03/11/2026
BUILDLAB
4 min readDesigning Low-Voltage for MDU: 5 Costly Mistakes You Can Avoid
Most low-voltage budget overruns happen before the first wire is pulled. Here are the five design-stage errors we see most often.
Low-voltage budgets fail in design, not in execution. By the time a sub is pulling cable, the cost overrun is already baked in. Here are the five most common mistakes BUILDLAB sees on multi-dwelling unit (MDU) projects.
1. Treating low-voltage as an afterthought
Architects often spec low-voltage at a high level — “provide cable for cameras, intercoms, and data.” That language gets bid wide because the sub has to assume the worst. A detailed Division 27/28 specification narrows the assumptions and tightens every bid.
2. Over-specifying redundancy
Belt-and-suspenders cabling is comforting but expensive. Modern PoE switches, mesh wireless, and SD-WAN make many redundant pathways unnecessary in residential MDU environments.
3. Ignoring ISP-furnished materials
When the ISP supplies fiber microducts and in-unit SMC panels at no cost (negotiable in the ROE), the developer pays for those same materials again under the low-voltage scope. We have seen $35K+ wasted on parallel material orders.
4. Designing surveillance to architect-only standards
Camera counts in CDs are usually conservative — they protect the architect, not the developer’s budget. A surveillance design review almost always finds a smaller, smarter camera count.
5. Skipping the MDF / IDF coordination
Network distribution rooms need power, cooling, conduit pathways, and grounded racks. If those are not coordinated with the electrical and HVAC trades during design, change orders during framing get expensive.
