Climate Control Self Storage Development - Design & Cost

[Joey Stelly]

Looking into ground up development for single story climate control self storage facilities in my market and looking for some general guidance on design & cost rule of thumbs - any help would be greatly appreciated. 

Currently working through some (very) preliminary due diligence with the goal of creating a template for 150 & 250 unit climate control buildouts in order to dial in an acreage size to focus in on for land acquisition, and to try and determine the most cost effective & scalable footprint to build as a "test" that can be scaled. 

Couple of questions & assumptions that I'd really appreciate some critiquing/input on:

Building Layout:

- Right now I'm assuming 1 acre (43,560ft) will yield about 60% (+/- 26,190ft) of climate control NRSF. 

- What is a good rule of thumb yield/acre, and how many sq ft of slab/building should i assume for every 1 ft of climate control NRSF?

Building Cost: 

- I've heard varying estimates $/ft for capex related to building a climate control facility, but what can I expect generally in total $/ft for an assumption when building 150 or 250 unit building. I've heard $50, 35, 40, etc for turnkey rule of thumb - shell, utilities, foundation, M&E, paving, etc, basically everything but land. 

Opex ratio: Is 35% of revenue a solid assumption for operational expenses - insurance, maintenance, etc? 

Right now my cost assumptions look something like this: 

25,000 ft to yield 250 units 

Acreage needed for 250 units = about 1 acre (Depends on local municipality requirements for detention, setbacks etc but for now this is my assumption)

25,000*$50 = total buildout cost less land 

revenue $ *.35 = opex cost 

thanks!