Short answer. No. Article 1950 of the Civil Code is clear: if the bailee incurs expenses beyond ordinary maintenance expenses and extraordinary preservation expenses for the purpose of using the thing, the bailee is not entitled to reimbursement. Extra spending that goes beyond those two specific categories comes out of the bailee's own pocket.
What the law says
If, for the purpose of making use of the thing, the bailee incurs expenses other than those referred to in articles 1941 and 1949, he is not entitled to reimbursement.
Civil Code, Article 1950 — Other Expenses Not Reimbursable. Read the full provision →
Two types of expenses the law does reimburse
To understand Article 1950, you need to know what it excludes. Article 1941 covers ordinary expenses: the bailee bears these personally — the cost of keeping the borrowed item in usable condition for day-to-day purposes. Article 1949 covers extraordinary preservation expenses: costs needed to prevent the item from being lost or seriously damaged, which the bailor must reimburse, subject to certain notice requirements. Everything outside of these two categories — money spent on improvements, upgrades, or optional enhancements — is governed by Article 1950: "he is not entitled to reimbursement."
What counts as an 'other' expense not reimbursable
Examples of non-reimbursable spending include: repainting or redecorating a borrowed house beyond what was needed to maintain it, adding features or fixtures to borrowed equipment, upgrading a borrowed vehicle with new accessories, or making repairs that improve rather than merely preserve the condition of the thing. If the spending was motivated by the bailee's desire to use the thing in a more convenient or comfortable way, rather than to maintain or save it, it almost certainly falls within the Article 1950 category of non-reimbursable expense.
Why the law sets this limit
Commodatum is a gratuitous arrangement. The bailor lends the item as a favour, receiving nothing in return. Allowing the bailee to spend freely on the borrowed item and then demand reimbursement would expose the bailor to open-ended financial risk. The bailor agreed to lend the thing in its current state, not to fund improvements to it. Article 1950 keeps the bailee's entitlements confined to what the law specifically recognises, and treats all other spending as a risk the bailee took voluntarily.
What to do before spending on a borrowed item
If you are considering spending money on borrowed property and want any prospect of being reimbursed, the only safe approach is to get the bailor's written agreement before spending. An ad hoc arrangement — where the bailor agrees to reimburse specific improvements — can create a contractual right to repayment that does not otherwise exist under the Civil Code. Without that agreement, you are taking the risk yourself. If you are a bailor who discovers a bailee has made improvements to your property, Article 1950 means you are not obliged to pay for those improvements unless you separately agreed to do so.