Does Momentum allow loans against their pension funds?

This matter is not determined by Momentum, but by the Pension Funds Act and your specific fund rules. You first need to check whether your fund permits loans as contemplated by s19(5) of the Pension Funds Act. If yes, your employer will have to determine whether your loan purpose meets the requirements set down by the Act. This is a lengthy section of the Act; the section that may apply to you refers to "additions or alterations" and to "maintain or repair a residence". Your employer and/or the trustees would have to determine whether the security upgrade qualifies under this section.