, and materials. We just never do this because it is not worth it. It is not important to know the code - it is crucial that you know there is one!! Make sure you have the correct spacing between units. This is not an area you want to be wrong on!! – seek good advice! Fire lanes Typically, the fire department wants to know how they are going to service the buildings in case of a fire. They have certain standards and each municipality is different. The most effective design typically includes a private road with buildings on both sides; therefore, a “separate” fire lane is not necessary. The fire department wants to be able to turn the trucks around without backing all the way out. Therefore, they usually require some sort of “turn around” which usually takes a fair amount of space. In fact, we had to eliminate an entire building on one project. It is important to familiarize yourself with the state requirements as a starting point even though the local municipality may be more restrictive. Just be aware that something has to be looked at in this area. As a side note, the smaller the project the less this becomes a factor. Typically, the fire trucks are ok with going into a private road up to 300ft without requiring a turn around. If it is not possible to put a turn around in and you are more than 300ft, then you could provide a sprinkler system for the farthest buildings in. I don’t recommend it (extra costs outweigh the benefit of extra buildings), but it has been done before. Storm water management Storm water management is a design element that can have a significant impact on the number of buildings that fit on a site. If you add the extra site work costs for the controls – it’s a double whammy. Pay careful attention to these requirements. As a general rule, I look for sites that
If the parcel has a pre-development impervious (water won’t infiltrate) condition, the storm water requirements will be less (most of the time). The required controls are based on the pre-development vs. the post-development increase in storm water. If the storm water controls were considered when they platted the park then of course, very little has to be done except to get the water to drain to the existing ponds.
The least amount of space necessary for storm water control, then more space available for units – it is that simple. When faced with the situation that you have to install some storm water controls, which quite frankly is most of the time, plan to use the space in the setbacks, building separation, naturally low areas, and if the lot is not perfectly rectangular, the areas you can’t utilize for buildings. Site topography This factor is more common sense than anything. If the site is on a big slope, just forget it. Look at how significant the drops in elevation would be between buildings. Make sure it is practical to build. Are there any really low areas or any steep slope areas that are not really useable? Does the lot slope down in the back so you can’t get the sewer to drain with out a lift station? Are there areas where it looks like there was some filling and if so would the material be suitable for a building sub grade. Look for any and all utility lines that could possible be inside a building envelop. Look at where the driveway would come from the street. Are there any nice trees that would really enhance the look of the property but could have to be cut down or do you take out a building to keep them? The goal here is to walk the site and determine roughly where the buildings would go and what might be a big enough issue that you have to scale back the number of buildings.
Site grading This element of the site design is usually a big ticket item. Anytime you have bulldozers move dirt around, it is costly. Look for relatively flat lots that are slightly elevated from the street. Actually, a flat lot takes more grading than one with a gentle slope. If the lot sits lower than the street, it is harder to drain to any existing storm water pipes. Most industrial properties are relatively flat but occasionally a lot with some nice elevation changes can give the site a very nice feel and look. The downside is it is difficult to estimate the cost before a grading plan is done. A grading plan could cost several thousand dollars, at a minimum. You just have to be aware of the “magnitude of the cost” and then be conservative in your estimate. Keep in mind that by selecting a site with more grading costs, you have to make up the additional cost in some other area (if you don’t, you increase the cost of the project which reduces the profit – read the Development Costs and Profit Section very carefully). I did a project that had substantial grading costs only because I acquired the land at a below market price. – I actually created lots which resulted in a great cost/soft. Site grading also includes clearing trees, concrete, etc to prepare the site for development. This can be a substantial amount and should be looked at as you select sites. One of the nice design features in the StorageShopUSA developments is that we have 2 different foundation designs as I described in the building design section. To help reduce grading costs, I can adjust the both the pad height from building to building, and the type of foundation I use. I can use the engineered slab if I don’t need fill material and the frost walls if I do need fill. In addition, I can change the foundation plan if the subsurface soil conditions are not as good as expected. I did a project and the land was purchased from the city and I knew they had done some filling on the lot. I choose to use the frost wall design so that the footings for the buildings were down in natural soils. The land wasn’t “low land” but I found out the water table was rather high and it was more difficult to build the concrete footings and walls. I then switched the plan and built a 6 inch gravel base over the next pad site, had a soil testing company check it, and then poured the “engineered slab” – try doing that with 1 larger building. Sewer and water extensions This is a very costly item but the nice thing is that it is relatively easy to budget for. Site improvement contractors usual quote based on a per foot basis for pipe and lump sum for items such as manholes, hydrants. It is easy to calculate once you rough out a basic site plan. The nice thing about the basic site plan is that once you have established a per foot cost, the price goes up proportionally with the number of buildings. – the more cost, the more buildings. It is when there are more costs and no extra benefits when it is a concern. The standard design allows for the sewer and water to run along the private road and then branches off to each building. There are generally not a lot of variables except the ones I will describe below. The point is that as long as you hit the buildings/acre design of 5.5 then this cost should be acceptable. The variables below can only help you save money.
Landscape Regardless of what is required for landscaping by the local municipalities/industrial park covenants, we encourage a nice simple landscaping plan. Some municipalities beef up the requirements but it is not a huge item when selecting a site. We do recommend using perennials in the island space between the buildings because they do not get in the way of snow plowing efforts. Also, we provide much more landscaping out along the street because it adds value to the development. Streetscape Since the buildings face the private road going in, the front (street side elevation or “streetscape”) is not as appealing. – especially to plan commission members. We have an additional set of plans which dresses up the side of the building. Refer to appendix ___. This really sets off the entrance to the development and gives more value to the units. It does cost more even though there are very few changes to the basic plan. It may add $10,000 or so to that building. Be prepared to have this plan available when you go before any planning board. They always want to see the front building dressed up more. ADA accessibility Commercial building codes and the Americans with Disabilities Act (ADA) should be addressed and can affect the site grading. A percentage of the total number of parking stalls need to be ‘accessible” handicap parking stalls. They must be able to access all the units via an “accessible” path. Mainly, the accessible path can’t exceed a certain slope and can’t cross a parking stall. It is something the both the architect and engineer will look at, especially on hilly sites.
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