Installation Schedule of Sub-Rough Plumbing and HVAC

Depending of the foundation type, we can find “the sub-rough plumbing” under the basement floor on a basement foundation or under the slab on grade foundation. Sub rough plumbing is all plumbing that should be done before the basement floor, or the concrete is poured.

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Sub-Rough Plumbing

1. First step is to pour foundation walls.
2. The next step is the DWV (Drain, Waste and Vent) pipe installation.

– It starts with digging of the trenches for the pipes.
– The main Drainpipe will be located under the footings.
– Generally, the pipes location is under the slab in accordance with plumbing fixture location.
– Residential – usually, the pipes location is above the finish slab.
– The leak testing – pipes are filled with air or water and if everything is OK, they are covered with sand which will protect the pipes from punctures.


HVAC installation is similar with plumbing installation.

– The subcontractor digs the trenches
– Then is ductwork installation
– The technician inspects the ductwork and then covers the ductwork with sand for protection.

The most common way to install heat registers is to put them in the ceiling of the basement. However, if you will place the registers under the slab, you will need two furnaces: one downdraft furnace for basement and another one, updraft furnace for the main floor. This is the best heating system but it will cost you more.

Schedule of  Sub-Rough Plumbing and HVAC Installation

Installation schedule of the sub-rough plumbing and HVAC is in accordance with the type of foundation.

1. Basement Foundation:
Installation of sub-rough plumbing and HVAC begin after the concrete pouring in the foundation walls and the formwork taking off. The plumber test the pipes, cover them with sand and then you can pour the concrete for the basement floor.
2. Slab on Grade:
Installation of sub-rough plumbing begins before the pouring of the concrete slab. In fact, the process is similar with the basement foundation process.
3. Monolithic Pour:
The sub-rough plumbing starts after the foundation is formed. Generally, in this case HVAC system is installed in the attic. There are two reasons for that. This way is cheaper than under slab installation and is more efficient when the air is blown down.
4. Crawlspace:
The best way in this case is to start the sub-rough plumbing and HVAC work before or even the framing of the flooring system. However, it is better to have the plumbing and HVAC systems installed after the stem wall concrete pouring.

Copper Plumbing – Advantages and Disadvantages (

Radiant Floor Heating

Radiant floor heating is one of the most popular heating systems when we have slab floor. Radiant floor heating is a very efficient system, more efficient than forced air system. It is more expensive but it deserves the money on long run.

First, you need to install the plumbing system and then to pour the concrete slab.