SUPPLEMENTAL GUARANTY ([property address])

Exhibit 10.5

SUPPLEMENTAL GUARANTY

([property address])

FOR VALUE RECEIVED, the sufficiency of which is hereby acknowledged, the undersigned, [property owning LLC], a Delaware limited liability company (whether one or more, hereinafter together called “Guarantor” in the singular) absolutely guarantees and agrees to pay to THE PRUDENTIAL INSURANCE COMPANY OF AMERICA (hereinafter called “Lender”) at the address designated in the Instrument (as hereinafter defined) for payment thereof or as such address may be changed as provided in the Instrument, all Other Indebtedness (as defined in the Instrument [defined below]) and Other Obligations (as defined in the Instrument) of the Related Borrowers (as defined below) under the Notes (as defined below), together with all interest, attorneys’ fees and collection costs provided for in the Notes (all such indebtedness is hereinafter called the “Indebtedness”). The term “Pool Obligations” as used herein shall have the same meaning as such term is defined in the Loan Agreement (as defined below).

RECITALS:

A. Guarantor and certain affiliates of Guarantor (individually, a “Related Borrower,” and collectively, the “Related Borrowers”) have entered into that certain Collateral Loan Agreement with Lender dated as of the date of this Supplemental Guaranty (as the same may be amended from time to time, the “Loan Agreement”). Capitalized terms used herein without definitions shall have the meaning ascribed to such term in the Loan Agreement or in that certain Deed of Trust and Security Agreement (First Priority - [property address]) made by Guarantor for the benefit of Lender dated as of the date of this Supplemental Guaranty (together with all amendments and modifications thereto, hereinafter collectively called the “Instrument”).

B. Lender has made certain loans to Guarantor and each of the Related Borrowers in the aggregate principal sum of Thirty-Two Million Five Hundred Eighty-Five Thousand and No/100 Dollars ($32,585,000.00) (collectively, the “Loans”) evidenced by certain promissory notes dated as of the date of this Supplemental Guaranty, payable to the order of Lender (as the same may be amended, renewed, extended, supplemented, restated or otherwise modified from time to time and all substitutions therefor, collectively, the “Notes”). The Notes are secured, in part, by certain first-priority mortgages, deeds of trust and deeds to secure debt.

C. This Supplemental Guaranty shall be secured by, inter alia, that certain Deed of Trust and Security Agreement (Second Priority - [property address]), made by Guarantor for the benefit of Lender dated as of the date of this Supplemental Guaranty (together with all amendments and modifications thereto, hereinafter collectively called the “Second Priority Instrument”), with respect to the real property and improvements situated thereon located at [property address], and that certain Assignment of Leases and Rents (Second Priority - [property address]), executed and delivered by Guarantor in favor of Lender (together with all amendments and modifications thereto, hereinafter collectively called the “Second Priority Assignment”).

D. Lender is willing to make the Loans to Guarantor and each of the Related Borrowers only if Guarantor delivered this Supplemental Guaranty.

In consideration of the Recitals, the principal sum of the Notes, and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, Guarantor hereby agrees as follows:

1. Except as otherwise limited as provided herein, in the event one or more of the Related Borrowers fails to pay the Indebtedness as and when due upon the expiration of any notice and/or cure period with respect thereto, Guarantor shall immediately upon written demand of Lender promptly and with due diligence pay for the benefit of Lender all of the Indebtedness.

2. Guarantor expressly waives presentment for payment, demand, notice of demand and of dishonor and non-payment of the Indebtedness, notice of intention to accelerate the maturity of the Indebtedness or any part thereof, notice of disposition of collateral, notice of acceleration of the maturity of the Indebtedness or any part thereof, protest and notice of protest, diligence in collecting, and the bringing of suit against any other party. Lender shall be under no obligation to notify Guarantor of its acceptance hereof or of any advances made or credit extended on the faith hereof or the failure of one or more of the Related Borrowers to pay any of the Indebtedness as it matures or any default in the performance of any of the Pool Obligations under the Instrument or any of the Notes, or to use diligence in preserving the liability of any person on the Indebtedness or the Pool Obligations or in bringing suit to enforce collection of the Indebtedness or performance of the Pool Obligations. Guarantor waives all

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defenses given to sureties or guarantors at law or in equity other than the actual payment of the Indebtedness and all defenses based upon questions as to the validity, legality or enforceability of the Indebtedness and/or the Pool Obligations and agrees that Guarantor shall be primarily liable hereunder.

3. Lender, without authorization from or notice to Guarantor and without impairing, modifying, changing, releasing, limiting or affecting the liability of Guarantor hereunder, may from time to time at its discretion and with or without valuable consideration, alter, compromise, accelerate, renew, extend or change the time or manner for the payment of any or all of the Indebtedness, increase or reduce the rate of interest thereon, take and surrender security, exchange security by way of substitution, or in any way it deems necessary take, accept, withdraw, subordinate, alter, amend, modify or eliminate security, add or release or discharge endorsers, guarantors or other obligors, make changes of any sort whatever in the terms of payment of the Indebtedness, in the Pool Obligations or in the manner of doing business with the Related Borrowers, or settle or compromise with the Related Borrowers or any other person or persons liable on the Indebtedness or the Pool Obligations on such terms as it may see fit, and may apply all moneys received from the Related Borrowers or others, or from any security held (whether held under a security instrument or not), in such manner upon the Indebtedness (whether then due or not) as it may determine to be in its best interest, without in any way being required to marshal securities or assets or to apply all or any part of such moneys upon any particular part of the Indebtedness. It is specifically agreed that Lender is not required to retain, hold, protect, exercise due care with respect thereto, perfect security interests in or otherwise assure or safeguard any security for the Indebtedness or the Pool Obligations; no failure by Lender to do any of the foregoing and no exercise or non-exercise by Lender of any other right or remedy of Lender shall in any way affect any of Guarantor’s obligations hereunder or any security furnished by Guarantor or give Guarantor any recourse against Lender.

4. The liability of Guarantor hereunder shall not be modified, changed, released, limited or impaired in any manner whatsoever on account of any or all of the following: (a) the incapacity, death, disability, dissolution or termination of Guarantor, a Related Borrower, Lender or any other person or entity; (b) the failure by Lender to file or enforce a claim against the estate (either in administration, bankruptcy or other proceeding) of a Related Borrower or any other person or entity; (c) any transfer or transfers of any of the property covered by the Instrument, the Second Priority Instrument or any other instrument securing the payment of any of the Notes; (d) any modifications, extensions, amendments, consents, releases or waivers with respect to any of the Notes, the Instrument, the Second Priority Instrument, the Second Priority Assignment, and any other instrument now or hereafter securing the payment of any of the Notes, or this Supplemental Guaranty; (e) any failure of Lender to give any notice to Guarantor of any default under any of the Notes, the Instrument, any other instrument securing the payment of any of the Notes, or this Supplemental Guaranty; (f) Guarantor is or becomes liable for any indebtedness owing by any Related Borrower to Lender other than under this Supplemental Guaranty; or (g) any impairment, modification, change, release or limitation of the liability of, or stay of actions or lien enforcement proceedings against, any Related Borrower, its property, or its estate in bankruptcy resulting from the operation of any present or future provision of the Federal Bankruptcy Code or any other present or future federal or state insolvency, bankruptcy or similar law (all of the foregoing hereinafter collectively called “applicable Bankruptcy Law”) or from the decision of any court.

5. Lender shall not be required to pursue any other remedies before invoking the benefits of the guaranties contained herein, and specifically it shall not be required to make demand upon or institute suit or otherwise pursue or exhaust its remedies against any Related Borrower or any surety other than Guarantor or to proceed against any security now or hereafter existing for the payment of any of the Indebtedness. Lender may maintain an action on this Supplemental Guaranty without joining any Related Borrower therein and without bringing a separate action against Related Borrower.

6. Guarantor absolutely and unconditionally covenants and agrees that in the event that one or more of the Related Borrowers does not or is unable to pay the Indebtedness or perform the Pool Obligations for any reason, including, without limitation, liquidation, dissolution, receivership, conservatorship, insolvency, bankruptcy, assignment for the benefit of creditors, sale of all or substantially all assets, reorganization, arrangement, composition, or readjustment of, or other similar proceedings affecting the status, composition, identity, existence, assets or obligations of such Related Borrower(s), or the disaffirmance or termination of any of the Indebtedness or Pool Obligations in or as a result of any such proceeding, Guarantor shall pay the Indebtedness and perform the Pool Obligations and no such occurrence shall in any way affect Guarantor’s obligations hereunder.

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7. Should the status, structure or composition of any Related Borrower change, this Supplemental Guaranty shall continue and also cover the Indebtedness and Pool Obligations of such Related Borrower under its new status, structure or composition according to the terms hereof. This Supplemental Guaranty shall remain in full force and effect notwithstanding any transfer of any of the property covered by the Instrument or the Second Priority Instrument.

8. In the event any payment by any Related Borrower to Lender is held to constitute a preference under any applicable Bankruptcy Law, or if for any other reason Lender is required to refund such payment or pay the amount thereof to any other party, such payment by such Related Borrower to Lender shall not constitute a release of Guarantor from any liability hereunder, but Guarantor agrees to pay such amount to Lender upon demand and this Supplemental Guaranty shall continue to be effective or shall be reinstated, as the case may be, to the extent of any such payment or payments.

9. Guarantor agrees that it shall not have (a) the right to the benefit of, or to direct the application of, any security held by Lender (including any of the property covered by the Instrument, the Second Priority Instrument, the Second Priority Assignment, or any other instrument securing the payment of any of the Notes), any right to enforce any remedy which Lender now has or hereafter may have against any Related Borrower, or any right to participate in any security now or hereafter held by Lender, or (b) any defense arising out of the absence, impairment or loss of any right of reimbursement or subrogation or other right or remedy of Guarantor against any Related Borrower or against any security resulting from the exercise or election of any remedies by Lender (including the exercise of any power of sale under the Instrument or the Second Priority Instrument), or any defense arising by reason of any disability or other defense of any Related Borrower or by reason of the cessation, from any cause, of the liability of such Related Borrower.

10. The payment by Guarantor of any amount pursuant to this Supplemental Guaranty shall not in any way entitle Guarantor to any right, title or interest (whether by way of subrogation or otherwise) in and to any of the Indebtedness or any proceeds thereof, or any security therefor, unless and until the full amount owing to Lender on the Indebtedness has been fully paid, but when the same has been fully paid Guarantor shall be subrogated as to any payments made by it to the rights of Lender as against the Related Borrowers and/or any endorsers, sureties or other guarantors.

11. Notwithstanding any payments made by or for the account of Guarantor on account of the Indebtedness, Guarantor shall not be subrogated to any rights of Lender until such time as Lender shall have received payment of the full amount of all Indebtedness. For the purposes of the preceding sentence only, the Indebtedness shall not be deemed to have been paid in full by foreclosure of the Instrument or by acceptance of a deed in lieu thereof, and Guarantor hereby waives and disclaims any interest which it might have in the property covered by the Instrument or other collateral security for the Indebtedness and the Pool Obligations, by subrogation or otherwise, following foreclosure of the Instrument or Lender’s acceptance of a deed in lieu thereof.

12. Guarantor expressly subordinates its rights to payment of any indebtedness owing from any Related Borrower to Guarantor, whether now existing or arising at any time in the future, to the prior right of Lender to receive or require payment in full of the Indebtedness and until payment in full of the Indebtedness (and including interest accruing on any of the Notes after any petition under applicable Bankruptcy Law, which post-petition interest Guarantor agrees shall remain a claim that is prior and superior to any claim of Guarantor notwithstanding any contrary practice, custom or ruling in proceedings under such applicable Bankruptcy Law generally), Guarantor agrees not to accept any payment or satisfaction of any kind of indebtedness of any Related Borrower to Guarantor or any security for such indebtedness. If Guarantor should receive any such payment, satisfaction or security for any indebtedness of any Related Borrower to Guarantor, Guarantor agrees forthwith to deliver the same to Lender in the form received, endorsed or assigned as may be appropriate for application on account of, or as security for, the Indebtedness and until so delivered, agrees to hold the same in trust for Lender.

13. Under no circumstances shall the aggregate amount paid or agreed to be paid hereunder exceed the highest lawful rate permitted under applicable usury law (the “Maximum Rate”) and the payment obligations of Guarantor hereunder are hereby limited accordingly. If under any circumstances, whether by reason of advancement or acceleration of the unpaid principal balance of any of the Notes or otherwise, the aggregate amounts paid hereunder shall include amounts which by law are deemed interest and which could exceed the Maximum Rate, Guarantor stipulates that payment and collection of such excess amounts shall have been and will be deemed to have been the result of a mistake on the part of both Guarantor and Lender, and Lender shall promptly credit such excess (only to the extent such interest payments are in excess of the Maximum Rate) against the unpaid principal balance

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of any of the Notes, and any portion of such excess payments not capable of being so credited shall be refunded to Guarantor. The term “applicable law” as used in this paragraph shall mean the laws of the Property State (as such term is defined in the Instrument) or the laws of the United States, whichever laws allow the greater rate of interest, as such laws now exist or may be changed or amended or come into effect in the future.

14. Guarantor hereby represents, warrants and covenants to and with Lender as follows: (a) the making of this Supplemental Guaranty by Guarantor is an express condition to Lender’s making the loans to the Related Borrowers evidenced by the Notes, and such loans are and will be of direct interest, benefit and advantage to Guarantor; (b) Guarantor is solvent, is not bankrupt and has no outstanding liens, garnishments, bankruptcies or court actions which could render Guarantor insolvent or bankrupt, and there has not been filed by or against Guarantor a petition in bankruptcy or a petition or answer seeking an assignment for the benefit of creditors, the appointment of a receiver, trustee, custodian or liquidator with respect to Guarantor or any substantial portion of Guarantor’s property, reorganization, arrangement, rearrangement, composition, extension, liquidation or dissolution or similar relief under applicable Bankruptcy Law; (c) all reports, financial statements and other financial and other data which have been or may hereafter be furnished by Guarantor to Lender in connection with this Supplemental Guaranty are or shall be true and correct in all material respects and do not and will not omit to state any fact or circumstance necessary to make the statements contained therein not misleading and do or shall fairly represent the financial condition of Guarantor as of the dates and the results of Guarantor’s operations for the periods for which the same are furnished, and no material adverse change has occurred since the dates of such reports, statements and other data in the financial condition of Guarantor; (d) the execution, delivery and performance of this Supplemental Guaranty do not contravene, result in the breach of or constitute a default under any mortgage, deed of trust, lease, promissory notes, loan agreement or other contract or agreement to which Guarantor is a party or by which Guarantor or any of its properties may be bound or affected and do not violate or contravene any law, order, decree, rule or regulation to which Guarantor is subject; (e) there are no judicial or administrative actions, suits or proceedings pending or, to Guarantor’s actual knowledge, threatened against or affecting Guarantor or involving the validity, enforceability or priority of this Supplemental Guaranty; and (f) this Supplemental Guaranty constitutes the legal, valid and binding obligation of Guarantor enforceable in accordance with its terms.

15. Where two or more persons or entities have executed this Supplemental Guaranty, unless the context clearly indicates otherwise, all references herein to “Guarantor” shall mean the guarantors hereunder or either or any of them. All of the obligations and liability of said guarantors hereunder shall be joint and several. Suit may be brought against said guarantors, jointly and severally, or against any one or more of them or less than all of them, without impairing the rights of Lender against the other or others of said guarantors; and Lender may compound with any one or more of said guarantors for such sums or sum as it may see fit and/or release a portion of said guarantors from all further liability to Lender for any Indebtedness without impairing the right of Lender to demand and collect the balance of such Indebtedness from the other or others of said guarantors not so compounded with or released; but it is agreed among said guarantors themselves, however, that such compounding and release shall in nowise impair the rights of said guarantors as among themselves.

16. Except as otherwise provided herein, the rights of Lender are cumulative and shall not be exhausted by its exercise of any of its rights hereunder or otherwise against Guarantor or by any number of successive actions until and unless all Indebtedness has been paid and each of the obligations of Guarantor hereunder has been performed.

17. Any notice or communication required or permitted hereunder shall be given in writing, sent by (a) personal delivery, or (b) expedited delivery service with proof of delivery, or (c) United States mail, postage prepaid, registered or certified mail, sent to the intended addressee at the address provided for in the Second Priority Instrument, or to such other address or to the attention of such other person as hereafter shall be designated in writing by the applicable party sent in accordance herewith. Any such notice or communication shall be deemed to have been given and received either at the time of personal delivery or, in the case of delivery service or mail, as of the date of first attempted delivery at the address and in the manner provided herein, or in the case of telegram, telex or telecopy, upon receipt.

18. This Supplemental Guaranty shall be deemed to have been made under and shall be governed by the laws of                      in all respects.

19. This Supplemental Guaranty may be executed in any number of counterparts with the same effect as if all parties hereto had signed the same document. All such counterparts shall be construed together and shall constitute one instrument, but in making proof hereof it shall only be necessary to produce one such counterpart.

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20. This Supplemental Guaranty may only be modified, waived, altered or amended by a written instrument or instruments executed by the party against which enforcement of said action is asserted. Any alleged modification, waiver, alteration or amendment which is not so documented shall not be effective as to any party.

21. The books and records of Lender showing the accounts between Lender and Related Borrower shall be admissible in any action or proceeding hereon as prima facie evidence of the items set forth herein.

22. Guarantor waives and renounces any and all homestead or exemption rights Guarantor may have under the Constitution or the laws of any state as against Guarantor, and does transfer, convey and assign to Lender a sufficient amount of such homestead or exemption as may be allowed, including such homestead or exemption as may be set apart in bankruptcy, to pay the Indebtedness. Guarantor hereby directs any trustee in bankruptcy having possession of such homestead or exemption to deliver to Lender a sufficient amount of property or money set apart as exempt to pay the Indebtedness.

23. The terms, provisions, covenants and conditions hereof shall be binding upon Guarantor and the heirs, devisees, representatives, successors and assigns of Guarantor and shall inure to the benefit of Lender and all transferees, credit participants, successors, assignees and/or endorsees of Lender. Within this Supplemental Guaranty, words of any gender shall be held and construed to include any other gender and words in the singular number shall be held and construed to include the plural and words in the plural number shall be held and construed to include the singular, unless the context otherwise requires. A determination that any provision of this Supplemental Guaranty is unenforceable or invalid shall not affect the enforceability or validity of any other provision and any determination that the application of any provision of this Supplemental Guaranty to any person or circumstance is illegal or unenforceable shall not affect the enforceability or validity of such provision as it may apply to any other persons or circumstances.

24. Notwithstanding anything to the contrary contained herein, Guarantor shall not have any personal liability hereunder for the Other Indebtedness or Other Obligations guaranteed hereby; instead, except as otherwise provided in the Second Priority Instrument and the Second Priority Assignment, Lender shall look only and solely to Guarantor’s interest in the collateral granted to Lender by the Second Priority Instrument and the Second Priority Assignment to satisfy the Other Indebtedness and the Other Obligations. Notwithstanding the preceding sentence, Lender may bring a foreclosure action or other appropriate action to enforce the Second Priority Instrument and the Second Priority Assignment or realize upon and protect any or all of the collateral described therein (including, without limitation, naming the Guarantor in such actions).

25. [various state-specific provisions]

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EXECUTED this 25^th day of August, 2010.

The address of Guarantor and Related Borrowers is:

[property owning LLC]

c/o Strategic Storage Trust, Inc.

111 Corporate Drive, Suite 120

Ladera Ranch, California 92694

Attention: Mr. H. Michael Schwartz

The address of Lender is:

The Prudential Insurance Company of America

Prudential Asset Resources

2100 Ross Avenue, Suite 2500

Dallas, Texas 75201

Attention: Asset Management Department

Reference Loan No.                         

With a copy to:

The Prudential Insurance Company of America

Prudential Asset Resources

2100 Ross Avenue, Suite 2500

Dallas, Texas 75201

Attention: Legal Department

Reference Loan No.                         

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