Round Rock ADU Builders: Attached ADU & In-Law Suite Additions in Round Rock, TX

An attached unit shares at least one wall with the primary residence and has its own exterior entry. It needs far less open yard than a detached casita, ties into utilities that are already close by, and on a narrow lot it is frequently the option that actually fits.

Done carelessly it reads as a spare bedroom with a side door. Done properly it reads as its own home.

What Is an Attached ADU?

Direct answer: An attached accessory dwelling shares a wall with the main house but functions independently, with its own exterior entrance, kitchen, bathroom and living space. Because it borrows the existing structure on one side and sits near existing utility service, it costs less than a detached unit and needs a much smaller buildable envelope.

The Three Details That Decide Whether It Works

The entry. It belongs on a different elevation than the main entrance, with its own approach path. Nobody should feel they are entering through someone else’s house. This single decision does more for how the unit is perceived than any interior finish.

The shared wall. Decoupled framing, insulation in the cavity, and attention to where plumbing runs. This is inexpensive during construction and effectively impossible to fix afterwards. It is the difference between two households living comfortably and two households hearing each other’s television.

The connection. Either no interior door between the two dwellings, or one that locks from both sides and is treated as a wall rather than a passage. Families often want the door. It works, provided both sides control it.

What the Scope Covers

• Assessment of the existing structure, roofline and buildable envelope
• Foundation extension tied to the existing slab and engineered to the soil profile
• Framing and roof structure matched to the primary residence
• Sound-separated shared wall assembly
• Independent exterior entry and approach path
• Utility connection with dedicated sub-panel and fixture rough-in
• Independent HVAC so both households control their own temperature
• Interior finish out and inspection coordination

When an Attached Suite Is the Right Call

It suits narrow lots, multigenerational households, and anyone housing a parent who wants independence without being at the far end of the garden. Our guide to attached against detached on a small lot works through that comparison, and aging-in-place design features covers what is worth building in when a parent is the intended occupant. On a Pflugerville or Wells Branch lot where a detached unit will not clear setbacks, it is usually the strongest remaining option.

It is the wrong call where the primary residence has no elevation that can take a second entry sensibly, and where the intended use is a short-term rental with frequent turnover, since proximity works against both households in that case.

Before You Commit

Establish where a second exterior entry can reasonably go. Check the buildable envelope after setbacks. Confirm the existing electrical service has capacity for a second dwelling, which older homes often do not. Decide early whether you want an interior connecting door, because it changes the wall assembly.

Call (512) 690-0340 to arrange a site assessment.